Although oxidation is the most common biological and energy producing reaction, oxidative stress is harmful to cell, because the products of oxidation such as free radicals and peroxides damage the cellular components, causing several diseases. Damage in DNA is responsible for cancer formation and progression. However, several enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase etc. act as antioxidants to influence oxidative stress. Polymorphisms in these enzymes are supposed to be associated with DNA damage and subsequently the individual’s risk of cancer susceptibility. This review article aims to further elucidate the relationship between antioxidant enzymes and cancers by summarizing the findings of some of the important study concerning expression levels and genetic polymorphisms of antioxidant enzymes in cancer patients.

Resveratrol (RSV) is a natural polyphenol that is known as a powerful chemopreventive and chemotherapeutic anticancer molecule. This study focused on the effects of RSV on the activities and expression levels of antioxidant enzymes in the cancer cells. Prostate cancer PC-3 cells, hepatic cancer HepG2 cells, breast cancer MCF-7 cells and the non-cancerous HEK293T kidney epithelial cells were treated with a wide range of RSV concentrations (10-100 μM) for 24–72 h. Cell growth was estimated by trypan blue staining, activities of the antioxidant enzymes were measured spectrophotometrically, expression levels of the antioxidant enzymes were quantified by digitalizing the protein band intensities on Western blots, and the percentage of apoptotic cells was determined by flow cytometry. Treatment with a low concentration of RSV (25 μM) significantly increased superoxide dismutase (SOD) activity in PC-3, HepG2 and MCF-7 cells, but not in HEK293T cells. Catalase (CAT) activity was increased in HepG2 cells, but no effect was found on glutathione peroxidase (GPX) upon RSV treatment. RSV-induced SOD2 expression was observed in cancer cells, although the expression of SOD1, CAT and GPX1 was unaffected. Apoptosis increased upon RSV treatment of cancer cells, especially in PC-3 and HepG2 cells. Together, our data demonstrated that RSV inhibits cancer cell growth with minimal effects on non-cancerous cells. We postulate that the disproportional up-regulation of SOD, CAT and GPX expression and enzymatic activity in cancer cells results in the mitochondrial accumulation of H₂O₂, which in turn induces cancer cell apoptosis.

TRIM28 regulates its target genes at both transcriptional and posttranscriptional levels. Here we report that a TRIM28-TWIST1-EMT axis exists in breast cancer cells and TRIM28 promotes breast cancer metastasis by stabilizing TWIST1 and subsequently enhancing EMT. We find that TRIM28 is highly expressed in both cancer cell lines and advanced breast cancer tissues and the levels of TRIM28 and TWIST1 are positively correlated with the aggressiveness of breast carcinomas. Overexpression and depletion of TRIM28 up- and down-regulates the protein, but not the mRNA levels of TWIST1, respectively, suggesting that TRIM28 upregulates TWIST1 post-transcriptionally. Overexpression of TRIM28 in breast cancer cell line promotes cell migration and invasion. Knockdown of TRIM28 reduces the protein level of TWIST1 with concurrent upregulation of E-cadherin and downregulation of N-cadherin and consequently inhibits cell migration and invasion. Furthermore, Immunoprecipitation and GST pull-down assays demonstrated that TRIM28 interacts with TWIST1 directly and this interaction is presumed to protect TWIST1 from degradation. Our study revealed a novel mechanism in breast cancer cells that TRIM28 enhances metastasis by stabilizing TWIST1, suggesting that targeting TRIM28 could be an efficacious strategy in breast cancer treatment.

Hepatic copper determination is an important test for the diagnosis of Wilson's disease (WD). However, the method has not been standardized, the diagnostic accuracy has not been evaluated prospectively, and the optimal cut‐off value remains controversial. Accordingly, we aimed to prospectively evaluate the diagnostic accuracy of hepatic copper content, as determined using the entire core of a liver biopsy sample. Patients for whom a liver biopsy was indicated were consecutively enrolled. Hepatic copper content was determined with atomic absorption spectroscopy. All assays were performed using careful quality control by a single technician. WD diagnosis was based on WD score or its combination with clinical follow‐up results. A total of 3,350 consecutive patients underwent liver biopsy. Six hundred ninety‐one patients, including 178 with WD, underwent two passes of liver biopsy with hepatic copper determination. Mean hepatic content in WD patients was 770.6 ± 393.2 μg/g dry weight (wt). Sensitivity, specificity, and positive and negative predictive values of hepatic copper content for WD diagnosis in the absence of primary biliary cirrhosis (PBC) or primary sclerosing cholangitis at the cut‐off value of 250 μg/g dry wt. were 94.4%, 96.8%, 91.8%, and 97.8%, respectively. The most useful cut‐off value was 209 μg/g dry wt, with a sensitivity and specificity of 99.4% and 96.1%, respectively. A total of 23.3% of patients without WD and PBC had hepatic copper content >75 μg/g dry wt. Conclusion: A liver biopsy sample of more than 1 mg dry wt may reliably reflect hepatic copper content and should be used for hepatic copper determination. Hepatic copper determination is a very valid procedure for the diagnosis of WD, and the most useful cut‐off value is 209 μg/g dry wt.(Hepatology 2015;62:1731–1741)