Apoptosis In Epithelial Ovarian Cancer Cells Research Articles

Overexpression of HOXC8 is Associated With Poor Prognosis in Epithelial Ovarian Cancer.

Homeobox C8 (HOXC8) is a transcription factor that has been reported as a potential driver oncogene in several tumors and involved in the regulation of many cancer-related proteins. In this study, we investigated the expression and role of HOXC8 in ovarian cancer. Western blot and immunohistochemistry analyses were performed to detect the expression of HOXC8. Kaplan-Meier curve showed that high expression of HOXC8 was related to poor prognosis of patients with epithelial ovarian cancer (EOC). Starvation and refeeding assay were used to assess cell cycle, suggesting that HOXC8 played a critical role in EOC cell proliferation. HOXC8 depletion by small interfering RNA inhibited cell proliferation, migration, and induced apoptosis in EOC cells. Moreover, HOXC8 knockdown increased the expression of ZAC1. Owing to the overexpression of HOXC8, our findings implied that HOXC8 is involved in the progression of EOC and could be a potential therapeutical approach of EOC.

Linalool-Incorporated Nanoparticles as a Novel Anticancer Agent for Epithelial Ovarian Carcinoma.

Although cytotoxic chemotherapy is widely used against epithelial ovarian cancer (EOC), adverse side effects and emergence of resistance can limit its utility. Therefore, new drugs with systemic delivery platforms are urgently needed for this disease. In this study, we developed linalool-incorporated nanoparticles (LIN-NP) as a novel anticancer agent. We prepared LIN-NPs by the self-assembly water-in-oil-in-water (w/o/w) emulsion method. LIN-NP-mediated cytotoxicity and apoptosis was assessed in EOC cells, and the role of reactive oxygen species (ROS) generation as the mechanism of action was evaluated. In addition, therapeutic efficacy of LIN-NP was assessed in cell lines and patient-derived xenograft (PDX) models for EOC. LIN-NPs had significant cytotoxicity and apoptotic activity against EOC cells, including A2780, HeyA8, and SKOV3ip1. LIN-NP treatment increased apoptosis in EOC cells through ROS generation and a subsequent decrease in mitochondrial membrane potential and increase in caspase-3 levels. In addition, 100 mg/kg LIN-NPs significantly decreased tumor weight in the HeyA8 (P < 0.001) and SKOV3ip1 (P = 0.006) in vivo models. Although treatment with 50 mg/kg LIN-NP did not decrease tumor weight compared with the control group, combination treatment with paclitaxel significantly decreased tumor weight compared with paclitaxel alone in SKOV3ip1 xenografts (P = 0.004) and the patient-derived xenograft model (P = 0.020). We have developed LIN-NPs that induce ROS generation as a novel anticancer agent for EOC. These findings have broad applications for cancer therapy. Mol Cancer Ther; 15(4); 618-27. ©2016 AACR.

MicroRNA-137 suppresses tumor growth in epithelial ovarian cancer in vitro and in vivo.

Epithelial ovarian cancer (EOC) remains a major gynecological problem, with a poor 5-year-survival rate due to distant metastases. The identification of microRNAs (miRNAs) may provide a novel avenue for diagnostic and treatment regimens for EOC. Several miRNAs have been reported to be involved in the progression of EOC, among which miRNA (miR)-137 has been observed to be downregulated in the ovarian tissues of patients with EOC. However, the functions of miR-137 in EOC cell apoptosis, migration and invasion remain to be elucidated. In the present study, the expression of miR-137 was measured in clinical ovarian cancer specimens and cell lines using reverse transcription-quantitative polymerase chain reaction. The role of miR-137 in the growth and survival of the SKOV3 human ovarian cancer cell line was determined using several in vitro approaches and in nude mouse models. The results demonstrated that the expression of miR-137 was downregulated in the ovarian cancer specimens and cell lines. It was also observed that enforced expression of miR-137 in the EOC cell lines decreased cell proliferation, clonogenicity, migration and invasion, and induced G1 arrest and cell apoptosis in vitro. Notably, the enforced expression of miR-137 suppressed tumor growth in the nude mice models. These findings suggested that miR-137 may act as a tumor suppressor and be used as a potential therapeutic agent for the treatment of EOC.

MicroRNA-29a inhibits cell migration and invasion by targeting Roundabout 1 in breast cancer cells.

