Disruption of the CCDC43-FHL1 interaction triggers apoptosis in gastric cancer cells.

The coiled-coil domain-containing protein 43 (CCDC43) is essential to promote gastric cancer (GC) proliferation and invasion, while four and a half LIM domains 1 (FHL1) involves GC cells apoptosis. We attempted to address inter-relationship between CCDC43 and FHL1 in modulating GC cells growth and apoptosis. Levels of protein expression were assessed by western blot, immunofluorescence. Using EdU, plate colony formation, Matrigel invasion and animal models, we evaluated the function in vitro and in vivo. Apoptosis was evaluated by flow cytometry and Hoechst 33258 staining. Reciprocal co-immunoprecipitation (co-IP) analyses indicated that CCDC43 physically interacted with FHL1. The expression of CCDC43 was negatively correlated with FHL1. Moreover, up-regulation of CCDC43 resulted in FHL1 level decline, and the reverse is also true. CCDC43 expressed jointly with FHL1 group significantly decreases the ability of the growth, metastasis and invasion of GC cells compared with that of the CCDC43 group. Furthermore, siRNA-mediated repression of CCDC43 results in dissociation from FHL1 and causes suppression of GC cell proliferation and metastasis. CCDC43 repression mediates the stability of FHL1 protein. In addition, CCDC43 interacts with FHL1. Knockdown of CCDC43 plus FHL1 overexpression inhibits proliferation and migration and induces apoptosis of GC cells in vitro and vivo.