Analysis of microRNAs expression changes in human breast cancer cell lines following exposure to ionizing radiation

Background: the expression alterations of specific mirnas were analysed inresponse to gamma-irradiation in two breast cancer cell lines mcf-7 and mda-mb-231 with low and high bcscs content to design probable strategies for sensitizingbreast cancer stem-like cells mda-mb-231 to radiation. materials and methods:the expression levels of hsa-mir-34a, hsa-let-7i and hsa-mir-21 were assessed byqrt-pcr in mcf-7 and mda-mb-231 breast cancer cells at three time points aftergamma irradiation using three different doses. results: the results showed thatthe over-expression of hsa-mir-34a in mcf-7 cells was much more significantthan mda-mb-231 cells. furthermore, there was a considerable overexpressionof hsa-mir-21 in mda-mb-231 cells following exposure to ionizingradiation (ir). the hsa-let-7i expression changes were different, depending onradiation dose, time post irradiation and cell type. conclusion: according to theresults, we may be able to sensitize stem-like mda-mb-231 breast cancer cells toradiation by increasing mir-34a and decreasing mir-21 expression levelssimultaneously.