Expression of microRNA let-7a in melanoma and its effect on the proliferation of A375 human melanoma cell line / 中华皮肤科杂志

ABSTRACT

Objective To investigate the expression of microRNA let-7a in formalin-fixed paraffinembedded (FFPE) melanoma tissue and its effect on the proliferation of A375 cell lines. Methods Tissue samples were obtained from 13 patients with malignant melanoma and 10 with congenital pigmented nevus,then fixed with formalin and embeded with paraffin. microRNAs were isolated from these samples and reversely transcripted to cDNA with stem-loop primer. Then, real time quantitative PGR was performed with Taqman MGB probe and matched primers to measure the expression of microRNA let-7a. cy3-Labeled negative control siRNA was transfected into A375 cells followed by the examination of transfection efficiency under fluorescense microscopy. Subsequently, hsa-let-7a mimics were transfected into A375 cells to observe their effect on the proliferation of these cells. Results microRNAs were successfully isolated from FFPE tissues, and quantitative PGR showed a significant reduction in the expression of microRNA let-7a in melanoma tissue compared with nevus tissue (t = 2.364, P ＜ 0.05). The transfection efficiency was found to be about 80% ～90%. After transfection with hsa-let-7a mimics, the proliferation of A375 cells was inhibited and the inhibition rate amounted to 32.7% at 24 hours. Conclusions The expression of microRNA-let-7a is attenuated in melanoma, and overexpression of let-7a can inhibit the proliferation of A375 cells, which implies that let-7a functions as a tumor suppressor gene in melanoma.