Publications by authors named "Maha Al-Rasheed"

21 Publications

  • Page 1 of 1

PD-L1 Expression Is an Independent Marker for Lymph Node Metastasis in Middle Eastern Endometrial Cancer.

Diagnostics (Basel) 2021 Feb 25;11(3). Epub 2021 Feb 25.

Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia.

Programmed death ligand 1 (PD-L1) expression in endometrial cancer (EC) tumor cells have been reported in several studies with inconsistent results. Furthermore, there is scarcity of data on the prevalence and prognostic significance of PD-L1 expression in EC from Middle Eastern ethnicity. We aimed to assess PD-L1 expression in a large cohort of Middle Eastern EC and to correlate this with clinico-pathological factors, as well as mismatch repair (MMR) protein status and patients' outcome. PD-L1 expression was investigated using immunohistochemistry on tissue microarray in an unselected cohort of 440 EC. Kaplan-Meier and logistic regression analysis were used to compare the outcome and prognostic factors. PD-L1 expression in tumor tissue was detected in 18.9% (83/440) EC cases with no impact on survival. When stratified for MMR protein status, PD-L1 expression was similar for both MMR deficient and MMR proficient ECs. However, the expression of PD-L1 in tumor cells was significantly associated with type II (non-endometrioid) histology ( = 0.0005) and lymph node metastasis ( = 0.0172). Multivariate analysis showed PD-L1 expression to be an independent risk factor for lymph node metastasis (odds ratio: 2.94; 95% CI: 1.26-6.84; = 0.0123). In conclusion, PD-L1 was strongly associated with non-endometrioid EC and was an independent prognostic marker of lymph node metastasis.
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http://dx.doi.org/10.3390/diagnostics11030394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996603PMC
February 2021

PD-L1 Expression Is Associated with Deficient Mismatch Repair and Poor Prognosis in Middle Eastern Colorectal Cancers.

J Pers Med 2021 Jan 26;11(2). Epub 2021 Jan 26.

Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia.

Several clinical trials are investigating the use of immune-targeted therapy with Programmed death ligand-1 (PD-L1) inhibitors for colorectal cancer (CRC), with promising results for patients with mismatch repair (MMR) deficiency or metastatic CRC. However, the prognostic significance of PD-L1 expression in CRC is controversial and such data are lacking in CRC from Middle Eastern ethnicity. We carried out this large retrospective study to investigate the prognostic and clinico-pathological impact of PD-L1 expression in Middle Eastern CRC using immunohistochemistry. A total of 1148 CRC were analyzed for PD-L1 expression. High PD-L1 expression was noted in 37.3% (428/1148) cases and was correlated with aggressive clinico-pathological features such as high malignancy grade ( < 0.0001), larger tumor size ( = 0.0007) and mucinous histology ( = 0.0005). Interestingly, PD-L1 expression was significantly higher in patients exhibiting MMR deficiency ( = 0.0169) and mutation ( = 0.0008). Furthermore, the expression of PD-L1 was found to be an independent marker for overall survival (HR = 1.45; 95% CI = 1.06 - 1.99; = 0.0200). In conclusion, the results of this study indicate that PD-L1 expression could be a valid biomarker for poor prognosis in Middle Eastern CRC patients. This information can help in decision-making for anti-PD-L1 therapy in Middle Eastern CRC, especially for patients with MMR deficient tumors.
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http://dx.doi.org/10.3390/jpm11020073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911042PMC
January 2021

POLE and POLD1 germline exonuclease domain pathogenic variants, a rare event in colorectal cancer from the Middle East.

Mol Genet Genomic Med 2020 08 22;8(8):e1368. Epub 2020 Jun 22.

Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Center, iyadh, Saudi Arabia.

Background: Colorectal cancer (CRC) is a major contributor to morbidity and mortality related to cancer. Only ~5% of all CRCs occur as a result of pathogenic variants in well-defined CRC predisposing genes. The frequency and effect of exonuclease domain pathogenic variants of POLE and POLD1 genes in Middle Eastern CRCs is still unknown.

Methods: Targeted capture sequencing and Sanger sequencing technologies were employed to investigate the germline exonuclease domain pathogenic variants of POLE and POLD1 in Middle Eastern CRCs. Immunohistochemical analysis of POLE and POLD1 was performed to look for associations between protein expression and clinico-pathological characteristics.

