EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) POLYMORPHIC VARIATIONS (-216G/T & -191 C/A) POSE A HIGH RISK TO PATIENTS WITH MALIGNANT GLIOMA.

BACKGROUND: Malignant gliomas are the most frequent and lethal brain tumors. Their molecular aspects remain intangible but current studies have pointed to certain genetic polymorphic loci that pose the risk. The polymorphic sequence variations of the epidermal growth factor receptor gene (EGFR) pathway play a vital role in the glioma risk, and the EGFR variants (216G>T and 191C>A) are identified to affect the risk for the development of different tumors including glioma. AIM: To examine genetic variations of EGFR T rs712829 (216G/T) and rs712830 (191C>A) with respect to glioma risk. MATERIALS AND METHODS: 129 confirmed glioma cases were genotyped against 180 malignancy-free healthy controls by polymerase chain reaction-restriction fragment length polymorphism technique (RFLP). RESULTS: The frequency of the TT homozygous variant of the EGFR -216 G/T genotype differed significantly between cases and controls (49.6% vs. 23.0%) (p < 0.0001). The EGFR -216 G>T allele 'T' was found significantly more frequently in cases (0.56 vs. 0.33 in controls; p < 0.0001). The EGFR -191C>A homozygous 'AA' genotype was implicated significantly more frequently in cases than in controls (p < 0.0001). The distribution of the 'A' variant allele was also more frequent in cases (41.9%) than in controls (14.0%) (0.55 vs. 0.30; p < 0.0001). TC and TA haplotypes showed varied frequency in cases and controls. CONCLUSION: EGFR -216 G>T and -191 C>A variants and haplotypes (TA and TC) of the EGFR gene are very strong risk factors in the development of glioma in the Kashmiri population.

Evaluation of chromosome 1p/19q deletion by Fluorescence in Situ Hybridization (FISH) as prognostic factors in malignant glioma patients on treatment with alkylating chemotherapy.

BACKGROUND: Either deletion or co-deletion of chromosomal arms 1p or 19q is a characteristic and early genetic event in oligodendroglial tumors that is associated with a better prognosis and enhanced response to therapy. Information of 1p/19q status is now regarded as the standard of care when managing oligodendroglial tumors for therapeutic options in anticipation of the increased survival and progression-free survival times associated with it. Keeping this in view, we first time attempted to establish the FISH based detection of 1p/19q deletion in glioma tissue samples to evaluate its role and involvement in the disease. METHOD: Overall 39 glioma cases of different histologies were evaluated by fluorescence in situ hybridization (FISH) technique using specific FISH probes with Olympus BX43 fluorescent microscope to detect chromosomes 1p and 19q or co-deletions therein. RESULTS: Of the 39 glioma samples, overall 27 (69.2%) were found to have deletion either in 1p, 19q or both. Deletions were observed in 23.0%, 7.6% and 38.4% in 1p, 19q and 1p/19q co-deletions respectively. Overall oligidendrioglioma presented with 53.8% (21 of 39) deletions, astrocytoma group showed 12.8% and GBM accounted for 2.5% deletions. Overall survival and disease free survival was seen significantly better in oligidendrioglioma and astrocytoma with deleted tumors as compared to non-deleted ones (p<0.05). CONCLUSION: Allelic losses on 1p and 19q, either discretely or shared, were more frequent in classic oligodendrogliomas than in either astrocytoma or Glioblastoma with better survival and response to therapy.

Favorable role of IDH1/2 mutations aided with MGMT promoter gene methylation in the outcome of patients with malignant glioma.

AIM: The implications of molecular biomarkers IDH1/2 mutations and MGMT gene promoter methylation were evaluated for prognostic outcome of glioma patients. MATERIALS & METHODS: Glioma cases were analyzed for IDH1/2 mutations and MGMT promoter methylation by DNA sequencing and methylation-specific PCR, respectively. RESULTS: Mutations found in IDH1/2 genes totaled 63.4% (N = 40) wherein IDH1 mutations were significantly associated with oligidendrioglioma (p = 0.005) and astrocytoma (p = 0.0002). IDH1 mutants presented more, 60.5% in MGMT promoter-methylated cases (p = 0.03). IDH1 mutant cases had better survival for glioblastoma and oligodendrioglioma (log-rank p = 0.01). Multivariate analysis confirmed better survival in MGMT methylation carriers (hazard ratio [HR]: 0.59; p = 0.031). Combination of both biomarkers showed better prognosis on temozolomide (p < 0.05). CONCLUSION: IDH1/2 mutations proved independent prognostic factors in glioma and associated with MGMT methylation for better survival.

