Associations differ by sex for catechol-O-methyltransferase genotypes and bladder cancer risk in South Egypt

Uncovering the epidemiology of bladder cancer in the Arab world: A review of risk factors, molecular mechanisms, and clinical features

Objective

Bladder cancer (BC) is a significant public health concern in the Middle East and North Africa, but the epidemiology and clinicopathology of the disease and contributors to high mortality in this region remain poorly understood. The aim of this systematic review was to investigate the epidemiological features of BC in the Arab world and compare them to those in Western countries in order to improve the management of this disease.

Methods

An extensive electronic search of the PubMed/PMC and Cochrane Library databases was conducted to identify all articles published until May 2022, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. A total of 95 articles were included in the final analysis after title, abstract, and full-text screening, with additional data obtained from the GLOBOCAN and WHO 2020 databases.

Results

Most of the included articles were case-control studies examining the risk factors and molecular mechanisms of BC. These studies originated from 10 different countries, with Egypt being the most active contributor. While BC in the Arab world shares some common risk factors with Western countries, such as smoking and occupational exposure, it also exhibits unique features related to schistosomiasis. The high mortality rates in this region are alarming and can be attributed to various factors, including the prevalence of smoking, the impact of schistosomiasis, a combination of genetic and socioeconomic factors, treatment shortages, and limited access to care or inadequate assessment of the quality of care.

Conclusion

Despite the relatively low incidence of BC in Arab countries, the mortality rates are among the highest worldwide. BC tends to be more aggressive in the Arab world, making it essential to implement strategies to address this burden.

Polymorphisms in drug-metabolizing genes and urinary bladder cancer susceptibility and prognosis: Possible impacts and future management

Epidemiological studies have shown the association of genetic variants with risks of occupational and environmentally induced cancers, including bladder (BC). The current review summarizes the effects of variants in genes encoding phase I and II enzymes in well-designed studies to highlight their contribution to BC susceptibility and prognosis. Polymorphisms in genes codifying drug-metabolizing proteins are of particular interest because of their involvement in the metabolism of exogenous genotoxic compounds, such as tobacco and agrochemicals. The prognosis between muscle-invasive and non-muscle-invasive diseases is very different, and it is difficult to predict which will progress worse. Web of Science, PubMed, and Medline were searched to identify studies published between January 1, 2010, and February 2023. We included 73 eligible studies, more than 300 polymorphisms, and 46 genes/loci. The most studied candidate genes/loci of phase I metabolism were CYP1B1, CYP1A1, CYP1A2, CYP3A4, CYP2D6, CYP2A6, CYP3E1, and ALDH2, and those in phase II were GSTM1, GSTT1, NAT2, GSTP1, GSTA1, GSTO1, and UGT1A1. We used the 46 genes to construct a network of proteins and to evaluate their biological functions based on the Reactome and KEGG databases. Lastly, we assessed their expression in different tissues, including normal bladder and BC samples. The drug-metabolizing pathway plays a relevant role in BC, and our review discusses a list of genes that could provide clues for further exploration of susceptibility and prognostic biomarkers.

Genetic Polymorphisms Involved in Bladder Cancer: A Global Review

Bladder cancer (BC) has been associated with genetic susceptibility. Single peptide polymorphisms (SNPs) can modulate BC susceptibility. A literature search was performed covering the period between January 2000 and October 2020. Overall, 334 articles were selected, reporting 455 SNPs located in 244 genes. The selected 455 SNPs were further investigated. All SNPs that were associated with smoking and environmental exposure were excluded from this study. A total of 197 genes and 343 SNPs were found to be associated with BC, among which 177 genes and 291 SNPs had congruent results across all available studies. These genes and SNPs were classified into eight different categories according to their function.

