Combinations of the Variant Genotypes of CYP1A1, GSTM1 and GSTT1 are Associated with an Increased Lung Cancer Risk in North Indian Population: a Case-Control Study

Synergistic polymorphic interactions of phase II metabolizing genes and their association toward lung cancer susceptibility in North Indians

Lung cancer is a multifactorial carcinoma with diverse heterogeneity. Genetic variations in drug-metabolizing enzymes may lead to defective detoxification and clearance of carcinogenic compounds. The high-order gene-gene interaction has been carried out between different genotypes of Phase II detoxification genes (NQO1, SULT1A1, NAT2, and EPHX1). Our results depict the genetic combination of SULT1A1 R213H with NAT2 × 5B L161L, SULT1A1 R213H with NAT2 × 5C K268R, EPHX1 H139R and NAT2 × 5B L161L exhibit a protective effect towards lung cancer risk. Further, the triple combinations of NQO1 P187S, EPHX1 Y113H, and EPHX1 H139R; NQO1 P187S, EPHX1 Y113H, and NAT2 × 6 R197Q; NQO1 P187S, EPHX1 Y113H, and NAT2 × 7 G286E; SULT1A1 R213H, EPHX1 H139R, and NAT2 × 7 G286E suggested a two-fold increased risk of lung cancer for subjects. Genetic polymorphisms of phase II detoxifying genes (NAT2, NQO1, EPHX1, SULT1A1) are prognostic markers for lung cancer.

The lncRNA FENDRR inhibits colorectal cancer progression via interacting with and triggering GSTP1 ubiquitination by FBX8

Background

Colorectal cancer (CRC) is characterized by its aggressiveness and high fatality rate. Long noncoding RNAs (lncRNAs) as molecular scaffolding in CRC have received little attention.

Methods

The TCGA database was used to find putative anti-oncogenic lncRNAs in CRC. The effect of FENDRR on CRC was evaluated using the colony formation assay, transwell assays, and wound healing assays, and FENDRR expression was validated by qRT-PCR. The location of the FENDRR binding proteins was determined by an RNA pull-down experiment, and the retrieved proteins were recognized by mass spectrometry. RNA immunoprecipitation (RIP) studies were used to demonstrate the interaction of GSTP1, FBX8, and FENDRR. Co-IP and immunofluorescence were utilized to confirm the connection between GSTP1 and FBX8. To determine the precise signaling pathways implicated in the action of FENDRR in CRC, we performed next-generation sequencing (NGS) on CRC cells transfected with a vector overexpressing FENDRR.

Results

The expression of FENDRR was significantly downregulated in CRC tissue and cells. The results of the function experiments showed that overexpression of FENDRR reduced CRC cells' ability to proliferation, invasion, migration and tube formation. In terms of mechanism, FENDRR could bind both GSTP1 and FBX8, act as a molecular scaffold, and utilize FBX8 to regulate the stability of GSTP1's protein. Additionally, the outcomes of NGS and qRT-PCR demonstrated that the expression of genes linked to the HIF-1 pathway was down-regulated following FENDRR overexpression. Lastly, rescue tests demonstrated that overexpression of GSTP1 in CRC cells could completely restore the inhibition induced by FENDRR.

Conclusion

In this study, we found that the molecular scaffolding protein FENDRR regulates the ubiquitination of GSTP1 and the suppression of the HIF-1 signaling pathway in the development of CRC. Our research provides more evidence of FENDRR's crucial role in the emergence of CRC and identifies it as a potential therapeutic target for CRC patients.

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Gene-gene and gene-environment interaction: an important predictor of oral cancer among smokeless tobacco users in Karachi

