Publications by authors named "Maria Pik Wong"

31 Publications

Sub-multiplicative interaction between polygenic risk score and household coal use in relation to lung adenocarcinoma among never-smoking women in Asia.

Environ Int 2021 02 29;147:105975. Epub 2020 Dec 29.

Department of Internal Medicine, Kaohsiung Medical University Hospital, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.

We previously identified 10 lung adenocarcinoma susceptibility loci in a genome-wide association study (GWAS) conducted in the Female Lung Cancer Consortium in Asia (FLCCA), the largest genomic study of lung cancer among never-smoking women to date. Furthermore, household coal use for cooking and heating has been linked to lung cancer in Asia, especially in Xuanwei, China. We investigated the potential interaction between genetic susceptibility and coal use in FLCCA. We analyzed GWAS-data from Taiwan, Shanghai, and Shenyang (1472 cases; 1497 controls), as well as a separate study conducted in Xuanwei (152 cases; 522 controls) for additional analyses. We summarized genetic susceptibility using a polygenic risk score (PRS), which was the weighted sum of the risk-alleles from the 10 previously identified loci. We estimated associations between a PRS, coal use (ever/never), and lung adenocarcinoma with multivariable logistic regression models, and evaluated potential gene-environment interactions using likelihood ratio tests. There was a strong association between continuous PRS and lung adenocarcinoma among never coal users (Odds Ratio (OR) = 1.69 (95% Confidence Interval (CI) = 1.53, 1.87), p=1 × 10). This effect was attenuated among ever coal users (OR = 1.24 (95% CI: 1.03, 1.50), p = 0.02, p-interaction = 6 × 10). We observed similar attenuation among coal users from Xuanwei. Our study provides evidence that genetic susceptibility to lung adenocarcinoma among never-smoking Asian women is weaker among coal users. These results suggest that lung cancer pathogenesis may differ, at least partially, depending on exposure to coal combustion products. Notably, these novel findings are among the few instances of sub-multiplicative gene-environment interactions in the cancer literature.
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http://dx.doi.org/10.1016/j.envint.2020.105975DOI Listing
February 2021

Nidogen 1-Enriched Extracellular Vesicles Facilitate Extrahepatic Metastasis of Liver Cancer by Activating Pulmonary Fibroblasts to Secrete Tumor Necrosis Factor Receptor 1.

Adv Sci (Weinh) 2020 Nov 19;7(21):2002157. Epub 2020 Aug 19.

Department of Pathology, Li Ka Shing Faculty of Medicine The University of Hong Kong Hong Kong.

In hepatocellular carcinoma (HCC) patients with extrahepatic metastasis, the lung is the most frequent site of metastasis. However, how the lung microenvironment favors disseminated cells remains unclear. Here, it is found that nidogen 1 (NID1) in metastatic HCC cell-derived extracellular vesicles (EVs) promotes pre-metastatic niche formation in the lung by enhancing angiogenesis and pulmonary endothelial permeability to facilitate colonization of tumor cells and extrahepatic metastasis. EV-NID1 also activates fibroblasts, which secrete tumor necrosis factor receptor 1 (TNFR1), facilitate lung colonization of tumor cells, and augment HCC cell growth and motility. Administration of anti-TNFR1 antibody effectively diminishes lung metastasis induced by the metastatic HCC cell-derived EVs in mice. In the clinical perspective, analysis of serum EV-NID1 and TNFR1 in HCC patients reveals their positive correlation and association with tumor stages suggesting the potential of these molecules as noninvasive biomarkers for the early detection of HCC. In conclusion, these results demonstrate the interplay of HCC EVs and activated fibroblasts in pre-metastatic niche formation and how blockage of their functions inhibits distant metastasis to the lungs. This study offers promise for the new direction of HCC treatment by targeting oncogenic EV components and their mediated pathways.
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http://dx.doi.org/10.1002/advs.202002157DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7640351PMC
November 2020

CAMK2A supported tumor initiating cells of lung adenocarcinoma by upregulating SOX2 through EZH2 phosphorylation.

Cell Death Dis 2020 06 1;11(6):410. Epub 2020 Jun 1.

Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.

Tumor initiating cells (TIC) of lung cancer are mainly induced by stress-related plasticity. Calcium/Calmodulin dependent protein kinase II alpha (CAMK2A) is a key calcium signaling molecule activated by exogenous and endogenous stimuli with effects on multiple cell functions but little is known about its role on TIC. In human lung adenocarcinomas (AD), CAMK2A was aberrantly activated in a proportion of cases and was an independent risk factor predicting shorter survivals. Functionally, CAMK2A enhanced TIC phenotypes in vitro and in vivo. CAMK2A regulated SOX2 expression by reducing H3K27me3 and EZH2 occupancy at SOX2 regulatory regions, leading to its epigenetic de-repression with functional consequences. Further, CAMK2A caused kinase-dependent phosphorylation of EZH2 at T487 with suppression of EZH2 activity. Together, the data demonstrated the CAMK2A-EZH2-SOX2 axis on TIC regulation. This study provided phenotypic and mechanistic evidence for the TIC supportive role of CAMK2A, implicating a novel predictive and therapeutic target for lung cancer.
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http://dx.doi.org/10.1038/s41419-020-2553-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264342PMC
June 2020

MRP4 sustains Wnt/β-catenin signaling for pregnancy, endometriosis and endometrial cancer.

Theranostics 2019 9;9(17):5049-5064. Epub 2019 Jul 9.

Deparment of Biomedical Engineering, Faculty of Engineering, the Hong Kong Polytechnic University.

: Abnormal Wnt/β-catenin signaling in the endometrium can lead to both embryo implantation failure and severe pathogenic changes of the endometrium such as endometrial cancer and endometriosis. However, how Wnt/β-catenin signaling is regulated in the endometrium remains elusive. We explored possible regulation of Wnt/β-catenin signaling by multi-drug resistance protein 4 (MRP4), a potential target in cancer chemotherapy, and investigated the mechanism. : Knockdown of MRP4 was performed in human endometrial cells or in a mouse embryo-implantation model . Immunoprecipitation, immunoblotting and immunofluorescence were used to assess protein interaction and stability. Wnt/β-catenin signaling was assessed by TOPflash reporter assay and quantitative PCR array. Normal and endometriotic human endometrial tissues were examined. Data from human microarray or RNAseq databases of more than 100 participants with endometriosis, endometrial cancer or IVF were analyzed. and tumorigenesis was performed. : MRP4-knockdown, but not its transporter-function-inhibition, accelerates β-catenin degradation in human endometrial cells. MRP4 and β-catenin are co-localized and co-immunoprecipitated in mouse and human endometrium. MRP4-knockdown in mouse uterus reduces β-catenin levels, downregulates a series of Wnt/β-catenin target genes and impairs embryo implantation, which are all reversed by blocking β-catenin degradation. Analysis of human endometrial biopsy samples and available databases reveals significant and positive correlations of MRP4 with β-catenin and Wnt/β-catenin target genes in the receptive endometrium in IVF, ectopic endometriotic lesions and endometrial cancers. Knockdown of MRP4 also inhibits and endometrial tumorigenesis. : A previously undefined role of MRP4 in stabilizing β-catenin to sustain Wnt/β-catenin signaling in endometrial cells is revealed for both embryo implantation and endometrial disorders, suggesting MRP4 as a theranostic target for endometrial diseases associated with Wnt/β-catenin signaling abnormality.
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http://dx.doi.org/10.7150/thno.32097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6691374PMC
August 2020