Genetic and Proteinic Linkage of MAO and COMT with Oral Potentially Malignant Disorders and Cancers of the Oral Cavity and Pharynx

Simple Summary

The prevention and treatment of cancers of the oral cavity and pharynx are currently important issues for national health. Currently, the incidence of oral cavity and pharynx cancers is globally the highest in Taiwanese men. Regarding the occurrence of oral cavity and pharynx cancers and oral potentially malignant disorders (OPMD), no report has ascertained how betel quid (BQ) can induce the expression of monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). We aimed to explore the role and clinical significance of specific markers of BQ exposure and human susceptibility to MAO and COMT. Our findings highlight the association of MAO and COMT biomarkers to risks of oral and pharyngeal cancers and OPMD. These novel findings will provide important strategies for disease prevention, early clinical diagnosis, and treatment effectiveness, and will offer a strong foundation to reduce BQ-related cancers of the oral cavity and pharynx and OPMD.

Abstract

Betel quid (BQ), a group I human carcinogen, strongly contributes to an increased risk of oral potentially malignant disorders (OPMD) and cancers of the oral cavity and pharynx. This study was conducted to discover whether monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) variants play a potential role in the risk assessment of oral cavity and pharynx cancers and OPMD, particularly among BQ users. We applied a case–control study to confirm the polymorphism of MAO and COMT using single-nucleotide polymorphisms. We used qRT-PCR, Western blotting, and immunohistochemistry (IHC) to determine MAO and COMT expression. Carriers of the MAOA rs6323 G-allele, MAOB rs6324 G-allele, and COMT rs4633 C/C-genotype had a prominently increased risk of oral cavity and pharynx cancers (AOR = 56.99; p < 0.001). Compared to adjacent noncancerous tissues, a significant downregulation of MAO and COMT expression was exhibited in cancerous tissues (p < 0.01). Furthermore, in different cell models, MAO and COMT expression was significantly downregulated with an increased dose of arecoline (p < 0.01). In personalized preventive medicine for oral and pharyngeal cancers, our findings are the first to demonstrate the potential role of lower MAO and COMT expression levels, with the risk polymorphisms utilized as clinical biomarkers.

Evaluation of COMT Gene rs4680 Polymorphism as a Risk Factor for Endometrial Cancer

Catechol-O-methyletransferase (COMT) enzyme is involved in the inactivation of catecholamine and catechol estrogens. Catechol estrogens have carcinogenic potential and DNA damaging ability. Several studies investigated COMT Val158Met polymorphism as risk factor for endometrial cancer but the results were inconclusive. Hence the objective of present study was to find out exact association between COMT gene Val158Met polymorphism and endometrial cancer by a meta-analysis. Pubmed, Google Scholar, Springer Link and Science Direct databases were searched for case-control articles which investigated COMT Val158Met polymorphism in endometrial cancer cases. All statistical analysis was performed using MetaAnalyst and Mix programs. The results of meta-analysis suggested that there were no association between COMT Val158Met polymorphism and endometrial cancer risk (allele contrast model-OR_{A vs. G} = 0.97, 95% CI = 0.86-1.10, p = 0.67; co-dominant model-OR_{AG vs. GG} = 0.91, 95% CI = 0.77-1.06, p = 0.23; homozygote model-OR_{AA vs. GG} = 1.01, 95% CI = 0.84-1.19, p = 0.29; dominant model-OR_{AA+AG vs. GG} = 0.93, 95% CI = 0.77-1.11, p = 0.43; recessive model-OR_{AA vs. AG+GG} = 1.02, 95% CI = 0.89-1.20, p = 0.62). Publication bias was absent. Subgroup analysis based on source of controls was also performed. In conclusion, results of present meta-analysis showed no association between COMT Val158Met polymorphism and susceptibility to endometrial cancer.

Impact of Occupational Exposures and Genetic Polymorphisms on Recurrence and Progression of Non-Muscle-Invasive Bladder Cancer

