Association between CYP2E1 polymorphisms and risk of gastric cancer: An updated meta-analysis of 32 case-control studies

Association between CYP2E1 polymorphisms and colorectal cancer risk: a systematic review and meta-analysis

CYP2E1 encodes an enzyme that participates in the activation of several carcinogenic substances. Thus, numerous studies have investigated the association between CYP2E1 polymorphisms and colorectal cancer (CRC) risk, but inconclusive results have been obtained. We performed a meta-analysis to precisely evaluate the relationship of CYP2E1 rs2031920, rs3813867, and rs6413432 polymorphisms with the susceptibility to CRC. Scopus, Web of Science and PubMed databases were searched to identify eligible studies, and the association between the polymorphisms and CRC risk was then quantitatively synthesized using different genetic models. Eighteen studies with 23,598 subjects were selected for inclusion into the analysis. Significant association between rs2031920 and an increased CRC risk was observed in homozygous (OR = 1.496, 95% CI 1.177-1.901, P = 0.001), recessive (OR = 1.467, 95% CI  1.160-1.857, P = 0.001) and allele (OR = 1.162, 95% CI  1.001-1.349, P = 0.048) models. Significant association was not found for rs3813867 and rs6413432 (P > 0.05). In conclusion, our results suggest that rs2031920, but not rs3813867 and rs6413432, is associated with the risk of CRC.

CYP2D6 and CYP2E1 Gene Polymorphisms and their Association with Cervical Cancer Susceptibility: A Hospital Based Case-Control Study from South-Western Maharashtra

BACKGROUND

In last few years several studies all over the world discovered the genetic polymorphisms in different cytochrome P450 genes associated with risk of various cancers, but contradictory outcomes were evidenced in case of cervical cancer risk.  In this case-control study we aimed to see whether the polymorphism of CYP2D6 or CYP2E1 genes may or may not be associated with cervical cancer risk in women of rural Maharashtra.

METHODS

In this case-control study, the association of CYP2D6 and CYP2E1 gene polymorphism with cervical cancer risk was studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The study was conducted with 350 clinically confirmed cervical cancer patients and 350 healthy women in a population of South-Western Maharashtra. The Odds ratio (OR) with 95% confidence interval and p-value were evaluated, where p ≤0.005 was considered as statistically significant.

RESULTS

After the analysis of SNP (rs389209) of CYP2D6 and SNPs (rs2031920, rs6413432, rs6413420) of CYP2E1, we noticed that variant allele A of CYP2E1*6 showed significant increase in cervical cancer cases (OR=4.81; 95% CI: 1.57- 14.77; p=0.005). The genotypic distribution of heterozygote G/A genotype of CYP2D6*4 showed negative association with cervical cancer development when age of cancer occurrence (OR=0.41; 95% CI: 0.27- 0.61; p<0.0001) and tobacco history (OR=0.35; 95% CI: 0.20- 0.59; p=0.0001) was considered.

CONCLUSION

The findings from this study supported that rs6413432 SNP of CYP2E1*6 increased cervical cancer risk in the studied rural women population.

Effects of Genetic Polymorphism on Susceptibility to Nephrotoxic Properties of BTEXs Compounds

OBJECTIVE

The aim of this study was to ascertain whether genetic polymorphism affects susceptibility of individuals to nephrotoxic potentials of benzene, toluene, ethyl-benzene, and xylenes (BTEXs).

METHODS

Fifty BTEXs exposed workers with one or more abnormal parameter of kidney function and 232 referent subjects, with similar exposure history, free from any abnormal kidney parameters were investigated. Atmospheric concentrations of BTEXs were measured. In addition, genetic polymorphisms were determined by multiplex polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP).

RESULTS

The frequencies of GSTP1 Ile-Val/Val-Val, null GSTT1, and null GSTT1/GSTM1 genotypes and mean values of blood urea nitrogen and plasma creatinine were significantly higher, while average glomerular filtration rate was significantly lower in cases than in referent subjects.

CONCLUSION

These findings indicate that individuals carrying null GSTT1 or null GSTT1/GSTM1 are more susceptible to nephrotoxic properties of BTEXs compounds.

