Publications by authors named "Liang-In Lin"

68 Publications

Association between risk factors, molecular features and CpG island methylator phenotype colorectal cancer among different age groups in a Taiwanese cohort.

Br J Cancer 2021 Apr 12. Epub 2021 Apr 12.

Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan.

Background: CpG island methylator phenotype (CIMP) represents a carcinogenesis pathway of colorectal cancer (CRC) and the association between CIMP CRC, molecular features and risk factors in East Asian population is less studied.

Methods: We prospectively enrolled newly diagnosed CRC patients at the National Taiwan University Hospital. Clinicopathological data and risk factors for CRC were collected during interview. The tumour samples were subjected to CIMP, RAS/BRAF mutation and microsatellite instability tests. CIMP-high was determined when ≧3 methylated loci of p16, MINT1, MINT2, MINT31 and MLH1 were identified. Multivariate logistic regression was used to evaluate the association between risk factors and CIMP-high CRC.

Results: Compared with CIMP-low/negative CRC, CIMP-high CRC was associated with more stage IV disease, BRAF V600E mutation and high body mass index (BMI ≧ 27.5 kg/m) in younger patients (age < 50 y), and more right-sided tumour, BRAF V600E mutation, MSI-high and colorectal polyp in elder patients (age ≧ 50 y). Multivariate analyses showed that BMI ≧27.5 kg/m was significantly associated with CIMP-high CRC in younger patients.

Conclusions: We identified distinct clinicopathological features for CIMP-high CRC among different age groups in Taiwan. Our data suggest the association between BMI ≧27.5 kg/m and CIMP-high CRC in patients younger than 50 years.
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http://dx.doi.org/10.1038/s41416-021-01300-5DOI Listing
April 2021

Repurposing cabozantinib with therapeutic potential in KIT-driven t(8;21) acute myeloid leukaemias.

Cancer Gene Ther 2021 Apr 8. Epub 2021 Apr 8.

Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan.

Cabozantinib is an orally available, multi-target tyrosine kinase inhibitor approved for the treatment of several solid tumours and known to inhibit KIT tyrosine kinase. In acute myeloid leukaemia (AML), aberrant KIT tyrosine kinase often coexists with t(8;21) to drive leukaemogenesis. Here we evaluated the potential therapeutic effect of cabozantinib on a selected AML subtype characterised by t(8;21) coupled with KIT mutation. Cabozantinib exerted substantial cytotoxicity in Kasumi-1 cells with an IC of 88.06 ± 4.32 nM, which was well within clinically achievable plasma levels. The suppression of KIT phosphorylation and its downstream signals, including AKT/mTOR, STAT3, and ERK1/2, was elicited by cabozantinib treatment and associated with subsequent alterations of cell cycle- and apoptosis-related molecules. Cabozantinib also disrupted the synthesis of an AML1-ETO fusion protein in a dose- and time-dependent manner. In a mouse xenograft model, cabozantinib suppressed tumourigenesis at 10 mg/kg and significantly prolonged survival of the mice. Further RNA-sequencing analysis revealed that mTOR-mediated signalling pathways were substantially inactivated by cabozantinib treatment, causing the downregulation of ribosome biogenesis and glycolysis, along with myeloid leukocyte activation. We suggest that cabozantinib may be effective in the treatment of AML with t(8;21) and KIT mutation. Relevant clinical trials are warranted.
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http://dx.doi.org/10.1038/s41417-021-00329-1DOI Listing
April 2021

Measurement of uracil-DNA glycosylase activity by matrix assisted laser desorption/ionization time-of-flight mass spectrometry technique.

DNA Repair (Amst) 2021 Jan 24;97:103028. Epub 2020 Nov 24.

Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan, ROC; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan, ROC. Electronic address:

Uracil-DNA glycosylase (UDG) is a highly conserved DNA repair enzyme that acts as a key component in the base excision repair pathway to correct hydrolytic deamination of cytosine making it critical to genome integrity in living organisms. We report here a non-labeled, non-radio-isotopic and very specific method to measure UDG activity. Oligodeoxyribonucleotide duplex containing a site-specific G:U mismatch that is hydrolyzed by UDG then subjected to Matrix Assisted Laser Desorption/Ionization time-of-flight mass spectrometry analysis. A protocol was developed to maintain the AP product in DNA without strand break then the cleavage of uracil was identified by the mass change from uracil substrate to AP product. From UDG kinetic analysis, for G:U substrate the K is 50 nM, V is 0.98 nM/s and K = 9.31 s. The method was applied to uracil glycosylase inhibitor measurement with an IC value of 7.6 pM. Single-stranded and double-stranded DNAs with uracil at various positions of the substrates were also tested for UDG activity albeit with different efficiencies. The simple, rapid, quantifiable, scalable and versatile method has potential to be the reference method for monofunctional glycosylase measurement, and can also be used as a tool for glycosylase inhibitors screening.
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http://dx.doi.org/10.1016/j.dnarep.2020.103028DOI Listing
January 2021

Proofreading of single nucleotide insertion/deletion replication errors analyzed by MALDI-TOF mass spectrometry assay.

DNA Repair (Amst) 2020 04 30;88:102810. Epub 2020 Jan 30.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, 10002, Taiwan, ROC; Department of Laboratory Medicine, National Taiwan University Hospital, 10063, Taipei, Taiwan, ROC. Electronic address:

Small nucleotide insertion/deletion (indel) errors are one of the common replication errors in DNA synthesis. The most frequent occurrence of indel error was thought to be due to repeated sequences being prone to slippage during DNA replication. Proofreading and DNA mismatch repair are important factors in indel error correction to maintain the high fidelity of genetic information transactions. We employed a MALDI-TOF mass spectrometry (MS) analysis to measure the efficiency of Klenow polymerase (KF) proofreading of indel errors. Herein, a non-labeled and non-radio-isotopic oligonucleotide primer is annealed to a template DNA forming a single nucleotide indel error and was proofread by KF in the presence of a combination of different deoxyribonucleotide triphosphates and/or dideoxyribonucleotide triphosphates. The proofreading products were identified by the KF modified mass change of the primer. We examined proofreading of DNAs containing indel errors at various positions of the primer-template junction. We found that indel errors located 1-5-nucleotides (nt) from the primer terminus can be proofread efficiently, while insertion/deletions at 6-nt from the 3' end are partially corrected and extended. Indels located 7-9-nt from the primer terminus escape proofreading and are elongated by polymerase. The possible underlying mechanisms of these observations are discussed in the context of the polymerase and primer-template junction interactions via a structure analysis.
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http://dx.doi.org/10.1016/j.dnarep.2020.102810DOI Listing
April 2020

Cytarabine-Resistant -ITD Leukemia Cells are Associated with Mutation and Multiple Pathway Alterations-Possible Therapeutic Efficacy of Cabozantinib.