Tuberculosis infection and lung adenocarcinoma: Mendelian randomization and pathway analysis of genome-wide association study data from never-smoking Asian women.

Genomics 2020 03 12;112(2):1223-1232. Epub 2019 Jul 12.

Guangdong Lung Cancer Institute, Medical Research Center and Cancer Center of Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.

We investigated whether genetic susceptibility to tuberculosis (TB) influences lung adenocarcinoma development among never-smokers using TB genome-wide association study (GWAS) results within the Female Lung Cancer Consortium in Asia. Pathway analysis with the adaptive rank truncated product method was used to assess the association between a TB-related gene-set and lung adenocarcinoma using GWAS data from 5512 lung adenocarcinoma cases and 6277 controls. The gene-set consisted of 31 genes containing known/suggestive associations with genetic variants from previous TB-GWAS. Subsequently, we followed-up with Mendelian Randomization to evaluate the association between TB and lung adenocarcinoma using three genome-wide significant variants from previous TB-GWAS in East Asians. The TB-related gene-set was associated with lung adenocarcinoma (p = 0.016). Additionally, the Mendelian Randomization showed an association between TB and lung adenocarcinoma (OR = 1.31, 95% CI: 1.03, 1.66, p = 0.027). Our findings support TB as a causal risk factor for lung cancer development among never-smoking Asian women.
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http://dx.doi.org/10.1016/j.ygeno.2019.07.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6954985PMC
March 2020

NFATc2 enhances tumor-initiating phenotypes through the NFATc2/SOX2/ALDH axis in lung adenocarcinoma.

Elife 2017 07 24;6. Epub 2017 Jul 24.

Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.

Tumor-initiating cells (TIC) are dynamic cancer cell subsets that display enhanced tumor functions and resilience to treatment but the mechanism of TIC induction or maintenance in lung cancer is not fully understood. In this study, we show the calcium pathway transcription factor NFATc2 is a novel regulator of lung TIC phenotypes, including tumorspheres, cell motility, tumorigenesis, as well as in vitro and in vivo responses to chemotherapy and targeted therapy. In human lung cancers, high NFATc2 expression predicted poor tumor differentiation, adverse recurrence-free and cancer-specific overall survivals. Mechanistic investigations identified NFATc2 response elements in the 3' enhancer region of , and NFATc2/SOX2 coupling upregulates ALDH1A1 by binding to its 5' enhancer. Through this axis, oxidative stress induced by cancer drug treatment is attenuated, leading to increased resistance in a mutation-independent manner. Targeting this axis provides a novel approach for the long-term treatment of lung cancer through TIC elimination.
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http://dx.doi.org/10.7554/eLife.26733DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5570574PMC
July 2017

Association between GWAS-identified lung adenocarcinoma susceptibility loci and EGFR mutations in never-smoking Asian women, and comparison with findings from Western populations.

Hum Mol Genet 2017 01;26(2):454-465

Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center, Nashville, TN, USA.

To evaluate associations by EGFR mutation status for lung adenocarcinoma risk among never-smoking Asian women, we conducted a meta-analysis of 11 loci previously identified in genome-wide association studies (GWAS). Genotyping in an additional 10,780 never-smoking cases and 10,938 never-smoking controls from Asia confirmed associations with eight known single nucleotide polymorphisms (SNPs). Two new signals were observed at genome-wide significance (P < 5 × 10-8), namely, rs7216064 (17q24.3, BPTF), for overall lung adenocarcinoma risk, and rs3817963 (6p21.3, BTNL2) which is specific to cases with EGFR mutations. In further sub-analyses by EGFR status, rs9387478 (ROS1/DCBLD1) and rs2179920 (HLA-DPB1) showed stronger estimated associations in EGFR-positive compared to EGFR-negative cases. Comparison of the overall associations with published results in Western populations revealed that the majority of these findings were distinct, underscoring the importance of distinct contributing factors for smoking and non-smoking lung cancer. Our results extend the catalogue of regions associated with lung adenocarcinoma in non-smoking Asian women and highlight the importance of how the germline could inform risk for specific tumour mutation patterns, which could have important translational implications.
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http://dx.doi.org/10.1093/hmg/ddw414DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5856088PMC
January 2017

Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome.

Nat Commun 2016 06 13;7:11843. Epub 2016 Jun 13.

National Institute of Cancer Research, National Health Research Institutes, Zhunan 35053, Taiwan.

To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases.
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http://dx.doi.org/10.1038/ncomms11843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4909985PMC
June 2016

NDUFA4L2 Fine-tunes Oxidative Stress in Hepatocellular Carcinoma.

Clin Cancer Res 2016 06 27;22(12):3105-17. Epub 2016 Jan 27.

Department of Pathology, The University of Hong Kong, Hong Kong. State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong.

Purpose: Hepatocellular carcinoma (HCC) lacks effective curative therapy. Hypoxia is commonly found in HCC. Hypoxia elicits a series of protumorigenic responses through hypoxia-inducible factor-1 (HIF1). Better understanding of the metabolic adaptations of HCC cells during hypoxia is essential to the design of new therapeutic regimen.

Experimental Design: Expressions of genes involved in the electron transport chain (ETC) in HCC cell lines (20% and 1% O2) and human HCC samples were analyzed by transcriptome sequencing. Expression of NDUFA4L2, a less active subunit in complex I of the ETC, in 100 pairs of HCC and nontumorous liver tissues were analyzed by qRT-PCR. Student t test and Kaplan-Meier analyses were used for clinicopathologic correlation and survival studies. Orthotopic HCC implantation model was used to evaluate the efficiency of HIF inhibitor.