Association between polymorphisms in the CYP1A1, CYP2E1 and GSTM1 genes, and smoking, alcohol and upper digestive tract carcinomas in a high-incidence area of northern China

Metabolic gene variants, smoking, and alcohol consumption are important upper digestive tract cancer (UDTC) risk factors. However, the gene-gene and gene-environment interactions remain unclear. A case-control study in a high incidence area for upper digestive tract cancer was conducted in China. DNA was extracted from buffy coat samples for PCR or PCR-restriction fragment length polymorphism. Smoking and alcohol drinking status was determined by questionnaires. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the associations. After adjusting for confounding factors, smoking increased esophageal cancer (EC), gastric cardia cancer (GCC) and gastric antral carcinoma (GAC) risk by 3.594, 4.658, and 3.999-fold, respectively. Alcohol consumption increased EC, GCC and GAC risk by 1.953, 2.442 and 1.765-fold, respectively. The cytochrome P4501A1 (CYP1A1) rs4646903 T>C polymorphism increased GCC risk, the cytochrome P4502E1 (CYP2E1) rs2031920 C>T polymorphism increased EC risk, while the GSTM1 null genotype decreased EC risk. An association existed between the following: CYP1A1 rs4646903 and smoking in EC, GCC and GAC; CYP1A1 rs4646903 and alcohol consumption in EC and GCC; CYP2E1 rs2031920 and smoking in EC, GCC and GAC and CYP2E1 rs2031920 and alcohol consumption in EC and GCC. No association was observed between CYP1A1 and CYP2E1. The glutathione S-transferase mu 1 (GSTM1) null genotype decreased EC risk (OR=0.510). Smoking/drinking are upper digestive tract cancer risk factors. The CYP1A1 rs4646903 and CYP2E1 rs2031920 polymorphisms were risk factors of GCC or EC, and the GSTM1 null genotype may serve a protective role against EC. The results of the present study indicated that gene-environment interactions increase the risk of UDTC.

Genetic polymorphisms and gastric cancer risk: a comprehensive review synopsis from meta-analysis and genome-wide association studies

Objective

In the past few decades, more than 500 reports have been published on the relationship between single nucleotide polymorphisms (SNPs) on candidate genes and gastric cancer (GC) risk. Previous findings have been disputed and are controversial. Therefore, we performed this article to summarize and assess the credibility and strength of genetic polymorphisms on the risk of GC.

Methods

We used Web of Science, PubMed, and Medline to identify meta-analyses published before July 30th, 2018 that assessed associations between variants on candidate genes and the risk of GC. Cumulative epidemiological evidence of statistical associations was assessed combining Venice criteria and a false-positive report probability (FPRP) test.

Results

Sixty-one variants demonstrated a significant association with GC risk, whereas 29 demonstrated no association. Nine variants on nine genes were rated as presenting strong cumulative epidemiological evidence for a nominally significant association with GC risk, including APE1 (rs1760944), DNMT1 (rs16999593), ERCC5 (rs751402), GSTT1 (null/presence), MDM2 (rs2278744), PPARG (rs1801282), TLR4 (rs4986790), IL-17F (rs763780), and CASP8 (rs3834129). Eleven SNPs were rated as moderate, and 33 SNPs were rated as weak. We also used the FPRP test to identify 13 noteworthy SNPs in five genome-wide association studies.

Conclusions

Sixty-one variants are significantly associated with GC risk, and 29 variants are not associated with GC risk; however, five variants on five genes presented strong evidence for an association upgraded from moderate. Further study of these variants may be needed in the future. Our study also provides referenced information for the genetic predisposition to GC.

Genetic polymorphism in cytochrome P450 2E1 and alcoholic pancreatitis sus-ceptibility: a meta-analysis

BACKGROUND

The association between cytochrome P450 2E1 (CYP2E1) polymorphism and the risk of alcoholic pancreatitis is contentious. This meta-analysis aimed to demonstrate the association between CYP2E1 RsaI/PstI, or DraI polymorphisms and the susceptibility of alcoholic pancreatitis.