Int J Mol Sci 2019 Mar 11;20(5). Epub 2019 Mar 11.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 100, Taiwan.

Internal tandem duplication of FLT3 juxtamembrane domain (FLT3-ITD)-positive acute myeloid leukemia (AML) leads to poor clinical outcomes after chemotherapy. We aimed to establish a cytarabine-resistant line from -ITD-positive MV4-11 (MV4-11-P) cells and examine the development of resistance. The -ITD mutation was retained in MV4-11-R; however, the protein was underglycosylated and less phosphorylated in these cells. Moreover, the phosphorylation of ERK1/2, Akt, MEK1/2 and p53 increased in MV4-11-R. The levels of Mcl-1 and p53 proteins were also elevated in MV4-11-R. A p53 D281G mutant emerged in MV4-11-R, in addition to the pre-existing R248W mutation. MV4-11-P and MV4-11-R showed similar sensitivity to cabozantinib, sorafenib, and MK2206, whereas MV4-11-R showed resistance to CI-1040 and idarubicin. MV4-11-R resistance may be associated with inhibition of Akt phosphorylation, but not ERK phosphorylation, after exposure to these drugs. The multi-kinase inhibitor cabozantinib inhibited FLT3-ITD signaling in MV4-11-R cells and MV4-11-R-derived tumors in mice. Cabozantinib effectively inhibited tumor growth and prolonged survival time in mice bearing MV4-11-R-derived tumors. Together, our findings suggest that Mcl-1 and Akt phosphorylation are potential therapeutic targets for p53 mutants and that cabozantinib is an effective treatment in cytarabine-resistant FLT3-ITD-positive AML.
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http://dx.doi.org/10.3390/ijms20051230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6429333PMC
March 2019

Incorporation of long non-coding RNA expression profile in the 2017 ELN risk classification can improve prognostic prediction of acute myeloid leukemia patients.

EBioMedicine 2019 Feb 17;40:240-250. Epub 2019 Jan 17.

Division of Hematology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan. Electronic address:

Background: Expression of long non-coding RNAs (lncRNAs) has recently been recognized as a potential prognostic marker in acute myeloid leukemia (AML). However, it remains unclear whether incorporation of the lncRNAs expression in the 2017 European LeukemiaNet (ELN) risk classification can further improve the prognostic prediction.

Methods: We enrolled 275 newly diagnosed non-M3 AML patients and randomly assigned them to the training (n = 183) and validation cohorts (n = 92). In the training cohort, we formulated a prognostic lncRNA scoring system composed of five lncRNAs with significant prognostic impact from the lncRNA expression profiling.

Findings: Higher lncRNA scores were significantly associated with older age and adverse gene mutations. Further, the higher-score patients had shorter overall and disease-free survival than lower-score patients, which were also confirmed in both internal and external validation cohorts (TCGA database). The multivariate analyses revealed the lncRNA score was an independent prognosticator in AML, irrespective of the risk based on the 2017 ELN classification. Moreover, in the 2017 ELN intermediate-risk subgroup, lncRNA scoring system could well dichotomize the patients into two groups with distinct prognosis. Within the ELN intermediate-risk subgroup, we found that allogeneic hematopoietic stem cell transplantation could provide better outcome on patients with higher lncRNA scores. Through bioinformatics approach, we identified high lncRNA scores were correlated with leukemia/hematopoietic stem cell signatures.

Interpretation: Incorporation of lncRNA scoring system in 2017 ELN classification can improve risk-stratification of AML patients and help clinical decision-making. FUND: This work was supported Ministry of Science and Technology, and Ministry of Health and Welfare of Taiwan.
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http://dx.doi.org/10.1016/j.ebiom.2019.01.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6413345PMC
February 2019

Chemotherapy agents induce tartrate-resistant acid phosphatase 5a contributing to the symptom distress in lung cancer patients.

Eur J Pharmacol 2019 Mar 15;846:38-48. Epub 2019 Jan 15.

Department of Nursing, Oriental Institute of Technology, New Taipei City, Taiwan; Department of Emergency, Cathay General Hospital, Taipei, Taiwan; School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan. Electronic address:

Tartrate-resistant acid phosphatase 5a (TRACP5a) is mainly secreted by activated macrophages in chronic inflammation. Serum TRACP5a is associated with symptom distress in lung cancer patients during chemotherapy. Therefore, this study aimed to investigate whether chemotherapy drugs modulate TRACP5a as an inducible marker for symptom distress in lung cancer patients during chemotherapy. In clinical analysis, lung cancer participants completely received the six-cycle chemotherapy process (n = 42). Clinical determinations for TRACP5a, C-reactive protein (CRP), interleukin-6 (IL-6), white blood cells, monocytes, and hemoglobin were analyzed at six time points: BL, C1d8, C2d1, C4d1, C4d8, and Ed28. Meanwhile, five questionnaires for fatigue, sleep disturbance, pain, depression, and confusion were finished before drug treatment. For monocyte-to-macrophage differentiation, THP-1 cells were treated with phorbol 12-myristate 13-acetate (PMA). TRACP5a secretion in THP-1 cells was determined at the following days up to 6 days after 1-day incubation of chemotherapy drugs by dot blotting. Clinical analysis revealed that TRACP5a significantly increased at C1d8 and C4d8, but dropped at C2d1 and Ed28. CRP and IL-6 displayed a broad-range variation, resulting in no significant difference among the assessment time points. In contrast, monocytes decreased at C1d8 and C4d8, but rose again at C2d1 and Ed28. In symptom distress, the changes only in fatigue and sleep disturbance were positively associated with the trend in TRACP5a. In PMA-treated THP-1 cells, TRACP5a significantly increased after stimulation with gemcitabine and paclitaxel. Taken together, induction of TRACP5a by chemotherapy drugs might be generated from monocyte-differentiated macrophages, further causing clinical symptom distress in lung cancer patients.
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http://dx.doi.org/10.1016/j.ejphar.2019.01.011DOI Listing
March 2019

CpG Island Methylator Phenotype May Predict Poor Overall Survival of Patients with Stage IV Colorectal Cancer.

