Effects of microRNA-34a overexpression on radiosensitivity of four human cervical cancer cell lines

Abstract

Objective To investigate the effects of miRNA-34a overexpression on the radiosensitivity of four human cervical cancer cell lines. Methods Cervical cancer lines, C33A, HeLa, SiHa, and CaSki, were transfected with pGenesil-1-miRNA-34a plasmid using the liposome 2000 kit. Cervical cancer lines overexpressing miRNA-34a (miRNA-34a/C33A, miRNA-34a/HeLa, miRNA-34a/SiHa, and miRNA-34a/CaSki) were constructed by G418 selection. These cells were exposed to different doses of 60Coγ-ray. The expression of miRNA-34a was determined using TaqMan real-time PCR and Western blot. The cell growth inhibition rate and colony formation ability were measured by MTT assay and colony formation assay, respectively. Apoptosis and expression of apoptosis-related proteins were evaluated using flow cytometry and Western blot, respectively. Results The expression of miRNA-34a was significantly higher in positive cervical cancer cell lines than in the negative control groups (P<0.05). The cervical cancer cell lines overexpressing miRNA-34a had significantly elevated growth inhibition rates and significantly weaker colony formation ability than the negative control groups (both P<0.05). The results of flow cytometry showed that cervical cancer cell lines overexpressing miRNA-34a had significantly higher apoptosis rates than the negative control groups (P<0.05). The results of Western blot indicated that cervical cancer lines overexpressing miRNA-34a had increased expression of cleaved caspase 9 and cleaved PARP proteins after exposure to 4 Gy+ radiation. Conclusions Cervical cancer lines overexpressing miRNA-34a are successfully constructed in this study. Overexpression of miRNA-34a enhances the radiosensitivity of cervical cancer cells. The mechanism is related to the activation of apoptosis pathway. Key words: miRNA-34a; Cervical neoplasm cell line; Radiosensitivity; Cell growth; Apoptosis