MicroRNA-222 promotes human non-small cell lung cancer H460 growth by targeting p27

Two highly homologous microRNAs (miRNAs, miRs), miR-222 and miR-221, act as a cluster in cellular regulation. We have previously reported that miR-221 promoted the growth of human non-small cell lung cancer cell line H460. However, the role of miR-222 in regulating the growth of H460 is unclear. H460 cells were transfected with miR-222 mimics, inhibitors or their negative controls and their effects were confirmed by Real-time quantitative reverse transcription polymerase chain reactions (qRT-PCRs). Cell viability was assessed by Cell Counting Kit-8 (CCK-8) while cell proliferation was determined by 5-Ethynyl-2'-deoxyuridine (EdU) assay. P27 and P57, two putative targets of miR-222, were checked by qRT-PCRs. We found that miR-222 overexpression increased cell viability and proliferative rate in H460 cells while opposite effects were obtained by down-regulation of miR-222. P27 but not P57 was identified as a potential target of miR-222 in H460 cells as P27 was negatively regulated by miR-222 in the protein level. In summary, the present study indicates that miR-222 controls the growth of H460 likely by targeting P27. Inhibition of miR-222 might be a novel therapy for human non-small cell lung cancer.