MicroRNA-21 affects proliferation and apoptosis by regulating expression of PTEN in human keloid fibroblasts.

Background: MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate gene expression in the progress of proliferation, differentiation, and apoptosis. A keloid is considered to be a type of benign tumor. The exact contribution of miRNAs in keloid fibroblasts remains largely unknown. Methods: Loss and gain of function was used by transfecting the keloid fibroblast cells with chemically synthesized oligonucleotides complementary to microRNA-21 (miR-21). Expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in keloid tissues and adjacent normal skin tissues were investigated by quantitative real-time polymerase chain reaction and Western blot assay. Moreover, cell apoptosis and proliferation were checked in keloid cells, and related proteins were determined by Western blot assay. Results: MiR-21 inhibitor and mimic transfection changed the apoptosis and DNA synthesis. Of the 23 paired samples analyzed, expression of PTEN was low in keloid tissues relative to adjacent normal skin tissues. Cells showed an inverse correlation between miR-21 and PTEN protein after transfection. In addition, cell proliferation was increased when normal skin fibroblasts were transfected with miR-21 mimics. It is worth noting that the expression of phosphorylated AKT decreased to relatively low levels after miR-21 inhibitor treatment. Conclusions: This in vitro study demonstrates important interactions among miR-21 expression, keloid fibroblast apoptosis, cell proliferation, and some related proteins. These findings may provide some hints toward effective applications of miR-21 as a therapy target for keloids.