Occupational bladder cancer: Polymorphisms of xenobiotic metabolizing enzymes, exposures, and prognosis

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.

[Occupation-related cancer in urology-Current knowledge including environmental medical aspects]

Occupation-related cancers are of considerable importance, which is not yet adequately recognized in the field of urology. The three numerically most significant entities are tumors of the urinary tract caused by carcinogenic aromatic amines or polycyclic aromatic hydrocarbons, renal cell cancer after high exposure to the solvent trichloroethylene, and mesotheliomas of the tunica vaginalis of the testis after exposure to asbestos; however, these can only be recognized as occupation-related if an occupational history regarding the hazard relevant to the organ bearing the tumor is documented from the beginning of employment, e.g. by a questionnaire. This is because the relevant exposures generally date back several decades. With the exception of high exposure to trichloroethylene, the substances mentioned can also environmentally trigger the same tumors. In the context of environmental risk factors, it is of considerable importance that smoking is now considered to be a trigger for some 50% of all bladder cancers in men and women; however, smoking cessation results in a reduction in smoking-related cancer risk of over 30% after only 3-4 years. Work and commuting accidents, which are considered occupational risks, can lead to urological sequelae. For example, increased tumors of the bladder can occur after spinal cord injury lasting longer than 10 years.

Mechanism of Sex Differences in Bladder Cancer: Evident and Elusive Sex-biasing Factors

Bladder cancer incidence is drastically higher in males than females across geographical, racial, and socioeconomic strata. Despite potential differences in tumor biology, however, male and female bladder cancer patients are still clinically managed in highly similar ways. While sex hormones and sex chromosomes have been shown to promote observed sex differences, a more complex story lies beneath these evident sex-biasing factors than previously appreciated. Advances in genomic technology have spurred numerous preclinical studies characterizing elusive sex-biasing factors such as epigenetics, X chromosome inactivation escape genes, single nucleotide polymorphism, transcription regulation, metabolism, immunity, and many more. Sex-biasing effects, if properly understood, can be leveraged by future efforts in precision medicine based on a patient's biological sex. In this review, we will highlight key findings from the last half century that demystify the intricate ways in which sex-specific biology contribute to differences in pathogenesis as well as discuss future research directions.

Role of N-acetyltransferase 2 gene polymorphism in the human pathology

Nowadays multiple heterogeneous chemicals affect the human body. They include drugs, household chemicals, dyes, food supplements and others. The human organism can modify, inactivate, and eliminate the chemicals by biotransformation enzymes. But it is well known that biotransformation can lead to toxification phenomenon. Individuals differ from each other by the rate of chemical modification that promotes accumulation of toxins and carcinogens in some patients. An N-acetyltransferase 2 enzyme participates in the aromatic amines second phase metabolism. This work reviews the acetyltransferase gene polymorphism possible role in diseases development including drug-induced organs damage.

Gene of acetyltransferase has polymorphisms associated with two haplotypes of  fast and slow substrate acetylation. Gene alleles combine in three genotypes: fast, intermediate, and slow acetylators. Acetylation rate plays a significant role in side effects development during tuberculosis treatment and cancer pathogenesis. Recently, new data described the role of enzyme in development of non-infectious diseases in the human. Scientists consider that slow acetylation genotype in combination with high xenobiotic load result in accumulation of toxic substances able to damage cells.

Therefore, acetyltransferase genotyping helps to reveal risk groups of cancer and non-infectious disease development and to prescribe more effective and safe doses of drugs. 

[Occupational cancers in urology]

Cancers can be triggered by occupational causes. In the field of urology, bladder cancer is by far the most frequent occupationally induced tumor disease. Causes are particularly carcinogenic aromatic amines and carcinogenic polycyclic aromatic hydrocarbons. The frequency of this disease has shifted over the last decades from the classical hazard in the chemical industry to the users. Among a variety of hazardous occupations, hairdressers and painters are the best known. Rarely, renal cell carcinoma can be triggered by high trichloroethylene exposure and mesothelioma of the tunica vaginalis testis by asbestos. If a disease that can be caused by occupational activities has been confirmed (e.g. urinary bladder cancer), the risk factors must be recorded by a complete occupational history from the first employment on in order to be able to report a suspected occupational disease. In addition, spinal cord injury due to occupational and commuting accidents can lead to urinary bladder cancer over the long term.