Results: NDUFA4L2 was drastically overexpressed in human HCC and induced by hypoxia. NDUFA4L2 overexpression was closely associated with tumor microsatellite formation, absence of tumor encapsulation, and poor overall survival in HCC patients. We confirmed that NDUFA4L2 was HIF1-regulated in HCC cells. Inactivation of HIF1/NDUFA4L2 increased mitochondrial activity and oxygen consumption, resulting in ROS accumulation and apoptosis. Knockdown of NDUFA4L2 markedly suppressed HCC growth and metastasis in vivo HIF inhibitor, digoxin, significantly suppressed growth of tumors that expressed high level of NDUFA4L2.

Conclusions: Our study has provided the first clinical relevance of NDUFA4L2 in human cancer and suggested that HCC patients with NDUFA4L2 overexpression may be suitable candidates for HIF inhibitor treatment. Clin Cancer Res; 22(12); 3105-17. ©2016 AACR.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-1987DOI Listing
June 2016

Utility of 18F-FDG PET/CT in the assessment of lymphoepithelioma-like carcinoma.

Nucl Med Commun 2016 May;37(5):437-45

aLi Ka Shing Faculty of Medicine, The University of Hong Kong Departments of bPathology cMedicine dDiagnostic Radiology, Queen Mary Hospital, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.

Lymphoepithelioma-like carcinoma (LELC) is a rare Epstein-Barr virus (EBV)-related disease, which commonly originates from the lung and is associated with more favourable treatment outcomes compared with other non-LELC thoracic carcinomas. Radiological assessment utilizing fluorine-18 fluorodeoxyglucose PET combined with computed tomography (F-FDG PET/CT) is important for initial disease staging to tailor the treatment strategy, evaluation of treatment response and detection of disease recurrence. The aim of this article was to highlight the utility of F-FDG PET/CT in different stages of disease evaluation of LELC. We reviewed seven patients with histologically proven LELC who underwent F-FDG PET/CT for disease evaluation. We described the F-FDG-avidity of LELC (ranged from maximum standardized uptake value 7.6 to maximum standardized uptake value 14.5 in our series) and highlighted the clinical values of F-FDG PET/CT in different stages of disease evaluation. F-FDG PET/CT enables accurate evaluation of the primary tumour, its relationship with the surrounding structures and accurate staging. It is also useful in treatment response assessment to monitor the efficacy of the treatment and to decide upon treatment strategy. Given the F-FDG-avidity of LELC, F-FDG PET/CT is advantageous in detecting tumour recurrence of LELC. LELC is a rare disease entity associated with EBV and is more prevalent in Asia, where EBV is endemic. LELC is an F-FDG-avid tumour. Although the features on F-FDG PET/CT are not specific, F-FDG PET/CT provides valuable information for disease management of LELC.
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http://dx.doi.org/10.1097/MNM.0000000000000475DOI Listing
May 2016

Meta-analysis of genome-wide association studies identifies multiple lung cancer susceptibility loci in never-smoking Asian women.

Hum Mol Genet 2016 Feb 4;25(3):620-9. Epub 2016 Jan 4.

Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan.

Genome-wide association studies (GWAS) of lung cancer in Asian never-smoking women have previously identified six susceptibility loci associated with lung cancer risk. To further discover new susceptibility loci, we imputed data from four GWAS of Asian non-smoking female lung cancer (6877 cases and 6277 controls) using the 1000 Genomes Project (Phase 1 Release 3) data as the reference and genotyped additional samples (5878 cases and 7046 controls) for possible replication. In our meta-analysis, three new loci achieved genome-wide significance, marked by single nucleotide polymorphism (SNP) rs7741164 at 6p21.1 (per-allele odds ratio (OR) = 1.17; P = 5.8 × 10(-13)), rs72658409 at 9p21.3 (per-allele OR = 0.77; P = 1.41 × 10(-10)) and rs11610143 at 12q13.13 (per-allele OR = 0.89; P = 4.96 × 10(-9)). These findings identified new genetic susceptibility alleles for lung cancer in never-smoking women in Asia and merit follow-up to understand their biological underpinnings.
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http://dx.doi.org/10.1093/hmg/ddv494DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4731021PMC
February 2016

Targeting Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer by Inducing Epidermal Growth Factor Receptor Degradation via Methionine 790 Oxidation.

Antioxid Redox Signal 2016 Feb 14;24(5):263-79. Epub 2015 Dec 14.

1 State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology , Macau (SAR), China .

Aims: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been developed to treat non-small cell lung cancer (NSCLC) patients with EGFR mutation, but TKI resistance is common. Almost half of the acquired resistance patients are due to additional T790M mutation on EGFR (EGFR(T790M)), thus overcoming TKI resistance is important. In this study, we aim to investigate the role of reactive oxygen species (ROS) in TKI resistance as well as the molecular and biological effects of EGFR(T790M) after redox manipulation.

Results: The basal ROS levels in EGFR(T790M)-containing TKI-resistant NSCLC cell lines were substantially high. Sixty-three human lung tumors showed higher NADPH oxidase isoform 2 (NOX2) expression than normal lung tissues, which may contribute to high basal ROS in cancer and poor survival. Interestingly, only NOX3 was upregulated by sanguinarine, a pharmacological agent to elevate ROS, and resulted in EGFR overoxidation, degradation, and apoptosis. By contrast, such responses were lacking in EGFR(WT) cells. Selective EGFR(T790M) degradation was manipulated by redox imbalance between NOX3 and methionine reductase A (MsrA). Furthermore, the in vivo tumor suppression effect of sanguinarine, NOX3 upregulation, and EGFR degradation were confirmed.

Innovation: We have found a new treatment strategy to overcome TKI resistance by selectively inducing EGFR(T790M) degradation via specific stimulation of methionine 790 (M790) oxidation. It can be achieved via manipulating redox imbalance between NOX3 and MsrA.

Conclusion: Targeting EGFR by elevating ROS and redox imbalance is a potential new strategy to develop a new EGFR inhibitor for TKI-resistant patients with a wide therapeutic window between EGFR(T790M) and EGFR(WT).
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http://dx.doi.org/10.1089/ars.2015.6420DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4753639PMC
February 2016

Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for Thirteen Cancer Types.

J Natl Cancer Inst 2015 Dec 12;107(12):djv279. Epub 2015 Oct 12.

Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD (JNS, OP, SIB, QL, CCA, LTA, JDF, MTL, LM, SAS, PRT, KAM, PR, DA, DB, BAB, AB, LBr, WHC, CCC, JSC, JFFJr, NDF, LEBF, MGC, AMG, RNH, NH, WH, PDI, BTJ, CK, CMK, LML, MSL, LEM, LPO, RSSS, WeiT, MT, CWa, SW, NW, KY, PH, LMM, NEC, NR, DTS, SJC, NC); Information Management Services, Silver Spring, MD (WAW, CG); Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Gaithersburg, MD (MY, ZW, LBu, AH, CLi); Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (IDV, KAB, BMB, CoC, MCB, CF, EG, SL, JP, MSt, DJH); Department of Epidemiology, Harvard School of Public Health, Boston, MA (IDV, OA, KAB, CoC, MCB, EG, RSK, SL, JP, HDS, MSt, DTr, DJH, PK); Ontario Health Study, Toronto, Ontario, Canada (MPP); Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden (HOA, EWe); Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (AA, MF); UCL Cancer Institute, London, UK (MFA, AMF, DH); Royal National Orthopaedic Hospital NHS Trust, Stanmore, Middlesex, UK (MFA, AMF, DH, RT); Guangdong Lung Cancer Institute, Guangdong Provincial Key Laboratory of Translational Medicine in Lung Cancer, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China (SJA, JS, YLW, XCZ); Department of Radiation Sciences, Oncology, Umea University, Umea, Sweden (UA, RH, BSM); Division of Urologic Surgery, Washington University School of Medicine, Saint Louis, MO (GAJr, RGIII); Litwin Centre for Cancer Genetics, University of Toronto, Ontario, Canada (ILA, NG, JSW); Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada (ILA, SG, NG, JSW); Hematology Unit, Ospedale Oncologico di Riferimento Regionale A. Businco, Cagliari, Italy (EA); Department of Medicin

Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites.

Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers.

Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, hl (2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (ρ = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (ρ = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (ρ = 0.51, SE =0.18), and bladder and lung (ρ = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures.

Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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http://dx.doi.org/10.1093/jnci/djv279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4806328PMC
December 2015

Characterization of large structural genetic mosaicism in human autosomes.

Am J Hum Genet 2015 Mar;96(3):487-97

Department of Thoracic and Cardiovascular Surgery, Cancer Research Institute, College of Medicine, Seoul National University, Seoul 151-742, Republic of Korea.

Analyses of genome-wide association study (GWAS) data have revealed that detectable genetic mosaicism involving large (>2 Mb) structural autosomal alterations occurs in a fraction of individuals. We present results for a set of 24,849 genotyped individuals (total GWAS set II [TGSII]) in whom 341 large autosomal abnormalities were observed in 168 (0.68%) individuals. Merging data from the new TGSII set with data from two prior reports (the Gene-Environment Association Studies and the total GWAS set I) generated a large dataset of 127,179 individuals; we then conducted a meta-analysis to investigate the patterns of detectable autosomal mosaicism (n = 1,315 events in 925 [0.73%] individuals). Restricting to events >2 Mb in size, we observed an increase in event frequency as event size decreased. The combined results underscore that the rate of detectable mosaicism increases with age (p value = 5.5 × 10(-31)) and is higher in men (p value = 0.002) but lower in participants of African ancestry (p value = 0.003). In a subset of 47 individuals from whom serial samples were collected up to 6 years apart, complex changes were noted over time and showed an overall increase in the proportion of mosaic cells as age increased. Our large combined sample allowed for a unique ability to characterize detectable genetic mosaicism involving large structural events and strengthens the emerging evidence of non-random erosion of the genome in the aging population.
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http://dx.doi.org/10.1016/j.ajhg.2015.01.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4375431PMC
March 2015

Metabolic phenotype of stage IV lung adenocarcinoma: relationship with epidermal growth factor receptor mutation.

Clin Nucl Med 2015 Mar;40(3):e190-5

From the Departments of *Diagnostic Radiology, †Clinical Oncology, and ‡Pathology, Queen Mary Hospital, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.

Purpose: Epidermal growth factor receptor (EGFR) mutation status is important in treatment stratification of stage IV lung adenocarcinoma. We evaluated the relationship between the SUV max measured on PET/CT and EGFR mutations and the value of SUV max in predicting EGFR mutations.

Patients And Methods: Seventy-one stage IV lung adenocarcinoma patients with verified EGFR mutations (48 EGFR mutant, 23 EGFR wild-type) having pretreatment PET/CT were retrospectively reviewed. SUV max values of the primary tumors (n = 71), nodal (n = 246), and distant metastases (n = 618) were compared between EGFR-mutant and EGFR wild-type adenocarcinoma by Mann-Whitney U test. The receiver operating characteristics curve and logistic regression were performed for factors, SUV max, age, sex, and smoking status. The significant predictors were assessed individually and in combination in discriminating EGFR mutation status. Statistical significance was assumed at P < 0.05 RESULTS: The metastases in EGFR-mutant adenocarcinoma had lower SUV max than EGFR wild-type adenocarcinoma (nodal SUV max 3.4 vs 5.5, distant metastasis SUV max 3.4 vs 4.7, respectively; both P < 0.001). No statistical significant difference was observed in the primary tumors SUV max between the 2 groups (SUV max 7.4 vs 8.1, P = 0.311). A receiver operating characteristics-derived SUV max less than or equal to 7.2 in metastasis could separate EGFR-mutant from EGFR wild-type adenocarcinoma (area under the curve, 0.71-0.74; P < 0.05). SUV max was a significant independent predictor, and when combined with age, sex, and smoking status, it is highly predictive of EGFR mutation status (area under the curve, 0.90).

Conclusions: Low SUV max in the metastasis favors the presence of EGFR mutations in stage IV lung adenocarcinoma, and SUV max is an independent predictor of EGFR mutations.
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http://dx.doi.org/10.1097/RLU.0000000000000684DOI Listing
March 2015

Interactions between household air pollution and GWAS-identified lung cancer susceptibility markers in the Female Lung Cancer Consortium in Asia (FLCCA).

Hum Genet 2015 Mar 8;134(3):333-41. Epub 2015 Jan 8.

Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Ave. Belfer 1309, 10461, Bronx, NY, USA,

We previously carried out a multi-stage genome-wide association study (GWAS) on lung cancer among never smokers in the Female Lung Cancer Consortium in Asia (FLCCA) (6,609 cases, 7,457 controls) that identified novel susceptibility loci at 10q25.2, 6q22.2, and 6p21.32, and confirmed two previously identified loci at 5p15.33 and 3q28. Household air pollution (HAP) attributed to solid fuel burning for heating and cooking, is the leading cause of the overall disease burden in Southeast Asia, and is known to contain lung carcinogens. To evaluate the gene-HAP interactions associated with lung cancer in loci independent of smoking, we analyzed data from studies participating in FLCCA with fuel use information available (n = 3; 1,731 cases; 1,349 controls). Coal use was associated with a 30% increased risk of lung cancer (OR 1.3, 95% CI 1.0-1.6). Among the five a priori SNPs identified by our GWAS, two showed a significant interaction with coal use (HLA Class II rs2395185, p = 0.02; TP63 rs4488809 (rs4600802), p = 0.04). The risk of lung cancer associated with coal exposure varied with the respective alleles for these two SNPs. Our observations provide evidence that genetic variation in HLA Class II and TP63 may modify the association between HAP and lung cancer risk. The roles played in the cell cycle and inflammation pathways by the proteins encoded by these two genes provide biological plausibility for these interactions; however, additional replication studies are needed in other non-smoking populations.
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http://dx.doi.org/10.1007/s00439-014-1528-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537621PMC
March 2015

Genetic variants associated with longer telomere length are associated with increased lung cancer risk among never-smoking women in Asia: a report from the female lung cancer consortium in Asia.

