PIM2 kinase is induced by cisplatin in ovarian cancer cells and limits drug efficacy

Platinum-based chemotherapy is widely used to treat various cancers, but many patients ultimately relapse due to drug resistance. We employed phosphoproteomic analysis and functional assays of the response of SK-OV-3 ovarian cancer cells to cisplatin as a strategy to identify kinases as candidate druggable targets to sensitize cells to platinum. A SILAC-based approach combined with TiO2-based phosphopeptide enrichment allowed the direct identification of ERK1/2, p90RSK, and ERBB2 as kinases whose phosphorylation is regulated by cisplatin. Bioinformatic analysis revealed enrichment in linear phosphorylation motifs predicted to be targets of p38MAPK, CDK2, and PIM2. All three PIM kinases were found expressed in a panel of 10 ovarian cancer cell lines, with the oncogenic PIM2 being the most commonly induced by cisplatin. Targeting PIM2 kinase by either biochemical inhibitors or RNA interference impaired cell growth, decreased cisplatin-triggered BAD phosphorylation, and sensitized ovarian cancer cells to dru...