Rs11892031[A] on chromosome 2q37 in an intronic region of the UGT1A locus is associated with urinary bladder cancer risk

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.

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.

The Interplay between Oxidative Stress, Inflammation and Angiogenesis in Bladder Cancer Development

In 2018, 550,000 people were diagnosed with bladder cancer (BC), of which nearly 200,000 people died. Moreover, men are 4 times more likely than women to be diagnosed with BC. The risk factors include exposure to environmental and occupational chemicals, especially tobacco smoke, benzidine and genetic factors. Despite numerous studies, the molecular basis of BC development remains unclear. A growing body of evidence suggests that inflammation, oxidant-antioxidant imbalance and angiogenesis disorders may play a significant role in the development and progression of bladder cancer. The patients with bladder cancer were characterised by an increased level of reactive oxygen species (ROS), the products of lipid peroxidation, proinflammatory cytokines and proangiogenic factors as compared to controls. Furthermore, it was shown that polymorphisms localised in genes associated with these pathways may modulate the risk of BC. Interestingly, ROS overproduction may induce the production of proinflammatory cytokines, which finally activated angiogenesis. Moreover, the available literature shows that both inflammation and oxidative stress may lead to activation of angiogenesis and tumour progression in BC patients.

Genetic variant of MAML2 in the NOTCH signaling pathway and the risk of bladder cancer: A STROBE-compliant study

The NOTCH signaling pathway plays a crucial role in cell phenotype and transformation. Single nucleotide polymorphisms (SNPs) may regulate gene expression to trigger bladder cancer susceptibility. Here, we aimed to explore the relationships between genetic variants in the NOTCH pathway and bladder cancer progression.We screened SNPs located in NOTCH pathway genes using the 1000 Genomes Project dataset (CHB). A case-control cohort study including 580 bladder cancer cases and 1101 controls was conducted to genotype the candidate SNPs. The expression quantitative trait locus (eQTL) and bioinformatics analyses were performed to explore the biological function of the SNPs' host gene and their relationship. Kaplan-Meier analysis was performed to assess the association between host gene expression and bladder cancer patient prognosis.The rs7944701 in the intron of mastermind-like 2 (MAML2) had the strongest signal and was related to bladder cancer risk (OR = 1.329, 95% CI = 1.115-1.583, P = .001). eQTL analysis showed that rs7944701 with a C allele was negatively associated with mastermind-like 2 (MAML2) expression (TT versus TC/CC). Bioinformatics analysis indicated that MAML2expression was lower in bladder cancer tissues than in non-tumor tissues (P = 5.46 × 10). Additionally, bladder cancer patients with high MAML2 expression had a significantly poorer prognosis (HR = 1.53, 95% CI = 1.29-1.82, P = .010).The rs7944701 in MAML2 was strongly associated with bladder cancer susceptibility in a Chinese population. This genetic variant and its host gene could be a potential novel biomarker for individuals suffering from bladder cancer.

The UDP-Glycosyltransferase (UGT) Superfamily: New Members, New Functions, and Novel Paradigms

UDP-glycosyltransferases (UGTs) catalyze the covalent addition of sugars to a broad range of lipophilic molecules. This biotransformation plays a critical role in elimination of a broad range of exogenous chemicals and by-products of endogenous metabolism, and also controls the levels and distribution of many endogenous signaling molecules. In mammals, the superfamily comprises four families: UGT1, UGT2, UGT3, and UGT8. UGT1 and UGT2 enzymes have important roles in pharmacology and toxicology including contributing to interindividual differences in drug disposition as well as to cancer risk. These UGTs are highly expressed in organs of detoxification (e.g., liver, kidney, intestine) and can be induced by pathways that sense demand for detoxification and for modulation of endobiotic signaling molecules. The functions of the UGT3 and UGT8 family enzymes have only been characterized relatively recently; these enzymes show different UDP-sugar preferences to that of UGT1 and UGT2 enzymes, and to date, their contributions to drug metabolism appear to be relatively minor. This review summarizes and provides critical analysis of the current state of research into all four families of UGT enzymes. Key areas discussed include the roles of UGTs in drug metabolism, cancer risk, and regulation of signaling, as well as the transcriptional and posttranscriptional control of UGT expression and function. The latter part of this review provides an in-depth analysis of the known and predicted functions of UGT3 and UGT8 enzymes, focused on their likely roles in modulation of levels of endogenous signaling pathways.