Int J Cancer 2015 Jul 29;137(2):311-9. Epub 2014 Dec 29.

Department of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.

Recent evidence from several relatively small nested case-control studies in prospective cohorts shows an association between longer telomere length measured phenotypically in peripheral white blood cell (WBC) DNA and increased lung cancer risk. We sought to further explore this relationship by examining a panel of seven telomere-length associated genetic variants in a large study of 5,457 never-smoking female Asian lung cancer cases and 4,493 never-smoking female Asian controls using data from a previously reported genome-wide association study. Using a group of 1,536 individuals with phenotypically measured telomere length in WBCs in the prospective Shanghai Women's Health study, we demonstrated the utility of a genetic risk score (GRS) of seven telomere-length associated variants to predict telomere length in an Asian population. We then found that GRSs used as instrumental variables to predict longer telomere length were associated with increased lung cancer risk (OR = 1.51 (95% CI = 1.34-1.69) for upper vs. lower quartile of the weighted GRS, p value = 4.54 × 10(-14) ) even after removing rs2736100 (p value = 4.81 × 10(-3) ), a SNP in the TERT locus robustly associated with lung cancer risk in prior association studies. Stratified analyses suggested the effect of the telomere-associated GRS is strongest among younger individuals. We found no difference in GRS effect between adenocarcinoma and squamous cell subtypes. Our results indicate that a genetic background that favors longer telomere length may increase lung cancer risk, which is consistent with earlier prospective studies relating longer telomere length with increased lung cancer risk.
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http://dx.doi.org/10.1002/ijc.29393DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4733320PMC
July 2015

Imputation and subset-based association analysis across different cancer types identifies multiple independent risk loci in the TERT-CLPTM1L region on chromosome 5p15.33.

Hum Mol Genet 2014 Dec 15;23(24):6616-33. Epub 2014 Jul 15.

Department of Preventive Medicine, Biostatistics Division, Keck School of Medicine and.

Genome-wide association studies (GWAS) have mapped risk alleles for at least 10 distinct cancers to a small region of 63 000 bp on chromosome 5p15.33. This region harbors the TERT and CLPTM1L genes; the former encodes the catalytic subunit of telomerase reverse transcriptase and the latter may play a role in apoptosis. To investigate further the genetic architecture of common susceptibility alleles in this region, we conducted an agnostic subset-based meta-analysis (association analysis based on subsets) across six distinct cancers in 34 248 cases and 45 036 controls. Based on sequential conditional analysis, we identified as many as six independent risk loci marked by common single-nucleotide polymorphisms: five in the TERT gene (Region 1: rs7726159, P = 2.10 × 10(-39); Region 3: rs2853677, P = 3.30 × 10(-36) and PConditional = 2.36 × 10(-8); Region 4: rs2736098, P = 3.87 × 10(-12) and PConditional = 5.19 × 10(-6), Region 5: rs13172201, P = 0.041 and PConditional = 2.04 × 10(-6); and Region 6: rs10069690, P = 7.49 × 10(-15) and PConditional = 5.35 × 10(-7)) and one in the neighboring CLPTM1L gene (Region 2: rs451360; P = 1.90 × 10(-18) and PConditional = 7.06 × 10(-16)). Between three and five cancers mapped to each independent locus with both risk-enhancing and protective effects. Allele-specific effects on DNA methylation were seen for a subset of risk loci, indicating that methylation and subsequent effects on gene expression may contribute to the biology of risk variants on 5p15.33. Our results provide strong support for extensive pleiotropy across this region of 5p15.33, to an extent not previously observed in other cancer susceptibility loci.
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http://dx.doi.org/10.1093/hmg/ddu363DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4240198PMC
December 2014

FaSD-somatic: a fast and accurate somatic SNV detection algorithm for cancer genome sequencing data.

Bioinformatics 2014 Sep 14;30(17):2498-500. Epub 2014 May 14.

Department of Biochemistry, LKS Faculty of Medicine, Hong Kong SAR, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Shenzhen, Guangdong 518057, HKU-BGI Bioinformatics Algorithms and Core Technology Research Laboratory, Department of Computer Science, Department of Pathology and Centre for Genomic Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China Department of Biochemistry, LKS Faculty of Medicine, Hong Kong SAR, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Shenzhen, Guangdong 518057, HKU-BGI Bioinformatics Algorithms and Core Technology Research Laboratory, Department of Computer Science, Department of Pathology and Centre for Genomic Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China Department of Biochemistry, LKS Faculty of Medicine, Hong Kong SAR, Shenzhen Institute of Research and Innovation, The University of Hong Kong, Shenzhen, Guangdong 518057, HKU-BGI Bioinformatics Algorithms and Core Technology Research Laboratory, Department of Computer Science, Department of Pathology and Centre for Genomic Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.

Unlabelled: Recent advances in high-throughput sequencing technologies have enabled us to sequence large number of cancer samples to reveal novel insights into oncogenetic mechanisms. However, the presence of intratumoral heterogeneity, normal cell contamination and insufficient sequencing depth, together pose a challenge for detecting somatic mutations. Here we propose a fast and an accurate somatic single-nucleotide variations (SNVs) detection program, FaSD-somatic. The performance of FaSD-somatic is extensively assessed on various types of cancer against several state-of-the-art somatic SNV detection programs. Benchmarked by somatic SNVs from either existing databases or de novo higher-depth sequencing data, FaSD-somatic has the best overall performance. Furthermore, FaSD-somatic is efficient, it finishes somatic SNV calling within 14 h on 50X whole genome sequencing data in paired samples.

Availability And Implementation: The program, datasets and supplementary files are available at http://jjwanglab.org/FaSD-somatic/.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/btu338DOI Listing
September 2014

High-resolution detection of recurrent aberrations in lung adenocarcinomas by array comparative genomic hybridization and expression analysis of selective genes by quantitative PCR.

