Is there a link between talcum powder, oxidative stress, and ovarian cancer risk?

INTRODUCTION: The link between talcum powder use and cancer, particularly ovarian cancer, has been a topic of scientific research and legal debate for several years. Studies have suggested a potential association between long-term talcum powder use in the genital area and an increased risk of ovarian cancer. AREAS COVERED: The following report includes up-to-date evidence to support the potential link between talcum powder use and the risk of developing ovarian cancer. The International Agency for Research on Cancer, which is part of the World Health Organization, classified talc-based body powder as possibly carcinogenic to humans when used in the female genital area. However, other studies have not consistently supported this association, and thus more research is needed to establish a clear and definitive link between talcum powder use and cancer. Despite this, recent molecular-level data have linked talc to alterations in redox balance, gene mutations, and inflammatory responses. Specifically, we have identified a role for talc to induce the pro-oxidant state, inhibit apoptosis, and more importantly induced cellular transformation in normal ovarian cells. EXPERT OPINION: We presented unequivocal evidence to support our opinion that talc is not biologically inert and induces molecular changes that mimic the hallmarks of cancer.

Monomeric myeloperoxidase is a specific biomarker for early-stage ovarian cancer.

Background: Ovarian cancer cells are known to express myeloperoxidase (MPO), an oxidant-producing enzyme with a 150 kDa homodimer, consisting of two identical monomers connected by a disulfide bond. Here, we aim to validate monomeric MPO (mMPO) as a biomarker for the early detection of ovarian cancer.Methods: Human ovarian cancer cells, sera from patients at various stages, sera from non-cancer inflammatory gynecological diseases, and healthy volunteers were used. Monomeric and dimeric MPO were measured by ELISA. Receiver operating curves were used to compare the predictive powers of serum dimeric and monomeric MPO to discriminate between samples.Results: The expression of MPO was unique to ovarian cancer cells. Specifically, mMPO was found to be the only form of MPO in all ovarian cancer cell lines. Intriguingly, mMPO was detected in the sera from all patients with ovarian cancer at various stages, but not from healthy individuals. Serum mMPO discriminated between early-stage ovarian cancer, healthy controls, and benign inflammatory gynecologic disorders. In addition, mMPO discriminated between the early and late stages of the disease.Conclusion: This work highlights mMPO as a potential biomarker for early detection of ovarian cancer, which is critically needed.

Talcum powder induces malignant transformation in normal human primary ovarian epithelial cells.

BACKGROUND: Several studies have linked perineal use of talcum powder to increased risk of ovarian cancer (OC). Here, we determined that exposure to talcum powder induces malignant transformation in human normal ovarian cells. METHODS: Human primary ovarian epithelial cells (HPOE), ovarian epithelial cells (HOSEpiC), and primary fibroblasts (NF) were treated with either 100 or 500 µg/mL of talcum powder or titanium dioxide (TiO2) as a particulate control for 72 hours before assessment with a cell transformation assay and p53 and Ki-67 immunohistochemistry. RESULTS: Treatment with talcum powder resulted in formation of colonies, indicating cell malignant transformation in a dose dependent manner in ovarian cell lines. No colonies formed in the untreated ovarian cells or control ovarian cells (TiO2 treated) at either dose. There were no colonies formed in talc treated NF cells. Transformed ovarian cells were increased by 11% and 20% in HPOE and 24% and 40% in HOSEpic cells for talcum powder 100 and 500 µg/mL doses, respectively (P<0.05). There were no detectible transformed cells when cells were treated with TiO2. Importantly, p53 mutant type as well as increased expression of Ki-67 were detected in HPOE and HOSEpic cells when exposed to talcum powder. CONCLUSIONS: Exposure to talcum powder induces malignant transformation in ovarian epithelial cells but not in NF cells. These findings represent a direct effect of talcum powder exposure that is specific to normal ovarian cells and further supports previous studies demonstrating an association between the genital use of talcum powder and an increased risk of OC.

Association between redundant endometrium and endometrial polyps: a pilot study.