New insights for risks of chlorophenols (CPs) exposure: Inhibition of UDP-glucuronosyltransferases (UGTs)

Chlorophenols (CPs) are important pollutants extensively utilized in industry, agriculture and forestry. The present study aims to determine the inhibition of CPs on the activity of the important phase II drug-metabolizing enzymes (DMEs) UDP-glucuronosyltransferases (UGTs). 100 μM of fourteen CPs were used for preliminary screening using in vitro incubation. Furthermore, half inhibition concentration (IC₅₀) and inhibition kinetics were determined for CPs with significant inhibition towards UGT isoforms. In silico docking was used to explain the inhibition difference among CPs. Multiple UGT isoforms were inhibited by CPs. In silico docking showed that higher free binding energy due to hydrophobic interactions of 2.4-Dichlorophenol (2.4-DCP) or 4-Chloro-3-methylphenol (4C3MP) with UGT1A9 contributed to stronger inhibition potential of 2.4-Dichlorophenol (2.4-DCP) or 4-Chloro-3-methylphenol (4C3MP) towards UGT1A9 than 4-CP. Pentachlorophenol (PCP) was chosen as the representative CPs to determine the IC₅₀ value towards UGT1A6, UGT1A9 and UGT2B7. IC₅₀ was calculated to be 0.33 μM, 0.24 μM and 31.35 μM for the inhibition of PCP towards UGT1A6, UGT1A9 and UGT2B7. PCP was demonstrated to show competitive inhibition towards UGT1A6, UGT1A9 and UGT2B7, and the inhibition kinetic parameters (Ki) was calculated to be 0.18 μM, 0.01 μM and 5.37 μM for the inhibition of PCP towards UGT1A6, UGT1A9 and UGT2B7. All these information will be beneficial for elucidating the risk of CPs exposure from a new perspective.

Uridine 5'diphospho-glucuronosyltransferase 1A expression as an independent prognosticator in urothelial carcinoma of the upper urinary tract

OBJECTIVE

To determine the expression status of uridine 5'diphospho-glucuronosyltransferase 1A, a major phase II drug metabolism enzyme, in upper urinary tract urothelial carcinoma, as well as to assess its prognostic significance.

METHODS

We immunohistochemically stained for uridine 5'diphospho-glucuronosyltransferase 1A in tissue microarray consisting of 99 upper urinary tract urothelial carcinoma samples and paired non-neoplastic urothelial tissues. We also assessed the effect of uridine 5'diphospho-glucuronosyltransferase 1A knockdown on urothelial cancer cell growth.

RESULTS

Uridine 5'diphospho-glucuronosyltransferase 1A was positive in 92.9% (27.3% weak [1+], 37.4% moderate [2+], 28.3% strong [3+]) of tumors, which was significantly (P < 0.001) lower than in benign urothelial tissues (98.8%; 3.5% 1+, 18.8% 2+, 76.4% 3+). All 37 (100%) non-muscle-invasive versus 55 (88.7%) of 62 muscle-invasive tumors (P = 0.043) were immunoreactive for uridine 5'diphospho-glucuronosyltransferase 1A. The rates of moderate-to-strong uridine 5'diphospho-glucuronosyltransferase 1A expression and its positivity were also strongly associated with the absence of concomitant carcinoma in situ (P = 0.034) and lymphovascular invasion (P = 0.016), respectively. However, there were no statistically significant associations between uridine 5'diphospho-glucuronosyltransferase 1A expression and tumor grade or pN/M status. Uridine 5'diphospho-glucuronosyltransferase 1A loss in M0 tumors was strongly associated with lower progression-free survival (P < 0.001) and cancer-specific survival (P < 0.001) rates. Multivariate analysis further identified a strong correlation of uridine 5'diphospho-glucuronosyltransferase 1A positivity with reduced cancer-specific mortality (hazard ratio 0.28, P = 0.018). Meanwhile, uridine 5'diphospho-glucuronosyltransferase 1A knockdown in urothelial cancer cells resulted in significant increases in their viability and migration.