Int J Oncol 2014 Jun 11;44(6):2068-76. Epub 2014 Apr 11.

Department of Pathology, The University of Hong Kong, Hong Kong, SAR, P.R. China.

Genomic abnormalities are the hallmark of cancers and may harbor potential candidate genes important for cancer development and progression. We performed array comparative genomic hybridization (array CGH) on 36 cases of primary lung adenocarcinoma (AD) using an array containing 2621 BAC or PAC clones spanning the genome at an average interval of 1 Mb. Array CGH identified the commonest aberrations consisting of DNA gains within 1p, 1q, 5p, 5q, 7p, 7q, 8q, 11q, 12p, 13q, 16p, 17q, 20q, and losses with 6q, 9p, 10q and 18q. High-level copy gains involved mainly 7p21-p15 and 20q13.3. Dual color fluorescence in situ hybridization (FISH) was performed on a selective locus for validation of array CGH results. Genomic aberrations were compared with different clinicopathological features and a trend of higher number of aberrations in tumors with aggressive phenotypes and current tobacco exposure was identified. According to array CGH data, 23 candidate genes were selected for quantitative PCR (qPCR) analysis. The concordance observed between the genomic and expression changes in most of the genes suggested that they could be candidate cancer-related genes that contributed to the development of lung AD.
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http://dx.doi.org/10.3892/ijo.2014.2384DOI Listing
June 2014

Identification and characterization of ALK kinase splicing isoforms in non-small-cell lung cancer.

J Thorac Oncol 2014 Feb;9(2):248-53

*Department of Medicine, Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts; †Department of Pathology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China; and ‡Department of Medical Oncology, Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.

Introduction: Anaplastic lymphoma kinase (ALK) rearrangements are present in an important subset of non-small-cell lung cancer (NSCLC) and predict for response to the tyrosine kinase inhibitor crizotinib. In this study, we evaluated the yet unknown frequency and functional role of ALK splicing isoforms in NSCLC.

Methods: We analyzed 270 cases of NSCLC for ALK kinase domain splicing aberrations and in addition generated constructs with full-length echinoderm microtubule-associated protein-like 4 (EML4)-ALK (E13;A20) and a splicing isoform.

Results: Splicing isoforms of the kinase domain of ALK-including complete skipping of exon 23 (ALKdel23, ALK p.I1171fs*42) and exon 27 (ALKdel27, ALK p.T1312fs*0)-were identified in 11.1% (30 of 270 cases) of NSCLC, and these changes coexisted with ALK rearrangements, KRAS mutations, and EGFR mutations. ALK splicing isoforms were observed with full-length EML4-ALK in crizotinib-naive and treated NSCLCs. ALK T1312fs*0 was unable to render cells solely dependent on ALK signaling. Unlike EML4-ALK and EML4-ALK p.L1196M, EML4-ALK T1312fs*0 did not autophosphorylate ALK or other phosphotyrosine sites. Coexpression of equal amounts of EML4-ALK T1312fs*0 and EML4-ALK did not result in resistance to crizotinib, whereas coexpression of EML4-ALK L1196M with EML4-ALK resulted in resistance to inhibition of ALK by crizotinib.

Conclusions: ALK kinase splicing isoforms were present in NSCLC and even if translated seemed to be nonfunctional variants of ALK.
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http://dx.doi.org/10.1097/JTO.0000000000000050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4096850PMC
February 2014

Lung cancer tumorigenicity and drug resistance are maintained through ALDH(hi)CD44(hi) tumor initiating cells.

Oncotarget 2013 Oct;4(10):1698-1711

Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR China.

Limited improvement in long term survival of lung cancer patients has been achieved by conventional chemotherapy or targeted therapy. To explore the potentials of tumor initiating cells (TIC)-directed therapy, it is essential to identify the cell targets and understand their maintenance mechanisms. We have analyzed the performance of ALDH/CD44 co-expression as TIC markers and treatment targets of lung cancer using well-validated in vitro and in vivo analyses in multiple established and patient-derived lung cancer cells. The ALDH(hi)CD44(hi) subset showed the highest enhancement of stem cell phenotypic properties compared to ALDH(hi)CD44(lo), ALDH(lo)CD44(hi), ALDH(lo)CD44(lo) cells and unsorted controls. They showed higher invasion capacities, pluripotency genes and epithelial-mesenchymal transition transcription factors expression, lower intercellular adhesion protein expression and higher G2/M phase cell cycle fraction. In immunosuppressed mice, the ALDH(hi)CD44(hi)xenografts showed the highest tumor induction frequency, serial transplantability, shortest latency, largest volume and highest growth rates. Inhibition of sonic Hedgehog and Notch developmental pathways reduced ALDH+CD44+ compartment. Chemotherapy and targeted therapy resulted in higher AALDH(hi)CD44(hi) subset viability and ALDH(lo)CD44(lo) subset apoptosis fraction. ALDH inhibition and CD44 knockdown led to reduced stemness gene expression and sensitization to drug treatment. In accordance, clinical lung cancers containing a higher abundance of ALDH and CD44-coexpressing cells was associated with lower recurrence-free survival. Together, results suggested theALDH(hi)CD44(hi)compartment was the cellular mediator of tumorigenicity and drug resistance. Further investigation of the regulatory mechanisms underlying ALDH(hi)CD44(hi)TIC maintenance would be beneficial for the development of long term lung cancer control.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3858556PMC
http://dx.doi.org/10.18632/oncotarget.1246DOI Listing
October 2013

Genome-wide association analysis identifies new lung cancer susceptibility loci in never-smoking women in Asia.

Nat Genet 2012 Dec 11;44(12):1330-5. Epub 2012 Nov 11.

Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.

To identify common genetic variants that contribute to lung cancer susceptibility, we conducted a multistage genome-wide association study of lung cancer in Asian women who never smoked. We scanned 5,510 never-smoking female lung cancer cases and 4,544 controls drawn from 14 studies from mainland China, South Korea, Japan, Singapore, Taiwan and Hong Kong. We genotyped the most promising variants (associated at P < 5 × 10(-6)) in an additional 1,099 cases and 2,913 controls. We identified three new susceptibility loci at 10q25.2 (rs7086803, P = 3.54 × 10(-18)), 6q22.2 (rs9387478, P = 4.14 × 10(-10)) and 6p21.32 (rs2395185, P = 9.51 × 10(-9)). We also confirmed associations reported for loci at 5p15.33 and 3q28 and a recently reported finding at 17q24.3. We observed no evidence of association for lung cancer at 15q25 in never-smoking women in Asia, providing strong evidence that this locus is not associated with lung cancer independent of smoking.
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http://dx.doi.org/10.1038/ng.2456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169232PMC
December 2012

A novel KIF5B-ALK variant in nonsmall cell lung cancer.