Results: Five damaging or possibly damaging variants (0.44%) were detected in 1,135 CRC cases, four in POLE gene (0.35%, 4/1,135) and one (0.1%, 1/1,135) in POLD1 gene. Furthermore, low POLE protein expression was identified in 38.9% (417/1071) cases and a significant association with lymph node involvement (p = .0184) and grade 3 tumors (p = .0139) was observed. Whereas, low POLD1 expression was observed in 51.9% (555/1069) of cases and was significantly associated with adenocarcinoma histology (p = .0164), larger tumor size (T3 and T4 tumors; p = .0012), and stage III tumors (p = .0341).

Conclusion: POLE and POLD1 exonuclease domain pathogenic variants frequency in CRC cases was very low and these exonuclease domain pathogenic variants might be rare causative events of CRC in the Middle East. POLE and POLD1 can be included in multi-gene panels to screen CRC patients.
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http://dx.doi.org/10.1002/mgg3.1368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7434734PMC
August 2020

Telomerase reverse transcriptase promoter mutations in cancers derived from multiple organ sites among middle eastern population.

Genomics 2020 03 31;112(2):1746-1753. Epub 2019 Oct 31.

Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia. Electronic address:

Sanger Sequencing and immunohistochemistry was employed to investigate the TERT promoter mutations and TERT protein expression with their association to clinicopathological characteristics in over 2200 samples of Middle Eastern origin from 13 different types of cancers. The TERT promoter mutations were most frequently present in bladder cancer (68.6%), followed by central nervous system tumors (28.7%), thyroid cancer (15.4%), prostate cancer (9.3%), endometrial carcinoma (3.7%), rhabdomyosarcoma (1.4%), colorectal cancer (1%), epithelial ovarian carcinoma (0.7%) and breast cancer (0.7%). No mutations were observed in other types of cancers. In bladder cancer, we found significant inverse association with metastasis and a trend to good survival in patients with TERT mutations. In gliomas, TERT promoter mutations predicted poor prognosis. In thyroid cancer, high frequency of TERT mutation was observed in poorly differentiated carcinoma. In addition, TERT promoter mutations were associated with aggressive markers and poor outcome in follicular thyroid carcinomas.
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http://dx.doi.org/10.1016/j.ygeno.2019.09.017DOI Listing
March 2020

Prognostic significance of DNMT3A alterations in Middle Eastern papillary thyroid carcinoma.

Eur J Cancer 2019 08 4;117:133-144. Epub 2019 Jul 4.

Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Center, Riyadh, 11211, Saudi Arabia. Electronic address:

Background: Thyroid cancer is the second most common cancer affecting Saudi women after breast cancer, with papillary thyroid carcinoma (PTC) accounting for 80-90% of thyroid cancers. DNA methyltransferases affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers.

Methods: We sought to evaluate the frequency of DNA methyltransferase 3A (DNMT3A) alterations in a large cohort of >1000 PTC cases using exome sequencing, capture sequencing, immunohistochemistry and methylation-specific polymerase chain reaction. We also performed in vitro analysis to investigate the role of DNMT3A methylation in PTC cell lines.

Results: DNMT3A pathogenic mutations were noted in 1.2% (12/1013) of PTC cases. Reduced/loss of DNMT3A expression was seen in 59.8% (579/968) of PTC cases and was significantly associated with the DNMT3A mutation (p = 0.0120). DNMT3A alterations (mutation and/or loss of expression) were associated with aggressive clinical parameters and a poor outcome. The promoter region of the DNMT3A gene was methylated in 57.1% of PTC cases tested and was significantly associated with reduced DNMT3A protein expression (p = 0.0253). Treatment of the methylated PTC cell line with 5-aza-2'-deoxycytidine resulted in demethylation of the DNMT3A gene, leading to restoration of its expression. Demethylation significantly potentiated the TRAIL-mediated apoptosis in PTC cells. Interestingly, silencing of DNMT3A using siRNA suppressed TRAIL-mediated apoptosis.

Conclusion: These findings suggest that DNMT3A alterations play an important role in PTC pathogenesis and demethylation agents can be used to restore the function of DNMT3A in a subset of patients with PTC.
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http://dx.doi.org/10.1016/j.ejca.2019.05.025DOI Listing
August 2019

Telomerase reverse transcriptase mutations are independent predictor of disease-free survival in Middle Eastern papillary thyroid cancer.

Int J Cancer 2018 05 29;142(10):2028-2039. Epub 2017 Dec 29.

Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, , Riyadh, 11211, Saudi Arabia.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. Tumor recurrence occurs in ∼20% of PTCs and some reach advanced stages. Promoter mutation in the telomerase reverse transcriptase (TERT) gene is identified to be a prognostic marker in PTC. However, the contribution of TERT promoter mutation to cancer progression in PTC patients is still not fully understood. In this study, we investigated the incidence of TERT promoter mutations and TERT protein expression and their association with clinicopathological outcomes in a large cohort of PTC samples using direct sequencing technology and immunohistochemistry. Furthermore, two PTC cell lines were utilized to investigate role of TERT mutations in mediating metastasis. Two promoter hotspot mutations C228T and C250T were identified in 18.0% (167/927) of our cohort and were significantly associated with poor 5 years disease-free survival and distant metastasis of PTC. TERT protein overexpression was noted in 20.1% of our PTC cohort and was significantly associated with poor prognostic markers such as older age, extrathyroidal extension and Stage IV tumors. A significant association was also found between TERT overexpression and epithelial-mesenchymal transition (EMT) markers. Functional analysis showed that TERT inhibition reduced cell growth, invasion, migration and angiogenesis in PTC via suppression of EMT in PTC cells. Our results suggest that TERT promoter mutation is an independent predictor of disease-free survival and might drive the metastasis, and downregulation of TERT could potentiate antitumor and antimetastatic activities in PTC.
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http://dx.doi.org/10.1002/ijc.31225DOI Listing
May 2018

Molecular markers and pathway analysis of colorectal carcinoma in the Middle East.

Cancer 2015 Nov 28;121(21):3799-808. Epub 2015 Jul 28.

Human Cancer Genomic Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Background: Colorectal cancer (CRC) is one of the most common cancers in the world. A newly proposed integrated pathway comprising traditional, alternate, and serrated pathways by genetic and epigenetic factors was defined recently and hypothesized to play a role in the pathogenesis of CRC; however, to the authors' knowledge, there is a paucity of information regarding these proposed molecular pathways in different ethnic groups.

Methods: Molecular characterization of 770 CRC specimens was performed for microsatellite instability, BRAF, and KRAS by polymerase chain reaction and 500 cases for CpG island methylator phenotype (CIMP) high phenotype by MethyLight technology. Tumors were assigned to different molecular pathways and examined for clinicopathological correlation and survival analysis.

Results: The traditional pathway constituted 33.4% of CRC cases, the alternate pathway comprised 11.6%, and the serrated molecular pathway accounted for only 0.8% of Middle Eastern CRC cases. Approximately 54.2% of CRC cases did not qualify to fit into any pathway and thus were designated as an unassigned group. Molecular pathways were found to be significantly associated with tumor site and grade. A subset of cases with an uncategorized pathway demonstrated a significant survival difference (P = .0079).

Conclusions: The serrated pathway was found to account for a very low percentage of the CRC patient cohort in the current study. The unassigned group accounted for the majority of Middle Eastern CRC cases, and therefore methods of CRC pathway analysis might not be applicable to this ethnic group. The current study demonstrates the need to unravel the molecular genetic basis of this disease to further subcategorize these CRC cases. It also identifies a need for further studies on different populations for a better understanding of their exact role and incidence.
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http://dx.doi.org/10.1002/cncr.29580DOI Listing
November 2015

The potential role of the sodium iodide symporter gene polymorphism in the development of differentiated thyroid cancer.

Gene 2015 Nov 6;572(2):163-8. Epub 2015 Jul 6.

King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Electronic address:

The sodium iodide symporter (NIS) (solute carrier family 5; SLC5A), mediates the active transport of iodine anion (I(-)) into thyroid follicular cells to facilitate thyroid hormone biosynthesis. Considering its fundamental role in thyroid function, our objective in this study is to explore its potential involvement in the pathogenesis of differentiated thyroid cancer (DTC). Following a preliminary sequencing of the gene in a representative sample of the general population, five variants, (1) rs45602038, (2) rs4808708, (3) rs4808709, (4) rs7250346 and (5) rs12327843, were selected for a larger population-based association study consisting of 507 cases and 597 controls, of which only the rs45602038_TT [Odds ratio (95% confidence interval)=1.90 (1.26-2.88); p=0.002] was associated with disease following adjustment for other confounders using the multivariate analysis. Furthermore, a 5-mer haplotype CGAGT constructed from the five studied SNPs conferred a significant risk (χ(2)=10.98; p=0.0009) for DTC. This association trickled down through shorter derivatives, with the 4-mer haplotype CGAG (χ(2)=13.25; p=0.0003) displaying the most significant association and the 3-mer GAG (χ(2)=11.80; p=0.0006) being equally strongly linked to the disease. Comparison of the flanking derivatives of the primary 5-mer haplotype also indicated that the 3-mer CGA (χ(2)=4.04; p=0.045) constructed from SNP block 1-3 was a lot weaker than that of the AGT (χ(2)=6.73; p=0.0095) constructed from the blocks 3-5 from the other end of the gene. Put together, these data implicate the three nucleotide changes at the rs4808708, rs4808709 and rs7250346 loci (blocks 2-4) as the core for this relationship.
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http://dx.doi.org/10.1016/j.gene.2015.07.009DOI Listing
November 2015

Prevalence of Lynch syndrome in a Middle Eastern population with colorectal cancer.