BACKGROUND: The aim of this study was to explore the organic features of redundant endometrium (RE), we examined the expression of different endometrial hormone receptors, oncogenes, and cell replication markers, in normal endometrium (NE), endometrial polyps (EP) and RE specimens. METHODS: This was an experimental study examining endometrial tissue expression of estrogen receptors (ER1 and 2), progesterone receptors (PR-A+B), androgen receptor (AR), insulin receptor (Insulin-R), insulin-like growth factor receptor 1 (IGFR-1), thyroid hormone receptor (TH-RB), B-cell lymphoma 2 (Bcl-2), Ki67, HOXA10, in women with NE, EP and RE, of women undergoing hysteroscopy for benign gynecologic pathology. Specimens were separated in 3 groups: NE, EP, RE. Endometrial samples were processed for real-time RT-PCR analyses. Main outcome measure was tissue expression of the markers in the three groups. RESULTS: Of the 16 patients, 2 had NE, 8 had RE, 5 had EP, 1 had both, RE and EP. Compared to NE, RE and EP showed significantly increased Bcl-2, Insulin-R, ER-ß, PR-A+B, and TRB expression (P<0.044), with EP showing significantly increased PR-A+B, compared to RE (3.29±0.47 fg/µg RNA versus 1.86±0.34 fg/µg RNA; P=0.023). The other markers were not significantly different across the three groups: Ki67 appeared non-significantly decreased, while HOXA10, IGF-R1, AR, and ER-α, were non-significantly increased. CONCLUSIONS: RE showed biochemical characteristics different from NE. Similar to endometrial polyps, RE showed enhanced cell differentiation, but not cell replication. These changes in RE could be detrimental for embryo implantation and should be of consideration in women undergoing fertility treatments.

Binding of Intracellular Myeloperoxidase to αV/ß1 Integrin Serves as a Mechanism of Survival in Epithelial Ovarian Cancer.

We were the first to report that epithelial ovarian cancer (EOC) cells and tissues express myeloperoxidase (MPO) that is known to play a role in immune surveillance and inflammation by myeloid cells. Additionally, we reported that MPO is colocalized with inducible nitric oxide synthase (iNOS), a key pro-oxidant enzyme, and plays a key role in regulating apoptosis in EOC cells. Whereas myeloid cells express MPO in a dimeric form, intriguingly, here we report the unique expression of only the monomeric form of MPO in EOC cells, tissues, and blood of an ovarian cancer patient. Additionally, we have identified a cell membrane receptor, αV/ß1 integrin, that is uniquely expressed by both chemosensitive and chemoresistant EOC cells with significantly higher expression in chemoresistant EOC cells. More importantly, we have demonstrated that monoclonal antibodies against αV/ß1 integrin induced cytotoxicity in EOC cells, but not in normal cells, that is also synergistic with conventional chemotherapies. Cytotoxicity of αV/ß1 antibodies is due to conformational changes in αV/ß1 integrin which prevents monomeric MPO binding to αV/ß1 integrin inhibiting the activation of MPO, leading to increased apoptosis. Since normal epithelial cells and macrophages lack monomeric MPO and αV/ß1 integrin system, targeting this unique MPO-dependent survival mechanism will selectively eliminate EOC cells and will be the target for developing specific ovarian cancer therapies.

Epigenetics: new insights into postoperative adhesion development.

BACKGROUND: The link between post-operative adhesion development and epigenetic modifications is important in understanding the mechanism behind their formation. The purpose of this study was to determine whether epigenetic differences exist between primary fibroblasts of normal peritoneum and adhesion tissues isolated from the same patient(s). METHODS: DNA from fibroblasts isolated from normal peritoneum and adhesion tissues was isolated using Qiagen's EZ1 Advanced Kit. Methylation patterns of genes were quantified and compared in both cell lines using the Infinium Human Methylation 27 Beadchip system. RESULTS: A total of 7364 genes had been found to manifest significantly different DNA methylation levels in adhesion fibroblasts as compared to normal peritoneal fibroblasts (p<0.01). A total of 1685 genes were found to have increased DNA methylation by 50% in adhesion compared to peritoneal fibroblasts, and were enriched in Gene Ontology categories, Glycoprotein, and Defense Response. Furthermore, 1287 genes were found to have decreased DNA methylation patterns with enriched Gene Ontology categories, "Homeobox", and Transcription Factor Activity in adhesion fibroblasts. CONCLUSIONS: Epigenetic differences in fibroblasts isolated from normal peritoneum and adhesion tissues were observed. Future studies focusing on the precise role of these genes in the development of post operative adhesions will allow us to more fully appreciate regulatory mechanisms leading to adhesion development, thereby establishing targets for therapeutic interventions to prevent or limit adhesion development.