Cancer 2011 Jun 10;117(12):2709-18. Epub 2011 Jan 10.

Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China.

Background: The anaplastic lymphoma kinase (ALK) gene is involved frequently in chromosomal translocations, resulting in fusion genes with different partners found in various lymphoproliferative conditions. It was recently reported in nonsmall cell lung cancer (NSCLC) that the fusion protein encoded by echinoderm microtubule-associated protein-like 4-ALK (EML4-ALK) fusion gene conferred oncogenic properties. The objective of the current study was to identify other possible ALK fusion genes in NSCLC.

Methods: Immunohistochemical analysis was used to screen for aberrant ALK expression in primary NSCLC. The authors used 5' rapid amplification of complementary DNA ends to screen for potential, novel 5' fusion partners of ALK other than EML4-ALK. Reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization analyses were used to confirm the identity of 5' fusion partners. The genomic breakpoint was verified using genomic sequencing. Overexpression of the novel ALK fusion gene and variants 3a and 3b of EML4-ALK was performed to assess downstream signaling and functional effects.

Results: The authors identified a novel gene resulting from the fusion of kinesin family member 5B (KIF5B) exon 15 to ALK exon 20 in a primary lung adenocarcinoma. Western blot analysis of clinical tumor tissues revealed the expression of a protein whose size correlated with that of the predicted KIF5B-ALK. Overexpression of KIF5B-ALK in mammalian cells led to the activation of signal transducer and activator of transcription 3 and protein kinase B and to enhanced cell proliferation, migration, and invasion.

Conclusions: The discovery of the novel KIF5B-ALK variant further consolidated the role of aberrant ALK signaling in lung carcinogenesis.
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http://dx.doi.org/10.1002/cncr.25843DOI Listing
June 2011

Non-small cell lung cancer cells expressing CD44 are enriched for stem cell-like properties.

PLoS One 2010 Nov 19;5(11):e14062. Epub 2010 Nov 19.

Department of Pathology, The University of Hong Kong, Hong Kong, Special Administrative Region, China.

Background: The cancer stem cell theory hypothesizes that cancers are perpetuated by cancer stem cells (CSC) or tumor initiating cells (TIC) possessing self-renewal and other stem cell-like properties while differentiated non-stem/initiating cells have a finite life span. To investigate whether the hypothesis is applicable to lung cancer, identification of lung CSC and demonstration of these capacities is essential.

Methodology/principal Finding: The expression profiles of five stem cell markers (CD34, CD44, CD133, BMI1 and OCT4) were screened by flow cytometry in 10 lung cancer cell lines. CD44 was further investigated by testing for in vitro and in vivo tumorigenecity. Formation of spheroid bodies and in vivo tumor initiation ability were demonstrated in CD44(+) cells of 4 cell lines. Serial in vivo tumor transplantability in nude mice was demonstrated using H1299 cell line. The primary xenografts initiated from CD44(+) cells consisted of mixed CD44(+) and CD44(-) cells in similar ratio as the parental H1299 cell line, supporting in vivo differentiation. Semi-quantitative Real-Time PCR (RT-PCR) showed that both freshly sorted CD44(+) and CD44(+) cells derived from CD44(+)-initiated tumors expressed the pluripotency genes OCT4/POU5F1, NANOG, SOX2. These stemness markers were not expressed by CD44(-) cells. Furthermore, freshly sorted CD44(+) cells were more resistant to cisplatin treatment with lower apoptosis levels than CD44(-) cells. Immunohistochemical analysis of 141 resected non-small cell lung cancers showed tumor cell expression of CD44 in 50.4% of tumors while no CD34, and CD133 expression was observed in tumor cells. CD44 expression was associated with squamous cell carcinoma but unexpectedly, a longer survival was observed in CD44-expressing adenocarcinomas.

Conclusion/significance: Overall, our results demonstrated that stem cell-like properties are enriched in CD44-expressing subpopulations of some lung cancer cell lines. Further investigation is required to clarify the role of CD44 in tumor cell renewal and cancer propagation in the in vivo environment.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0014062PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2988826PMC
November 2010

Double EGFR mutants containing rare EGFR mutant types show reduced in vitro response to gefitinib compared with common activating missense mutations.

Mol Cancer Ther 2009 Aug 11;8(8):2142-51. Epub 2009 Aug 11.

Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Hong Kong.

Epidermal growth factor receptor (EGFR) mutations are common in lung adenocarcinomas, especially from nonsmoking women of Asian descent. We have previously shown EGFR mutations occur in >70% of lung adenocarcinoma from nonsmokers in our population with a complex mutational profile, including 13% of EGFR double mutations. In this study, we investigated the in vitro gefitinib response of four EGFR double mutants identified in untreated patients, including Q787R+L858R, E709A+G719C, T790M+L858R, and H870R+L858R. The phosphorylation profiles of EGFR and downstream effectors AKT, STAT3/5, and ERK1/2 were compared by immunoblot analyses among the single and double mutants transfected into H358 cells. Results showed that mutants responded to in vitro gefitinib treatment with different sensitivities. The G719C and L858R single mutants showed the highest gefitinib sensitivity compared with the corresponding coexisting single mutants E709A, Q787R, H870R, and T790M. The double mutants E709A+G719C, Q787R+L858R, and H870R+L858R showed attenuated responses to gefitinib in the EGFR and downstream effector phosphorylation profiles compared with G719C or L858R alone. T790M+L858R showed strong resistance to gefitinib. Clinically, the patient whose tumor contained H870R+L858R showed tumor stabilization by 250 mg oral gefitinib daily but cerebral metastasis developed 6 months later. Correlation with the in vitro phosphorylation profile of H870R+L858R suggested that treatment failure was probably due to inadequate suppression of EGFR signaling by the drug level attainable in the cerebrospinal fluid at the given oral dosage. Overall, the findings suggested that rare types of EGFR substitution mutations could confer relative gefitinib resistance when combined with the common activating mutants.
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http://dx.doi.org/10.1158/1535-7163.MCT-08-1219DOI Listing
August 2009

SRC promotes survival and invasion of lung cancers with epidermal growth factor receptor abnormalities and is a potential candidate for molecular-targeted therapy.

Mol Cancer Res 2009 Jun 2;7(6):923-32. Epub 2009 Jun 2.

Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong.

