Low level of BRCA2 in peripheral blood lymphocytes is associated with an increased risk for head and neck squamous cell carcinoma (HNSCC) in a population of North-East India: a case-control study.

Background: We investigated the role of DNA repair proteins breast cancer susceptibility 2 (BRCA2), xeroderma pigmentosum group D (XPD) and apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) in determining the risk for head and neck squamous cell cancer (HNSCC) in a case-control study from North-East India. Methods: Expression of BRCA2, XPD and APE1 genes in the matched tumour, normal adjacent tissue (NAT) and blood of 12 HNSCC patients and blood of 8 age- and gender-matched controls was determined by quantitative real-time PCR. Results were validated by expression analysis of the corresponding proteins in the peripheral blood lymphocytes (PBLs) of 228 subjects (106 patients and 122 controls) by a slot-blot immunoassay. Findings: Expression of the BRCA2 and XPD genes in tumour tissue of HNSCC patients declined progressively as the cancer stage advanced, was reverse that of the NAT, but was mirrored by the expression in the blood. BRCA2 and XPD proteins were significantly (p < 0.0001) downregulated in the PBL of HNSCC patients to 71% and 77% the levels in controls, showing significant negative correlation with HNSCC stage (Spearman correlation coefficient (r s) of -0.9060, p < 0.0001 for BRCA2; r s of -0.8008, p < 0.01 for XPD). On the contrary, APE1 was significantly upregulated in PBL of HNSCC patients to 1.47 fold the level in controls, showing significant positive correlation with HNSCC stage (r s of 0.7023, p < 0.01). Classification and regression tree analyses predicted low levels of BRCA2 protein in PBL as the single most important risk factor for HNSCC, independent of gender. Smokers above 36 years of age with low level of BRCA2 appeared to exhibit a 1.78-fold increased risk for HNSCC (with a 1.78-fold increased risk for HNSCC (OR = 1.78, 95% confidence interval (CI) = 0.33-9.52) though this risk was not significant statistically. Similarly, low levels of BRCA2 appeared to indicate a moderate, but non-significant risk for HNSCC in non-smokers aged between 36 and 56 years (OR = 1.15, 95% CI = 0.21-6.37). Conclusions: Low level of BRCA2 protein in the peripheral blood indicates increased risk for HNSCC.

The GSTM1 and GSTT1 Null Genotypes Increase the Risk for Type 2 Diabetes Mellitus and the Subsequent Development of Diabetic Complications: A Meta-analysis.

BACKGROUND: Studies pertaining to association of GSTM1 and GSTT1 null genotypes with risk of T2DM and its complications were often inconclusive, thus spurring the present study. METHODS: Meta-analysis of 25 studies for evaluating the role of GSTM1/GSTT1 null polymorphisms in determining the risk for T2DM and 17 studies for evaluating the role of GSTM1/GSTT1 null polymorphisms in development of T2DM related complications were conducted. RESULTS: Our study revealed an association between GSTM1 and GSTT1 null polymorphism with T2DM (GSTM1; OR=1.37;95% CI =1.10-1.70 and GSTT1; OR=1.29;95% CI =1.04-1.61) with an amplified risk of 2.02 fold for combined GSTM1-GSTT1 null genotypes. Furthermore, the GSTT1 null (OR=1.56;95%CI=1.38-1.77) and combined GSTM1-GSTT1 null genotypes (OR=1.91;95%CI=1.25- 2.94) increased the risk for development of T2DM related complications, but not the GSTM1 null genotype. Stratified analyses based on ethnicity revealed GSTM1 and GSTT1 null genotypes increase the risk for T2DM in both Caucasians and Asians, with Asians showing much higher risk of T2DM complications than Caucasians for the same. DISCUSSION: GSTM1, GSTT1 and combined GSTM1-GSTT1 null polymorphism may be associated with increased risk for T2DM; while GSTT1 and combined GSTM1-GSTT1 null polymorphism may increase the risk of subsequent development of T2DM complications with Asian population carrying an amplified risk for the polymorphism. CONCLUSION: Thus GSTM1 and GSTT1 null genotypes increases the risk for Type 2 diabetes mellitus alone, in combination or with regards to ethnicity.

BRCA1 and MDM2 as independent blood-based biomarkers of head and neck cancer.