CONCLUSIONS

These results suggest a preventive role of uridine 5'diphospho-glucuronosyltransferase 1A signals in the development and progression of upper urinary tract urothelial carcinoma. Loss of uridine 5'diphospho-glucuronosyltransferase 1A expression might serve as an independent predictor of poor prognosis in patients with upper urinary tract urothelial carcinoma.

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

Approximately 7% of all bladder cancer cases in males are associated with occupation. The question arises whether the use of genome-wide association studies was able to identify bladder cancer risk factors that may modulate occupational bladder cancer risk and prognosis. One hundred and forty-three bladder cancer cases with suspected occupational bladder cancer and 337 controls were genotyped for the following polymorphisms: N-acetyltransferase 2 (NAT2), glutathione S-transferase M1 (GSTM1), glutathione S-transferase T1 (GSTT1), UDP-glucuronyltransferase 1A rs11892031 (UGT1A), rs9642880 (close to c-MYC), and rs710521 (close to TP63). The most relevant polymorphisms for occupational bladder cancer risk were GSTM1 and UGT1A, especially when co-occurring (GSTM1 negative and rs11892031[A/A]: 48% cases vs. 38% controls, OR 1.47, 95% CI 0.99-2.20). The effect was more pronounced in smokers. GSTM1 negative genotype occurred more frequently in cancer cases exposed to aromatic amines, carbolineum, and in painters and varnishers. UGT1A (rs11892031[A/A]) was found frequently in cases exposed to carbolineum, crack test spray, PAH, and in painters and varnishers. All investigated polymorphisms except rs710521 (TP63) seemed to exert an impact on recurrence risk. Relapse-free times were shorter for NAT2 slow and ultra-slow, GSTT1 positive and GSTM1 negative cases. Occupational bladder cancer cases with a number of risk variants displayed significantly shorter relapse-free times compared to cases with few, less relevant risk alleles as evidenced by median difference 8 months. In conclusion, in the present, suspected occupational bladder cancer cases phase II polymorphisms involved in bladder carcinogen metabolism modulate bladder cancer recurrence. Most relevant for bladder cancer risk were GSTM1 and UGT1A but not NAT2.

Urinary bladder cancer risk factors in an area of former coal, iron, and steel industries in Germany

This study was performed to investigate the frequency of bladder cancer in patients with an occupational history such as underground hard coal mining and/or painting after the structural change in the local industry. A total of 206 patients with bladder cancer and 207 controls were enlisted regarding occupational and nonoccupational bladder cancer risk factors by questionnaire. The phase II enzymes N-acetyltransferase 2 (NAT2), glutathione S-transferases M1 (GSTM1), and T1 (GSTT1) and the single nucleotide polymorphism (SNP) rs11892031[A/C] reported to be associated with bladder cancer in genome-wide association studies were genotyped. The bladder cancer risk in varnishers and underground hard coal miners was increased as previously shown in a study in this area performed in the 1980s. The occupation of a car mechanic was associated with a significantly elevated bladder cancer risk and higher in the case of underground hard coal miners even though the mine was closed in 1987. The frequency of GSTM1 negative genotype was comparable in cases and controls (53% versus 54%). In the case of NAT2, the slow NAT2 genotype was more frequent (62% versus 58%) and ultra-slow NAT2 genotype (NAT2*6A and/or *7B alleles only) was 23% versus 15%. An occupational history of a varnisher or an underground hard coal miner remains a risk factor for bladder cancer occurrence. Data indicate that in the case of bladder cancer, GSTM1 is a susceptibility factor related to environmental and/or occupational exposure.

