Radiosensitizing effects of miR-101 on HeLa cancer cells and underlying mechanism

Objective: To study the effects of microRNA101(miR-101) on radiosensitization of human uterine cervix cancer HeLa cells and underlying mechanism. Methods: HeLa cells were divided into three groups including blank control, miRNA negative control and miR-101 transfection group. The cells were irradiated by 160 kVp X-ray generated from a linear accelerator at a dose rate of 1.15 Gy/min. Real-time quantitative PCR (qRT-PCR) was used to detect the expression of miR-101. The clonogenic survival assay was applied to evaluate the effect of miR-101 on radiosensitization of HeLa cells. γ-H2AX immunofluorescence and Western blot assays were performed to observe DNA double-strand breaks and the protein expressions of ATM and DNA-PKcs of HeLa cells, respectively. Results: Compared with the negative control group, the expression of miR-101 was significantly increased in the HeLa cells at 48 h after transfection with miR-101 mimic, and the survival of HeLa cells over expression of miR-101 was significantly reduced(t = 10.75, P < 0.05). The miR-101 had remarkable radiosensitive effect on HeLa cells(F = 7.72, P < 0.05) with a SER_D0 of 1.29. Moreover, over-expression of miR-101 could inhibit the repair of DNA damage induced by irradiation. Compared with the control group, the protein expressions of ATM and DNA-PKcs were significantly decreased in the HeLa cells over expression of miR-101. Conclusions: Over-expressions of miR-101 could inhibit cell growth and enhance radiosensitivity of HeLa cells by inhibiting the repair of radiation-induced DNA damage. (authors)