Molecular-targeted therapy using tyrosine kinase inhibitors against epidermal growth factor receptor (EGFR) is an effective therapy for non-small cell lung cancer that harbor EGFR mutations. This study aimed to investigate the role of Src, a close EGFR associator, as a drug target in NSCLC cells with different EGFR genomic statuses. Src inhibition was achieved using 4-(4'-Phenoxyanilino)-6,7-dimethoxyquinazolinee (SKI-1) and the specificity of action was verified by RNA interference. The results showed that SKI-1 induced significant apoptosis in a dose-dependent manner in cancer cells with high basal Src activation. Activation of FAK and p130Cas was involved in Src-mediated invasion in SKI-1-sensitive cells. SKI-1 inhibited phosphorylation of EGFR as well as EGFR downstream effectors, such as signal transducers and activators of transcription 3/5, extracellular signal-regulated kinase 1/2 and AKT in the mutant cells but not the wild-type cells. This inhibition profile of EGFR implicates that induction of apoptosis and sensitivity of mutant cells to SKI treatment is mediated by EGFR and EGFR downstream pathways. Cotreatment with SKI-1 and gefitinib enhanced apoptosis in cancer cells that contained EGFR mutation and/or amplification. SKI-1 treatment alone induced significant apoptosis in H1975 cells known to be resistant to gefitinib. Src phosphorylation was shown by immunohistochemistry in around 30% of primary lung carcinomas. In 152 adenocarcinomas studied, p-Src was associated with EGFR mutations (P = 0.029). Overall, the findings indicated that Src could be a useful target for treatment of non-small cell lung cancer. Besides EGFR genomic mutations, other forms of EGFR and related family member abnormalities such as EGFR amplification might enhance SKI sensitivity.
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http://dx.doi.org/10.1158/1541-7786.MCR-09-0003DOI Listing
June 2009

The EML4-ALK fusion gene is involved in various histologic types of lung cancers from nonsmokers with wild-type EGFR and KRAS.

Cancer 2009 Apr;115(8):1723-33

Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong Special Administrative Region, China.

Background: The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion gene resulting from the chromosome inversion inv(2)(p21;p23) recently was identified in nonsmall cell lung cancer (NSCLC). The authors of this study investigated the frequency, genetic and clinicopathologic profiles of EML4-ALK in Chinese patients with NSCLC.

Methods: EML4-ALK was investigated in 266 resected primary NSCLC, including adenocarcinomas (AD), lymphoepithelioma-like carcinomas, squamous cell carcinomas, mucoepidermoid carcinomas, and adenosquamous carcinomas, by reverse transcriptase-polymerase chain reaction and was verified by sequencing. EML4-ALK protein expression was studied by immunohistochemistry.

Results: Thirteen tumors (4.9%) had EML4-ALK comprising 4 fusion transcript variants with fusion of the variable segments from 5' EML4 to 3' ALK and with preservation of the ALK kinase domain. The most common variant consisted of 8 tumors with variant 3 that involved EML4 exon 6. The others included 2 tumors with variant 1 (exon 13), 2 tumors with variant 2 (exon 20), and 1 tumor with the novel variant 5 (exon 18). There were 11 ADs and 2 unusual carcinomas with mixed squamous and glandular components. Immunohistochemistry demonstrated diffuse ALK fusion proteins in the tumor cell cytoplasm. EML4-ALK was associated with nonsmokers (P = .009). Tumors with the fusion gene had the wild-type epidermal growth factor receptor (EGFR) (P = .001) and v-Ki-ras2/Kirsten rat sarcoma viral oncogene homolog (KRAS) genes. Patients who had EML4-ALK-positive AD had a younger median age (P = .018) compared with patients who did not have the fusion gene.

Conclusions: The EML4-ALK fusion gene was present in various histologic types of NSCLC. It occurred in mutual exclusion to EGFR and KRAS mutations and was associated with nonsmokers. The authors concluded that EML4-ALK may be useful for predicting the potential response to ALK inhibitors as a therapeutic option for patients with lung cancer.
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http://dx.doi.org/10.1002/cncr.24181DOI Listing
April 2009

High resolution analysis of genomic aberrations by metaphase and array comparative genomic hybridization identifies candidate tumour genes in lung cancer cell lines.

Cancer Lett 2007 Jan 6;245(1-2):303-14. Epub 2006 Mar 6.

Department of Pathology, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Hong Kong, China.

Tumours develop from clonally expanded population of cells harbouring aberrations of oncogenes and tumour suppressor genes. In this study, metaphase and array comparative genomic hybridization showed good correlation of aberration profiles in lung adenocarcinoma cell lines from patients with different tobacco exposure. Recurrent DNA gains were found at chromosomes 1, 7, 8, 17, 20, and deletions at 1, 3, 8, 9, 10, 12, 17, 18, 19. Candidate tumour loci and encompassed genes at 7p21 (AGR2), 8q21(TPD52), 20q13 (ZNF217, WFDC2, EEF1A2) and 10p15 (KLF6) were analyzed by dual colour FISH for genomic changes and quantitative PCR for expression changes. Results indicated that EEF1A2 and KLF6 were strong candidates of oncogene and tumour suppressor genes, respectively. This study illustrates, a practical strategy for identifying candidate cancer genes from microarray data.
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http://dx.doi.org/10.1016/j.canlet.2006.01.020DOI Listing
January 2007

Frequent allelic loss of 21q11.1 approximately q21.1 region in advanced stage oral squamous cell carcinoma.

Cancer Genet Cytogenet 2005 May;159(1):37-43

Oral Biosciences, Dental Faculty, University of Hong Kong, 34 Hospital Road, Hong Kong.

A fine mapping of loss of heterozygosity (LOH) was performed in oral squamous cell carcinoma (OSCC), using 12 markers on 21q11.1 approximately q21.1. We studied 43 resected primary invasive tumors and their paired normal tissues, concurrent dysplasia or carcinoma in situ in separate areas from 8 of the specimens, and 6 local recurrent carcinomas. LOH status was compared between lesions of different phases of progression within the same patient. A high frequency of LOH was observed for D21S1410, D21S120, and D21S1433 (60% each) in the primary lesions, constituting two interstitial deleted regions encompassing eight known genes. Cases showing LOH of D21S120 were significantly associated with advanced clinical stages (III and IV; P=0.02). Consistent allelic loss was observed in 64.2% of the informative cases between the precursor lesions and their corresponding invasive tumors, and in 59.5% of those between the primary lesions and their recurrent counterparts. Fewer than half of the different lesions within a given patient showed discordant allelic loss for tested markers. Our results suggest that 21q11.1 approximately q21.1 harbors tumor suppressor genes in OSCC. Genetic divergence may develop during tumor clone evolution.
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http://dx.doi.org/10.1016/j.cancergencyto.2004.09.011DOI Listing
May 2005
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