Ginsenoside Rh2 inhibits glioma cell proliferation by targeting microRNA-128.

To examine the influence of ginsenoside Rh2 (Rh2), a triterpene saponin extracted from the traditional medicinal plant ginseng, on the expression of miRNAs in human glioma cells. The expression profile of miRNA (miR) was analyzed in human U251, T98MG and A172 glioma cells using a miRNA array and quantitative real-time PCR. Cell viability was assessed using a colorimetric assay (cell counting kit-8). Transfection of miR-128 was performed using Lipofectamine 2000. Caspase 3 activity was determined using a caspase colorimetric assay kit. Apoptosis was assessed using annexin V and propidium iodide staining. Protein expression was determined with Western blot analysis. miRNA-128 targeting activity was measured using a luciferase reporter assay. In U251 cells treated with Rh2 (12 μg/mL), 14 of 452 human miRNAs were up-regulated and 12 were down-regulated as detected with the miRNA array assay. The up-regulation of miR-128 by Rh2 was further verified in human U251, T98MG and A172 cells using quantitative real-time PCR. In U251 cells, transfection of a miR-128 inhibitor (50 nmol/L) prevented the overexpression of miR-128 by Rh2, and significantly blunted Rh2-induced cytotoxicity, apoptosis, caspase 3 activation, transcriptional activation of E2F3a, a miR-128 target gene, as well as E2F3a protein expression. The anti-proliferative effect of Rh2 in human glioma cells was mediated in part through up-regulation of miRNA-128 expression.