MATERIALS AND METHODS

We searched for sources and background in Pubmed, Medline, Web of science and CNKI (Chinese national knowledge infrastructure), using the following keywords: "cytochrome P450 2E1" or "CYP2E1", "polymorphism" or "genotype", in combination with "alcoholic pancreatitis". All meta-analyses were performed with Stata 12.0. Subgroup analyses on ethnicity and type of alcoholic pancreatitis were conducted as well.   Results: Eleven articles, which met the inclusion criteria, included 595 patients with alcoholic pancreatitis, and 1767 controls. For the general population, our analysis suggested no obvious association between CYP2E1 RsaI/PstI or DraI polymorphisms and the risk of alcoholic pancreatitis. However, in the non-Asian subgroup, significant associations were found between the risk for alcoholic pancreatitis and CYP2E1 RsaI/PstI polymorphism [dominant model: odds ratio (OR) =1.92, 95 % confidence interval (CI): 1.25-2.95, p =0.003; allelic contrast model: OR =1.99, 95 % CI: 1.35-2.92, p <0.001. There was not a significant association found within the Asian group. Meanwhile, the susceptibilities of chronic alcoholic pancreatitis were significantly increased for dominant and allelic contrast models of CYP2E1 RsaI/PstI polymorphism [OR =1.62, 95 % CI: 1.12-2.34; p =0.011; OR =1.62, 95 % CI: 1.17-2.24, p = 0.004, respectively] but not for acute alcoholic pancreatitis for all population.

CONCLUSIONS

CYP2E1 RsaI/PstI polymorphism may increase the risk of alcoholic pancreatitis in the non-Asian population. Additionally, the CYP2E1 RsaI/PstI polymorphism may increase the susceptibility for chronic alcoholic pancreatitis for all population. HIPPOKRATIA 2018, 22(2): 60-67.

Meta-Analysis of the Relationship between NM23 Expression to Gastric Cancer Risk and Clinical Features

The prognostic value of reduced NM23 expression for gastric cancer (GC) patients is still contradictory. Thus, we conducted a meta-analysis to quantitatively evaluate the association of NM23 expression with GC risk and clinical features by analyzing 27 publications. The result of our meta-analysis indicated that NM23 expression is markedly reduced in gastric cancer tissues (OR = 3.15; 95% CI = 1.97–5.03; P < 0.001). Furthermore, NM23 expression was negatively correlated with N stage, TNM stage, and histological grade. However, NM23 expression was not correlated with T stage, lymphatic invasion, vascular invasion, and 5-year overall survival rate. In conclusion, reduced NM23 expression correlated with gastric cancer risk, but its association with GC clinical features remains inconclusive. Therefore, large-scale and well-designed studies, which use uniform antibody and criterion of NM23 positive expression, are required to further validate the role of the NM23 in predicting GC progression.

Toxicological Implications of Mitochondrial Localization of CYP2E1

Cytochrome P450 2E1 (CYP2E1) metabolizes an extensive array of pollutants, drugs, and other small molecules, often resulting in bioactivation to reactive metabolites. Therefore, it is unsurprising that it has been the subject of decades of research publications and reviews. However, while CYP2E1 has historically been studied in the endoplasmic reticulum (erCYP2E1), active CYP2E1 is also present in mitochondria (mtCYP2E1). Relatively few studies have specifically focused on mtCYP2E1, but there is growing interest in this form of the enzyme as a driver in toxicological mechanisms given its activity and location. Many previous studies have linked total CYP2E1 to conditions that involve mitochondrial dysfunction (fasting, diabetes, non-alcoholic steatohepatitis, and obesity). Furthermore, a large number of reactive metabolites that are formed by CYP2E1 through metabolism of drugs and pollutants have been demonstrated to cause mitochondrial dysfunction. Finally, there appears to be significant inter-individual variability in targeting to the mitochondria, which could constitute a source of variability in individual response to exposures. This review discusses those outcomes, the biochemical properties and toxicological consequences of mtCYP2E1, and highlights important knowledge gaps and future directions. Overall, we feel that this exciting area of research is rich with new and important questions about the relationship between mtCYP2E1, mitochondrial dysfunction, and pathology.