Objective: To determine the risk for oral cancer caused by simultaneous occurrence of more than one of the tested cytochrome P450 1A1MspI, glutathione S-transferaseM1 null gnd Glutathione S-transferasesT1 null gene polymorphisms. Method: The cross-sectional case-control study was conducted from December 2011 to October 2016 at the Ziauddin University, Karachi, in collaboration with Dow University of Health Sciences, Karachi, and comprised oral squamous cell carcinoma cases in group A and healthy tobacco habit-matched controls in group B. All investigations were done using standardised laboratory protocols. The outcomes were determined in terms of association of various combinations of cytochrome P450 1A1MspI, glutathione S-transferasesM1 null and glutathione S-transferases T1 null polymorphisms with oral cancer. Data was analysed using SPSS 20. Results: Of the 238 subjects, 140(58.8%) were in group A and 98(41.2%) were in group B. Mean ages in group A and B were 47.1±12.22 and 41.6±14.58 years, respectively. Male/Female ratio in group A was 1.88:1 while 83.4% were using tobacco. When cytochrome P450 1A1MspI homozygous (m2/m2) and glutathione S-transferasesM1 null variants occured simultaneously in an individual, an odds ratio of 12.8 (95% confidence interval: 1.20-135.5; p=0.03) among overall tobacco chewers was observed. For glutathione S-transferasesM1 not null and glutathione S-transferasesT1 null variant combination among overall tobacco users, the conferred odds ratio was 4.58 (95% confidence interval: 0.99-21.2; p=0.05). The other studied gene combinations did not reveal significant associations (p>0.05). ---Continue

Association between the combined effects of GSTM1 present/null and CYP1A1 MspI polymorphisms with lung cancer risk: an updated meta-analysis

Background: Many studies have been performed to explore the combined effects of glutathione-S-transferase M1 (GSTM1) present/null and cytochrome P4501A1 (CYP1A1) MspI polymorphisms with lung cancer (LC) risk, but the results are contradictory. Two previous meta-analyses have been reported on the issue in 2011 and 2014. However, several new articles since then have been published. In addition, their meta-analyses did not valuate the credibility of significantly positive results.

Objectives: We performed an updated meta-analysis to solve the controversy following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Methods: False-positive report probability (FPRP), Bayesian false discovery probability (BFDP), and the Venice criteria were used to verify the credibility of meta-analyses.

Results: Twenty-three publications including 5734 LC cases and 7066 controls met the inclusion criteria in the present study. A significantly increased risk of LC was found in overall analysis, Asians and Indians. However, all positive results were considered as ‘less-credible’ when we used the Venice criteria, FPRP, and BFDP test to assess the credibility of the positive results.

Conclusion: These positive findings should be interpreted with caution and results indicate that significant associations may be less-credible, there are no significantly increased LC risk between the combined effects of GSTM1 present/null and CYP1A1 MspI polymorphisms.

Interactive potential of genetic polymorphism in Xenobiotic metabolising and DNA repair genes for predicting lung cancer predisposition and overall survival in North Indians

INTRODUCTION

Cancer, a multi-step, multifactorial and multi-gene disease, not only damages the genomic integrity of the cell but also hinders the DNA repair mechanisms of the body. Gene-gene and gene environment interactions amongst the genetic polymorphisms together modulate the susceptibility towards a cancer. We have studied the high order gene interactions between the genetic polymorphism of detoxifying genes (CYP1A1, Ahr, XRCC and GST1) that play a key role in the metabolism of the xenobiotics and have been proved to be prognostic markers for lung cancer METHODS: 237 cases and 250 controls have been genotyped using PCR-RFLP technique. In order to find out the association, unconditional logistic regression approach was used and to analyse high order interactions MDR and CART was used.

RESULTS

In the MDR analysis, the best model was one factor model which included GSTM1 (CVC 10/10, Prediction error = 0.43, p < .001). The best three factor model comprised of XRCC1 632, XRCC1 206, GSTM1 (CVC 10/10, Prediction error = 0.45, p < .0001). The CART analysis exhibited that Node 1 carrying mutant type of GSTM1 imposed the highest risk towards lung cancer (OR = 11.0, 95%C.I. = 6.05-20.03, p = .000001). Wild type of GSTM1 when combined with mutant type of CYP1A1 M2 and XRCC1 632, an 8 fold risk towards lung cancer was observed (95%C.I. = 4.07-16.29, p = .00001). The high order interactions were used to predict the prognosis of lung cancer patients. Of all the genetic variants, XRCC1 632, GSTM1 and AhR rs2066853 was the most important determinant of overall survival of lung cancer patients CONCLUSION: Through the study we introduced the concept of polygenic approach to get an insight about the various polymorphic variants in determining cancer susceptibility. Lesser number of subjects were found in the high risk subgroups. Further studies with larger sample size are required to warranty the above findings.