Abstract LB-323: Comparative miRNA microarray profiling indicates miR-363 promotes chemoresistance in ovarian cancer cells by targeting the Hippo member, LATS2

Abstract Ovarian cancer is the most aggressive female reproductive tract tumours. Taxane (TX) is widely used for ovarian cancer treatment. However, ovarian cancer often acquire chemoresistance. MicroRNAs (miR) have been reported to regulate many tumours’ chemoresistance. Here, we investigated the comparative microRNA expression profile between the ovarian cancer cells and their taxane-resistant counterpart, KF-TX to get novel markers for taxane resistance in ovarian cancer. The array data revealed that miR-486, miR143,miR145 and miR363 are the most upregulated miRNAs in association with TX resistance. However, miR-155, miR-100, miR-31 and miR-629 are the most significantly downregulated miRNAs after resistance development. We then focused on the role of miR-363 in chemoresistance of the ovarian cancer. qRT-PCR indicated that miR-363 was upregulated in KF-TX cells, confirming the array data, and introduction of miR-363 into sensitive ovarian cancer cells confers TX-resistance and significantly inhibited the expression of the Hippo member, LATS2, as indicated by viability, clonogenic assays and expression analysis. Furthermore, we validated the role of LATS2 in the TX-response by sh-based silencing, which also confers TX-resistance in the responsive ovarian cancer cells. On the other hand, specific inhibitor against miR-363 restored the response to TX. In addition, miR-363 was found to bind to the 3′-UTR of LATS2 mRNA, confirming that miR-363 directly targets LATS2 as indicated by dual luciferase assay. RT-PCR-based evaluation of miR-363 in a panel of human ovarian tumours revealed its upregulation in most of the tumour tissues identified as resistant while downregulation of the same gene in most of the tissues identified as sensitive ones. Moreover, higher levels of miR-363 in human ovarian cancer specimens were significantly correlated with TX chemoresistance and poor prognosis. Taken together, our study reveals the involvement of miR-363 in chemoresistance by targeting LATS2 in ovarian cancers, raising the possibility that combination therapy with a miR-363 inhibitor and TX may increase TX efficacy and reduce the chance of TX-resistance. Note: This abstract was not presented at the meeting. Citation Format: Noriaki Sakuragi, Mohamed Kamel Farah, Zeinab Mohamed, Safwat Okasha, Hidemichi Watari, Takashi Mitamura, sherif El Khamisy, Yusuke Ohba. Comparative miRNA microarray profiling indicates miR-363 promotes chemoresistance in ovarian cancer cells by targeting the Hippo member, LATS2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-323. doi:10.1158/1538-7445.AM2017-LB-323