Association of androgen receptor, prostate-specific antigen, and CYP19 gene polymorphisms with prostate carcinoma and benign prostatic hyperplasia in a north Indian population.

The genes involved in androgen pathway and metabolism have been reported to contribute considerably to prostate carcinoma (CaP) risk. The present study investigated the association of androgen receptor (AR), prostate-specific antigen (PSA or KLK3), and cytochrome P450 (CYP19) gene polymorphisms in CaP (n=105) and benign prostatic hyperplasia (BPH) (n=120) in comparison to normal healthy controls (n=106) in an Indian population. We also evaluated the functional consequences of these gene variants on AR and PSA mRNA expression. Significant association of short AR CAG repeats (≤24) with risk of CaP (odds ratios [OR]=2.98, p<0.001) and BPH (OR=1.96, p=0.01) was observed; however, CYP19 gene polymorphism was not found to be associated with disease phenotype (p>0.05). PSA G-158A SNP was found to be significantly associated with risk of CaP (AA: OR=2.68, p=0.016 and GA: OR=2.07, p=0.018) p-trend 0.031 and BPH (AA: OR=3.46, p<0.001 and GA: OR=2.47, p=0.03) p-trend 0.009, respectively. PSA G-158A genotype independently increased the risk of developing BPH (OR=16.37, p<0.001), irrespective of AR CAG repeat length. Using quantitative real-time polymerase chain reaction, we found a significant upregulation of AR and PSA mRNA expression in CaP comparison to BPH. While short AR CAG (≤24) repeats were associated with higher AR mRNA expression in CaP (p=0.002), the PSA SNP did not correlate with its mRNA expression. Interestingly, significantly higher risk estimates for CaP were observed for the combined analysis of short AR CAG and CYP19 genotypes (A2A2) (OR=7.18, p<0.001) or A2A3 (OR=7.60, p=0.004). Our results suggest significant association of androgen signaling gene polymorphisms with risk of CaP and BPH and provide evidence for a putative functional role of AR CAG repeat in regulating its mRNA expression and warrant the need of larger studies in the Indian population to confirm our results.

Study on predictive role of AR and EGFR family genes with response to neoadjuvant chemotherapy in locally advanced breast cancer in Indian women.

Locally advanced breast cancer (LABC) remains a clinical challenge as the majority of patients with this diagnosis develop distant metastases despite appropriate therapy. We analyzed expression of steroid and growth hormone receptor genes as well as gene associated with metabolism of chemotherapeutic drugs in locally advanced breast cancer before and after neoadjuvant chemotherapy (NACT) to study whether there is a change in gene expression induced by chemotherapy and whether such changes are associated with tumor response or non-response. Fifty patients were included with locally advanced breast cancer treated with cyclophosphamide, adriamycin, 5-fluorouracil (CAF)-based neoadjuvant chemotherapy before surgery. Total RNA was extracted from 50 match samples of pre- and post-NACT tumor tissues. RNA expression levels of epidermal growth factor receptor family genes including EGFR, ERBB2, ERBB3, androgen receptor (AR), and multidrug-resistance gene 1 (MDR1) were determined by quantitative real-time reverse transcriptase-polymerase chain reaction. Responders show significantly high levels of pre-NACT AR gene expression (P = 0.016), which reduces following NACT (P = 0.008), and hence can serve as a useful tool for the prediction of the success of neoadjuvant chemotherapy in individual cancer patients with locally advanced breast carcinoma. Moreover, a significant post-therapeutic increase in the expression levels of EGFR and MDR1 gene in responders (P = 0.026 and P < 0.001) as well as in non-responders (P = 0.055, P = 0.001) suggests that expression of these genes changes during therapy but they do not have any impact on tumor response, whereas a post-therapeutic reduction was observed in AR in responders. This indicates an independent predictive role of AR with response to NACT.

Androgen receptor status predicts response to chemotherapy, not risk of breast cancer in Indian women.

