TRAF6 Affects RAC1 Expression and Apoptosis in SK-Hep1 Cells

Abstract

RAC1 is a small-molecule G protein that regulates multiple cell cycle, cytoskeletal reorganization, cell migration, and apoptosis. FADD-dependent TRAIL can promote tumor metastasis through RAC1 and PI3K, and down-regulating RAC1 expression can reduce FasL-induced apoptosis. In addition, RIP1 bound to GTP acts as an activating protein for RAC1 and is involved in cytoskeletal reorganization. TRAF6 promotes migration and metastasis by regulating the RAS pathway in tumors. Thus, it is necessary to understand the interaction between RAC1 and TRAF6 as well as FADD and RIP1. In this study, we cultured hepatoma SK-Hep1 cells in vitro, specifically blocked the necroptosis pathway with Nec-1, and silenced FADD, RIP1 and TRAF6 gene expression using RNAi technology. At the same time, the expression of RAC1 was evaluated separately using RT-PCR and Western blot. The hepatoma SK-Hep1 cells survival rate was highest when the concentration of Nec-1 was 60 μM and the concentration of Z-vad-fmk was 20 μM. And the apoptosis rate of the transfected RAC1 siRNA cells was 3.59% compared with transfected siRNA cells 10.01% which was significantly decreased (P < 0.01). RAC1 could promote the occurrence of apoptosis in SK-Hep1 cells. RAC1 expression was suppressed in both protein and gene level in SK-Hep1 cells when the TRAF6 gene was silenced, but there was no significant change in RAC1 gene and protein expression when FADD and RIP1 genes were silenced. TRAF6 affects RAC1 expression and apoptosis in SK-Hep1 cells, while the FADD and RIP1 genes do not affect the role of RAC1. The TRAF6 gene is an important target in liver cancer cells.