Project description:Epithelial ovarian cancer is the leading cause of death from gynecological malignancies. Currently platinum-based chemotherapy, coupled with a taxane based drug is the primary treatment for ovarian cancer. Approximately 25% of patients either present with or rapidly develop resistance to platinum based chemotherapy and all recurrent tumors ultimately become resistant. Epigenetic modifications have been associated with tumor formation and progression and may contribute to therapy response. We performed a methylation screen on a set of tumors and have found a number of genes and family members differentially methylated between resistant patients and sensitive patients. Here we show that loss of expression of CHD3, a member of the Mi-2/NuRD complex, causes increased resistance to platinum chemotherapy drugs. Additionally, ovarian cell lines transcriptionally silenced for CHD3 are more invasive, have migratory ability, and display a transformed epithelial to mesenchymal (EMT) phenotype. Taken together, we provide the first evidence of a role for CHD3 as an important epigenetic regulator of chemoresistance in ovarian cancer and hypothesize EMT as one of the underlying mechanisms. Furthermore, CHD3 expression might represent a therapy response predictor and could be a future therapeutic target for ovarian cancer. We have developed a method to profile genome wide methylation. 71 ovarian tumor samples and 9 normal tissue samples from individuals were analyzed for CpG methylation. Some of these regions were validated for their methylation as a proof of principle for the method. Kamalakaran S., et. al. Mol Oncol. 2011;5:77-92 (PMID: 21169070).
Project description:Epithelial ovarian cancer is the leading cause of death from gynecological malignancies. Currently platinum-based chemotherapy, coupled with a taxane based drug is the primary treatment for ovarian cancer. Approximately 25% of patients either present with or rapidly develop resistance to platinum based chemotherapy and all recurrent tumors ultimately become resistant. Epigenetic modifications have been associated with tumor formation and progression and may contribute to therapy response. We performed a methylation screen on a set of tumors and have found a number of genes and family members differentially methylated between resistant patients and sensitive patients. Here we show that loss of expression of CHD3, a member of the Mi-2/NuRD complex, causes increased resistance to platinum chemotherapy drugs. Additionally, ovarian cell lines transcriptionally silenced for CHD3 are more invasive, have migratory ability, and display a transformed epithelial to mesenchymal (EMT) phenotype. Taken together, we provide the first evidence of a role for CHD3 as an important epigenetic regulator of chemoresistance in ovarian cancer and hypothesize EMT as one of the underlying mechanisms. Furthermore, CHD3 expression might represent a therapy response predictor and could be a future therapeutic target for ovarian cancer.
Project description:Aims: Deubiquitinases (DUBs) are proteases with emerging roles in cancer progression and therapy resistance, yet their contribution to drug resistance in ovarian cancer remains underexplored. Ovarian cancer patients often fail to benefit from platinum-based therapy, highlighting the need to identify novel factors involved in drug resistance. To this end we performed a CRISPR/Cas9 screen targeting DUB family to identify genes essential for platinum- resistant ovarian carcinoma cell survival. Methods: A CRISPR/CAS9 DUB knockout screen was performed on IGROV-1 parental and platinum-resistant ovarian carcinoma cells. Preclinical pharmacology approaches were also applied. Results: We identified USP18 as a survival factor in platinum-resistant ovarian cancer cells. USP18 expression was elevated at the mRNA and protein levels across five platinum-resistant cell lines. Knockdown and CRISPR/CAS9 editing of USP18 sensitized cells to cisplatin, coinciding with impaired repair of cisplatin-induced DNA damage. RNA-seq of USP18 RNA interfered and edited cells revealed the modulation of pathways including DNA repair. A peptide-based USP18 inhibitor suppressed growth of resistant cells, supporting its role in sustaining the growth of platinum-resistant cells. Conclusion: We identified USP18 as a novel mediator of platinum resistance in ovarian cancer, through modulating DNA repair. Targeting USP18 may offer a therapeutic strategy to improve outcomes in platinum-resistant ovarian cancer.
Project description:Platinum resistance is a major drawback in the treatment of ovarian cancer. Evidence suggests that microRNAs are key players in the initiation, progression, and drug resistance of cancer cells. However, the precise miRNAs dysregulated and contributing to platinum resistance in ovarian cancer cells have not been fully elucidated. Here, we conducted a miRNA expression profiling of cisplatin-sensitive (A2780) and cisplatin-resistant (CP20 and CIS) ovarian cancer cells to identify potential miRNAs involved in platinum resistance.
Project description:Ovarian Cancer (OC) is one of the gynecological malignancies with the highest mortality rate. Among the numerous subtypes of ovarian cancer, high-grade serous ovarian cancer (HGSOC) is the most common subtype and has a significant impact on prognosis, accounting for approximately 70%-80% of ovarian cancer-related deaths. Platinum-based chemotherapy combined with paclitaxel is the main approach for treating HGSOC. However, up to 75% of patients with advanced HGSOC will experience recurrence and eventually develop platinum-based resistance, among which approximately 20% of patients do not respond to first-line platinum-based treatment initially. Studies have shown that Cancer Stem cells (CSCs) play a key role in chemotherapy resistance of ovarian cancer. Bmi1 is an important protein for maintaining the stemness of tumor cells. Targeting Bmi1 is regarded as an effective treatment strategy for tumor drug resistance.
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.
Project description:Platinum-based chemotherapy causes genetic damage and induces apoptosis in ovarian cancer cells. Enhancing the ability to resist platinum drug-induced DNA damage and apoptotic stress is critical for tumor cells to acquire drug resistance. Here, we found that Y-box binding protein 1 (YBX1) was highly expressed in platinum-resistant patient-derived organoids (PDOs) and was a crucial gene for alleviating platinum-induced stress and maintaining drug resistance characteristics in ovarian cancer cells.
Project description:Platinum compounds display clinical activity against a wide variety of solid tumors. However, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux-kinetics indicated that ATP11B enhances the export of cisplatin from cells. The co-localization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins such as syntaxin-6 (STX6) and vesicular associated membrane protein 4 (VAMP4) strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, silencing ATP11B expression might be a therapeutic strategy to overcome cisplatin resistance. We performed the transfection of control-siRNA and ATP11B-siRNA to both cisplatin-sensitive A2780-PAR and cisplatin-resistant A2780-CP20 cells respectively.
Project description:Ovarian cancer (OC) is the leading cause of death from gynecologic malignancies. The most difficult issue in the treatment of ovarian cancer is the eventual development of platinum resistance. Accumulating studies have shown that circRNAs are abnormally aberrantly expressed in tumors and play critical roles in tumor growth, metastasis, stemness and resistance to therapy.To identify circRNAs that play crucial roles in maintaining the platinum resistance of ovarian cacner, we performed RNA-seq analysis in platinum-resistant(n=9) and -sensitive(n=10) ovarian cacner tissues. Candidate genes were identified by bioinformatic analysis and literature review.