Effects of microRNA-125b on multiple myeloma cell growth in vitro and in vivo

Abstract

Multiple myeloma (MM) is a heterogeneous disease with a poor prognosis. The expression of microRNA-125b (miR-125b), a novel oncomiR, is elevated in various cancer types. The present study found that the expression of miR-125b was increased in plasma samples from 35 patients with MM, compared with that in samples from 20 healthy controls, by performing real-time PCR. CCK-8 assay, migration and invasion assay showed that the downregulation of miR-125b inhibited cell proliferation and migration and reduced the levels of phosphorylated Akt, compared with those of the blank and negative control groups. Dual-Luciferase activity assay demonstrated that the tumor suppressor PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2) was a target of miR-125b, which inhibited PHLPP2 and directly bound to the 3'untranslated region of PHLPP2, resulting in elevated Akt signaling. Furthermore, the expression of a miR-125b inhibitor in MM cells in a xenograft mouse model suppressed tumor growth. These results showed that the inhibition of miR-125b suppressed MM progression by inhibiting Akt signaling, and suggested that miR-125b may be a novel molecular therapeutic target for MM treatment.