Cancer 2015 Jun 24;121(11):1762-71. Epub 2015 Feb 24.

Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Background: Lynch syndrome (LS; hereditary nonpolyposis colorectal cancer) is a common cause of hereditary colorectal cancer (CRC). CRC is the most common cancer diagnosed among males in Saudi Arabia but to the authors' knowledge there is a lack of data regarding the prevalence of LS in patients with CRC. There currently are no clear guidelines for the selection criteria for these patients to screen for LS.

Methods: A comprehensive molecular characterization was performed in a cohort of 807 CRC cases by immunohistochemical and microsatellite analysis using polymerase chain reaction. BRAF mutation screening, high CpG island methylator phenotype, and analysis for germline mutations were performed in 425 CRC samples. These were all high microsatellite instability (MSI-H) samples (91 cases), all low MSI samples (143 cases), and selected cases from the microsatellite stable group (191 cases) that met revised Bethesda guidelines.

Results: Polymerase chain reaction identified 91 MSI-H cases (11.3%) and sequencing revealed mismatch repair germline mutations in 8 CRC cases only. Of the total of 807 CRC cases, these 8 cases (0.99%) were MSI-H, met the revised Bethesda guidelines, and did not harbor BRAF mutations.

Conclusions: The results of the current study confirmed cases of LS in approximately 1.0% of CRC samples and reflects the efficacy of screening among MSI-H cases that lack BRAF mutations. This comprehensive study from Saudi Arabia will help in implementing a universal screening/reflex testing strategy in a clinical setting in Saudi Arabia and in conducting a national screening program that benefits both patients and their relatives.
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http://dx.doi.org/10.1002/cncr.29288DOI Listing
June 2015

A very low incidence of BRAF mutations in Middle Eastern colorectal carcinoma.

Mol Cancer 2014 Jul 8;13:168. Epub 2014 Jul 8.

Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Center, MBC#98-16, P,O, Box 3354 Riyadh 11211, Saudi Arabia.

Background: Recent studies emphasize the role of BRAF as a genetic marker for prediction, prognosis and risk stratification in colorectal cancer. Earlier studies have reported the incidence of BRAF mutations in the range of 5-20% in colorectal carcinomas (CRC) and are predominantly seen in the serrated adenoma-carcinoma pathway characterized by microsatellite instability (MSI-H) and hypermethylation of the MLH1 gene in the setting of the CpG island methylator phenotype (CIMP). Due to the lack of data on the true incidence of BRAF mutations in Saudi Arabia, we sought to analyze the incidence of BRAF mutations in this ethnic group.

Methods: 770 CRC cases were analyzed for BRAF and KRAS mutations by direct DNA sequencing.

Results: BRAF gene mutations were seen in 2.5% (19/757) CRC analyzed and BRAF V600E somatic mutation constituted 90% (17/19) of all BRAF mutations. BRAF mutations were significantly associated with right sided tumors (p = 0.0019), MSI-H status (p = 0.0144), CIMP (p = 0.0017) and a high proliferative index of Ki67 expression (p = 0.0162). Incidence of KRAS mutations was 28.6% (216/755) and a mutual exclusivity was noted with BRAF mutations (p = 0.0518; a trend was seen).

Conclusion: Our results highlight the low incidence of BRAF mutations and CIMP in CRC from Saudi Arabia. This could be attributed to ethnic differences and warrant further investigation to elucidate the effect of other environmental and genetic factors. These findings indirectly suggest the possibility of a higher incidence of familial hereditary colorectal cancers especially Hereditary non polyposis colorectal cancer (HNPCC) syndrome /Lynch Syndrome (LS) in Saudi Arabia.
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http://dx.doi.org/10.1186/1476-4598-13-168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4109832PMC
July 2014

Colorectal cancer risk is not associated with increased levels of homozygosity in Saudi Arabia.

Genet Med 2013 5;14(8):720-728. Epub 2012 Apr 5.