We investigated the role of BRCA1, MDM2, and p53 in the pathogenesis of head and neck cancer (HNC) and evaluated their potential utility as blood-based predictive biomarkers of HNC. Immunostaining of tissue biopsies and whole blood lymphocytes (WBL) of 36 HNC patients were evaluated by immunohistochemistry (IHC) and immunocytochemistry (ICC), respectively. The staining intensities of BRCA1 and MDM2 in matched tissue and blood samples were significantly associated with cancer stage. Furthermore, the cellular levels of BRCA1, MDM2, and p53 were evaluated in peripheral blood lymphocytes (PBL) of 134 HNC patients and 126 controls by slot blotting. Expression levels of all three proteins in PBL of HNC patients varied significantly with respect to those of controls (p < 0.0001) with BRCA1 downregulated to 75 % of control and MDM2 and p53 upregulated to 1.7- and 1.4-fold the control level, respectively. Moreover, positive correlation was observed between expression levels of BRCA1, MDM2, and p53 in matched tissue biopsies-WBL (r s = 0.840, 0.754, and 0.806, respectively), tissue biopsies-PBL (r s = 0.745, 0.736, and 0.776, respectively), and PBL-WBL (r s = 0.709, 0.758, and 0.740, respectively), validating the hypothesis that these proteins may serve as blood-based biomarkers of HNC. Bias-corrected and accelerated (BCa) bootstrap cross-validation estimation of receiver operating characteristics (ROC) analysis established BRCA1 (AUC = 0.726, sensitivity = 89 %, NPV = 82 %) and MDM2 (AUC = 0.827, sensitivity = 85 %, NPV = 81 %) as predictive biomarkers for HNC. In conclusion, this study suggests that BRCA1 and MDM2 play a crucial role in the pathogenesis of HNC and could be used independently as predictive biomarkers for HNC.

Association between OGG1 Ser326Cys polymorphism and risk of upper aero-digestive tract and gastrointestinal cancers: a meta-analysis.

Cancers of the upper aero-digestive and gastrointestinal tract are one of the major causes of mortality around the world. DNA repair genes play a vital role in preventing carcinogenesis by maintaining genomic integrity. Polymorphisms in the nucleotide sequence of DNA repair genes are often reported to be associated with an increased risk for different cancers. The OGG1 gene encodes the enzyme 8-oxoguanine DNA glycosylase which removes oxidatively damaged bases of DNA. Several studies report that the OGG1 Ser326Cys polymorphism increases the risk for cancers of the upper aero-digestive and gastrointestinal tract. However, other studies provide evidence that such an association does not exist. A meta-analysis to assess the role of OGG1 Ser326Cys polymorphism in the cancers of the upper aero-digestive and gastrointestinal tract was therefore undertaken in order to resolve this ambiguity. Seventeen studies were recruited for this meta-analysis after screening 58 articles with a total of 5533 cases and 6834 controls for which the odds ratio with 95 % confidence interval was calculated. Begg's funnel test and Egger's test were performed for calculating publication bias. Our study reveals an association between OGG1 Ser326Cys polymorphism and cancer susceptibility of the upper aero-digestive and gastrointestinal tract (CG + GG vs CC; odds ratio, OR 1.22; 95 % CI 1.05-1.41; GG vs CG + CC; OR 1.36; 95 % CI 1.09-1.70; GG vs CC; OR 1.46; 95 % CI 1.12-1.92). Subgroup analysis based on cancer types and ethnicity also revealed the association of OGG1 Ser326Cys polymorphism to the risk for upper aero-digestive and gastrointestinal tract cancers among both the Asian and the Caucasian populations. No risk was however observed for smoking habits and OGG1 Ser326Cys polymorphism. In conclusion, OGG1 Ser326Cys polymorphism may be associated with the increased risk for aero-digestive tract and gastro-intestinal cancers in both Asian and Caucasian populations.

ATM rs189037 (G > A) polymorphism and risk of lung cancer and head and neck cancer: A meta-analysis.

