Abstract 898: Clear cell renal cell carcinoma resistance to RTKs inhibitors is mediated by c-Met receptor and MCPIP1

Abstract

Abstract Introduction Clear cell renal cell carcinoma (ccRCC) treatment with small molecules that inhibit multiple receptor tyrosine kinases (RTKs),showed in approximately 38% of patients significant tumor control. However, despite the efficacy of treatment, ccRCC often develops resistance to targeted drugs and the majority of patients who receive such treatment exhibit progressive disease after 1 year. Several hypotheses have been proposed regarding the mechanisms underlying resistance to RTKs inhibitors, but the precise pathways have not yet been fully elucidated. Aim The main objective of our study was to determine the role of c-Met and anti-inflammatory protein MCPIP1 in the acquisition of resistance to RTKs inhibitors in ccRCC. Materials and methods ccRCC cell lines (Caki-1 and Caki-2) as well as normal epithelial cell lines (Hek293, RPTEC/TERT1) were treated with sunitinib, sorafenib or SU11274 constantly for 24h, 1 and 3 weeks. The level and localization of key proteins were examined using western blots and IF staining. ccRCC patient samples were divided into four histological grades, and levels of genes or proteins were investigated using microarray analysis, western blots, protein arrays, mass spectrometry and real time PCR. Results Our study shows that short term (24h) and long term (3 weeks) stimulation with sunitinib or sorafenib induced phosphorylation of c-Met receptor, STAT3 and Src kinase. Furthermore, sunitinib treatment resulted in the acquisition of cancer stem cells features and the formation of clones. In addition, after sunitinib and sorafenib treatment we observed a decrease in the protein level of MCPIP1, postulated tumor suppressor. Interestingly, after MCPIP1 overexpression, we observed c-Met downregulation, regulated by RNase activity of MCPIP1. Moreover, our results show that in patient samples, together with MCPIP1 downregulation, level of phosphorylated and total c-Met receptor increase. Conclusions We showed that acquisition of therapy resistance in ccRCC may be affected by MCPIP1 decrease, together with phopsphorylation of c-Met receptor and it can be partially reversed by overexpressing the MCPIP1 protein, which may act as a potent tumor suppressor. Proposed research may help in understanding the mechanisms responsible for tumor resistance to targeted therapy. Obtained results may contribute to increased understanding of the biology of clear cell renal cell carcinoma, which in the future may help in identifying new, more effective therapeutic purposes or improving existing ones. Acknowledgment This study was supported by research grant from the National Science Centre 2013/09/D/NZ/00249, 2017/25/N/NZ5/03014 and grant from Jagiellonian University BMN 16/2017. Citation Format: Paulina Marona, Judyta Górka, Jolanta Jura, Katarzyna Miękus. Clear cell renal cell carcinoma resistance to RTKs inhibitors is mediated by c-Met receptor and MCPIP1 [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 898.