Introduction: Additional or better markers are needed to guide the clinical monitoring of patients with non-muscle-invasive bladder cancer (NMIBC). Aim: To investigate the influence of occupational exposures and genetic polymorphisms on recurrence and progression of NMIBC. Methods: The study includes 160 NMIBC patients. We collected on questionnaire information on demographic variables, lifetime smoking history, lifetime history of occupational exposure to aromatic amines and polycyclic aromatic hydrocarbons. Genetic polymorphism (glutathione S-transferase M1; T1; P1 (GSTM1; GSTT1; GSTP1); N-acetyltransferase 1; 2 (NAT1; NAT2); cytochrome P450 1B1 (CYP1B1); sulfotransferase 1A1 (SULT1A1); myeloperoxidase (MPO); catechol-O-methyltransferase (COMT); manganese superoxide dismutase (MnSOD); NAD(P)H:quinone oxidoreductase (NQO1); X-ray repair cross-complementing group 1; 3 (XRCC1; XRCC3) and xeroderma pigmentosum complementation group (XPD)) was assessed in peripheral blood lymphocytes. DNA adducts were evaluated by 32P-postlabeling. Predictors of recurrence (histological confirmation of a newly found bladder tumor) and progression (transition of tumor from low-grade to high-grade and/or increase in TNM stage) were identified by multivariate Cox proportional hazard regression with stepwise backward selection of independent variables. Hazard ratios (HR) with 95% confidence interval (95%CI) and two-tail probability of error (p-value) were estimated. Results: The risk of BC progression decreased with the homozygous genotype “ValVal” of both COMT and MnSOD (HR = 0.195; 95%CI = 0.060 to 0.623; p = 0.006). The results on BC recurrence were of borderline significance. No occupational exposure influenced recurrence or progression. Conclusion: Our results are supported by experimental evidence of a plausible mechanism between cause (ValVal genotype of both MnSOD and COMT) and effect (decreased progression of tumor in NMIBC patients). The genetic polymorphisms associated with better prognosis may be used in clinic to guide selection of treatment for patients initially diagnosed with NMIBC. However, external validation studies are required.

The Val158Met polymorphism in COMT gene and cancer risk: role of endogenous and exogenous catechols

Catechol-O-methyltransferase, COMT, is an important phase II enzyme catalyzing the transfer of a methyl-group from S-adenosylmethionine to a catechol-containing substrate molecule. A genetic variant Val158Met in the COMT gene leads to a several-fold decrease in the enzymatic activity giving rise to the accumulation of potentially carcinogenic endogenous catechol estrogens and their reactive intermediates and increasing thus the risk of tumorigenesis. However, numerous association studies between the COMT genotype and susceptibility to various malignancies have shown inconsistent and controversial findings indicating that additional gene-gene and gene-environment interactions might be crucial in modulating the physiological role of the COMT. In this review article, the important contribution of dietary catechol-containing flavonoids to modification of the relationships between the COMT genotype and cancer risk is discussed. Whereas, the diverse anticancer activities of common phytochemicals, such as green tea polyphenols, quercetin, fisetin or luteolin, can be markedly changed (both decreased or increased) by the COMT-mediated O-methylation of these exogenous substrates, flavonoids can also behave as potent inhibitors of the COMT enzyme slowing detoxification of endogenous catechol estrogens. Such a many-featured functioning of the COMT and its complex regulation by several different genetic and environmental factors, including plant-based food ingredients, emphasizes the necessity to further stratify the association studies between the COMT genotype and tumor risk by consumption of catechol-containing dietary flavonoids. Currently, it can be only speculated that some of the possible associations might be masked by the regular intake of specific food polyphenols, taking effect in certain communities or populations.

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.

Association between the COMT Val158Met polymorphism and risk of cancer: evidence from 99 case-control studies

Catechol-O-methyltransferase (COMT) plays a central role in DNA repair and estrogen-induced carcinogenesis. Many recent epidemiologic studies have investigated the association between the COMT Val158Met polymorphism and cancer risk, but the results are inconclusive. In this study, we performed a meta-analysis to investigate the association between cancer susceptibility and COMT Val158Met in different genetic models. Overall, no significant associations were found between COMT Val158Met polymorphism and cancer risk (homozygote model: odds ratio [OR] =1.05, 95% confidence interval [CI] = [0.98, 1.13]; heterozygote model: OR =1.01, 95% CI = [0.98, 1.04]; dominant model: OR =1.02, 95% CI [0.97, 1.06], and recessive model: OR =1.03, 95% CI [0.97, 1.09]). In the subgroup analysis of cancer type, COMT Val158Met was significantly associated with increased risks of bladder cancer in recessive model, and esophageal cancer in homozygote model, heterozygote model, and dominant model. Subgroup analyses based on ethnicities, COMT Val158Met was significantly associated with increased risk of cancer in homozygote and recessive model among Asians. In addition, homozygote, recessive, and dominant models were significantly associated with increased cancer risk in the subgroup of allele-specific polymerase chain reaction genotyping. Significant associations were not observed when data were stratified by the source of the controls. In summary, this meta-analysis suggested that COMT Val158Met polymorphism might not be a risk factor for overall cancer risk, but it might be involved in cancer development at least in some ethnic groups (Asian) or some specific cancer types (bladder and esophageal cell cancer). Further evaluations of more preclinical and epidemiological studies are required.