Oncology 2019 12;96(3):156-163. Epub 2018 Dec 12.

Department of Oncology, National Taiwan University Hospital, Taipei City, Taiwan,

Objective: We aimed to study the prognostic role of CpG island methylator phenotype (CIMP) in patients with different stages of colorectal cancer (CRC).

Material And Methods: We analyzed CIMP in stage I-IV CRC specimens from patients who were diagnosed between 2005 and 2013. CIMP status was determined using a 5-gene MethyLight-based assay. The clinicopathologic characteristics were reviewed and the overall survival (OS) was compared between patients with CIMP-high CRC and those with CIMP-low/negative CRC.

Results: Among 450 CRC specimens with successfully determined CIMP statuses, 74 (16.4%) were CIMP-high CRC. Although there was no difference in OS between patients with CIMP-high and CIMP-low/negative CRC across all stages (p = 0.4526), intriguingly, patients with stage IV CIMP-high CRC had significantly worse OS than those with stage IV CIMP-low/negative CRC (p = 0.0047). In a multivariate analysis, CIMP status remained an independent prognostic factor for overall mortality (HR = 5.60, 95% CI: 2.12-14.79, p = 0.0005) in metastatic CRC after adjusting for clinicopathologic variables and anti-cancer therapies.

Conclusion: Our results revealed that the presence of CIMP independently predicts poor OS in patients with stage IV CRC.
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http://dx.doi.org/10.1159/000493387DOI Listing
March 2019

GATA2 zinc finger 1 mutations are associated with distinct clinico-biological features and outcomes different from GATA2 zinc finger 2 mutations in adult acute myeloid leukemia.

Blood Cancer J 2018 08 31;8(9):87. Epub 2018 Aug 31.

Division of Hematology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.

Mutations of the GATA binding protein 2 (GATA2) gene in myeloid malignancies usually cluster in the zinc finger 1 (ZF1) and the ZF2 domains. Mutations in different locations of GATA2 may have distinct impact on clinico-biological features and outcomes in AML patients, but little is known in this aspect. In this study, we explored GATA2 mutations in 693 de novo non-M3 AML patients and identified 44 GATA2 mutations in 43 (6.2%) patients, including 31 in ZF1, 10 in ZF2, and three outside the two domains. Different from GATA2 ZF2 mutations, ZF1 mutations were closely associated with French-American-British (FAB) M1 subtype, CEBPA double mutations (CEBPA), but inversely correlated with FAB M4 subtype, NPM1 mutations, and FLT3-ITD. ZF1-mutated AML patients had a significantly longer overall survival (OS) than GATA2-wild patients and ZF2-mutated patients in total cohort as well as in those with intermediate-risk cytogenetics and normal karyotype. ZF1 mutations also predicted better disease-free survival and a trend of better OS in CEBPA patients. Sequential analysis showed GATA2 mutations could be acquired at relapse. In conclusion, GATA2 ZF1 mutations are associated with distinct clinico-biological features and predict better prognosis, different from ZF2 mutations, in AML patients.
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http://dx.doi.org/10.1038/s41408-018-0123-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127202PMC
August 2018

Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis.

J Vis Exp 2018 06 19(136). Epub 2018 Jun 19.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University; Department of Laboratory Medicine, National Taiwan University Hospital;

The maintenance of the genome and its faithful replication is paramount for conserving genetic information. To assess high fidelity replication, we have developed a simple non-labeled and non-radio-isotopic method using a matrix-assisted laser desorption ionization with time-of-flight (MALDI-TOF) mass spectrometry (MS) analysis for a proofreading study. Here, a DNA polymerase [e.g., the Klenow fragment (KF) of Escherichia coli DNA polymerase I (pol I) in this study] in the presence of all four dideoxyribonucleotide triphosphates is used to process a mismatched primer-template duplex. The mismatched primer is then proofread/extended and subjected to MALDI-TOF MS. The products are distinguished by the mass change of the primer down to single nucleotide variations. Importantly, a proofreading can also be determined for internal single mismatches, albeit at different efficiencies. Mismatches located at 2-4-nucleotides (nt) from the 3' end were efficiently proofread by pol I, and a mismatch at 5 nt from the primer terminus showed only a partial correction. No proofreading occurred for internal mismatches located at 6 - 9 nt from the primer 3' end. This method can also be applied to DNA repair assays (e.g., assessing a base-lesion repair of substrates for the endo V repair pathway). Primers containing 3' penultimate deoxyinosine (dI) lesions could be corrected by pol I. Indeed, penultimate T-I, G-I, and A-I substrates had their last 2 dI-containing nucleotides excised by pol I before adding a correct ddN 5'-monophosphate (ddNMP) while penultimate C-I mismatches were tolerated by pol I, allowing the primer to be extended without repair, demonstrating the sensitivity and resolution of the MS assay to measure DNA repair.
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http://dx.doi.org/10.3791/57862DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6101880PMC
June 2018

Hyperleukocytosis is associated with distinct genetic alterations and is an independent poor-risk factor in de novo acute myeloid leukemia patients.

Eur J Haematol 2018 Jul 22;101(1):86-94. Epub 2018 May 22.

Department of Internal Medicine, Division of Hematology, National Taiwan University Hospital, Taipei, Taiwan.

Objectives: Acute myeloid leukemia (AML) with hyperleukocytosis (HL) is intuitively thought as a unique group with dismal prognosis. However, comprehensive studies regarding the genetic landscape and clinical outcome in this group of patients are limited.

