Impact of polymorphisms in xeno(endo)biotic metabolism on pattern and frequency of p53 mutations in bladder cancer

DHCR24 predicts poor clinicopathological features of patients with bladder cancer: A STROBE-compliant study

To investigate the prognostic value of DHCR24 for patients with bladder cancer (BC). We used public bladder cancer microarray studies to evaluate the expression of DHCR24 between normal bladder tissues and BC cells, to investigate the relationship between the expression of DHCR24 and the clinical features of BC patients. Survival analysis was performed to investigate the correlation between DHCR24 expression and the survivals of BC patients. Gene set enrichment analysis was conducted to identify relevant mechanisms. The results showed that DHCR24 was up-regulated in BC cells compared with that in normal bladder tissues (P = .0389). Results of chi-square test suggested that BC patients in DHCR24 low expression group were proved to have better clinical characteristics (including tumor grade, disease progression, T staging, and N staging) as compared with those in DHCR24 low expression group (P < .0001, P = .002, P = .005, and P = .002, respectively). BC patients in DHCR24 low expression group were associated with better cancer-specific survival and overall survival (P < .0001 and P = .0008, respectively). DHCR24 might promote the proliferation of BC cells through several oncogenesis-associated biological processes (estrogen response, heme metabolism, P53 pathway, cholesterol homeostasis, mTORC1 signaling, peroxisome, xenobiotic metabolism, glycolysis, and protein secretion). Thus, DHCR24 might be a therapeutic target for patients with BC.

Significant association of catechol-O-methyltransferase Val158Met polymorphism with bladder cancer instead of prostate and kidney cancer

BACKGROUND

Urological cancers occur worldwide. Many factors, among which the catechol-O-methyltransferase (COMT) Val158Met polymorphism, are said to be associated with the cancer risk. We conducted a meta-analysis to investigate the association between urological cancer susceptibility and COMT Val158Met in different genetic models.

METHODS

This study was based on material obtained from the PubMed, HuGENet and Embase databases. Four models including dominant (AA + AG vs. GG), recessive (AA vs. AG + GG), codominant (AA vs. AG, AA vs. GG) and per-allele analysis (A vs. G) were applied. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were used to evaluate the power of the associations.

RESULTS

Fourteen eligible studies comprising 3,285 cases and 3,594 controls were included. Although we could not detect a positive function of the COMT Val158Met polymorphism in urological cancers, the polymorphism might be significantly associated with bladder cancer risk (dominant model [AA + AG vs. GG]: OR = 0.736, 95% CI = 0.586-0.925, I2 = 0.00%; recessive model [AA vs. AG + GG]: OR = 0.822, 95%CI = 0.653-1.035, I2 = 6.30%; codominant model [AA vs. AG]: OR = 0.908, 95% CI = 0.710-1.161, I2 = 0.00%; codominant model [AA vs. GG]: OR = 0.693, 95% CI = 0.524-0.917, I2 = 30.20%; allele analysis [A vs. G]: OR = 0.826, 95%CI = 0.717-0.951, I2 = 30.20%). The same significant associations were not found for kidney cancer and prostate cancer risk in different ethnicities. There also seemed to be no distinct effect of the polymorphism on benign prostatic hyperplasia.

CONCLUSIONS

We suggest that bladder cancer but not prostate cancer and kidney cancer could be significantly associated with the Val158Met polymorphism. Interaction of COMT genetic and related environmental factors for urological cancers should not be ignored in future.

Polymorphisms in apoptosis-related genes and TP53 mutations in non-small cell lung cancer

Apoptosis plays an essential role in the elimination of mutated or transformed cells from the body. Therefore, polymorphisms of apoptosis-related genes may lead to an alteration in apoptotic capacity, thereby affecting the occurrence of TP53 mutations in lung cancer. We investigated the relationship between potentially functional polymorphisms of apoptosis-related genes and TP53 mutations in non-small cell lung cancer (NSCLC). Twenty-seven single nucleotide polymorphisms in 20 apoptosis-related genes were genotyped by a sequenome mass spectrometry-based genotyping assay in 173 NSCLCs and the associations with TP53 mutations in the entire coding exons (exons 2-11), including splicing sites of the gene, were analyzed. None of the 27 polymorphisms was significantly associated with the occurrence of TP53 mutations. This suggests that apoptosis-related genes may not play an important role in the occurrence of TP53 mutations in lung cancer.