Human Cancer Genomic Research, Research Centre, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Purpose:Runs of homozygosity (ROHs) represent a measure of the extent of autozygosity and are correlated with the extent of inbreeding. Recently, it has been suggested that ROHs may contribute to the risk of colorectal cancer (CRC). The high rate of consanguinity and CRC in the Saudi population prompted us to test the role of autozygosity in the CRC risk.Methods:We compared 48 Saudi CRC patients to 100 ethnically matched controls, processed on the Affymetrix 250K StyI SNP GeneChip platform and analyzed using the plink package.Results:We could find no evidence of a significant relationship between autozygosity and CRC risk.Conclusion:The negative results in our study add additional significance to what has been previously reported in literature, as this is the first study to address these questions in an inbred population. Our subgroup analysis of patients with microsatellite unstable-positive tumors as compared with other groups did not significantly change our results. Although these results do not rule out the presence of recessively acting CRC-predisposing genes in a small percentage of patients, which our relatively small sample size could not capture, they suggest that such genes are unlikely to account for the disturbingly high incidence of CRC in our consanguineous population.Genet Med advance online publication 5 April 2012.
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http://dx.doi.org/10.1038/gim.2012.27DOI Listing
April 2012

Diagnostic value of recombinant human thyrotropin-stimulated ¹²³I whole-body scintigraphy in the follow-up of patients with differentiated thyroid cancer.

Clin Nucl Med 2012 Mar;37(3):229-34

Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Purpose: Published data on recombinant human thyrotropin- (rhTSH-) stimulated iodine-123 (¹²³I) diagnostic whole-body scintigraphy (DxWBS) in differentiated thyroid cancer (DTC) surveillance after initial treatment are limited. We sought to evaluate this modality's diagnostic value in this setting.

Materials And Methods: We retrospectively compared rhTSH-stimulated ¹²³I DxWBS results with DTC status concurrently determined by stimulated serum thyroglobulin (Tg) measurement, neck ultrasonography, and other imaging studies. Disease was considered present based on stimulated Tg level ≥1 μg/L without interfering Tg autoantibodies with or without positive imaging or biopsy-proven DTC. We also compared scan positivity and disease detection rates of rhTSH-stimulated DxWBS scans obtained with ¹²³I with those acquired with iodine-131 (¹³¹I) during the same period. The sample comprised 105 consecutive totally thyroidectomized patients undergoing rhTSH-aided DxWBS with I-123 (n = 67) or with ¹³¹I (n = 38) for diagnostic follow-up. rhTSH, 0.9 mg/d, was injected intramuscularly on 2 consecutive days. Oral diagnostic activities of 5 to 10 mCi (185-370 MBq) ¹²³I or 3 mCi (111 MBq) ¹³¹I were given on the third day. DxWBS was performed 24 hours (¹²³I) or 48 to 72 hours (¹³¹I) later.

Results: rhTSH-aided ¹²³I DxWBS scans showed 35.3% sensitivity, 98.0% specificity, 85.7% positive predictive value, and 81.6% negative predictive value. rhTSH-stimulated ¹²³I and ¹³¹I DxWBS did not differ in scan positivity (10.4% vs. 13.2%, P = 0.75) or disease detection rates (35.3% vs. 27.8%, P = 1.00).

Conclusions: In DTC, rhTSH-aided ¹²³I DxWBS achieves comparable results in diagnostic follow-up with those of rhTSH-aided ¹³¹I DxWBS. Future studies should address the preablation setting and scan activity and timing.
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http://dx.doi.org/10.1097/RLU.0b013e31823ea463DOI Listing
March 2012

Demethylation of TMS1 gene sensitizes thyroid cancer cells to TRAIL-induced apoptosis.

J Clin Endocrinol Metab 2011 Jan 6;96(1):E215-24. Epub 2010 Oct 6.

Department of Human Cancer Genomics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.

Context: TMS1 is a tumor suppressor gene that encodes for caspase recruitment domain containing regulatory protein and has been shown to be hypermethylated in various cancers. However, its methylation status has not been investigated in thyroid cancer. Therefore, we studied the methylation of TMS1 and its functional consequence in thyroid cancer.

Design: The methylation status of the promoter region of the TMS1 gene was determined using methylation-specific PCR in 40 papillary thyroid cancer samples, 10 normal thyroid tissue, and seven thyroid cancer cell lines. RT-PCR and Western blot analysis were used to assess the expression levels. 5-aza-2'-deoxycytidine was used to demethylate the thyroid cancer cell lines. Cell viability and apoptosis was determined by dimethylthiazoldiphenyltetra-zoliumbromide and flow cytometry.

Results: Twenty-three percent of the papillary thyroid carcinoma samples were found to be methylated for the TMS1 gene. Two of seven thyroid cell lines were either completely or partially methylated for the TMS1 gene. The treatment of methylated thyroid cancer cell lines with 5-aza-2'-deoxycytidine resulted in the demethylation of the TMS1 gene leading to the restoration of its expression. After demethylation, treatment of cells with TNF-related apoptosis-inducing ligand (TRAIL) led to the induction of apoptosis via activation of caspases-8, caspase-3, and poly(ADP-ribose) polymerase. Interestingly, gene silencing of TMS1 using TMS1-specific small interfering RNA prevented TRAIL-mediated apoptosis.