A functional variant rs1464938 in the promoter of fibroblast growth factor 12 is associated with an increased risk of bladder transitional cell carcinoma

Increasing evidence shows that inflammation plays critical roles in the tumorigenesis of bladder cancer. Fibroblast growth factor 12 (FGF12), a kind of inflammatory cytokine, is located in the region of 3q28 that has been demonstrated to be a bladder cancer risk locus by genome wide association study (GWAS). In this study, we aimed to investigate the association of GWAS signal rs710521 and rs884309 and rs1464938 in the promoter of FGF12 with the risk of bladder transitional cell carcinoma (TCC). The polymorphisms were analyzed by using a Taqman assay in 331 TCC patients and 516 age-, gender-, and ethnicity-matched controls. The expression levels of FGF12 mRNA were examined in TCC and non-cancerous normal tissues by using quantitative real-time PCR and the luciferase activity was determined by using the Dual-Luciferase Assay System. The rs1464938 AA genotype and A allele were associated with a significantly increased risk of TCC (AA vs. GG: adjusted OR = 2.54, 95% CI, 1.49-4.35, P < 0.001; AA vs. AG/GG: adjusted OR = 2.25, 95% CI, 1.36-3.71, P = 0.002; A vs. G: adjusted OR = 1.44, 95% CI, 1.15-1.80, P = 0.001, respectively). Haplotype analysis showed that rs884309G- rs1464938A haplotype was associated with an increased risk of TCC (OR = 1.61, 95% CI, 1.23-2.11, P = 0.001). Functional analysis showed that the rs1464938 AG/AA genotypes exhibited higher levels of FGF12 mRNA in TCC tissues and the rs1464938 A allele enhanced FGF12 promoter activity (P < 0.05). These findings suggest that the rs1464938 A allele at the 3q28 locus contribute to the development of TCC by regulating FGF12 expression levels.

N-acetyltransferase 2 polymorphism is associated with bladder cancer risk: An updated meta-analysis based on 54 case-control studies

OBJECTIVE

N-acetyltransferase 2 (NAT2) polymorphism could participate in the metabolism of carcinogens through regulating the activity of a series of critical enzymes. However, the effects of NAT2 polymorphism on bladder cancer (BCa) risk were still inconclusive. In order to illustrate whether NAT2 polymorphism may influence the susceptibility to BCa, we conducted this updated meta-analysis.

MATERIALS AND METHODS

Databases including PubMed, Medline, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure(CNKI) were systematically retrieved and we applied MetaGenyo to perform final meta-analysis. Odds ratios (ORs) as well as 95% confidence intervals (CIs) were calculated and Bonferroni method was applied to correct the P-value for multiple comparisons. The registration of this study protocol is at PROSPERO and ID is CRD42019133957.

RESULTS

Ultimately, 54 case-control studies were identified for final meta-analysis (13343 BCa cases and 18,586 controls). Overall analysis indicated that the slow genotype in NAT2 polymorphism was obviously associated with BCa risk (P_Bonferroni < 0.001). Subgroup analyses demonstrated that significant risk with the slow genotype was observed in Caucasians, Asians, smokers, non-exposed individuals, high grade bladder cancer (HGBC) patients and muscle-invasive bladder cancer (MIBC) patients. In addition, the intermediate NAT2 genotype was revealed to increase the BCa risk of Asians and transitional cell carcinoma (TCC) patients. However, no correlation was identified in Africans with the NAT2 polymorphism.

CONCLUSIONS

The slow NAT2 genotype was identified to be the risk genotype for BCa. The intermediate genotype could serve as the candidate risk genotype. The gene-smoking interaction with NAT2 polymorphism might accelerate the tumor progression.

Polymorphism of Glutathione S-transferase Genes and the Risk of Toxic Liver Damage in Petrochemical Workers

BACKGROUND

Exposure to numerous chemicals, including industrial ones, may result in liver damage. The body susceptibility to the environmental hazards largely depends on the activity of the enzymes in the xenobiotic detoxification system. Function abnormalities of such enzymes due to genetic variations would increase the risk of developing various diseases.

