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Genital use of talcum powder and its associated risk of ovarian cancer is an important controversial topic. Epithelial ovarian cancer (EOC) cells are known to manifest a persistent prooxidant state. Here we demonstrated that talc induces significant changes in key redox enzymes and enhances the prooxidant state in normal and EOC cells. Using real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, levels of CA-125, caspase-3, nitrate/nitrite, and selected key redox enzymes, including myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GSR), were determined. TaqMan genotype analysis utilizing the QuantStudio 12K Flex was used to assess single-nucleotide polymorphisms in genes corresponding to target enzymes. Cell proliferation was determined by MTT proliferation assay. In all talc-treated cells, there was a significant dose-dependent increase in prooxidant iNOS, nitrate/nitrite, and MPO with a concomitant decrease in antioxidants CAT, SOD, GSR, and GPX (P <.05). Remarkably, talc exposure induced specific point mutations that are known to alter the activity in some of these key enzymes. Talc exposure also resulted in a significant increase in inflammation as determined by increased tumor marker CA-125 (P <.05). More importantly, talc exposure significantly induced cell proliferation and decreased apoptosis in cancer cells and to a greater degree in normal cells (P <.05). These findings are the first to confirm the cellular effect of talc and provide a molecular mechanism to previous reports linking genital use to increased ovarian cancer risk. [ABSTRACT FROM AUTHOR]

Oxidative stress plays an important role in the pathophysiology of ovarian cancer. Resistance to chemotherapy presents a significant challenge for ovarian cancer treatment. Specific single nucleotide polymorphisms (SNPs) in key redox enzymes have been associated with ovarian cancer survival and progression. The objective of this study was to determine whether chemotherapy induces point mutations in key redox enzymes that lead to the acquisition of chemoresistance in epithelial ovarian cancer (EOC). Human EOC cell lines and their chemoresistant counterpart were utilized for this study. Specific SNPs in key redox enzymes were analyzed by TaqMan SNP Genotyping. Activities and levels of key redox enzymes were determined by real-time RT-PCR, ELISA and a greiss assay. Point mutations in key redox enzymes were introduced into sensitive EOC cells via the CRISPR/Cas9 system. Cell viability and IC 50 for cisplatin were determined by the MTT Cell Proliferation Assay. Data was analyzed with SPSS using Student's two-tailed t -tests and One-way ANOVA followed by Dunnett's or Tukey's post hoc tests, p<0.05. Here, we demonstrate that chemoresistant EOC cells are characterized by a further enhancement in oxidative stress as compared to sensitive counterparts. Additionally, chemoresistant EOC cells manifested specific point mutations, which are associated with altered enzymatic activity, in key redox enzymes that are not detected in sensitive counterparts. Supplementation of an antioxidant was able to successfully sensitize EOC cells to chemotherapeutics. Causality was established by the induction of these point mutations in sensitive EOC cells, which resulted in a significant increase in the level of chemoresistance. These findings indicate that chemotherapy induces specific point mutations in key redox enzymes that contribute to the acquisition of chemoresistance in EOC cells, highlighting a potential novel mechanism. Identification of targets for chemoresistance with either biomarker and/or screening potential will have a significant impact for the treatment of this disease. [ABSTRACT FROM AUTHOR]