Abstract 1062: Downregulation of miR-200c stabilizes XIAP mRNA and contributes to invasion and lung metastasis of bladder cancer

Abstract

Abstract Our previous studies have demonstrated that X-linked inhibitor of apoptosis protein (XIAP) plays a regulatory role in cancer invasion via mediation of RhoGDIα protein SUMOylation at Ser138 in colorectal cancer HCT116 cells. However, the alteration/association of XIAP in invasion, progression, and lung metastasis of bladder cancer (BC) as well as the molecular mechanisms leading to this XIAP alteration during BC development have not been explored yet. Herein, we found that XIAP was overexpressed in human high grade BCs, high metastatic human BC T24T cells, and in mouse invasive BCs. Mechanistic studies indicated that XIAP overexpression in the highly metastatic T24T cells was due to increased mRNA stability of XIAP in comparison to the parental non-metastatic T24 cells. Results from XIAP mRNA stability regulation revealed that miR-200c was profoundly downregulated in T24T cells and in highly invasive BCs, and that such miR-200c downregulation was mediated by CREB inactivation. Furthermore, miR-200c downregulation reduced its binding to the 3'-UTR region of XIAP mRNA, and resulted in its mRNA stabilization, protein overexpression, and invasive capabilities in T24T cells. Moreover, our results from XIAP-specific shRNA and miR-200c ectopic expression showed that suppression of XIAP profoundly attenuated lung metastasis of T24T cells in nude mice. In conclusion, our findings demonstrate the molecular basis leading to XIAP overexpression and the crucial role of XIAP in BC invasion in vitro and lung metastasis in nude mice. Citation Format: Zhongxian Tian, Honglei Jin, Jingxia Li, Chao Huang, Chuanshu Huang. Downregulation of miR-200c stabilizes XIAP mRNA and contributes to invasion and lung metastasis of bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1062.