The potential benefits of dinitrophenol combination with chemotherapy in the treatment of ovarian cancer.

BACKGROUND: 2,4-dinitrophenol (DNP), an uncoupling mitochondrial agent, has been identified as a source of oxidative stress and linked to the pathogenesis of ovarian cancer. In this study, we determine the cytotoxic effect of DNP alone or in combination with chemotherapies in ovarian cancer cells. METHODS: We utilized human ovarian cancer cell lines SKOV-3 and MDAH-2774 with their chemoresistant counterparts. Cancer stem cells (CSCs) were isolated from SKOV-3 utilizing magnetic-activated cell sorting technique for CD44+/CD117+ cells. Human normal primary ovarian epithelial (NOEC) and HOSEpiC cell lines were used as a control. Cells were treated with and without chemotherapy (Taxotere 0.3µM or cisplatin 50 µM), with or without increasing doses of DNP (0.125, 0.25, or 0.5 mM) for 24 hours followed by evaluation of cell viability and IC50 utilizing MTT assay. For determination of synergism, Facombination index plots were created using the CompuSyn software. All data were run in triplicates and analyzed by t-test. RESULTS: DNP treatment of ovarian cancer and chemoresistant ovarian cancer cell lines as well as CSCs resulted in decreased cell viability in a dose dependent manner with no effect on normal cells. Combination of DNP with chemotherapy synergistically enhances cytotoxicity of chemotherapeutics in all ovarian cancer cells as compared to chemotherapy alone. CONCLUSIONS: Our data indicates the potential of the addition of DNP to the arsenal of drugs available to treat ovarian cancer, whether alone or in combination with chemotherapies. The synergistic effects of DNP in reducing the required amount of chemotherapy, is critical for the alleviation of harmful side effects.

Anti-Müllerian Hormone (AMH) regulates BRCA1 and BRCA2 gene expression after ovarian cortex transplantation.

OBJECTIVE: To test whether recombinant anti-Müllerian hormone (rAMH) could exert an inhibitory function on BRCA1/2 expression in human ovarian cortex. METHODS: Pilot study on ovariectomized nude mice xenotransplanted with human vitrified/warmed ovarian cortex and treated with rAMH via infusion pump. Twelve nude mice were ovariectomized and Alzet pumps delivering 1.23 mcg rAMH/day to reach a serum concentration of 17.5 ng/mL, or placebo (controls), were inserted intraabdominally. Previously vitrified/warmed 2x2 mm ovarian cortex fragments were transplanted on day 7 and then harvested on day 14 after pump placement. PCR analyses determined mRNA levels for BRCA1 and BRCA2 in the human ovarian cortex. RESULTS: In mice treated with rAMH, BRCA1 expression was significantly lower (0.196 fg/µg RNA, IQR 0.158, 0.236) than in controls (0.544 fg/µg RNA, IQR 0.458, 0.554; p = .030), while BRCA2 expression remained similar in rAMH mice (5.355 fg/µg RNA, IQR 4.479, 6.230) and in controls (4.011 fg/µg RNA, IQR 3.650, 4.182; p = .327). CONCLUSION: Administration of rAMH in the peri-transplant period caused downregulation of BRCA1, but not of BRCA2 expression, in human ovarian cortex. These results help our understanding of DNA repair mechanism in the ovarian cortex and identify AMH's possible protective effect on ovarian reserve in BRCA1 mutation carriers.

Recombinant Anti-Müllerian Hormone (rAMH) for Stalling In Vitro Granulosa Cell Replication.

To investigate whether recombinant AMH (rAMH) is able to decrease cellular proliferation/apoptosis in luteinized granulosa cells (GCs) through hormonal regulation, a primary culture of GCs was established from GCs obtained at time of oocyte retrieval from follicular fluid of 3 patients. Cells were seeded in well cell culture plates at a density of 100,000 cells/well in medium and treated with rAMH 20 ng/ml (rAMH group), or phosphate-buffered saline (PBS-control group), for 24 h. Total RNA was extracted from all cells, followed by cDNA synthesis and real-time RT-PCR to quantify the expression levels of AMH, AMH-R2, FSH-R, inhibin B, cell proliferation (Ki67), and apoptosis (Caspase 3). We used independent sample t test (SPSS v25) and a p < 0.05 significance. Cellular expressions of AMH, AMH-R2, FSH-R, and inhibin B were reduced greater than 50% in the rAMH group, compared with that of the the control group (p ≤ 0.005 for all). Ki67 and Caspase3 were also reduced greater than 30% in the rAMH group (p ≤ 0.001 for both). Our findings show a direct inhibitory effect of AMH on luteinized GCs' expression of the major regulatory hormones, in addition to a significant decrease in markers of cell proliferation and apoptosis. These results confirm the inhibitory effects of AMH on follicular development.