OBJECTIVE

To elucidate the relationship between polymorphism in glutathione S-transferase genes (GSTM1, GSTT1 and GSTP1) and the risk of toxic liver damage in a group of petrochemical workers.

METHODS

This study was conducted on 72 workers with toxic liver injury, 156 healthy workers, and 322 healthy individuals without history of occupational exposure to chemicals. Genotyping of the GSTP1 rs1695 gene polymorphism was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Polymerase chain reaction (PCR) was used to perform genotyping of the GSTM1 and GSTT1 genes polymorphism.

RESULTS

There was a significant difference in genotype frequencies of the GSTP1 rs1695 gene polymorphism among the groups studied. The distribution of Val/Val genotype of the GSTP1 rs1695 gene polymorphism had a higher incidence in healthy workers compared with patients with toxic liver damage (p=0.036). No significant association was found between the GSTM1 and GSTT1 polymorphisms and toxic liver damage.

CONCLUSION

The GSTP1 rs1695 gene polymorphism can play a protective role in the development of toxic liver damage in petrochemical workers.

Lifestyle and Non-muscle Invasive Bladder Cancer Recurrence, Progression, and Mortality: Available Research and Future Directions

BACKGROUND:

A broad, comprehensive review of studies exploring associations between lifestyle factors and non-muscle invasive bladder cancer (NMIBC) outcomes is warranted to consolidate recommendations and identify gaps in research.

OBJECTIVE:

To summarize the literature on associations between lifestyle factors and clinical outcomes among patients with NMIBC.

METHODS:

PubMed was systematically queried for articles published through March 2019 regarding lifestyle factors and recurrence, progression, cancer-specific mortality, and all-cause mortality among patients with NMIBC.

RESULTS:

Notwithstanding many ambiguities, there is good-quality evidence suggesting a benefit of smoking avoidance/cessation, healthy body mass index (BMI), and type II diabetes mellitus prevention and treatment. Lactobacillus casei probiotic supplementation may reduce recurrence. There have been individual studies suggesting a benefit for uncooked broccoli and supplemental vitamin E as well as avoidance of supplemental vitamin B9, areca nut chewing, and a “Western diet” pattern high in fried foods and red meat. Additional studies do not suggest associations between NMIBC outcomes and use of fibrin clot inhibitors; insulin and other oral hypoglycemics; statins; supplemental selenium, vitamin A, vitamin C, and vitamin B6; fluid intake and intake of specific beverages (e.g., alcohol, coffee, green tea, cola); various dietary patterns (e.g., Tex-Mex, high fruit and vegetable, low-fat); and occupational and chemical exposures.

CONCLUSIONS:

Despite a myriad of publications on lifestyle factors and NMIBC, a need remains for research on unexplored associations (e.g., physical activity) and further studies that can elucidate causal effects. This would inform future implementation strategies for healthy lifestyle change in NMIBC patients.

Serum Metabolic Profiling Identified a Distinct Metabolic Signature in Bladder Cancer Smokers: A Key Metabolic Enzyme Associated with Patient Survival

BACKGROUND

The current system to predict the outcome of smokers with bladder cancer is insufficient due to complex genomic and transcriptomic heterogeneities. This study aims to identify serum metabolite-associated genes related to survival in this population.

METHODS

We performed LC/MS-based targeted metabolomic analysis for >300 metabolites in serum obtained from two independent cohorts of bladder cancer never smokers, smokers, healthy smokers, and healthy never smokers. A subset of differential metabolites was validated using Biocrates absoluteIDQ p180 Kit. Genes associated with differential metabolites were integrated with a publicly available cohort of The Cancer Genome Atlas (TCGA) to obtain an intersecting signature specific for bladder cancer smokers.

RESULTS

Forty metabolites (FDR < 0.25) were identified to be differential between bladder cancer never smokers and smokers. Increased abundance of amino acids (tyrosine, phenylalanine, proline, serine, valine, isoleucine, glycine, and asparagine) and taurine were observed in bladder cancer smokers. Integration of differential metabolomic gene signature and transcriptomics data from TCGA cohort revealed an intersection of 17 genes that showed significant correlation with patient survival in bladder cancer smokers. Importantly, catechol-O-methyltransferase, iodotyrosine deiodinase, and tubulin tyrosine ligase showed a significant association with patient survival in publicly available bladder cancer smoker datasets and did not have any clinical association in never smokers.

