Abstract 5970: Function and regulatory mechanism of GPM6A in hepatocellular carcinoma development and progression

Abstract

Abstract BACKGROUND: GPM6A is a glycoprotein found in endothelial cells and is considered to be a malignant lymphoma oncogene. However, the role of GPM6A in the development of hepatocellular carcinoma (HCC) is unknown. Through Affymetrix gene expression microarray and bioinformatics analysis, very low GPM6A expression was found in HCC tissue. The present study aims to explore the function and regulatory mechanism of GPM6A in HCC development and progression. METHODS: Levels of GPM6A expression was determined in various hepatoma cell lines and HCC specimens from different base disorders, and its role on cell proliferation was investigated in GPM6A stably over-expressing cell lines. Modulating effects of a specific miRNA were evaluated with miRNA mimetic transfection. RESULTS: Much lower GPM6A levels were found in HCC occuring in HBV-infection or nonalcoholic steatohepatitis. TCGA data confirmed that low GPM6A expression in HCC correlates with a poor overall survival and progression-free survival rate (p=0.018 and 0.004). Over-expression of GPM6A inhibited proliferation in SMMC-7721 and MHCC-97H cells by 31% and 30%, respectively (p<0.01), and led to decreased colony formation by 40%. Overexpression of GPM6A was found to significantly reduce wound healing and migration rates in these two cell types. miR-96-5p was expressed at 6 to 61-fold higher in HCC tissues than adjacent tissues (p<0.01); whereas GPM6A gene expression was at 3 to 55-fold lower (p<0.01) in a negative correlation between miR-96-5p levels and GPM6A levels in HCC specimens (r=-0.64, p<0.05). Further experiments demonstrated that miR-96-5p acted directly on the 3'UTR of the GPM6A gene, and transfection of miR-96-5p significantly decreased GPM6A mRNA expression by 50% in two hepatoma cell lines. Moreover, MiR-96-5p transfection promoted proliferation (66%, 59%, p<0.01), migration (10%, 9%, p<0.05) and invasion (557±66 vs. 226±19; 235±36 vs. 153±17, p<0.05-0.01) of SMMC-7721 and MHCC-97H hepatoma cells; whereas the function of oncogenic microRNA-96 was significantly inhibited in GPM6A-overexpressed hepatoma cells. CONCLUSIONS: GPM6A expression in HCC is commonly suppressed, and correlated to a poor prognosis. Its low expression in HCC tissues is most likely attributed to upregulated miR-96-5p, which may function as an oncolytic regulator through suppressed GMP6A that may block proliferation, cloning formation, migration and invasion of hepatoma cells. Citation Format: Rui Zong Li, Gang Xu, Min Ji Zhu, Jian Wu, Jian Wu. Function and regulatory mechanism of GPM6A in hepatocellular carcinoma development and progression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5970.