Tissue factor promotes HCC carcinogenesis by inhibiting BCL2-dependent autophagy

Abstract

Introduction: Tissue factor (TF) is an important predictor for poor prognosis of Hepatocellular carcinoma (HCC). TF can also upregulate the expression of BCL2, which is a key inhibitor of autophagy responses. This study aims to explore the role of BCL2-dependent autophagy in TF-regulated HCC carcinogenesis.

Methods: In this study, we explored the roles of TF in HCC using gene overexpression and silencing assays. Besides, we further identified the significance of BCL2-Beclin1-autophagy signaling on TF-regulated HCC tumorigenesis by combining TF silencing with pharmacological autophagy inhibitor (3-MA).

Results: The experimental data showed that the overexpressed TF promoted BCL2 protein expression and inhibited the autophagy activity (shown as LC3 conversion rate, p62 expression and autophagosomes) while maintaining the survival in HCC cells. In contrast, the silent TF showed the completely opposite results. Furthermore, TF knockdown promoted the dissociation of Beclin1 from BCL2-Beclin1 complex. In addition, the enhanced autophagy and inhibited survival by TF knockdown could be reversed by autophagy inhibition with 3-MA or spautin-1 (Beclin1 specific inhibitor) in HCC cells. Xenografts assays also showed that TF-silencing HCC cells had stronger tumorigenicity in vivo, which was recovered by spautin-1 administration.

Conclusions: TF inhibits autophagy-related death by enhancing BCL2 expression, whereby promoting HCC tumorigenesis.

Keywords: Tissue factor, Hepatocellular carcinoma, BCL2, Autophagy, Beclin1.