CUL4A promotes proliferation and inhibits apoptosis of colon cancer cells via regulating Hippo pathway

OBJECTIVE: The aim of this study was to investigate the effect of cullin 4A (CUL4A) on the proliferation and apoptosis of colon cancer (CC) cells, and to elucidate its regulatory relationship with the Hippo pathway. PATIENTS AND METHODS: Paired CC tissues and adjacent normal tissues were obtained from patients. CC cells were isolated and cultured in vitro. CUL4A was interfered by small interfering ribonucleic acid (siRNA) (siR-CUL4A group) or overexpressed by overexpression vector (CUL4A-Vector group), with negative control (NC)-CUL4A or CUL4A -NC as the control group. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression level of CUL4A in CC tissues and cells. The proliferative ability of cells was detected by cell counting kit-8 (CCK-8) assay. Flow cytometry was applied to measure the apoptosis of cells in each group. Western blotting (WB) was conducted to determine the protein expression of CUL4A. In addition, the proliferative ability was examined in vivo through subcutaneous injection of cells into nude mice. RESULTS: QRT-PCR showed that CUL4A was highly expressed in 66.67% of CC samples (p<0.01). In vivo and in vitro proliferative ability was significantly reduced in siR-CUL4A group (p<0.01), whereas the apoptosis rate was promoted (p<0.01). However, in vivo and in vitro proliferative ability increased significantly in CUL4A-Vector group (p<0.01), while the apoptosis rate was reduced (p<0.01). The protein expressions of MST1, LATS1 and p-YAP were significantly up-regulated in siR-CUL4A group (p<0.01), while they were remarkably down-regulated in CUL4A-Vector group (p<0.05, p<0.01). CONCLUSIONS: CUL4A is highly expressed in CC and promotes the proliferation and inhibits the apoptosis of CC cells by regulating the Hippo pathway.