Abstract 4421: Molecular features of hepatocellular carcinoma arising from non-alcoholic fatty liver

Abstract

Abstract (Background) The incidence of hepatocellular carcinoma (HCC) arising from non-alcoholic fatty liver (NAFL) has been recently increasing according to increase of patients having metabolic syndrome. HCC, which shows steatosis, cellular ballooning, Mallory-Denk bodies, inflammation and fibrosis in cancer tissue, are recognized as steatohepatitic HCC (SH-HCC). This HCC phenotype is more frequently found in NAFL patients than in viral-hepatitic patients. (Purpose) The purpose of this study is to elucidate molecular features of SH-HCC with NAFL background. (Methods) To profile SH-HCC-related genes, mRNA expression patterns in SH-HCCs were compared with those in viral hepatitis HCCs by RNA array. RNA expression of the identified SH-HCC related gene was analyzed in three human liver carcinoma cell lines (HepG2, Huh7, and HLE) in normal conditioned medium. By mimicking the lipid-rich environment, these cell lines were also cultured in the presence of saturated (palmitic or stearic acid, recognized as endoplasmic reticulum stressors) or unsaturated fatty acids (oleic acid: OA). To address the role of SH-HCC-related gene, cell proliferation and apoptosis were assessed in the presence or absence of fatty acids, by knock-down of the objective gene using siRNA. (Results) (1) Caveolin (cav)-1 and -2 were identified as SH-HCC related genes (1.63 and 1.58 fold expression of cav-1 and -2, respectively) by RNA microarray analysis. (2) HLE and Huh7 showed high and low expression of both cav-1 and -2 mRNA, whereas HepG2 did not express either on qRT-PCR. (3) In the presence of OA, HepG2 and Huh7 did not well proliferate, whereas HLE cell proliferation increased with concentration of OA and culture duration. (4) Knock-down of cav-1 and -2 canceled OA-induced increase of cell proliferation. In the same condition, expression of cleaved caspase 3 was increased, suggesting the promotion of apoptosis. (Consideration) Cav-1 and -2, the important protein for endocytosis and cellular signaling, are highly expressed in SH-HCC. These proteins would increase cell proliferation and inhibit apoptosis in the presence of unsaturated fatty acids, presumably by using these fatty acids as energy source or by caveolae-related anti-apoptotic process. Citation Format: Makoto Takeda, Takanori Sakaguchi, Ryouta Kiuchi, Takanori Hiraide, Yasushi Shibasaki, Yoshihumi Morita, Hirotoshi Kikuchi, Mitsutoshi Setou, Hiroyuki Konno. Molecular features of hepatocellular carcinoma arising from non-alcoholic fatty liver. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4421.