Concordant association validates MGMT methylation and protein expression as favorable prognostic factors in glioma patients on alkylating chemotherapy (Temozolomide).

O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation and its subsequent loss of protein expression has been identified to have a variable impact on clinical outcome of glioma patients indicated for chemotherapy with alkylating agents (Temozolomide). This study investigated methylation status of MGMT gene along with in situ protein expression in malignant glioma patients of different histological types to evaluate the associated clinical outcome vis-a-vis use of alkylating drugs and radiotherapy. Sixty three cases of glioma were evaluated for MGMT promoter methylation by methylation-specific PCR (MS-PCR) and protein expression by immunostaining (IHC). Methylation status of MGMT and loss of protein expression showed a very high concordant association with better survival and progression free survival (PFS) (p < 0.0001). Multivariate Cox regression analysis showed both MGMT methylation and loss of protein as significant independent prognostic factors in glioma patients with respect to lower Hazard Ratio (HR) for better OS and PFS) [p < 0.05]. Interestingly concordant MGMT methylation and lack of protein showed better response in TMZ therapy treated patient subgroups with HR of 2.02 and 0.76 (p < 0.05). We found the merits of prognostication of MGMT parameters, methylation as well as loss of its protein as predictive factors for favorable outcome in terms of better survival for TMZ therapy.

ACE I/D sequence variants but not MTHFR C677T, is strongly linked to malignant glioma risk and its variant DD genotype may act as a promising predictive biomarker for overall survival of glioma patients.

OBJECTIVE: ACE I/D and MTHFR C677T gene polymorphisms can be seen as candidate genes for glioma on the basis of their biological functions and their involvement in different cancers. The aim of this study was to analyze potential association and overall survival between MTHFR C677T and ACE I/D polymorphism in glioma patients in our population. MATERIALS AND METHODS: We tested genotype distribution of 112 glioma patients against 141 cancer-free controls from the same region. Kaplan-Meier survival analysis was performed to evaluate overall survival of patients for both genes. RESULTS: No significant differences were found among MTHFR C677T wild type C and variant genotypes CT/TT with glioma patients. In ACE, the distribution of variant ID and DD was found to be significantly higher in glioma cases as compared to controls (p<0.0001). ACE DD genotypes were highly presented in glioma cases 26.8% versus 10.6% in controls (p<0.0001) and conferred 5-fold risk for predisposition in glioma cases. Per copy D allele frequency was found higher in cases than in controls (0.54 versus 0.25: p<0.0001). Interestingly we found a significant overall survival (with log rank p<0.01) in patients who presented with ACE DD genotypes had the least estimated overall survival of 13.4months in comparison to 21. 7 and 17.6months for ACE II and I/D genotypes respectively. CONCLUSION: We conclude ACE I/D polymorphism plays a vital role in predisposition of higher risk for glioma. We also suggest that ACE DD genotypes may act as an important predictive biomarker for overall survival of glioma patients.

The XRCC1 Arg399Gln gene polymorphism and risk of colorectal cancer: a study in Kashmir.

BACKGROUND: The DNA repair gene XRCC1 Arg399Gln gene polymorphism has been found to be implicated in the development of various cancers, including colorectal cancer (CRC), in different populations. We aimed to determine any association of this polymorphism with the risk of CRC in Kashmir. MATERIALS AND METHODS: A total of 120 confirmed cases of CRC and 146 healthy cancer free controls from the Kashmiri population were included in this study. Genotyping was carried out by the polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: Genotype frequencies of XRCC1 Arg399Gln observed in controls were 34.2%, 42.5% and 23.3% for GG (Arg/Arg), GA (Arg/Gln), AA( Gln/Gln), respectively, and 28.3%, 66.7% and 5% in cases, with an odds ratio (OR)=5.7 and 95% confidence interval (CI) =2.3-14.1 (p=0.0001). No significant association of Arg399Gln SNP with any clinicopathological parameters of CRC was found. CONCLUSIONS: We found the protective role of 399Gln allele against risk to the development of CRC. The XRCC1 heterozygote status appears to be a strong risk factor for CRC development in the Kashmiri population.