Abstract 354: Resistance to TGF-beta-induced apoptosis is not associated with the de-differentiation in hepatocellular carcinoma

Abstract

Abstract Aim: Transforming growth factor (TGF)-beta is a cytokine which induces apoptosis of hepatocellular carcinoma (HCC) cells. However, some HCC cells show resistance to the induction of apoptosis by TGF-beta. The analyses of the molecular mechanism underlying these phenomena may be related with the mechanisms of acquirement of drug-resistance. Thus, we examined molecularly the apoptosis-resistant HCC cells which we previously established, especially emphasizing on the analyses of the stem-cell marker expression in this study. Methods: Previously established HuH7R cells, which acquired a resistance to TGF-beta-induced apoptosis after a long-term culture under small amount of TGF-beta, and control parental HuH7 cells, were used. Apoptosis rate and cell cycle state of these cells after TGF-beta treatment were determined by a flow-cytometry. The expression levels of stem-cell surface markers, such as epithelial cell adhesion molecule (EpCAM) and CD133, and those of transcriptional factors: Oct4, HNF3alfa, HNF4beta, and C/EBPbeta, were analyzed by fluorescent labeling using specific antibodies, at 24hrs and 48hrs after TGF-beta treatment. Results: 1) HuH7 cells showed apoptosis after 48hrs of TGF-beta treatment, whereas HuH7R did not show apoptosis but entered cell-cycle arrest. 2) The expression levels of CD133 were not affected at both 24hrs and 48hrs after TGF-beta treatment, while EpCAM expression levels increased from 24hrs, in both HuH7 and HuH7R cells. 3) The expression levels of Oct4, HNF3alfa, HNF4beta, and C/EBPbeta were also increased in HCC cells. However, those expression profiles were almost comparable in between HuH7 and HuH7R cells. Conclusions: The acquisition of the resistance to TGF-beta-induced apoptosis in HCCs were not related with the expression changes of stem-cell markers. The acquisition of drug-resistance in HCC cells was considered through mechanisms other than the changes of the cellular differentiation status of HCC cells. Citation Format: Tomomi Kogiso, Etsuko Hashimoto, Kazuhisa Kodama, Yuichi Ikarashi, Nobuyuki Torii, Makiko Taniai, Katsutoshi Tokushige, Keiko Shiratori. Resistance to TGF-beta-induced apoptosis is not associated with the de-differentiation in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 354. doi:10.1158/1538-7445.AM2015-354