Abstract 3016: MCPIP1 endoribonuclease protects from liver fibrosis and regulates hepatocellular development

Abstract

Abstract Introduction: MCPIP1 (Monocyte Chemotactic Protein-1 Induced Protein), also known as Regnase-1, belongs to the CCCH zinc finger protein family, featuring a PilT N-terminus (PIN) domain-like RNase domain. Utilizing its intrinsic endonuclease activity, MCPIP1 functions as a precise modulator of cytokines, exhibiting an anti-inflammatory effect through the targeted degradation of specific mRNA transcripts. While recent studies have highlighted MCPIP1 as a potential tumor suppressor with decreased levels in breast cancer and clear cell renal cell carcinoma, its role in hepatocellular carcinoma (HCC) development remains unexplored. Material and Methods: To investigate the role of MCPIP1 in HCC development, we used tissue-specific knockout mice with the deletion of Mcpip1 in hepatocytes. HCC was induced by administering diethylnitrosamine (DEN) to two-week-old mice. We conducted a comprehensive analysis, including the assessment of EMT and fibrosis markers, proinflammatory cytokines, and immune cell infiltration, using Western blot (WB), mass spectrometry, quantitative PCR (qPCR), and multiple immunohistochemistry (IHC) stainings. To identify differences between the wild-type (wt) and Mcpip1 knockout (KO) mice groups more effectively, hepatocytes were isolated using the perfusion method, and RNA-Seq analysis was performed. Results and Discussion: The tissue-specific knockout of Mcpip1 in the liver has notable molecular consequences. Transcriptomic profiling revealed an upregulation of transcripts integral to tumor development, including Cxcr4, Met, Cxcl12, Hgf, and Src, alongside factors characteristically associated with cancer stem cells, Myc, Klf4, and CD133. The absence of MCPIP1 triggered immune cell activation in the liver, as evidenced by an augmented expression of markers specific to myeloid and lymphoid cell populations, indicative of an intensified immunological response. IHC examination of liver tissue from Mcpip1-deficient mice revealed significant fibrotic alterations, characterized by increased collagen deposition, and enhanced expression of alpha-smooth muscle actin (αSMA). The lack of Mcpip1 influences the increased levels of vimentin, fibronectin, and connective tissue growth factor (cTGF), indicating enhanced tissue remodeling. Conclusions: MCPIP1, recognized for its anti-inflammatory functions, appears to function as a potential tumor suppressor in HCC development. The lack of MCPIP1 results in the upregulation of transcripts linked to tumorigenesis, immune cell activation, and notable fibrotic changes, highlighting its involvement in the complex molecular dynamics of HCC progression. This study was supported by National Science Center grants no. 2017/26/E/NZ5/00691, 2021/41/N/NZ4/04187. Citation Format: Katarzyna Miekus, Oliwia Kwapisz, Paulina Marona, Judyta Gorka, Jerzy Kotlinowski, Ewelina Pospiech, Jolanta Jura. MCPIP1 endoribonuclease protects from liver fibrosis and regulates hepatocellular development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3016.