Influence of GSTM1, GSTT1, GSTP1 and NAT2 genotypes on the p53 mutational spectrum in bladder tumours

Genetic polymorphisms affecting expression or activity of the corresponding enzymes can influence the risk of acquiring gene mutations and various cancers. We have studied 327 bladder cancer patients with regard to the functionally related polymorphisms of GSTM1, GSTT1, GSTP1 and NAT2 and analysed the p53 mutational status of their tumours. Fifty p53 mutations, 26% transversions and 74% transitions, were detected in 44 patients. P53 mutation frequency was significantly higher in higher-grade tumours than in low-grade tumours (OR = 2.09, 95% CI 1.44-3.02, adjusted for age and sex). Also, a significant association was found between tumour stage (Tis and T2+ vs. Ta and T1) and presence of the GSTP1 val allele (adjusted OR = 2.00, CI 1.14-3.52). Overall, there was no significant difference in frequency of p53 mutation among patients with different genotypes. Among patients with p53 mutation, transversions were significantly more frequent in GSTM1-negative as compared to GSTM1-positive individuals (OR = 5.18, CI 1.07-25.02, adjusted for age, sex and tumour stage). With one exception, all tumours with the most common type of transversion, G:C-C:G, occurred in GSTM1-negative patients. Among smokers, all transversions (3 of 3), but only 2 of 13 transitions, were found among carriers of the GSTP1 variant allele, and samples carrying at least 1 variant GSTP1 allele had more transitions at CpG sites than wild-type samples (adjusted OR = 4.61, CI 0.82-26.04). No significant associations were found for the NAT2 gene. Our results suggest that impaired glutathione conjugation may affect the mutation spectrum in critical target genes.

Genetic polymorphisms of CYP2D6, GSTM1, and GSTT1 genes and bladder cancer risk in North India

The study consisted of 100 patients (97 males and 3 females) suffering from bladder cancer and 76 matching controls. The maximum number of patients in this study was in the age group of 61-70 years. The prevalence of genetic polymorphism in the CYP2D6, GSTM1, and GSTT1 genes has been investigated to find their association with risk of bladder cancer. While there was no association between the heterozygous (HEM) genotype of the CYP2D6 gene with the risk of bladder cancer [odds ratio (OR)=1.00; 95% confidence interval (CI)=0.46-2.16], it was 1.5-fold with poor metabolizers (PM) genotype. When stratified according to different grades of bladder cancer, a significant association was found with an OR=3.54 (95% CI=0.89-13.98) in grade II, 3.3 (95% CI=0.12-20.6) in grade III, and 1.67 (95% CI=0.15-18.45) in grade IV. When stratified in relation to smoking status, significant association of the disease was found in heavy smokers with an OR=2.13 (95% CI=0.71-6.43). Subjects with the null genotype for GSTM1 had a slightly significant association with the bladder cancer risk and the risk increased to 2-fold with the GSTT1 null genotype. Smoking status also revealed an impact on the prevalence of bladder cancer in the individuals with GSTM1 and GSTT1 null genotypes. The results indicated that there is a 3-fold increase in risk of developing this cancer in the presence of one copy of the variant CYP2D6 (HEM) allele and null GSTT1.

Tobacco smoking,GSTP1 polymorphism, and bladder carcinoma

BACKGROUND

Although cigarette smoking is considered a major risk factor for bladder carcinoma, little is known about the interaction between metabolic genes such as glutathione-S-transferase P1 and tobacco smoking in this process. GSTP1 may play a role in detoxification of tobacco-related carcinogens.