Heat Shock Protein 60 (HSP60) Serves as a Potential Target for the Sensitization of Chemoresistant Ovarian Cancer Cells.

HSP60 is a mitochondrial chaperone protein that is associated with decreased overall survival of ovarian cancer patients. We determined whether targeting HSP60 with its monoclonal antibody would induce cytotoxicity in sensitive and chemoresistant ovarian cancer cells and whether it is synergistic when combined with chemotherapeutic drugs. Epithelial ovarian cancer (EOC) cells and their docetaxel- or cisplatin-resistant counterparts were utilized. HSP60 mRNA levels were determined by real-time RT-PCR. Cytotoxicity of HSP60 antibody (0.5 or 1.5 µg/ml) alone and in combination with chemotherapy were assessed by MTT Cell Proliferation Assay. Unpaired t tests were used to compare groups for real-time RT-PCR. One-way ANOVA followed by Tukey's post hoc tests with Bonferroni correction was performed for cytotoxicity comparisons. Significant synergistic effects of the antibody combined with chemotherapy were determined by the CompuSyn Software. Basal HSP60 mRNA levels were increased in chemoresistant EOC cells as compared with their sensitive counterparts (p < 0.05). There was no significant difference in cytotoxicity between EOC cell types; however, treatment with the HSP60 antibody for 24 h showed a dose response (0.5 and 1.5 µg/ml) cytotoxic effect to both sensitive and chemoresistant EOC cells as compared with the isotype control (p < 0.05). Importantly, treatment with both doses of HSP60 antibody was not cytotoxic to normal macrophages. Combination of the HSP60 antibody with docetaxel or cisplatin was significantly synergistic in both sensitive and chemoresistant EOC cells. Here, we identify a novel target that may serve not only for ovarian cancer treatment but also for sensitization of patients to chemotherapy. The cytotoxic effect of HSP60 monoclonal antibody and its synergism with chemotherapeutic agents highlight HSP60 as a promising target for therapy and chemosensitization in ovarian cancer treatment.

Molecular Basis Supporting the Association of Talcum Powder Use With Increased Risk of Ovarian Cancer.

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.

Evitar (l-Alanyl-l-Glutamine) Regulates Key Signaling Molecules in the Pathogenesis of Postoperative Tissue Fibrosis.

AIMS: Hypoxia and the resulting oxidative stress play a major role in postoperative tissue fibrosis. The objective of this study was to determine the effect of l-alanyl-l-glutamine (Ala-Gln) on key markers of postoperative tissue fibrosis: hypoxia-inducible factor (HIF) 1α and type I collagen. METHODS: Primary cultures of human normal peritoneal fibroblasts (NPF) established from normal peritoneal tissue were treated with increasing doses of Ala-Gln (0, 1, 2, or 10 mM) with hypoxia ([2% O2] 0-48 hours; continuous hypoxia) or after hypoxia (0.5, 1, 2, 4 hours) and restoration of normoxia (episodic hypoxia) with immediate treatment with Ala-Gln. Hypoxia-inducible factor 1α and type 1 collagen levels were determined by enzyme-linked immunosorbent assay. Data were analyzed with 1-way analysis of variance followed by Tukey tests with Bonferroni correction. RESULTS: Hypoxia-inducible factor 1α and type I collagen levels increased in untreated controls by 3- to 4-fold in response to continuous and episodic hypoxia in human NPF. Under continuous hypoxia, HIF-1α and type I collagen levels were suppressed by Ala-Gln in a dose-dependent manner. l-alanyl-l-glutamine treatment after episodic hypoxia also suppressed HIF-1α and type I collagen levels for up to 24 hours for all doses and up to 48 hours at the highest dose, regardless of exposure time to hypoxia. CONCLUSIONS: l-alanyl-l-glutamine significantly suppressed hypoxia-induced levels of key tissue fibrosis (adhesion) phenotype markers under conditions of continuous as well as episodic hypoxia in vitro. This effect of glutamine on molecular events involved in the cellular response to insult or injury suggests potential therapeutic value for glutamine in the prevention of postoperative tissue fibrosis.

