肝癌ARID1A突变促进外泌体-CTSB分泌诱导巨噬细胞M2极化和富集的分子机制研究

肿瘤相关巨噬细胞是介导免疫抑制微环境、促进肿瘤进展、引起肿瘤免疫逃逸的重要原因，肿瘤细胞对巨噬细胞具有"Education"的调控作用。我们前期发现肝细胞癌（HCC）驱动基因ARID1A突变可特异性引起M2-like TAM在肝癌组织中富集，体内外实验也验证肝癌细胞ARID1A突变可诱导巨噬细胞发生M2极化，并引起M2巨噬细胞在小鼠皮下肿瘤中富集。转录组测序及验证发现，ARID1A突变的HCC细胞可通过c-Myc上调CTSB蛋白分泌，而CTSB也可促进巨噬细胞的M2极化。并且细胞外CTSB主要定位于外泌体，作用于巨噬细胞，引起M2极化。本项目拟进一步通过体内外实验，阐明HCC患者ARID1A突变通过上调c-Myc继而促进CTSB的外泌体分泌并作用于巨噬细胞，引起M2极化和在肿瘤中富集的具体分子机制，为HCC免疫微环境调节异常的机制提供新见解。

Tumor-associated macrophages are an important component for mediating the immunosuppressive microenvironment, promoting tumor progression, and causing tumor immune escape. We found the ARID1A mutation can specifically cause the enrichment of M2-like TAM in HCC tissues. Further in vivo and in vitro experiments verified that ARID1A mutated hepatocellular carcinoma (HCC) cells can induce M2 polarization of macrophages. Enriched M2-like TAMs were found in subcutaneous tumors formed by ARID1A-KO cell line. Transcriptome data and further wet experiment verification indicated that ARID1A mutated HCC cells significantly upregulate the secretion of CTSB protein by increased c-MYC expression, therefore promoting the M2 polarization of macrophages. Finally, we verified that extracellular CTSB is mainly located in exosomes and acts on macrophages to cause M2 polarization; and the expression of CTSB is significantly related to the poor prognosis of HCC patients. This project intends to clarify how ARID1A mutated HCC promoted the secretion of CTSB-exosomes via upregulated c-MYC expression, therefore acting on macrophages, causing M2 polarization and enrichment in tumors. We wish to reveal the process of HCC cells education on macrophages, thus providing new insights for understanding the mechanism of tumor microenvironment dysregulation in HCC.