Conclusion: Our results demonstrated that the TMSI gene is methylated in thyroid cancer cells and repression of methylation by 5-aza-2'-deoxycytidine restored expression of the TMS1 gene and sensitized cells to TRAIL-induced apoptosis. These findings suggest that the TMS1 gene can be targeted by combination of demethylating agents with TRAIL to induce efficient apoptosis in thyroid cancer cells.
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http://dx.doi.org/10.1210/jc.2010-0790DOI Listing
January 2011

Leptin-R and its association with PI3K/AKT signaling pathway in papillary thyroid carcinoma.

Endocr Relat Cancer 2010 Mar 18;17(1):191-202. Epub 2010 Feb 18.

Department of Human Cancer Genomic Research, Research Center, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.

The putative role of leptin and its receptor (Ob-R) in the pathogenesis of various primary human malignancies has been reported; however, their role in papillary thyroid cancer (PTC) has not yet been evaluated. We investigated the role of Ob-R in a large tissue microarray cohort of PTC followed by in vitro studies using a panel of PTC cell lines. Ob-R overexpression was seen in 80% PTCs and was significantly associated with poor disease-free survival (P=0.0235). PTCs that overexpressed Ob-R showed a aggressive phenotype characterized by older age, extrathyroid extension, larger tumor size, nodal metastasis, advanced stage, tall cell variant histological subtype, and a poor disease-free survival (P=0.0005, P=0.0006, P=0.0398, P=0.0004, P=0.0111, P=0.0003, and P=0.0235 respectively). However, Ob-R expression was not an independent prognostic marker to predict disease-free survival in multivariate analysis. PTCs with overexpression of Ob-R showed a significant direct association with overexpression of XIAP (P<0.0001) and Bcl-XL (P<0.0001). In vitro analysis showed that leptin stimulated cell proliferation and inhibited apoptosis via activation of phosphatidylinisitol 3' kinase (PI3K)/protein kinase B (AKT) signaling pathway. Inhibition of PI3K activity by its inhibitor LY294002 abrogated leptin-mediated PI3K/AKT signaling. Gene silencing of Ob-R in PTC cells resulted in downregulation of phospho-AKT, Bcl-XL, and XIAP expression suggesting that leptin-mediated pathogenesis of PTC occurs via involvement of these downstream targets. Altogether, these data show that leptin plays an important role in PTC pathogenesis through PI3K/AKT pathway via Ob-R and is a potential prognostic marker associated with an aggressive phenotype and poor disease-free survival.
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http://dx.doi.org/10.1677/ERC-09-0153DOI Listing
March 2010

Fatty acid synthase and AKT pathway signaling in a subset of papillary thyroid cancers.

J Clin Endocrinol Metab 2008 Oct 5;93(10):4088-97. Epub 2008 Aug 5.

Department of Human Cancer Genomic Research, King Fahad National Center for Children's Cancer and Research, King Faisal Specialist Hospital and Research Cancer, Riyadh 11211, Saudi Arabia.

Context: Fatty acid synthase (FASN) is an enzyme that plays a critical role in de novo synthesis of fatty acids. FASN is overexpressed in variety of human cancers, but its role has not been elucidated in papillary thyroid carcinoma (PTC).

Objective: Our objective was to investigate the role of FASN and its relationship with phosphatidylinositol 3-kinase/AKT activation in a large series of PTC in a tissue microarray format followed by studies using PTC cell lines and Nude mice.

Design: Analysis of apoptosis and cell cycle were evaluated by flow cytometry and DNA fragmentation assays. FASN and phospho-AKT protein expression was determined by immunohistochemistry and Western blotting.

Results: Our data show that expression of FASN is associated with activated AKT (phospho-AKT) in a subset of PTC. Treatment of PTC cell lines (NPA-187, ONCO-DG-1, and B-CPAP) with C-75, an inhibitor of FASN, suppresses growth and induces apoptosis in all cell lines. Treatment of PTC cells with C-75 or expression of FASN small interfering RNA causes down-regulation of FASN and inactivation of AKT activity. Furthermore, treatment of PTC cell lines with C-75 results in apoptosis via the mitochondrial pathway involving the proapoptotic factor Bad, activation of Bax, activation of caspases, and down-regulation of antiapoptotic proteins. Finally, treatment of NPA-187 xenografts with C-75 results in growth inhibition of tumors in Nude mice via down-regulation of FASN expression and inactivation of AKT.