A number of different epidemiological studies have measured the association between the risk of different cancers and polymorphism at promoter region of 5' untranslated region (5'-UTR) of the Ataxia-telangiectasia mutated (ATM) gene. However the results were contentious rather than conclusive. The current study was aimed at evaluating the association between the SNP (rs189037 G>A) and the risk of head and neck cancer and lung cancer by conducting a meta-analysis. A total of 9 case-control studies were considered for this quantitative analysis. Stats Direct Statistical software (version 2.7.2) was used to evaluate the crude odds ratio (OR) with their 95% confidence interval (CI). The dominant model (GG vs. GA + AA) showed no heterogeneity and the fixed effects pooled OR was found to be significant (OR = 1.14, 95% CI = 1.05-1.25) at p = 0.003. The pooled OR for fixed effects of heterozygote and homozygote mutant allele (GA vs. AA) model was significant (OR = 1.17, 95% CI = 1.04-1.30, p = 0.006) and no heterogeneity was observed for this model. The current meta-analysis manifested that ATM rs189037 G>A genetic polymorphism may contribute increased risk of head and neck and lung cancer. Moreover, the AA mutant allele was found to be related significantly with the prognosis of lung cancer and head and neck cancer.

MDM2 and TP53 Polymorphisms as Predictive Markers for Head and Neck Cancer in Northeast Indian Population: Effect of Gene-Gene and Gene-Environment Interactions.

BACKGROUND: Polymorphisms in the MDM2 309 (T>G) and TP53 72 (G>C) genes are reported to increase the susceptibility to head and neck cancer (HNC) in various populations. The risk for HNC is also strongly associated with etiologic habits such as smoking, alcohol consumption and/or chewing of betel quid (BQ). In a case-control study, we investigated the significance of the above polymorphisms alone, and upon interaction with one another as well as with various etiologic habits in determining HNC risk in a Northeast Indian population. MATERIALS AND METHODS: Genotyping at 309 MDM2 and 72 TP53 in 122 HNC patients and 86 cancer free healthy controls was performed by PCR using allele specific primers, and the results were confirmed by DNA sequencing. RESULTS: Individuals with the GG mutant allele of MDM2 showed a higher risk for HNC in comparison to those with the TT wild type allele (OR=1.9, 95%CI: 1.1-3.3) (p=0.022). The risk was further increased in females by ~4-fold (OR=4.6, 95% CI: 1.1-19.4) (P=0.04). TP53 polymorphism did not contribute to HNC risk alone; however, interaction between the TP53 GC and MDM2 GG genotypes resulted in significant risk (OR=4.9, 95% CI: 0.2-105.1) (p=0.04). Smokers, BQ- chewers and alcohol consumers showed statistically significant and dose- dependent increase in HNC risk, irrespective of the MDM2 genotype. CONCLUSIONS: MDM2 genotype could serve as an important predictive biomarker for HNC risk in the population of Northeast India.

XPD, APE1, and MUTYH polymorphisms increase head and neck cancer risk: effect of gene-gene and gene-environment interactions.

In the present study, we investigated the effect of the DNA repair gene polymorphisms XPD Asp312Asn (G>A), APE1 Asp148Glu (T>G), and MUTYH Tyr165Cys (G>A) on the risk for head and neck cancer (HNC) in association with tobacco use in a population of Northeast India. The study subjects comprised of 80 HNC patients and 92 healthy controls. Genotyping was performed using amplification refractory mutation system-PCR (ARMS-PCR) for XPD Asp312Asn (G>A) and PCR using confronting two-pair primers (PCR-CTPP) for APE1 Asp148Glu (T>G) and MUTYH Tyr165Cys (G>A). The XPD Asp/Asn genotype increased the risk for HNC by 2-fold (odds ratio, OR = 2.072; 95 % CI, 1.025-4.190; p < 0.05). Interaction between APE1 Asp/Asp and XPD Asp/Asn as well as MUTYH Tyr/Tyr and XPD Asp/Asn genotypes further increased the risk by 2.9 (OR = 2.97; 95 % CI, 1.16-7.61; p < 0.05) and 2.3 (OR = 2.37; 95 % CI, 1.11-5.10; p < 0.05) folds, respectively. The risk was further increased in heavy smokers with the XPD Asp/Asn genotype and heavy tobacco chewers with XPD Asn/Asn genotype by 7.7-fold (OR = 7.749; 95 % CI, 2.53-23.70; p < 0.05) and 10-fold (OR = 10; 95 % CI, 1.26-79.13; p < 0.05), respectively. We thus conclude that the XPD Asp312Asn and APE1 Asp148Glu polymorphisms increase the risk for HNC in association with smoking and/or tobacco chewing in the population under study.