Abstract 5003: RNase activity of MCPIP1 regulates key elements of mesenchymal phenotype of clear cell renal cell carcinoma cells
Authors: Miekus Katarzyna , Marona Paulina , Górka Judyta , Jura Jolanta 
Published: August 2018

Introduction: Monocyte chemotactic protein 1-induced protein 1 (MCPIP1) regulates the mRNA of proinflammatory cytokines, such as IL-6, IL-1, IL-12 and IL-2 and influences NFκB and AP1 activity. MCPIP1 may also suppress miRNA biosynthesis. Last findings show that MCPIP1 affects viability and proliferation of tumor cells, degrades the mRNA of antiapoptotic gene transcripts in breast cancer cells and reduces tumor growth and metastatic disease of breast cancer. We have already demonstrated that MCPIP1 decreases during clear cell renal cell carcinoma (ccRCC) progression and is responsible for better tumor vascularity and the secretion of proangiogenic factors. Moreover, MCPIP1 downregulation promotes the metastatic spread of ccRCC cells.

Aim: The main objective of our study was to determine the role of RNase activity of MCPIP1 in the regulation of key elements in the EMT signaling axis and the acquisition of mesenchymal phenotype of ccRCC.

Materials and methods: Microarray analysis of tumor tissue was used to evaluate EMT signaling axis during ccRCC progression. For stable overexpression of MCPIP1, doxycycline-dependent TetON system was used: pLIX MCPIP1 for MCPIP1 overexpression, pLIX PURO as a control and mutant form pLIX D141N, with abolished MCPIP1 RNase activity. The level of genes and proteins were studied by real-time PCR, western blot, flow cytometry and immunoprecipitation. Chemotaxis, invasion and motility assays were performed to check migration and invasion. Foxn1nu/Foxn1nu and NOD-SCID mice were used in in vivo experiments.

Results: Microarray analysis revealed that the expression of mesenchymal markers increases during ccRCC progression together with decreased level of MCPIP1 protein in tumor tissue. We demonstrate that endonuclease activity of MCPIP1 regulates the mRNA expression and protein level of key elements in the EMT signaling pathways e.g. Snai1 and Snai2, ß-catenin, vimentin, E-cadherin and N-cadherin. Mutated form of MCPIP1 lacking RNAse activity upregulates β-catenin and vimentin and suppressed E-cadherin. Moreover, our study revealed that MCPIP1 influences the cytosolic or nuclear location of the E-cadherin repressors, transcription factor Snai1 and Snai2 and ß-catenin. Furthermore, motile activity of ccRCC cells is strongly increased in ccRCC with abolished MCPIP1 RNase activity. We also show that initial overexpression of MCPIP1 causes no tumor growth whereas the lack of RNase activity of MCPP1 led to an increase of tumor growth. Conclusions: We showed that endonuclease activity of MCPIP1 directly enhanced the mesenchymal phenotype of ccRCC through regulation of cell motility, expression and position of key elements in the EMT signaling pathways and tumor initiation.

Acknowledgement: The study was supported by research grants from the National Science Centre 2013/09/D/NZ/00249, 2015/19/B/NZ5/01405 and KNOW 35p/3/2015.

Citation Format: Katarzyna Miekus, Paulina Marona, Judyta Górka, Jolanta Jura. RNase activity of MCPIP1 regulates key elements of mesenchymal phenotype of clear cell renal cell carcinoma cells [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 5003.