Inhibitions of GSK3β Modulates Cell Death in Epithelial Ovarian Cancer

Epithelial ovarian cancer is one of the most common gynecological malignancies and the fifth most frequent cause of cancer death in women, affecting over 22,000 women annually. Nearly 15,500 affected women die from this disease annually, and chemoresistance from the commonly prescribed platinum-based drug, carboplatin, is a major contributor to this mortality rate. Previous studies have identified genes with CpG islands that are methylated and transcriptionally silenced in resistant epithelial ovarian cancer patients. One of these genes is GSK3β, an important regulator of apoptosis and cell growth in the Wnt pathway. Thus, understanding the role of GSK3β suppression in chemoresistance of epithelial ovarian cancer can help contribute to more effective treatments for this disease. By performing assays of cell growth, viability, and apoptosis, our study examined the functional role that GSK3β plays in carboplatin mediated apoptosis. Our results suggest that cells with suppressed GSK3β had increased proliferation and reduced apoptosis. We conclude that silenced GSK3β expression might therefore contribute to carboplatin resistance seen in tumors and our in vitro analysis suggests that GSK3β expression is vital to carboplatin chemosensitivity. Future research is required to further investigate the role of GSK3β methylation to facilitate the design of potential genome-guided treatments for patients with chemoresistant epithelial ovarian cancer

Abstract 4525: Hypoxia signaling pathway plays a role in ovarian cancer chemoresistance

Hypoxia-inducible factor 1 (HIF-1) is a basic helix-loop-helix transcription factor that when induced regulates the expression of many genes involved in cytoprotective stimuli, which attenuates apoptosis and improves survival. Increased expression of HIF-1α gene (HIF1A) has been found in several carcinomas, including ovarian cancer. Ovarian cancers are generally refractory to platinum-based chemotherapy. Despite the large number of studies, molecular events that govern the emergence of aggressive therapy-resistant cells after chemotherapy are poorly defined. Genomic instabilities, such as copy number variation(CNV), may play an important role in chemoresistance and have been implicated in many complex diseases, like cancer.. We analyzed CNV data that is publically available through the Cancer Genome Atlas and others. Of particular interest was the transcription factor HIF1A which plays an integral role in oxidative stress response such as those induced by chemotherapy reagents. The present study provides evidence for the rare escape of tumor cells from drug-induced cell death by entering a non-cycling senescent state. We report the adaptive response of human ovarian surface epithelium cells to CoCl2, a chemical hypoxia-mimicking agent resulting in a senescent-like state of chemoresistant cells. The effect of the treatment was evaluated on CNV of HIF-1α gene expression, cell proliferation, survival, and tumor invasiveness. We show here that CNV duplication events of HIF1α results in an oxidative stress response in cells leading to chemoresistance through the induction of cellular senescence. Understanding the molecular events associated with chemoresistance will ultimately lead to better patient treatment and outcomes

Novel Role of Hypoxia in Ovarian Cancer Chemo Resistance through Epigenetic Regulation of HIF1α

Ovarian cancer is the fifth deadliest cancer in woman, and epithelial malignancies account for 90% of cases. Tumor recurrence after chemotherapy or radiation remains a major obstacle to successful ovarian cancer treatment. Despite the large number of studies, molecular events that govern the emergence of aggressive therapy-resistant cells after chemotherapy are poorly defined. Genetic modifications, such as copy number variation (CNV), play an important role in controlling the expression of genes that are involved in chemo resistance. We analyzed CNV data that is publically available through the Cancer Genome Atlas and others. Of particular interest was the transcription factor HIF1α which plays an integral role in oxidative stress response such as those induced by chemotherapy reagents? The present study provides evidence for the rare escape of tumor cells from drug-induced cell death by entering a non-cycling senescent state. We report the adaptive response of human ovarian surface epithelium cells to CoCl2, a chemical hypoxia-mimicking agent resulting in a senescent-like state of chemo resistant cells. The effect of the treatment was evaluated on CNV of HIF-1α gene expression, cell proliferation, survival, and tumor invasiveness