Regulation of survivin and caspase/Bcl-2/Cyto-C signaling by TDB-6 induces apoptosis of colorectal carcinoma LoVo cells

BACKGROUND: Colorectal carcinoma (CRC) treatment remains severe. Survivin is aberrantly overexpressed in CRC tissues and might be a potential target for CRC treatment. TDB-6 is a new taspine derivative. The purpose of this study is to investigate the inhibitory effect of TDB-6 on CRC and its underlying mechanism. METHODS: The MTT assay and xenograft model were utilized to investigate the inhibitory effect of TDB-6 on LoVo cells in vitro and in vivo. Hoechst staining and Annexin-V FITC/PI analysis were conducted to study the effect of TDB-6 on LoVo cell apoptosis. Mitochondrial membrane potential (Δψm) assay was conducted to demonstrated whether TDB-6 could induce mitochondrial-mediated apoptosis of LoVo cells. Western blotting was conducted to investigate the effect of TDB-6 on survivin protein and caspase/Bcl-2/Cyto-C signaling. RESULTS: The results indicated that TDB-6 induced mitochondria-mediated apoptosis and inhibited the proliferation and growth of LoVo cells in vitro and in vivo. Mechanistic investigation utilizing western blotting indicated that TDB-6 inhibited survivin protein expression, and the inhibitory effect was augmented by TDB-6 and YM-155 co-administration, which revealed that TDB-6 might induce apoptosis of LoVo cells by targeted regulation of survivin. TDB-6 also regulated survivin downstream signaling. It significantly increased the protein level of cleaved caspase-3, cleaved caspase-7, cleaved caspase-9, cleaved-PARP, and Cyto-C, and decreased the protein level of Bcl-2. CONCLUSIONS: TDB-6 might be a promising survivin inhibitor with great potential for CRC treatment.