METHODS

In this case-control study of 145 cases with bladder carcinoma (male:female = 7.5:1) and 170 noncancer controls (male:female = 3.7:1), the relation between genetic polymorphisms of GSTP1 and susceptibility to bladder carcinoma was investigated and the gene-environment interaction between tobacco smoking and GSTP1 polymorphism was evaluated. Epidemiological data were collected for all cases and controls by a standard questionnaire. Polymorphisms of GSTP1 were measured by polymerase chain reaction-restriction fragment length polymorphism. The logistic regression model in SAS was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

Cigarette smoking was confirmed as a risk factor of bladder carcinoma with an OR of 3.1 (95% CI: 1.7-5.9) after controlling for potential confounding factors. The OR for pack-years of smoking as a continuous variable was 2.4 (95% CI: 2.0-2.8). The ORs were 7.6 (95% CI: 1.18-49.51) for isoleucine/valine (Ile/Val) and 6.5 (95% CI: 1.01-41.56) for Ile/Ile when the homozygous Val/Val was considered as comparison group after adjusting for age, gender, race, and education. The adjusted OR for interaction between smoking and the GSTP1 (any Ile genotype) was 11.42 (95% CI: 0.53-248.15).

CONCLUSIONS

The results indicate that the Ile 105 allele is associated with an increased risk of bladder carcinoma and suggest that individuals who smoke and possess the Ile allele might be at increased risk for bladder carcinoma.

An association between NQO1 genetic polymorphism and risk of bladder cancer

NAD(P)H:quinone oxidoreductase (NQO1) is a detoxification enzyme that plays a critical role in protecting cells against chemically induced oxidative stress, cytotoxicity, mutagenicity, and carcinogenicity. NQO1 protects cells from oxidative damage by preventing the generation of reactive oxygen species and reducing certain environmental carcinogens, such as nitroaromatic compounds, heterocyclic amines, and possible cigarette smoke condensate. A C-->T single nucleotide polymorphism in exon 6 was shown to reduce NQO1 enzyme activity, which may diminish the protection provided by NQO1. Therefore, we hypothesized that people with the variant allele genotypes of NQO1 are at higher risk for bladder cancer. In an ongoing case-control study, the NQO1 genotypes were successfully identified by polymerase chain reaction restriction fragment length polymorphism in 265 bladder cancer patients and 261 control subjects matched for age, sex, and ethnicity. The frequency of the variant NQO1 allele was 18% for controls and 21% for cases. The variant allele genotypes of NQO1 were associated with a higher risk of bladder cancer in Caucasians (odds ratio (OR)=1.51; 95% confidence interval (CI)=1.01-2.25). Further analysis in Caucasians showed an elevated bladder cancer risk in men (OR=1.75; 95% CI=1.08-2.85) but not in women (OR=1.16; 95% CI=0.57-2.37). In addition, the variant allele genotypes were associated with higher bladder cancer risk in ever smokers (OR=1.78; 95% CI=1.06-3.00), but not in never smokers (OR=1.19; 95% CI=0.65-2.20). These results suggest that the NQO1 genetic polymorphism modulates bladder cancer risk, especially in men and ever smokers.

The enhanced bladder cancer susceptibility of NAT2 slow acetylators towards aromatic amines: a review considering ethnic differences

Human bladder cancer may be caused by exposure to aromatic amines. The polymorphic enzyme N-acetyltransferase 2 (NAT2) is involved in the metabolism of these compounds. Two classical studies on chemical workers in Europe, exposed in the past to aromatic amines like benzidine, unambiguously showed that the slow acetylator status is a genetic risk factor for arylamine-induced bladder cancer. In the former benzidine industry in Huddington, Great Britain, 22 of 23 exposed cases with bladder cancer, but only 57% of 95 local controls without bladder cancer were of the slow acetylator phenotype. In Leverkusen, Germany, 82% of 92 benzidine-exposed chemical workers with bladder cancer were of the slow acetylator phenotype, whereas only 48% of 331 chemical workers who had worked at that plant were of the slow acetylator phenotype. This is in line with several smaller studies, which also show an over-representation of the slow acetylator status in formerly arylamine-exposed subjects with bladder cancer. Some of these studies included also subjects that were exposed to aromatic amines by having applied dyes, paints and varnishes. These European findings are in contrast to a large study on Chinese workers occupationally exposed to aromatic amines. In this study, only five of 38 bladder cancer cases occupationally exposed to arylamines were of the slow acetylator genotype. This is much lower than the ratio of slow acetylators to the general population in China. This points to different mechanisms of susceptibility for bladder cancer upon exposure to aromatic amines between European (Caucasian) and Chinese populations.