Xenotransplantation of pre-pubertal ovarian cortex and prevention of follicle depletion with anti-Müllerian hormone (AMH).

OBJECTIVE: To determine whether recombinant AMH (rAMH) could prevent post-transplant follicular depletion by acting on the stemness markers Oct-4, Sox2, and NANOG. MATERIALS AND METHODS: This was an experimental study where 12 ovariectomized nude mice were xenotransplanted with vitrified/warmed ovarian cortex obtained from a pre-pubertal girl and Alzet pumps delivering rAMH, or placebo (control), were inserted intra-abdominally. Previously vitrified/warmed ovarian cortex fragments were transplanted after 7 days and then harvested after 14 days from pump placement. We performed real-time RT-PCR analyses, ELISA for AMH, FSH, and estradiol, histologic measurement of ovarian follicles, and immunohistochemistry for Ki67 and TUNEL. The main outcome measures were serum levels and tissue expression of the parameters under investigation and follicle count. RESULTS: Serum AMH, FSH, and estradiol reflected post-ovariectomy profiles and were mildly influenced by rAMH administration. Ovarian cortex expression of AMH, AMH-R2, VEGF, GDF9, Oct-4, and Sox2 was lower in rAMH mice than in controls, while NANOG was upregulated. There was a non-significant decrease in primordial follicles after vitrification-warming, and xenotransplantation further decreased this number. There were lower cell replication and depressed apoptosis in the rAMH group. CONCLUSIONS: Administration of recombinant AMH in the peri-transplant period did not protect the initial follicular depletion but decreased apoptosis and cellular activation and regulated stem cell markers' tissue expression. These results aid our understanding of the inhibitory effects of AMH on follicular development and show the benefit of administering exogenous AMH at the time of pre-pubertal ovarian cortex transplant to protect the follicles from pre-activation and premature depletion.

Novel expression of CD11b in epithelial ovarian cancer: Potential therapeutic target.

OBJECTIVE: The objective of this study was to determine the expression, and effect of targeting CD11b with a monoclonal antibody in ovarian cancer cells. METHODS: CD11b expression was determined in epithelial ovarian cancer (EOC) cell lines and tissues by immunofluorescence and flow cytometry. Cytotoxicity of the CD11b antibody and synergism with chemothearapeutic drugs were determined by the MTT Cell Proliferation Assay in human macrophages, normal ovarian epithelial cells, and in both sensitive and chemoresistant EOC cell lines. Cell migration was assessed with a scratch assay and in vivo effects of the CD11b antibody was assessed with a nude mouse ovarian cancer xenograft model. Data was analyzed with either t-tests or one-way ANOVA. RESULTS: CD11b was unexpectedly expressed in several EOC lines and tissues, but not normal tissues. Targeting CD11b with its monoclonal antibody resulted in intriguing cytotoxic effects in sensitive and chemoresistant EOC lines, while surprisingly not affecting normal cells. More importantly, the cytotoxicity of the CD11b antibody when combined with chemotherapeutic drugs (cisplatin or docetaxel) was significantly synergistic, in both sensitive and chemoresistant EOC cells. The anti-tumorigenic effect of the CD11b antibody was confirmed in an ovarian cancer nude mouse xenograft model. CONCLUSION: Here we identify CD11b as a novel target, which selectively induces cytotoxicity in ovarian cancer cells.

Anti-Müllerian Hormone (AMH) May Stall Ovarian Cortex Function Through Modulation of Hormone Receptors Other Than the AMH Receptor.

