Effect of irradiation-induced miR-34a expression on irradiation-sensitivity of cells

Objective To investigate the relationship between miR-34a expression and the irradiation-sensitivity of cells and tissues.Methods RT-PCR was used to detect the miR-34a expression in different cells and tissues before and after irradiation;flow cytometry was employed to examine the apoptosis of cells and MTT assay was used to observe the cell viability.The U87MG tumor cells were transfected with miR-34a mimics to promote miR-34a expression and the cell viability was observed 24 h later.The HEK293 renal epithelial cells were transfected with miR-34a inhibitors to decrease miR-34a expression and the cells apoptosis was observed 24 h later.Results The expression of miR-34a was higher in highly irradiation-sensitive cells than in lowly irradiation-sensitive cells before irradiation;the increase of miR-34a expression was greatly higher in highly irradiation-sensitive cells than in lowly irradiation-sensitive cells 24 h after irradiation.The up-regulation of miR-34a decreased the viability of U87MG tumor cells,and down-regulation of miR-34a decreased the apoptosis of HEK293 cells.Conclusion The irradiation-sensitivity of cells is positively associated with miR-34a;cells with high irradiation-sensitivity have a greater up-regulation of miR-34a expression after irradiation.Increased miR-34a expression can noticeably increase the irradiation-sensitivity of U87MG tumor cells and decreased miR-34a expression has a irradiation prevention effect on normal HEK293 cells.