Conclusions: Our results suggest that FASN and activated AKT pathway may be a potential target for therapeutic intervention for the treatment of PTC.
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http://dx.doi.org/10.1210/jc.2008-0503DOI Listing
October 2008

Polymorphisms of selected xenobiotic genes contribute to the development of papillary thyroid cancer susceptibility in Middle Eastern population.

BMC Med Genet 2008 Jul 5;9:61. Epub 2008 Jul 5.

Cancer Genomics, Research Centre, King Fahad National Center for Children's Cancer & Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Background: The xenobiotic enzyme system that enables us to detoxify carcinogens exhibits identifiable genetic polymorphisms that are highly race specific. We hypothesized that polymorphisms of these genes may be associated with risk of thyroid cancer. To evaluate the role of genetic polymorphisms of xenobiotic genes in thyroid cancer, we conducted a hospital-based case-control study in Saudi population.

Methods: 223 incident papillary thyroid cancer cases and 513 controls recruited from Saudi Arabian population were analyzed for the association between polymorphisms in genes encoding folic acid metabolizing enzymes MTHFR and six xenobiotics-metabolizing enzymes including CYP1A1 T3801C, C4887A, GSTP1 A1578G, C2293T, GSTM1, GSTT1, NAT2 G590A, NQO*1 C609T, using PCR-RELP.

Results: Among selected genes, CYP1A1 C4887A genotypes CA, AA and variant allele A demonstrated significant differences and greater risk of developing thyroid cancer comparing to wild type genotype CC (CA vs. CC; p < 0.0001, OR = 1.91, 95% CI = 1.36-2.70, AA vs. CC; p < 0.001, OR = 3.48, 95% CI = 1.74-6.96 and CA+AA vs. CC; p < 0.0001, OR = 2.07, 95% CI = 1.49-2.88). GSTT1 null showed 3.48 times higher risk of developing thyroid cancer (p < 0.0001, 95% CI = 2.48-4.88) while GSTM1 null showed protective effect (p < 0.05, OR = 0.72, 95% CI = 0.52-0.99). Remaining loci demonstrated no significance with risk.

Conclusion: Of the 9 polymorphisms screened, we identified GST, GSTM1 and CYP1A1 C4887A, may be of importance to disease process and may be associated with papillary thyroid cancer risk in Saudi Arabian population.
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http://dx.doi.org/10.1186/1471-2350-9-61DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2492854PMC
July 2008

Polymorphisms of drug-metabolizing enzymes CYP1A1, GSTT and GSTP contribute to the development of diffuse large B-cell lymphoma risk in the Saudi Arabian population.

Leuk Lymphoma 2008 Jan;49(1):122-9

Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

The last four decades have seen significant increase in the incidence of non-Hodgkin lymphoma (NHL) as a possible result of increasing environmental carcinogens exposure. Based on the increasing evidence for the association between carcinogen-exposure-related cancer risk and xenobiotic gene polymorphisms, we have undertaken a hospital based case-control study on xenobiotic gene polymorphisms in Saudi individuals with a diagnosis of diffuse large B-cell lymphoma (DLBCL). Polymorphisms in five genes (CYP1A1, GSTT1, GSTP1, GSTM1, and NQO1) were characterized in 182 individuals with DLBCL and 513 normal controls using PCR-RFLP method. The CYP1A1*2C (p = 0.011, OR: 6.62, and 95% CI: 1.56-28.10), GSTT1 null (p < or = 0.001, OR: 11.94, 95% CI: 7.88-18.12), and GSTP1 TT genotypes (p = 0.017, OR: 3.42, 95% CI 1.26-9.38) demonstrated significant association of DLBCL risk. None of the other alleles tested for proved to be significant indicators of DLBCL risk. Our findings suggest that polymorphisms of xenobiotic metabolizing enzyme genes may modify the individual susceptibility to develop DLBCL in Saudi Arabian population.
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http://dx.doi.org/10.1080/10428190701704605DOI Listing
January 2008

Genetic polymorphisms of methylenetetrahydrofolate reductase and promoter methylation of MGMT and FHIT genes in diffuse large B cell lymphoma risk in Middle East.

Ann Hematol 2007 Dec 22;86(12):887-95. Epub 2007 Aug 22.

Department of Human Cancer Genomic Research Centre, King Fahad National Center for Children's Cancer and Research, Riyadh, Saudi Arabia.