UDP-glucuronosyltransferases (UGTs) and their related metabolic cross-talk with internal homeostasis: A systematic review of UGT isoforms for precision medicine

UDP-glucuronosyltransferases (UGTs) are the primary phase II enzymes catalyzing the conjugation of glucuronic acid to the xenobiotics with polar groups for facilitating their clearance. The UGTs belong to a superfamily that consists of diverse isoforms possessing distinct but overlapping metabolic activity. The abnormality or deficiency of UGTs in vivo is highly associated with some diseases, efficacy and toxicity of drugs, and precisely therapeutic personality. Despite the great effects and fruitful results achieved, to date, the expression and functions of individual UGTs have not been well clarified, the inconsistency of UGTs is often observed in human and experimental animals, and the complex regulation factors affecting UGTs have not been systematically summarized. This article gives an overview of updated reports on UGTs involving the various regulatory factors in terms of the genetic, environmental, pathological, and physiological effects on the functioning of individual UGTs, in turn, the dysfunction of UGTs induced disease risk and endo- or xenobiotic metabolism-related toxicity. The complex cross-talk effect of UGTs with internal homeostasis is systematically summarized and discussed in detail, which would be of great importance for personalized precision medicine.

Glucuronidation and UGT isozymes in bladder: new targets for the treatment of uroepithelial carcinomas?

Bladder cancer has been linked to numerous toxins which can be concentrated in the bladder after being absorbed into the blood and filtered by the kidneys. Excessive carcinogenic load to the bladder urothelium may result in the development of cancer. However, enzymes within the bladder can metabolize carcinogens into substrates that are safer. Importantly, these proteins, namely the UGT's (uridine 5'-diphospho-glucuronosyltransferases), have been shown to possibly prevent bladder cancer. Also, studies have shown that the UGT1 expression is decreased in uroepithelial carcinomas, which may allow for the accumulation of carcinogens in the bladder. In this review, we discuss the UGT system and its' protective role against bladder cancer, UGT genetic mutations that modulate risk from chemicals and environmental toxins, as well as targeting of the UGT enzymes by nuclear receptors.

Genetic variations rs11892031 and rs401681 are associated with bladder cancer risk in a Chinese population

Genome-wide association studies (GWAS) have identified a number of genetic variants associated with risk of bladder cancer in populations of European descent. Here, we assessed association of two of these variants, rs11892031 (2q37.1 region) and rs401681 (5p15.33 region) in a Chinese case-control study, which included 367 bladder cancer cases and 420 controls. We found that the AC genotype of rs11892031 was associated with remarkably decreased risk of bladder cancer (adjusted odds ratio (OR), 0.27; 95% confidence interval (CI), 0.09–0.81; p = 0.019), compared with the AA genotype of rs11892031; and that CT/CC genotypes of rs401681 were associated with significantly increased risk of bladder cancer (adjusted OR, 1.79; 95% CI, 1.10–2.91; p = 0.02), compared with the TT genotype of rs401681. We further conducted stratification analysis to examine the correlation between single nucleotide polymorphism (SNP) rs11892031/rs401681 and tumor grade/stage. Results showed that heterogeneity in ORs of tumor categories was not significant for either rs11892031 or rs401681 (p > 0.05), indicating that the two SNPs seemingly do not associate with tumor grade and stage of bladder cancer in our study population. The present study suggests that the SNPs rs11892031 and rs401681 are associated with bladder cancer risk in a Chinese population. Future analyses will be conducted with more participants recruited in a case-control study.

