Abstract 3580: Downregulated miR-30a promotes acquisition of chemoresistance by targeting endothelin A receptor in ovarian carcinoma
Authors: Sestito Rosanna , Cianfrocca Roberta , Rosanò Laura , Semprucci Elisa , Tocci Piera , Di Castro Valeriana , Ferrandina Gabriella , Bagnato Anna 
Published: August 2015

Abstract
Chemotherapy is the preferred therapeutic approach for the therapy of epithelial ovarian carcinoma (EOC), but a successful long-term treatment is prevented by the development of drug resistance. Endothelin-1 (ET-1)/ETA receptor (ETAR) axis is upregulated in chemoresistant EOC and associated with acquisition of chemoresistance and epithelial-mesenchymal transition (EMT) phenotype and poor prognosis. Therefore, interference with ET-1/ETAR signaling pathway has emerged as a promising strategy for cancer therapy. Because dysregulation of miRNAs has been associated with cancer development and drug-resistance, in this study we evaluated whether altered expression of miRNAs might regulate ETAR expression in 2008 and A2780 sensitive and resistant EOC cell lines. Based on bioinformatics tools, we selected putative miRNAs able to recognize the 3′UTR of ETAR. Among these, only miR-30a resulted downregulated in chemoresistant EOC cells compared with parental cells. Luciferase reporter assays using wild-type and mutant ETAR 3′ -UTR constructs, and transfection of miR-30a mimic showed that miR-30a targets the 3′ -UTR of ETAR mRNA. Indeed ectopic expression of miR-30a inhibited ETAR-driven signaling pathways. Interestingly, miR-30a re-introduction in chemoresistant EOC cells impaired their capacity to promote the invasive process and reverted EMT phenotype. Moreover, miR-30a overexpression was able to restore drug sensitivity by enhancing the susceptibility of resistant EOC cells to cisplatinum-induced apoptosis, as supported by the reduced viability and increased cleavage of caspase 7 and PARP. Similarly, we demonstrated that the treatment with macitentan, a potent ETAR antagonist with significant affinity for ETBR, counteracted the effects elicited by ETAR pathway in chemoresistant EOC cells restoring drug-sensitivity and regulating cell plasticity. In preclinical model of resistant EOC, macitentan treatment reduced tumor growth, vascularization, intravasation and metastatic progression. The combination of macitentan and cisplatinum inhibited tumor growth of resistant EOC xenografts more effective then chemotherapy alone. In addition, lower expression of miR-30a and higher expression of ETAR in platinum-resistant specimens from EOC patients were significantly associated with poor clinical outcome, representing potential predictive markers of chemoresistance. This study for the first time demonstrated miR-30a-dependent regulation of ETAR for chemoresistance of EOC, further supporting that the regulation of ETAR represents a valid therapeutic target for circumventing drug resistance.
Citation Format: Rosanna Sestito, Roberta Cianfrocca, Laura Rosanò, Elisa Semprucci, Piera Tocci, Valeriana Di Castro, Gabriella Ferrandina, Anna Bagnato. Downregulated miR-30a promotes acquisition of chemoresistance by targeting endothelin A receptor in ovarian carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3580. doi:10.1158/1538-7445.AM2015-3580