OBJECTIVE: To test whether recombinant anti-Müllerian hormone (AMH) can inhibit ovarian cortex function by modulating the expression of other hormone receptors. MATERIALS AND METHODS: Pilot experimental study with ovarian cortex obtained from 5 patients. Immediately after explant, the ovarian cortex specimens were divided into 5 equal fragments. One fragment was flash-frozen (uncultured) and 4 were incubated for 48 hours at 37°C in a pH-adjusted gamete buffer medium with increasing AMH concentrations of 0, 5, 25, and 50 ng/mL. After incubation, all specimens were rinsed and flash-frozen for polymerase chain reaction (PCR) executed in triplicates. We utilized real-time reverse transcription-polymerase chain reaction (RT-PCR) to determine messenger RNA (mRNA) levels of AMH and its receptor Anti-Müllerian Hormone-Receptor 2 (AMH-R2), follicle stimulating hormone receptor (FSH-R), luteinizing hormone receptor (LH-R), inhibin B, and insulin-like growth factor 1 receptor 1 (IGF1-R1) in ovarian cortex tissue. In addition, we performed Ki-67 immunostaining to evaluate cell proliferation in the treatment groups. RESULTS: Absence of recombinant human AMH (rAMH) caused upregulation of all markers. Exposure to increasing rAMH concentrations caused tissue AMH expression downregulation ( P = .024), while AMH-R2 ( P = .005), FSH-R ( P = .009), LH-R ( P = .003), and inhibin B ( P = .001) mRNA expression followed a bell-shaped response with an increased expression at low dose, followed by a decreased expression at higher doses. Expression of IGF1-R1 was independent ( P = .039) of rAMH exposure. The Ki-67 immunostaining showed an increased cell proliferation in the media control compared to the uncultured and the tissue cultured with rAMH. CONCLUSIONS: Culture with increasing rAMH concentrations caused downregulation of its own, as well as other hormone receptors, and a decreased ovarian cortex cell proliferation. These results help understanding the inhibitory effects of AMH on follicular development.

Oxidative stress: a key regulator of leiomyoma cell survival.

OBJECTIVE: To determine the effects of attenuating oxidative stress with the use of dichloroacetate (DCA) on the expression of key redox enzymes myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) as well as on apoptosis. DESIGN: Prospective experimental study. SETTING: University medical center. PATIENT(S): Cells established from myometrium and uterine fibroid from the same patients. INTERVENTION(S): Cells were exposed to normal (20% O2) or hypoxic (2% O2) conditions for 24 hours with or without DCA (20 µg/mL), a metabolic modulator that shifts anaerobic to aerobic metabolism. MAIN OUTCOME MEASURE(S): Nitrate/nitrite (iNOS activity indicator), iNOS, Bcl-2/Bax ratio, MPO, and caspase-3 activities and levels were determined by means of Greiss assay, real-time reverse-transcription polymerase chain reaction, and ELISA. Data were analyzed with the use of SPSS by means of one-way analysis of variance with Tukey post hoc analysis and independent t tests. RESULT(S): MPO, iNOS, and nitrate/nitrite expression were higher in leiomyoma than in myometrial cells, and they were further enhanced by hypoxia in myometrial cells. Treatment with the use of DCA decreased MPO, iNOS, and nitrate/nitrite levels and negated the effect of hypoxia in both types of cells. Leiomyoma cells showed less apoptosis, as indicated by both caspase-3 activity and the Bcl-2/Bax ratio, than myometrial cells. Hypoxia further decreased apoptosis in myometrial cells with no further effect on leiomyoma cells. Treatment with DCA resulted in increased apoptosis in both types of cells, even in the presence of hypoxia. CONCLUSION(S): Shifting anaerobic to aerobic metabolism with the use of DCA resulted in an increase in apoptosis in leiomyoma cells and protected myometrial cells from the acquisition of the leiomyoma-like phenotype.

Updates of the role of oxidative stress in the pathogenesis of ovarian cancer.

Clinical and epidemiological investigations have provided evidence supporting the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS), collectively known as oxidative stress, in the etiology of cancer. Exogenous factors such as chronic inflammation, infection and hypoxia are major sources of cellular oxidative stress. Specifically, oxidative stress plays an important role in the pathogenesis, neoangiogenesis, and dissemination of local or distant ovarian cancer, as it is known to induce phenotypic modifications of tumor cells by cross talk between tumor cells and the surrounding stroma. Subsequently, the biological significance of the relationship between oxidative stress markers and various stages of epithelial ovarian cancer highlights potential therapeutic interventions as well as provides urgently needed early detection biomarkers. In the light of our scientific research and the most recent experimental and clinical observations, this review provides the reader with up to date most relevant findings on the role of oxidative stress in the pathogenesis of ovarian cancer and the possible therapeutic implications.

Specific point mutations in key redox enzymes are associated with chemoresistance in epithelial ovarian cancer.

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 IC50 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.