Methods: A total of 693 newly diagnosed de novo non-M3 AML patients were consecutively enrolled. We compared relevant mutations in 20 genes between AML patients with or without HL and exposed their prognostic implications.

Results: Hyperleukocytosis, defined as initial white blood cell counts above 50 000/μL, occurred in 28.9% of AML patients. HL patients had higher incidences of FLT3-ITD, NPM1, DNMT3A, CEBPA, and TET2 mutations. Multivariate analysis demonstrated that HL was an independent poor prognostic factor for overall survival and disease-free survival in total patients, those with intermediate-risk cytogenetics and normal karyotype irrespective of genetic alterations. Intriguingly, HL predicted poor survival in CEBPA double mutated, NPM1 + /FLT3-ITD- and NPM1-/FLT3-ITD- patients. Further, HL patients who received allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR) had a significantly longer overall survival and disease-free survival than those without allo-HSCT.

Conclusions: Hyperleukocytosis is an independent poor prognostic factor irrespective of cytogenetics and mutation status. Allo-HSCT in first CR seems to ameliorate the poor prognostic impact of HL.
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http://dx.doi.org/10.1111/ejh.13073DOI Listing
July 2018

Incorporation of mutations in five genes in the revised International Prognostic Scoring System can improve risk stratification in the patients with myelodysplastic syndrome.

Blood Cancer J 2018 04 4;8(4):39. Epub 2018 Apr 4.

Division of Hematology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.

Gene mutations have not yet been included in the 2016 WHO classification and revised International Prognostic Scoring System (IPSS-R), which are now widely utilized to discriminate myelodysplastic syndrome (MDS) patients regarding risk of leukemia evolution and overall survival (OS). In this study, we aimed to investigate whether integration of gene mutations with other risk factors could further improve the stratification of MDS patients. Mutational analyses of 25 genes relevant to myeloid malignancies in 426 primary MDS patients showed that mutations of CBL, IDH2, ASXL1, DNMT3A, and TP53 were independently associated with shorter survival. Patients within each IPSS-R or 2016 WHO classification-defined risk group could be stratified into two risk subgroups based on the mutational status of these five genes; patients with these poor-risk mutations had an OS shorter than others in the same risk group, but similar to those with the next higher risk category. A scoring system incorporating age, IPSS-R and five poor-risk mutations could divide the MDS patients into four risk groups (P < 0.001 for both OS and leukemia-free survival). In conclusion, integration of gene mutations in current IPSS-R improves the prognostication of MDS patients and may help identify high-risk patients for more aggressive treatment in IPSS-R lower risk group.
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http://dx.doi.org/10.1038/s41408-018-0074-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5884776PMC
April 2018

DNA polymerase I proofreading exonuclease activity is required for endonuclease V repair pathway both in vitro and in vivo.

DNA Repair (Amst) 2018 04 17;64:59-67. Epub 2018 Feb 17.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, 100-02, Taiwan, ROC; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 100-02, Taiwan, ROC. Electronic address:

Deamination of adenine can occur spontaneously under physiological conditions to generate the highly mutagenic lesion, deoxyinosine (hypoxanthine deoxyribonucleotide, dI). In DNA, dI preferably pairs with cytosine rather than thymine and results in A:T to G:C transition mutations after DNA replication. The deamination of adenine is enhanced by ROS from exposure of DNA to ionizing radiation, UV light, nitrous acid, or heat. In Escherichia coli, dI repair is initiated by endonuclease V (endo V; nfi gene product) nicking but a complete repair mechanism has yet to be elucidated. Using in vitro minimum component reconstitution assays, we previously showed that endo V, DNA polymerase I (pol I), and E. coli DNA ligase were sufficient to repair this dI lesions efficiently and that the 3'-5' exonuclease of pol I is essential. Here we employed a phagemid-based T-I substrate mimicking adenine deamination product to demonstrate pol I proofreading exonuclease is required by the endo V repair pathway both in vitro and in vivo. In vivo we found that the repair level of an nfi mutant (11%) was almost 8-fold lower than the wild type (87%). while the polA- strain, a pol I mutant defective in 3'-5' exonuclease, showed a high repair level similar to wild type (both more than 80%). Using additional C-C mismatch as strand discrimination marker we found that the high level of dI removal in polA- was due to strand loss (more than 60%) associated with incomplete repair. Thus, pol I proofreading exonuclease is the major function responsible for dI lesion removal after endoV nicking both in vitro and in vivo. Finally, using MALDI-TOF to analyze single-nucleotide extension product we show that the pol I proofreading exonuclease excises only 2-nt 5' upstream of endo V incision site further honing the role of pol I in the endoV dI dependent repair pathway.
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http://dx.doi.org/10.1016/j.dnarep.2018.02.005DOI Listing
April 2018

Application of single nucleotide extension and MALDI-TOF mass spectrometry in proofreading and DNA repair assay.

DNA Repair (Amst) 2018 01 2;61:63-75. Epub 2017 Dec 2.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 10002, Taiwan, ROC; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 100-63, Taiwan, ROC. Electronic address:

Proofreading and DNA repair are important factors in maintaining the high fidelity of genetic information during DNA replication. Herein, we designed a non-labeled and non-radio-isotopic simple method to measure proofreading. An oligonucleotide primer is annealed to a template DNA forming a mismatched site and is proofread by Klenow fragment of Escherichia coli DNA polymerase I (pol I) in the presence of all four dideoxyribonucleotide triphosphates. The proofreading excision products and re-synthesis products of single nucleotide extension are subjected to MALDI-TOF mass spectrometry (MS). The proofreading at the mismatched site is identified by the mass change of the primer. We examined proofreading of Klenow fragment with DNAs containing various base mismatches. Single mismatches at the primer terminus can be proofread efficiently. Internal single mismatches can also be proofread at different efficiencies, with the best correction for mismatches located 2-4-nucleotides from the primer terminus. For mismatches located 5-nucleotides from the primer terminus there was partial correction and extension. No significant proofreading was observed for mismatches located 6-9-nucleotides from the primer terminus. We also subjected primers containing 3' penultimate deoxyinosine (dI) lesions, which mimic endonuclease V nicked repair intermediates, to pol I repair assay. The results showed that T-I was a better substrate than G-I and A-I, however C-I was refractory to repair. The high resolution of MS results clearly demonstrated that all the penultimate T-I, G-I and A-I substrates had been excised last 2 dI-containing nucleotides by pol I before adding a correct ddNMP, however, pol I proofreading exonuclease tolerated the penultimate C-I mismatch allowing the primer to be extended by polymerase activity.
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http://dx.doi.org/10.1016/j.dnarep.2017.11.011DOI Listing
January 2018

Significance of histone methyltransferase SETDB1 expression in colon adenocarcinoma.