Diffuse large B cell lymphoma (DLBCL) is one of the most common non-Hodgkin's lymphoma types. Methylenetetrahydrofolate reductase (MTHFR) balances the pool of folate coenzymes in one carbon metabolism of deoxyribonucleic acid (DNA) synthesis and methylation; both are implicated in carcinogenesis of many types of cancer including lymphoma. Two common variants in the MTHFR gene (C677T and A1298C) have been associated with reduced enzyme activity, thereby making MTHFR polymorphisms a potential candidate as a cancer-predisposing factor. The O6 methylguanine DNA methyltransferase (MGMT) and fragile histidine triad (FHIT) genes are transcriptionally silenced by promoter hypermethylation in DLBCL. These genetic differences are highly race specific and have never been screened in the Saudi DLBCL patients. We conducted a hospital-based case-control study including 160 DLBCL cases and 511 Saudi control samples analyzing the MTHFR C677T and A1298C functional polymorphisms by the restriction fragment length polymorphism method and their association with MGMT and FHIT genes promoter hypermethylation. Our data demonstrated that Saudi individuals carrying MTHFR genotype 1298CC (p < 0.001) and the 1298C allele (p = 0.012) had 4.23 and 1.73-fold higher risk of developing DLBCL, respectively. Additionally, combined genotype CCCC (MTHFR 677CC + MTHFR 1298CC) was associated with 3.489-fold, and CTCC (MTHFR 677 CT + 1298CC) was related to 9.515-fold higher risk, compared with full MTHFR enzyme activity. No significant association between MTHFR variant genotypes and methylation of MGMT and FHIT genes were observed. Our findings suggested that polymorphisms of MTHFR enzyme genes might be associated with the individual susceptibility to develop DLBCL. Additionally, the results indicated that MTHFR variants were not related to MGMT or FHIT hypermethylation in DLBCL.
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http://dx.doi.org/10.1007/s00277-007-0350-2DOI Listing
December 2007

Frequent silencing of fragile histidine triad gene (FHIT) in Burkitt's lymphoma is associated with aberrant hypermethylation.

Genes Chromosomes Cancer 2004 Dec;41(4):321-9

King Fahd National Centre for Children's Cancer, KFSHRC, Riyadh, Saudi Arabia.

The fragile histidine triad (FHIT) gene, a potential tumor-suppressor gene, is frequently inactivated in multiple human cancers. However, the FHIT gene remains largely unexplored in Burkitt's lymphoma (BL). Hence, we assessed whether loss of FHIT expression occurs in BL, and, if so, what is the mechanism of such loss. Lack of protein expression was observed in 50% of BL cell lines. Methylation-specific polymerase chain reaction (MSP) showed that 45% of BL cell lines carried aberrantly methylated FHIT alleles. Sequencing of bisulfite-treated DNA confirmed these data and indicated a very high density of methylation in all methylated alleles. Real-time, quantitative reverse-transcription PCR analysis indicated that attenuation of full-length FHIT transcription was correlated with methylation. Sequencing of transcripts illustrated that aberrant transcription resulting in loss of FHIT exons occurred more commonly in BL containing unmethylated FHIT genes. However, such transcripts often coexisted with full-length FHIT transcripts. Not surprisingly, therefore, loss of FHIT protein in BL correlated with CpG island methylation, rather than with aberrant transcription. FHIT methylation also was detected in 31% (16 of 51) of the primary BLs examined, including 2 samples whose derived cell lines also manifested FHIT hypermethylation. Aberrant methylation can thus occur in vivo. In summary, this report provides evidence that epigenetic modification frequently results in loss of FHIT expression in BL.
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http://dx.doi.org/10.1002/gcc.20099DOI Listing
December 2004

Differences in the expression of apoptotic proteins in Burkitt's lymphoma cell lines: potential models for screening apoptosis-inducing agents.

Leuk Lymphoma 2004 Feb;45(2):357-62

King Fahad National Centre for Children's Cancer & Research, KFSH&RC, Riyadh, Saudi Arabia.

Mammalian cells undergo programmed cell death by orchestrated interactions involving multiple independent pathways. At least one of them, the p53-dependent pathway is commonly compromised in Burkitt's lymphoma (BL) cell lines. Differences in the integrity of this pathway in various BL cell lines have made them useful experimental models in understanding response to standard or novel antitumor drugs vis-a-vis the p53 pathway. Non-p53-dependent loss of apoptotic regulation also contributes to the genesis and/or progression of lymphomas and it is possible that BL cell lines also represent these models. We have characterized the expression of multiple apoptotic proteins in a panel of BL cell lines and describe cell lines with loss of cIAP1, cIAP2, Bax, Bak, Bcl-Xs and p38 MAP-kinase. This data should make this panel of cell lines a useful screening system for testing novel apoptotic inducers.
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http://dx.doi.org/10.1080/10428190310001595713DOI Listing
February 2004