Pesticides, gene polymorphisms, and bladder cancer among Egyptian agricultural workers

This study examined the associations between pesticide exposure, genetic polymorphisms for

NAD(P)H

quinone oxidoreductase I (NQO1) and superoxide dismutase 2 (SOD2), and urinary bladder cancer risk among male agricultural workers in Egypt. Logistic regression was used to analyze data from a multicenter case-control study and estimate adjusted odds ratio (OR) and 95% confidence interval (CI). Exposure to pesticides was associated with increased bladder cancer risk (odds ratio (95% confidence interval): 1.68 (1.23-2.29)) in a dose-dependent manner. The association was slightly stronger for urothelial (1.79 (1.25-2.56)) than for squamous cell (1.55 (1.03-2.31)), and among participants with combined genotypes for low NQO1 and high SOD2 (2.14 (1.19-3.85)) activities as compared with those with high NQO1 and low SOD2 genotypes (1.53 (0.73-3.25)). In conclusion, among male agricultural workers in Egypt, pesticide exposure is associated with bladder cancer risk and possibly modulated by genetic polymorphism.

Agricultural workers and urinary bladder cancer risk in Egypt

The authors examined the associations between farming and the risk for squamous cell (SCC) or urothelial cell (UC) carcinoma of the urinary bladder among Egyptians. The authors used data from a multicenter case-control study (1,525 male and 315 female cases, and 2,069 male and 547 female age- and residence-matched, population-based controls) to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs). Men in farming and who never smoked had increased risk for either SCC or UC (AOR [95% CI]: 4.65 [2.59-8.36] and 6.22 [3.82-10.15], respectively). If they ever smoked, their risks were 2.27 (1.75-2.95) and 1.93 (1.58-2.35), respectively. Women in farmer households were at increased risk for SCC (1.40 [0.93-2.09] and UC [1.25 (0.82-1.89]), although not statistically significant. Occupational and environmental exposures to farming increased the risk for bladder cancer among Egyptians.

Impact of gender on bladder cancer incidence, staging, and prognosis

INTRODUCTION

While patient gender is an important factor in the clinical decision-making for the management of bladder cancer, there are minimal evidence-based recommendations to guide health care professionals. Recent epidemiologic and translational research has shed some light on the complex relationship between gender and bladder cancer. Our aim was to review the literature on the effect of gender on bladder cancer incidence, biology, mortality, and treatment.

METHODS

Using MEDLINE, we performed a search of the literature between January 1975 and April 2011.

RESULTS

Although men are nearly 3-4 times more likely to develop bladder cancer than women, women present with more advanced disease and have worse survival. Recently, a number of population-based and multicenter collaborative studies have shown that female gender is associated with a significantly higher rate of cancer-specific recurrence and mortality after radical cystectomy. The disparity between genders is proposed to be the result of a differences exposure to carcinogens (i.e., tobacco and chemicals) as well as reflective of genetic, anatomic, hormonal, societal, and environmental factors. Explanations for the differential behavior of bladder cancer between genders include sex steroids and their receptors as well as inferior quality of care for women (inpatient length of stay, referral patterns, and surgical outcomes).

CONCLUSIONS

It is imperative that health care practitioners and researchers from disparate disciplines collectively focus efforts to appropriately develop gender-specific evidence-based guidelines for bladder cancer patients. We must strive to develop multidisciplinary collaborative efforts to provide tailored gender-specific care for bladder cancer patients.