APMIS 2017 Nov 15;125(11):985-995. Epub 2017 Sep 15.

Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan.

This study investigated the clinical implications of SETDB1 (also known as KMT1E) in human colon adenocarcinoma. Expression levels of SETDB1 proteins were analyzed by immunohistochemistry staining, and tissue microarrays were used to examine expression profiles in human patients. Our results revealed that SETDB1 protein expression was significantly higher in tumor tissue than in normal tissue for the breast, colon, liver, and lung (p < 0.05). Moreover, an analysis with SurvExpress software suggested that elevated expression of SETDB1 mRNA was significantly associated with the overall survival of colon adenocarcinoma patients (p < 0.05); and additional analysis involving 90 paired samples of colon adenocarcinoma tissue and normal tissue revealed that SETDB1 protein expression was 82% higher in cancerous cells (p < 0.001). High SETDB1 expression was also found to be significantly correlated with histological grade (p = 0.005), TNM stage (p = 0.003), T-class/primary tumor (p = 0.001), and N-class/regional lymph nodes (p = 0.017); and Kaplan-Meier survival curves indicated that SETDB1 protein expression was significantly associated with poor survival. Finally, univariate analysis demonstrated that SETDB1 protein expression was related to TNM stage (p = 0.004) and SETDB1 score (p = 0.001), whereas multivariate analysis showed that the influence of SETDB1 on overall colon adenocarcinoma survival was independent from other risk factors. Taken together, our results suggest that the SETDB1 protein could serve as a clinical prognostic indicator for colon adenocarcinoma.
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http://dx.doi.org/10.1111/apm.12745DOI Listing
November 2017

Distinct molecular genetics of chronic lymphocytic leukemia in Taiwan: clinical and pathogenetic implications.

Haematologica 2017 06 2;102(6):1085-1090. Epub 2017 Mar 2.

Strategic Research Program on CLL and B-cell Neoplasia Unit, Division of Experimental Oncology, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy

Differences in chronic lymphocytic leukemia between the Asian and the Western population are widely known. To further clarify these ethnic differences, we profiled the molecular genetics in a cohort of 83 newly diagnosed patients from Taiwan. In detail, we assessed: (i) the usage and the mutational status of the clonotypic immunoglobulin heavy-chain variable region () genes, (ii) the presence of VH CDR3 stereotypes, and (iii) , and mutations. The gene repertoire was biased and distinct from that observed in the West with the most common genes being , and In terms of gene mutational status, 63.8% of patients carried mutated rearrangements, whereas 22.4% of patients were assigned to stereotyped subsets (6.9% to major subsets and 15.5% to minor ones). The frequencies of , and mutations were 9.6%, 7.2%, 1.2%, and 2.4%, respectively; however, the frequency of mutations was significantly higher (20.5%). Patients with mutations or del(17p), mutations and unmutated had a worse outcome compared to the other patients. In conclusion, the differences observed in properties suggest different pathogenetic factors implicated in the development of chronic lymphocytic leukemia, while the high frequency of mutations could in part explain the dismal outcome of these patients in Taiwan.
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http://dx.doi.org/10.3324/haematol.2016.157552DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5451340PMC
June 2017

Antiviral activities of niclosamide and nitazoxanide against chikungunya virus entry and transmission.

Antiviral Res 2016 11 11;135:81-90. Epub 2016 Oct 11.

Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan, ROC; School of Pharmacy, National Defense Medical Center, Taipei, Taiwan, ROC. Electronic address:

Chikungunya disease results from an infection with the arbovirus, chikungunya virus (CHIKV). Symptoms of CHIKV include fever and persistent, severe arthritis. In recent years, several antiviral drugs have been evaluated in clinical trials; however, no registered antivirals have been approved for clinical therapy. In this study, we established a high-throughput screening (HTS) system based on CHIKV 26S mediated insect cell fusion inhibition assay. Our screening system was able to search potential anti-CHIKV drugs in vitro. Using this system, four compounds (niclosamide, nitazoxanide, niflumic acid, tolfenamic acid) were identified. These compounds were then further analyzed using a microneutralization assay. We determined that niclosamide and nitazoxanide exhibit ability to against CHIKV-induced CPE. The anti-CHIKV abilities of these compounds were further confirmed by RT-qPCR and IFA. Moreover, niclosamide and nitazoxanide were found to (1) limit virus entry, (2) inhibit both viral release and cell-to-cell transmission, and (3) possess broad anti-alphavius activities, including against two clinical CHIKV isolates and two alphaviruses: Sindbis virus (SINV) and Semliki forest virus (SFV). In conclusion, our findings suggested that niclosamide and nitazoxanide were able to inhibit CHIKV entry and transmission, which might provide a basis for the development of novel human drug therapies against CHIKV and other alphavirus infections.
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http://dx.doi.org/10.1016/j.antiviral.2016.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7126800PMC
November 2016

Murine tribbles homolog 2 deficiency affects erythroid progenitor development and confers macrocytic anemia on mice.

Sci Rep 2016 08 23;6:31444. Epub 2016 Aug 23.

Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

Tribbles homolog 2 (Trib2) is a member of Tribbles protein pseudokinases and involves in apoptosis, autoimmunity, cancer, leukemia and erythropoiesis, however, the physiological function of Trib2 in hematopoietic system remains to be elucidated. Here, we report that Trib2 knockout (KO) mice manifest macrocytic anemia and increase of T lymphocytes. Although Trib2 deficient RBCs have similar half-life as the control RBCs, Trib2 KO mice are highly vulnerable to oxidant-induced hemolysis. Endogenous Trib2 mRNA is expressed in early hematopoietic progenitors, erythroid precursors, and lymphoid lineages, but not in mature RBCs, myeloid progenitors and granulocytes. Consistently, flow cytometric analysis and in vitro colony forming assay revealed that deletion of Trib2 mainly affected erythroid lineage development, and had no effect on either granulocyte or megakaryocyte lineages in bone marrow. Furthermore, a genetic approach using double knockout of Trib2 and C/ebpα genes in mice suggested that Trib2 promotes erythropoiesis independent of C/ebpα proteins in vivo. Finally, ectopic expression of human Trib2 in zebrafish embryos resulted in increased expression of erythropoiesis-related genes and of hemoglobin. Taking all data together, our results suggest that Trib2 positively promotes early erythrocyte differentiation and is essential for tolerance to hemolysis.
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http://dx.doi.org/10.1038/srep31444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4994003PMC
August 2016

Cabozantinib is selectively cytotoxic in acute myeloid leukemia cells with FLT3-internal tandem duplication (FLT3-ITD).

Cancer Lett 2016 07 6;376(2):218-25. Epub 2016 Apr 6.

Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan; Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan. Electronic address:

Cabozantinib is an oral multikinase inhibitor that exhibits anti-tumor activity in several cancers. We found that cabozantinib was significantly cytotoxic to MV4-11 and Molm-13 cells that harbored FLT3-ITD, resulting in IC50 values of 2.4 nM and 2.0 nM, respectively. However, K562, OCI-AML3 and THP-1 (leukemia cell lines lacking FLT3-ITD) were resistant to cabozantinib, showing IC50 values in the micromolar range. Cabozantinib arrested MV4-11 cell growth at the G0/G1 phase within 24 h, which was associated with decreased phosphorylation of FLT3, STAT5, AKT and ERK. Additionally, cabozantinib induced MV4-11 cell apoptosis in a dose-dependent manner (as indicated by annexin V staining and high levels of cleaved caspase 3 and PARP-1), down-regulated the anti-apoptotic protein survivin and up-regulated the pro-apoptotic protein Bak. Thus, cabozantinib is selectively cytotoxic to leukemia cells with FLT3-ITD, causing cell-cycle arrest and apoptosis. In mouse xenograft model, cabozantinib significantly inhibited MV4-11 and Molm-13 tumor growth at a dosage of 10 mg/kg and showed longer survival rate. Clinical trials evaluating the efficacy of cabozantinib in acute myeloid leukemia (AML) with FLT3-ITD are warranted.
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http://dx.doi.org/10.1016/j.canlet.2016.04.004DOI Listing
July 2016

BRAF mutation may have different prognostic implications in early- and late-stage colorectal cancer.

Med Oncol 2016 May 31;33(5):39. Epub 2016 Mar 31.

Department of Oncology, National Taiwan University Hospital, No 7, Chung-Shan South Rd, Taipei, 10002, Taiwan.

The prognostic implication of BRAF mutant colorectal cancer remains paradoxical. Records of BRAF mutant and wild-type colorectal cancer patients at all stages were reviewed. Clinicopathologic features, including microsatellite instability, CpG islands methylator phenotype, and overall survival, of these patients were analyzed. Between 2005 and 2013, 428 colorectal cancer patients were enrolled in this study. The overall survival between BRAF mutant and wild-type patients with early-stage (stages I and II) colorectal cancer differed nonsignificantly (P = 0.99). By contrast, in late-stage (stages III and IV) patients, the median overall survival of BRAF mutant patients (N = 25) was significantly poorer than that of BRAF wild-type (N = 207) patients (BRAF mutant: 21.3 months (95% confidence interval [CI] 7.1-35.5); BRAF wild-type: 53.5 months (95% CI 37.5-69.5), P < 0.0001). In early-stage patients, we found that BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P < 0.001), and microsatellite instability-high status (P = 0.0013). Conversely, in late-stage patients, BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P = 0.0015) and the right-side colon (P = 0.014). BRAF mutation may have different prognostic implications in early- and late-stage colorectal cancer.
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http://dx.doi.org/10.1007/s12032-016-0756-6DOI Listing
May 2016

Splicing factor mutations predict poor prognosis in patients with de novo acute myeloid leukemia.

Oncotarget 2016 Feb;7(8):9084-101

Division of Hematology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.

Mutations in splicing factor (SF) genes are frequently detected in myelodysplastic syndrome, but the prognostic relevance of these genes mutations in acute myeloid leukemia (AML) remains unclear. In this study, we investigated mutations of three SF genes, SF3B1, U2AF1 and SRSF2, by Sanger sequencing in 500 patients with de novo AML and analysed their clinical relevance. SF mutations were identified in 10.8% of total cohort and 13.2% of those with intermediate-risk cytogenetics. SF mutations were closely associated with RUNX1, ASXL1, IDH2 and TET2 mutations. SF-mutated AML patients had a significantly lower complete remission rate and shorter disease-free survival (DFS) and overall survival (OS) than those without the mutation. Multivariate analysis demonstrated that SFmutation was an independent poor prognostic factor for DFS and OS. A scoring system incorporating SF mutation and ten other prognostic factors was proved very useful to risk-stratify AML patients. Sequential study of paired samples showed that SF mutations were stable during AML evolution. In conclusion, SF mutations are associated with distinct clinic-biological features and poor prognosis in de novo AML patients and are rather stable during disease progression. These mutations may be potential targets for novel treatment and biomarkers for disease monitoring in AML.
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http://dx.doi.org/10.18632/oncotarget.7000DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891028PMC
February 2016

Tissue microarray-based study of hepatocellular carcinoma validating SPIB as potential clinical prognostic marker.

Acta Histochem 2016 Jan 21;118(1):38-45. Epub 2015 Nov 21.

Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan. Electronic address:

Currently, the prognostic significance of SPIB protein overexpression in human hepatocellular carcinoma (HCC) is unclear. The aim of the present study was to investigate the level of SPIB expression in human HCC in order to determine possible correlations between SPIB expression and clinicopathological findings. The expression of SPIB proteins was detected using immunohistochemical staining in commercial multiple-tissue microarrays as a means of examining expression profiles in patients. Using online biomarker validation tool SurvExpress, we focused on the correlation between SPIB overexpression and survival as well as relapse-free survival (RFS). Results show that SPIB protein expression levels were significantly higher in colon, liver, and stomach tumors than in non-tumor tissues (p<0.05). SPIB overexpression in patients with HCC was also significantly higher than that of the normal samples (p<0.001). Among patients with liver disease, SPIB protein expression levels differ significantly according to the stage of liver disease, specifically between stages I, II, and III of HCC (p<0.05). SPIB expression was also shown to be significantly correlated with age (p=0.046) and histological grade (p=0.027). Furthermore, the SurvExpress analysis suggested that high SPIB and KI-67 mRNA expression were significantly associated with the poor survival of patients with HCC (p<0.05). Our results indicate that cross-talk in the expression of SPIB and KI-67 may be associated with poor prognosis and may potentially serve as a clinical prognostic indicator of HCC. This is the first time that such an association has been reported.
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http://dx.doi.org/10.1016/j.acthis.2015.11.005DOI Listing
January 2016

Cyclin E1 Inhibition can Overcome Sorafenib Resistance in Hepatocellular Carcinoma Cells Through Mcl-1 Suppression.

Clin Cancer Res 2016 05 24;22(10):2555-64. Epub 2015 Nov 24.

Graduate Institute of Oncology, College of Medicine, National Taiwan University, Taipei, Taiwan. National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital, Taipei, Taiwan.

Purpose: To clarify the effects of cyclin E1 suppression on antitumor efficacy of sorafenib in hepatocellular carcinoma cells and to explore the potential of combining sorafenib with cyclin-dependent kinase (CDK) inhibition in therapy.

Experimental Design: The effects of cyclin E1 suppression on sorafenib-induced apoptosis were tested in both sorafenib-sensitive (Huh-7 and HepG2, IC50 5-6 μmol/L) and sorafenib-resistant (Huh-7R and HepG2R, IC50 14-15 μmol/L) hepatocellular carcinoma cells. The activity of pertinent signaling pathways and the expression of cell cycle and apoptosis-related proteins were measured using Western blotting. Efficacy of sorafenib combined with the pan-CDK inhibitor flavopiridol was tested both in vitro and in xenograft experiments. The pertinent downstream mediators of antitumor efficacy were tested in transient transfection and RNA interference experiments.

Results: Cyclin E1 mRNA and protein expressions were suppressed after sorafenib treatment in sorafenib-sensitive but not in sorafenib-resistant hepatocellular carcinoma cells. Changes in cyclin E2 or D1 were not correlated with sorafenib sensitivity. The knockdown of cyclin E1 expression reversed the resistance of hepatocellular carcinoma cells to sorafenib in terms of cell growth and apoptosis induction, whereas the overexpression of cyclin E1 increased the resistance to sorafenib. The growth-inhibitory and apoptosis-inducing effects of sorafenib were enhanced by flavopiridol, and Mcl-1 suppression was determined to play a critical role in mediating this enhancing effect.

Conclusions: The cyclin E1 suppression in hepatocellular carcinoma cells may serve as a pharmacodynamic biomarker for predicting sorafenib efficacy. The combination of sorafenib and CDK inhibitors may improve the efficacy of sorafenib in hepatocellular carcinoma. Clin Cancer Res; 22(10); 2555-64. ©2015 AACR.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-0499DOI Listing
May 2016

Zebrafish as a disease model for studying human hepatocellular carcinoma.

World J Gastroenterol 2015 Nov;21(42):12042-58

Jeng-Wei Lu, Yi-Ju Yang, Heng-An Liao, Liang-In Lin, Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei 100, Taiwan.

Liver cancer is one of the world's most common cancers and the second leading cause of cancer deaths. Hepatocellular carcinoma (HCC), a primary hepatic cancer, accounts for 90%-95% of liver cancer cases. The pathogenesis of HCC consists of a stepwise process of liver damage that extends over decades, due to hepatitis, fatty liver, fibrosis, and cirrhosis before developing fully into HCC. Multiple risk factors are highly correlated with HCC, including infection with the hepatitis B or C viruses, alcohol abuse, aflatoxin exposure, and metabolic diseases. Over the last decade, genetic alterations, which include the regulation of multiple oncogenes or tumor suppressor genes and the activation of tumorigenesis-related pathways, have also been identified as important factors in HCC. Recently, zebrafish have become an important living vertebrate model organism, especially for translational medical research. In studies focusing on the biology of cancer, carcinogen induced tumors in zebrafish were found to have many similarities to human tumors. Several zebrafish models have therefore been developed to provide insight into the pathogenesis of liver cancer and the related drug discovery and toxicology, and to enable the evaluation of novel small-molecule inhibitors. This review will focus on illustrative examples involving the application of zebrafish models to the study of human liver disease and HCC, through transgenesis, genome editing technology, xenografts, drug discovery, and drug-induced toxic liver injury.
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http://dx.doi.org/10.3748/wjg.v21.i42.12042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4641123PMC
November 2015

Frequent BRAF mutation in early-onset colorectal cancer in Taiwan: association with distinct clinicopathological and molecular features and poor clinical outcome.

J Clin Pathol 2016 Apr 23;69(4):319-25. Epub 2015 Oct 23.

Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Taiwan.

Background: Occurrence of early-onset colorectal cancer (EOCRC) under the age of 30 is very rare and the molecular characteristics are poorly understood. A low BRAF mutation rate has been noted in several studies of EOCRC from Western countries.

Aims: To determine the clinicopathological and molecular features of EOCRCs in Taiwan.

Methods: KRAS/BRAF gene mutation, mismatch repair protein immunohistochemistry, microsatellite instability and CpG island methylation phenotype analyses were examined to determine the molecular characteristics of EOCRC.