Pharmacogenomics of human uridine diphospho-glucuronosyltransferases and clinical implications

Glucuronidation by uridine diphospho-glucuronosyltransferase enzymes (UGTs) is a major phase II biotransformation pathway and, complementary to phase I metabolism and membrane transport, one of the most important cellular defense mechanisms responsible for the inactivation of therapeutic drugs, other xenobiotics, and endogenous molecules. Interindividual variability in UGT pathways is significant and may have profound pharmacological and toxicological implications. Several genetic and genomic processes underlie this variability and are discussed in relation to drug metabolism and diseases such as cancer.

Distinct SNP combinations confer susceptibility to urinary bladder cancer in smokers and non-smokers

Recently, genome-wide association studies have identified and validated genetic variations associated with urinary bladder cancer (UBC). However, it is still unknown whether the high-risk alleles of several SNPs interact with one another, leading to an even higher disease risk. Additionally, there is no information available on how the UBC risk due to these SNPs compare to the risk of cigarette smoking and to occupational exposure to urinary bladder carcinogens, and whether the same or different SNP combinations are relevant in smokers and non-smokers. To address these questions, we analyzed the genotypes of six SNPs, previously found to be associated with UBC, together with the GSTM1 deletion, in 1,595 UBC cases and 1,760 controls, stratified for smoking habits. We identified the strongest interactions of different orders and tested the stability of their effect by bootstrapping. We found that different SNP combinations were relevant in smokers and non-smokers. In smokers, polymorphisms involved in detoxification of cigarette smoke carcinogens were most relevant (GSTM1, rs11892031), in contrast to those in non-smokers with MYC and APOBEC3A near polymorphisms (rs9642880, rs1014971) being the most influential. Stable combinations of up to three high-risk alleles resulted in higher odds ratios (OR) than the individual SNPs, although the interaction effect was less than additive. The highest stable combination effects resulted in an OR of about 2.0, which is still lower than the ORs of cigarette smoking (here, current smokers' OR: 3.28) and comparable to occupational carcinogen exposure risks which, depending on the workplace, show mostly ORs up to 2.0.

Impact of the Interaction between 3'-UTR SNPs and microRNA on the Expression of Human Xenobiotic Metabolism Enzyme and Transporter Genes

Genetic variation in the expression of human xenobiotic metabolism enzymes and transporters (XMETs) leads to inter-individual variability in metabolism of therapeutic agents as well as differed susceptibility to various diseases. Recent expression quantitative traits loci (eQTL) mapping in a few human cells/tissues have identified a number of single nucleotide polymorphisms (SNPs) significantly associated with mRNA expression of many XMET genes. These eQTLs are therefore important candidate markers for pharmacogenetic studies. However, questions remain about whether these SNPs are causative and in what mechanism these SNPs may function. Given the important role of microRNAs (miRs) in gene transcription regulation, we hypothesize that those eQTLs or their proxies in strong linkage disequilibrium (LD) altering miR targeting are likely causative SNPs affecting gene expression. The aim of this study is to identify eQTLs potentially regulating major XMETs via interference with miR targeting. To this end, we performed a genome-wide screening for eQTLs for 409 genes encoding major drug metabolism enzymes, transporters and transcription factors, in publically available eQTL datasets generated from the HapMap lymphoblastoid cell lines and human liver and brain tissue. As a result, 308 eQTLs significantly (p < 10⁻⁵) associated with mRNA expression of 101 genes were identified. We further identified 7,869 SNPs in strong LD (r² ≥ 0.8) with these eQTLs using the 1,000 Genome SNP data. Among these 8,177 SNPs, 27 are located in the 3′-UTR of 14 genes. Using two algorithms predicting miR-SNP interaction, we found that almost all these SNPs (26 out of 27) were predicted to create, abolish, or change the target site for miRs in both algorithms. Many of these miRs were also expressed in the same tissue that the eQTL were identified. Our study provides a strong rationale for continued investigation for the functions of these eQTLs in pharmacogenetic settings.