Epithelial ovarian cancer (EOC) remains a major gynecological problem, with a poor 5-year-survival rate due to distant metastases. The identification of microRNAs (miRNAs) may provide a novel avenue for diagnostic and treatment regimens for EOC. Several miRNAs have been reported to be involved in the progression of EOC, among which miRNA (miR)-137 has been observed to be downregulated in the ovarian tissues of patients with EOC. However, the functions of miR-137 in EOC cell apoptosis, migration and invasion remain to be elucidated. In the present study, the expression of miR-137 was measured in clinical ovarian cancer specimens and cell lines using reverse transcription-quantitative polymerase chain reaction. The role of miR-137 in the growth and survival of the SKOV3 human ovarian cancer cell line was determined using several in vitro approaches and in nude mouse models. The results demonstrated that the expression of miR-137 was downregulated in the ovarian cancer specimens and cell lines. It was also observed that enforced expression of miR-137 in the EOC cell lines decreased cell proliferation, clonogenicity, migration and invasion, and induced G1 arrest and cell apoptosis in vitro. Notably, the enforced expression of miR-137 suppressed tumor growth in the nude mice models. These findings suggested that miR-137 may act as a tumor suppressor and be used as a potential therapeutic agent for the treatment of EOC.

Three-dimensional culture sensitizes epithelial ovarian cancer cells to EZH2 methyltransferase inhibition

Inhibitors of EZH2 methyltransferase activity have been demonstrated to selectively suppress the growth of diffused large B cell lymphoma (DLBCL) cells with gain-of-function mutations in EZH2, while exhibiting very limited effects on the growth of DLBCL cells with wild-type EZH2. Given that EZH2 is often overexpressed but not mutated in solid tumors, it is important to investigate the determinants of sensitivity of solid tumor cells to EZH2 inhibitors. In the current study, we show that three-dimensional (3D) culture of epithelial ovarian cancer (EOC) cells that overexpress EZH2 sensitizes these cells to EZH2 methyltransferase inhibition. Treatment of EOC cells with GSK343, a specific inhibitor of EZH2 methyltransferase, decreases the level of H3K27Me3, the product of EZH2’s enzymatic activity. However, GSK343 exhibited limited effects on the growth of EOC cells in conventional two-dimensional (2D) culture. In contrast, GSK343 significantly suppressed the growth of EOC cells cultured in 3D matrigel extracellular matrix (ECM), which more closely mimics the tumor microenvironment in vivo. Notably, GSK343 induces apoptosis of EOC cells in 3D but not 2D culture. In addition, GSK343 significantly inhibited the invasion of EOC cells. In summary, we show that the 3D ECM sensitizes EOC cells to EZH2 methyltransferase inhibition, which suppresses cell growth, induces apoptosis and inhibits invasion. Our findings imply that in EZH2 wild-type solid tumors, the ECM tumor microenvironment plays an important role in determining sensitivity to EZH2 inhibition and suggest that targeting the ECM represents a novel strategy for enhancing EZH2 inhibitor efficacy.

Dichloroacetate Induces Apoptosis of Epithelial Ovarian Cancer Cells Through a Mechanism Involving Modulation of Oxidative Stress

Epithelial ovarian cancer (EOC) cells are under intrinsic oxidative stress, which alters metabolic activity and reduces apoptosis. Key oxidative stress enzymes, including myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS), are upregulated and colocalized in EOC cells. Oxidative stress is also regulated, in part, by superoxide dismutase (SOD) and hypoxia-inducible factor (HIF) 1a. Dichloroacetate (DCA) converts anaerobic to aerobic metabolism and thus was utilized to determine the effects on apoptosis, iNOS, MPO, extracellular SOD (SOD-3), and HIF-1a, in EOC cells. Protein and messenger RNA (mRNA) levels of iNOS, MPO, SOD-3, and HIF-1a were evaluated by immunoprecipitation/Western blot and real-time reverse transcriptase-polymerase chain reaction (RT-PCR), respectively, utilizing SKOV-3 and MDAH-2774 treated with DCA. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and caspase 3 assays. Dichloroacetate induced apoptosis, reduced MPO, iNOS, and HIF-1a, whereas increased SOD, in both EOC cell lines. In conclusion, reduction of enhanced oxidative stress-induced apoptosis of EOC cells, which may serve as future therapeutic intervention for ovarian cancer.