BACKGROUND: Considerably little is known about the biological role and clinical significance of androgen receptor expression in breast cancer. The objectives of this study were to characterize AR-CAG repeat genotypes in a cohort of women with breast cancer and to determine the influence of AR on response to neoadjuvant chemotherapy and clinical outcome. MATERIALS AND METHODS: Genotyping of the AR CAG repeat region was done on 70 patients and 80 healthy aged- matched female controls. To assess response to NACT, tissue samples from 30 LABC cases were evaluated quantitatively by real time for AR mRNA expression. The clinical response was correlated with both the pre and post chemotherapy AR expression. The CAG alleles did not show differences between cases and controls when the mean of short, long and average length of both CAG alleles was considered. However, analysis when done defining short allele as CAGn < 20 (AR1) and the long as CAGn ≥ 20 (AR2), risk was found associated with AR2 allele with marginal significance (P = 0.09). Stratification by age of onset, FH, stage, grade ER and AR status failed to reveal any association with breast cancer risk. Genotype carriers with ≥ 20 CAGn showed decrease of AR mRNA expression although significance could not be established (P = 0.47). Tumours in responders had the higher AR mRNA expression levels in pre neo-adjuvant chemotherapy condition (p < 0.02) which got reduced after neoadjuvant chemotherapy and the difference was found to be significant (P = 0.014). CONCLUSIONS: Although, expansion of the CAGn in the AR gene doesn't show any major effect on breast cancer risk, patients with positive AR expression, pre neoadjuvant chemotherapy, were found to be good responders and a decrease in mRNA level of AR gene related to the chemotherapy-induced apoptosis could serve as an important independent predictor of response to NACT.

Betel quid chewing as an environmental risk factor for breast cancer.

Northeast region of India shows high incidence of tobacco-related cancer with widespread consumption of betel quid and tobacco in different forms. There is an increasing incidence of breast cancer and eminent use of tobacco in females in this region. Thus, we analysed the role of tobacco exposure and polymorphisms in detoxification enzymes in breast cancer risk. Polymorphisms in five gene variants (GSTT1, GSTM1, GSTP1, TP53 and CYP17) and four environmental exposure variables (tobacco smoking, tobacco chewing, betel quid chewing, alcohol) were analysed in 117 breast cancer cases and 174 cancer free controls. Multifactor dimensionality reduction identified betel quid chewing as the single main risk factor and women with betel quid chewing history had five times the risk of developing breast cancer [4.78 (2.87-8.00) 0.001]. In logistic regression analysis, GSTT1 null and GSTM1 null genotypes conferred 41% less [0.59 (0.34-1.03) 0.06] and 55% less [0.58 (0.30-1.02) 0.05] reduced risk to breast cancer, respectively. However, the risk increased in women with GSTP1 variant G allele which conferred 1.43 times [(0.96-2.11) 0.07] more risk to breast cancer. In conclusion this study suggests betel quid chewing as a significant risk factor for developing breast cancer. Moreover, the lack of detoxification enzymes GSTT1 and GSTM1 are associated with reduced breast cancer risk.

Vitamin D receptor gene polymorphism(s) and breast cancer risk in north Indians.

BACKGROUND: Vitamin D (1,25-dihydroxyVitamin D3) has shown experimentally anticarcinogenic effects and is thought to protect against breast cancer. The actions of Vitamin D are mediated via the Vitamin D receptor (VDR), and the polymorphisms at 3'UTR region of this gene are associated with the risk and progression of breast carcinoma. The current study is an attempt to examine the association of these variations with breast cancer risk in north Indians. METHODS: A total of 160 cases and 140 control subjects were studied for the polymorphisms at 3' end of the VDR gene. A polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method and fragment analysis was performed to determine ApaI and TaqI polymorphisms and variable length poly-A microsatellite repeats. Linkage disequilibrium (LD) was calculated for each pair of polymorphisms. Unadjusted and adjusted odds ratios for breast cancer with genotypes comprising the polymorphic sites were calculated to understand their role towards breast cancer susceptibility. RESULTS: Patient's with long poly-A repeat showed a significant association with disease (chi 2 = 9.52, df = 2, P

CYP17 gene polymorphism and its association with high-risk north Indian breast cancer patients.