CONCLUSIONS

Serum metabolic profiling of bladder cancer smokers revealed dysregulated amino acid metabolism. It provides a distinct gene signature that shows a prognostic value in predicting bladder cancer smoker survival.

IMPACT

Serum metabolic signature-derived genes act as a predictive tool for studying the bladder cancer progression in smokers.

Epidemiology of Bladder Cancer: A Systematic Review and Contemporary Update of Risk Factors in 2018

CONTEXT

Bladder cancer (BC) is a significant health problem, and understanding the risk factors for this disease could improve prevention and early detection.

OBJECTIVE

To provide a systematic review and summary of novel developments in epidemiology and risk factors for BC.

EVIDENCE ACQUISITION

A systematic review of original articles was performed by two pairs of reviewers (M.G.C., I.J., F.E., and K.P.) using PubMed/Medline in December 2017, updated in April 2018. To address our primary objective of reporting contemporary studies, we restricted our search to include studies from the last 5yr. We subdivided our review according to specific risk factors (PICO [Population Intervention Comparator Outcome]).

EVIDENCE SYNTHESIS

Our search found 2191 articles, of which 279 full-text manuscripts were included. We separated our manuscripts by the specific risk factor they addressed (PICO). According to GLOBOCAN estimates, there were 430000 new BC cases and 165000 deaths worldwide in 2012. Tobacco smoking and occupational exposure to carcinogens remain the factors with the highest attributable risk. The literature was limited by heterogeneity of data.

CONCLUSIONS

Evidence is emerging regarding gene-environment interactions, particularly for tobacco and occupational exposures. In some populations, incidence rates are declining, which may reflect a decrease in smoking. Standardisation of reporting may help improve epidemiologic evaluation of risk.

PATIENT SUMMARY

Bladder cancer is common worldwide, and the main risk factors are tobacco smoking and exposure to certain chemicals in the working and general environments. There is ongoing research to identify and reduce risk factors, as well as to understand the impact of genetics on bladder cancer risk.

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.

In vitro functional analysis of human cytochrome P450 2A13 genetic variants: P450 2A13*2, *3, *4, and *10

Humans possess three cytochrome P450 enzymes in the 2A subfamily (2A6, 2A7, and 2A13). P450 2A13 is mainly expressed in the human trachea and lung, whereas P450 2A6 is found in human liver. The P450 2A13 enzyme may be considered as the primary enzyme responsible for metabolic activation of many tobacco-specific carcinogens. Genetic variations significantly influence the toxicological consequences attributed to tobacco smoking. The aim of this study was to examine the in vitro functional activities of five P450 2A13 genetic variations (R257C, 133_134insT, R101Q, I331T, and R257C/I331T) in P450 2A13*2, *3, *4, and *10 alleles. Mutant clones were constructed and their recombinant enzymes were expressed in Escherichia coli. P450 2A13 mutants containing R257C, 133_134insT, I331T, and R257C/I331T displayed P450 holoenzyme spectra. The R101Q mutant was not apparently expressed. P450 2A13 enzymes displayed the typical type I binding spectra to coumarin and the calculated binding affinities of R257C, R257C/I331T, and 133_134insT mutants were decreased approximately three- to sevenfold. In catalytic analyses of purified mutant enzymes for coumarin and nicotine, the R257C and I331T mutants exhibited lower kcat values with catalytic efficiencies reduced up to approximately 20%. The double mutation of R257C/I331T induced increased Km values and diminished kcat values that resulted in >50% decrease in catalytic efficiencies. For 133_134insT mutant, catalytic activities were not markedly saturated but the measured rates at the highest concentrations were significantly lower than those of the wild-type or other mutant enzymes. Functional analysis of these variations in P450 2A13 allelic variants may help to understand the consequences of P450 2A13 polymorphism in bioactivation of many tobacco-derived carcinogens.