GSTM1 and GSTT1 copy number variants and the risk to Thai females of hepatocellular carcinoma

Influence of GSTM1, T1 genes polymorphisms on oxidative stress and liver enzymes in rural and urban pesticides-exposed workers

Several studies discussed the relationship between the toxicity of organophosphates (OPs) and carbamates pesticides and oxidative stress which affects human health. This study aimed to evaluate the effects of pesticides on the induction of oxidative stress and hepatotoxicity. It was also focused on glutathione-S-transferase gene polymorphism in the modulation of these effects. In addition, the role of the educational level of exposed workers was studied. Acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), liver enzymes, malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and glutathione S transferase (GST) were estimated at 100 pesticide-exposed workers (50 urban researchers (UE) and 50 rural sprayers (RE)), and 100 matched controls (50 urban controls (UC)and 50 rural controls (RC)). AChE and BuChE were decreased in RE and UE compared to RC. Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activity were elevated in UE and UC compared to the RE and RC. Alanine aminotransferase (ALT) was elevated in UE compared to RE. MDA in RE and UE showed elevation compared to RC. There was a significant reduction in the levels of GSH, GST, and GPx in UE compared to RE and RC. The most sensitive pesticide-induced hepatotoxicity group were exposed workers with the GSTT1 genotype. Within these workers, ALT and ALP were significantly correlated with MDA and inversely correlated with AChE and BuChE, while AST was inversely correlated with AChE and BuChE only in UE. Conclusion: GST gene polymorphisms appeared to have a significant role in workers' susceptibility to hepatotoxic effects due to occupational exposure to pesticides; GSTT1 was the most sensitive genotype.

Identification of Methylation-Regulated Differentially Expressed Genes and Related Pathways in Hepatocellular Carcinoma: A Study Based on TCGA Database and Bioinformatics Analysis

Background

In recent years, DNA methylation modification has been shown to be a critical mechanism in the field of epigenetics.

Methods

Hepatocellular carcinoma (HCC) data were obtained from The Cancer Genome Atlas project, including RNA expression profiles, Illumina Human Methylation 450K BeadChip data, clinical information, and pathological features. Then, differentially expressed genes (DEGs) and differentially methylated genes were identified using R software. Methylation-regulated DEGs (MeDEGs) were further analyzed using Spearman’s correlation analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed using the DAVID database and ClueGO in Cytoscape software. Kaplan–Meier survival analysis explored the relationship between methylation, expression of MeDEGs, and survival time. Gene set enrichment analysis (GSEA) was conducted to predict the function of prognosis-related MeDEGs.

Results

A total of nine up-regulated and 72 down-regulated MeDEGs were identified. GO and KEGG pathway analyses results indicated that multiple cancer-related terms were enriched. Kaplan–Meier survival analysis showed that the methylation status of four MeDEGs (CTF1, FZD8, PDK4, and ZNF334) was negatively associated with overall survival. Moreover, the methylation status of CDF1 and PDK4 was identified as an independent prognostic factor. According to GSEA, hypermethylation of prognosis-related MeDEGs was enriched in pathways that included “Spliceosome”, “Cell cycle”, “RNA degradation”, “RNA polymerase”, “DNA replication”, “Mismatch repair”, “Base excision repair”, “Nucleotide excision repair”, “Homologous recombination”, “Protein export”, and “Pyrimidine metabolism”.

Conclusions

Aberrant DNA methylation plays a critical role in malignant progression of HCC. Prognosis-related MeDEGs identified in this research may be potential biomarkers and targets in diagnosis and treatment.

Association of GSTM1 and GSTT1 Null Deletions and GSTP1 rs1695 Polymorphism with the Risk of Hepatocellular Carcinoma: A Systematic Review and Meta-analysis

Context: Hepatocellular carcinoma (HCC), as the most common type of primary liver cancer (accounting for 70% - 90% of all liver cancers), is the seventh most common malignancy worldwide. Glutathione S-transferases (GSTs) are a specific group of enzymes that are responsible for the detoxification of carcinogens. According to the available literature, genetic variations in this group of enzymes may be associated with the risk of HCC. In this study, we aimed to assess the association of GSTM1 and GSTT1 null deletions and GSTP1 rs1695 polymorphism with the risk of HCC. Methods: We systematically searched electronic databases, including PubMed, Scopus, and Web of Science, using appropriate keywords to gather relevant data until March 2019. Studies that met the inclusion criteria were included in the meta-analysis, using either fixed- or random-effects models based on the presence of heterogeneity. Results: This meta-analysis pooled 19 studies for GSTM1 null deletions, 14 studies for GSTT1 null deletions, and five studies for GSTP1 rs1695 polymorphism. In terms of heterogeneity, the pooled odds ratio (OR) was calculated in a random-effects model for both Asian and non-Asian populations. HCC was found to be associated with GSTM1 null deletions (OR = 1.26, 95% CI: 1.00 - 1.58, P = 0.05) and GSTT1 null deletions (OR = 1.39, 95% CI: 1.10 - 1.74, P = 0.005); however, no significant association was found between HCC and GSTP1 rs1695 polymorphism (OR = 1.14, 95% CI: 0.86 - 1.50, P = 0.36). Conclusions: We found that GSTM1 and GSTT1 null deletions increased the risk of HCC; however, the GSTP1 rs1695 polymorphism did not have a similar effect.

Estrogen Signaling Induces Mitochondrial Dysfunction-Associated Autophagy and Senescence in Breast Cancer Cells

Previous work has shown that although estrogen (E2) disrupts cellular iron metabolism and induces oxidative stress in breast and ovarian cancer cells, it fails to induce apoptosis. However, E2 treatment was reported to enhance the apoptotic effects of doxorubicin in cancer cells. This suggests that E2 can precipitate anti-growth effects that render cancer cells more susceptible to chemotherapy. To investigate such anti-growth non-apoptotic, effects of E2 in cancer cells, MDA-MB-231 and MCF-7 cells were evaluated for the expression of key autophagy and senescence markers and for mitochondrial damage following E2 treatment. Treated cells experienced mitochondrial membrane depolarization along with increased expression of LC3-I/II, Pink1 and LAMP2, increased LC3-II accumulation and increased lysosomal and mitochondrial accumulation and flattening. E2-treated MCF-7 cells also showed reduced P53 and pRb780 expression and increased Rb and P21 expression. Increased expression of the autophagy markers ATG3 and Beclin1 along with increased levels of β-galactosidase activity and IL-6 production were evident in E2-treated MCF-7 cells. These findings suggest that E2 precipitates a form of mitochondrial damage that leads to cell senescence and autophagy in breast cancer cells.