Results: Sixty-six patients with EOCRC at our hospital between 2000 and 2012 were studied. BRAF mutation was detected in 11 of the 59 tumours analysed (19%) and the rate was significantly higher than the overall BRAF mutation rate of colorectal cancer in patients older than 30 years (p<0.001). Clinically, 9 of 11 patients with BRAF-mutated tumours presented with advanced-stage diseases and they presented significantly more frequently with stage IV disease than those with BRAF wild-type tumours (p=0.042). Histologically, BRAF mutation was associated with a poorly differentiated histology, a serrated precursor polyp and focal signet ring cell differentiation (p=0.042, 0.008 and 0.008, respectively). None of the BRAF-mutated tumours was mismatch repair protein-deficient and/or microsatellite instability-high. Overall survival of patients with BRAF-mutated tumours was significantly worse than that of patients with BRAF wild-type tumours, despite adjustment for the disease stages and tumour differentiation.

Conclusions: BRAF mutation was frequent in EOCRCs in Taiwan and was associated with distinct clinicopathological and molecular features.
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http://dx.doi.org/10.1136/jclinpath-2015-203335DOI Listing
April 2016

Traditional serrated adenoma with BRAF mutation is associated with synchronous/metachronous BRAF-mutated serrated lesions.

Histopathology 2016 May 25;68(6):810-8. Epub 2015 Oct 25.

Department of Pathology, National Taiwan University, Taipei, Taiwan.

Aims: To determine whether traditional serrated adenoma (TSA) results in an increased risk of developing subsequent serrated polyps or colorectal cancer (CRC).

Methods And Results: We recruited 111 patients with an index TSA, and analysed the pathological and molecular features of their synchronous/metachronous serrated lesions. Fifty hyperplastic polyps, 14 sessile serrated adenomas, an additional 27 TSAs and 17 CRCs were identified from 46 patients. Twenty-seven percent of TSAs showed a precursor serrated polyp in the periphery and were strongly correlated with BRAF mutation (P < 0.001). Serrated polyps occurred more commonly in patients with BRAF-mutated index TSAs than in patients with KRAS-mutated index TSAs. BRAF-mutated index TSAs were strongly associated with a right-sided location and BRAF mutation of synchronous/metachronous serrated polyps (P = 0.013 and P = 0.005, respectively). The 17 CRCs occurred more frequently in women, and were characterized by a high BRAF mutation rate (59%), a positive CpG island methylator phenotype (59%), and stable or low levels of microsatellite instability (77%).

Conclusions: BRAF-mutated TSA is distinct from KRAS-mutated TSA in predisposing to the acquisition of subsequent serrated neoplasia. This indicates the presence of an intestinal field defect in the tumour microenvironment that results in tumour initiation and malignant progression.
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http://dx.doi.org/10.1111/his.12814DOI Listing
May 2016

Deoxyinosine repair in nuclear extracts of human cells.

Cell Biosci 2015 8;5:52. Epub 2015 Sep 8.

Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC ; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 10002 Taiwan ROC.

Background: Deamination of adenine can occur spontaneously under physiological conditions generating the highly mutagenic lesion, hypoxanthine. This process is enhanced by ROS from exposure of DNA to ionizing radiation, UV light, nitrous acid, or heat. Hypoxanthine in DNA can pair with cytosine which results in A:T to G:C transition mutations after DNA replication. In Escherichia coli, deoxyinosine (hypoxanthine deoxyribonucleotide, dI) is removed through an alternative excision repair pathway initiated by endonuclease V. However, the correction of dI in mammalian cells appears more complex and was not fully understood.

Results: All four possible dI-containing heteroduplex DNAs, including A-I, C-I, G-I, and T-I were introduced to repair reactions containing extracts from human cells. The repair reaction requires magnesium, dNTPs, and ATP as cofactors. We found G-I was the best substrate followed by T-I, A-I and C-I, respectively. Moreover, judging from the repair requirements and sensitivity to specific polymerase inhibitors, there were overlapping repair activities in processing of dI in DNA. Indeed, a hereditable non-polyposis colorectal cancer cell line (HCT116) demonstrated lower dI repair activity that was partially attributed to lack of mismatch repair.

Conclusions: A plasmid-based convenient and non-radioisotopic method was created to study dI repair in human cells. Mutagenic dI lesions processed in vitro can be scored by restriction enzyme cleavage to evaluate the repair. The repair assay described in this study provides a good platform for further investigation of human repair pathways involved in dI processing and their biological significance in mutation prevention.
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http://dx.doi.org/10.1186/s13578-015-0044-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4563847PMC
September 2015

Suramin Inhibits Chikungunya Virus Entry and Transmission.

PLoS One 2015 24;10(7):e0133511. Epub 2015 Jul 24.

Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Department and Graduate Institute of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan.

The mosquito-borne Chikungunya virus (CHIKV) is a profound global threat due to its high rate of contagion and the lack of vaccine or effective treatment. Suramin is a symmetric polyanionic naphthylurea that is widely used in the clinical treatment of parasite infections. Numerous studies have reported the broad antiviral activities of suramin; however, inhibition effects against CHIKV have not yet been demonstrated. The aim of this study was thus to investigate the antiviral effect of suramin on CHIKV infection and to elucidate the molecular mechanism underlying inhibition using plaque reduction assay, RT-qPCR, western blot analysis, and plaque assay. Microneutralization assay was used to determine the EC50 of suramin in the CHIKV-S27 strain as well as in three other clinical strains (0611aTw, 0810bTw and 0706aTw). Time-of-addition was used to reveal the anti-CHIKV mechanism of suramin. We also evaluated anti-CHIKV activity with regard to viral entry, virus release, and cell-to-cell transmission. Cytopathic effect, viral RNA, viral protein, and the virus yield of CHIKV infection were shown to diminish in the presence of suramin in a dose-dependent manner. Suramin was also shown the inhibitory activities of the three clinical isolates. Suramin inhibited the early progression of CHIKV infection, due perhaps to interference with virus fusion and binding, which subsequently prevented viral entry. Results of a molecular docking simulation indicate that suramin may embed within the cavity of the E1/E2 heterodimer to interfere with their function. Suramin was also shown to reduce viral release and cell-to-cell transmission of CHIKV. In conclusion, Suramin shows considerable potential as a novel anti-CHIKV agent targeting viral entry, extracellular transmission, and cell-to-cell transmission.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0133511PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514758PMC
May 2016