A single T > C change at the 5' promoter region of the CYP17 gene is reported to be associated with increased risk of breast cancer. This study evaluates the influence of genetic polymorphism of CYP17 on breast cancer susceptibility. Two hundred and forty-two patients with histopathologically confirmed breast cancer and 212 age-matched controls were included in the present study. Information relating to age at onset of the disease, family history and estrogen receptor status was elicited. Investigation for CYP17 polymorphism was carried out in 106 early onset, 80 late onset and 56 familial cases. The frequencies of two CYP17 alleles were also analyzed in 116 (47.9%) cases with known estrogen receptor (ER) status confirmed immunohistochemically. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect the polymorphism, and the genotypes identified were assigned as homozygous wild type (A1A1), heterozygous variant (A1A2), and homozygous variant (A2A2). Associations between the various genotypes in patients and controls were investigated with Fisher's exact test. All the tests were two tailed. The results showed that the frequency of heterozygous and homozygous CYP17 genotype was higher in early onset breast cancer patients (94.3%) than in controls (80.3%), and the difference was significant (P = 0.001). A highly statistically significant increased risk in carriers of homozygous A2 allele was found in young patients (P < or = 0.001) in comparison with patients having late onset condition (P = 0.260). However, no significant association between the genotype and breast cancer risk was observed among women with strong family history. Further, data had showed that patients (80.6%) with at least one A2 allele tended to exhibit ER-independent cell proliferation, although statistical significance could not be established (P = 0.160). The present findings suggest that CYP17 A2 allele gene polymorphism might play a significant role in breast cancer development in young Indian women.

Contribution of germline BRCA1 and BRCA2 sequence alterations to breast cancer in Northern India.

BACKGROUND: A large number of distinct mutations in the BRCA1 and BRCA2 genes have been reported worldwide, but little is known regarding the role of these inherited susceptibility genes in breast cancer risk among Indian women. We investigated the distribution and the nature of BRCA1 and BRCA2 germline mutations and polymorphisms in a cohort of 204 Indian breast cancer patients and 140 age-matched controls. METHOD: Cases were selected with regard to early onset disease (< or =40 years) and family history of breast and ovarian cancer. Two hundred four breast cancer cases along with 140 age-matched controls were analyzed for mutations. All coding regions and exon-intron boundaries of the BRCA1 and BRCA2 genes were screened by heteroduplex analysis followed by direct sequencing of detected variants. RESULTS: In total, 18 genetic alterations were identified. Three deleterious frame-shift mutations (185delAG in exon 2; 4184del4 and 3596del4 in exon 11) were identified in BRCA1, along with one missense mutation (K1667R), one 5'UTR alteration (22C>G), three intronic variants (IVS10-12delG, IVS13+2T>C, IVS7+38T>C) and one silent substitution (5154C>T). Similarly three pathogenic protein-truncating mutations (6376insAA in exon 11, 8576insC in exon19, and 9999delA in exon 27) along with one missense mutation (A2951T), four intronic alterations (IVS2+90T>A, IVS7+75A>T, IVS8+56C>T, IVS25+58insG) and one silent substitution (1593A>G) were identified in BRCA2. Four previously reported polymorphisms (K1183R, S1613G, and M1652I in BRCA1, and 7470A>G in BRCA2) were detected in both controls and breast cancer patients. Rare BRCA1/2 sequence alterations were observed in 15 out of 105 (14.2%) early-onset cases without family history and 11.7% (4/34) breast cancer cases with family history. Of these, six were pathogenic protein truncating mutations. In addition, several variants of uncertain clinical significance were identified. Among these are two missense variants, one alteration of a consensus splice donor sequence, and a variant that potentially disrupts translational initiation. CONCLUSION: BRCA1 and BRCA2 mutations appear to account for a lower proportion of breast cancer patients at increased risk of harboring such mutations in Northern India (6/204, 2.9%) than has been reported in other populations. However, given the limited extent of reported family history among these patients, the observed mutation frequency is not dissimilar from that reported in other cohorts of early onset breast cancer patients. Several of the identified mutations are unique and novel to Indian patients.