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.