MiR-148a participates in the growth of RPMI8226 multiple myeloma cells by regulating CDKN1B.

OBJECTIVE: The aim of this study is to explore the influence of miR-148a on cell proliferation and cell cycle of multiple myeloma (MM) cell line RPMI8226 and the related molecular mechanism.

METHODS: The expression of miR-148a and CDKN1B in MM cells and primary cells of normal bone marrow were determined by RT-PCR and western blotting. The cell proliferation and cell cycle of miR-148a knockdown MM cells and normal MM cells were determined by flow cytometry. The protein expression of p-NPAT, p-Rb and p-CDC6 was determined in normal and miR-148a knockdown MM cells. Luciferase reported assay was used to explore the relationship between miR-148a and CDKN1B.

RESULTS: The level of miR-148a in MM cells was much higher than that in primary cells from healthy bone marrow samples, while the expression of CDKN1B was lower in MM cells. After knockdown of miR-148a, cell cycle mainly distributed at G0/G1 and the proliferation capacity of MM cells decreased. Knockdown of miR-148a significantly reduced protein expression of p-NPAT, p-Rb and p-CDC6. Luciferase reported assay showed that miR-148a could directly target CDKN1B at 3'-UTR.

CONCLUSIONS: High level of miR-148a inhibits CDK activity and promotes the proliferation of MM cells at least partly by downregulating CDKN1B.