PPM1D silencing by RNA interference inhibits the proliferation of lung cancer cells

Background: PPM1D (protein phosphatase, Mg2+/Mn2+ dependent, 1D) has been reported to be involved in multiple human tumors. This study was designed to investigate the functional role of PPM1D in lung cancer cells. Methods: Expression levels of PPM1D were analyzed in A549 and H1299 cells by real-time PCR and Western blotting. Lentivirus-mediated short hairpin RNA (shRNA) was used to knock down PPM1D expression in both cell lines. The effects of PPM1D on lung cancer cell growth were investigated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), colony formation and flow cytometry assays. Results: Knockdown of PPM1D in lung cancer cells resulted in decreased cell proliferation and impaired colony formation ability. Moreover, flow cytometry analysis showed that knockdown of PPM1D arrested cell cycle at the G(0)/G(1) phase. Furthermore, PPM1D silencing downregulated the expression of cyclin B1 in H1299 cells. Therefore, it is reasonable to speculate that the mechanisms by which PPM1D knockdown alleviates cell growth may be partly via the induction of cell cycle arrest due to the suppression of cyclin B1. Conclusions: These results suggest that PPM1D silencing by RNA interference (RNAi) may be a potential therapeutic approach for the treatment of lung cancer.