Modulation of redox signaling promotes apoptosis in epithelial ovarian cancer cells

Objective Epithelial ovarian cancer (EOC) cells are known to be resistant to apoptosis through a mechanism that may involve alteration in their redox balance. NADPH oxidase is a major source of intracellular superoxide, which is converted to the less toxic product by superoxide dismutase (SOD). Superoxide contributes to hypoxia inducible factor (HIF)-1α stabilization. We sought to determine the effects of inhibiting the generation of intracellular reactive oxygen species (ROS) on apoptosis of EOC cells. Methods Diphenyleneiodonium (DPI), an irreversible ROS inhibitor, was used to inhibit the generation of ROS in EOC cell lines, SKOV-3 and MDAH-2774, followed by assessment of apoptosis, NADPH oxidase, SOD3 and HIF-1α expression. A combination of immunohistochemistry, immunoprecipitation/western blot, and real-time RT-PCR were utilized to evaluate the expression of these enzymes in EOC cells as well as normal ovarian tissue and ovarian cancer tissue specimens. Results DPI treatment significantly induced apoptosis in both EOC cell lines as evident by increased caspase-3 activity and TUNEL assay. Additionally, both EOC cell lines were found to express NADPH oxidase, HIF-1α, and SOD3, which were highly sensitive to DPI treatment. DPI treatment resulted in reduced NADPH oxidase, SOD3 and HIF-1α levels. Furthermore, ovarian cancer tissues were found to manifest higher NADPH oxidase levels as compared to normal ovarian tissues. Conclusions These data suggest that lowering oxidative stress, possibly through the inhibition of NADPH oxidase, induces apoptosis in ovarian cancer cells and may serve as a potential target for cancer therapy.

Molecular blockade of VEGFR2 in human epithelial ovarian carcinoma cells

Human epithelial ovarian cancer (EOC) is the most lethal neoplasm affecting the female genital tract, and is characterized by overexpression of vascular endothelial growth factor (VEGF) and growth as ascites. Anti-VEGF strategies are currently used in EOC therapy with promising results; however, molecular targeting of specific VEGF receptors on the cancer cells themselves has not been explored to date. We previously showed that activation of a VEGF/VEGFR2 signaling loop in EOC cells supports their survival in suspension, and short-term pharmacological inhibition of this loop increased EOC cell apoptosis in vitro. In this study, we stably knocked down VEGFR2 in OVCAR-3 and SKOV-3 EOC cells using short hairpin RNA (shRNA), an RNA interference strategy that could potentially overcome chemoresistance arising with angiogenic inhibitors. Unexpectedly, we observed an induction of more aggressive cellular behavior in transfected cells, leading to increased growth in mouse xenografts, enhanced accumulation of ascites, increased VEGF and neuropilin-1 (NRP-1) expression, and decreased expression of adhesion proteins, notably cadherins and integrins. Sonic hedgehog (SHH) pathways do not seem to be involved in the upregulation of NRP-1 message in VEGFR2 knockdown cells. Supporting our mouse model, we also found a significant increase in the ratio between NRP-1 and VEGFR2 with increasing tumor grade in 80 cases of human EOC. The change in EOC behavior that we report in this study occurred independent of the angiogenic response and shows the direct effect of VEGF blockade on the cancer cells themselves. Our findings highlight the possible confounding events that may affect the usefulness of RNAi in a therapeutic setting for disrupting EOC cell survival in ascites.

Microarray analysis of apoptosis-relevant genes modulated by glucocorticoids in ovarian cancer

Purpose: Almost all patients with epithelial ovarian cancer (EOC) receive chemotherapy and, concurrently, the synthetic steroid hormone dexamethasone to alleviate toxicity. This study was to test the impact of steroid hormones on apoptosis of EOC cells and to identify its mediators. Merthods: Microarray with 8K cDNA chips including apoptosis-relevant genes was used to study genes regulated by glucocorticoids in 2 representative EOC cell lines. Cells were incubated with dexamethasone at serum equivalent doses in hormone-depleted medium. Apoptosis was induced by application of TRAIL and determined by caspase 3 activity, PARP cleavage and cell survival. Results: In cell culture, apoptosis was reduced after treatment with dexamethasone or cortisol. Microarray analysis revealed a 7-fold upregulation of the key caspase inhibitor cIAP2 by dexamethasone. cIAP2 upregulation by glucocorticoids was confirmed by RT-PCR and Western blot analysis. Under clinical conditions, we observed significant upregulation of cIAP2 in the ascites cells of an ovarian cancer patient after treatment with dexamethasone. Conclusions: Activation of the glucocorticoid receptor in EOC cells caused an anti-apoptotic effect in EOC cells by enhancing the cellular expression level of cIAP2. Dexamethasone pretreatment of EOC patients receiving apoptosis-inducing therapy raises questions about a negative effect on anti-tumor efficacy.