Abstract 2982: Antineoplastic activity of the novel CDK2/9 inhibitor CCT68127 occurs via induced anaphase catastrophe and inhibition of PEA15 phosphorylation in lung cancer

Abstract

Abstract We reported the first generation CDK2/9/7 inhibitor seliciclib (R-roscovitine, CYC202) exerts antineoplastic effects against lung cancer by inducing anaphase catastrophe. In anaphase catastrophe, cells with aneuploidy (a hallmark of cancer) cannot cluster supernumerary centrosomes, triggering abnormal anaphase and apoptosis. This study now finds the new CDK2/9 inhibitor CCT68127 (Cyclacel) is a more potent and selective CDK2 inhibitor than seliciclib. CCT68127 exerted substantial antineoplastic effects against diverse lung cancer cells. It inhibited growth, caused cell cycle arrest, and induced apoptosis more than did seliciclib. Using a high throughput screen platform of 75 (57 KRAS wild-type and 18 KRAS mutant) lung cancer cell lines, those with KRAS mutation were significantly (p<0.05) more sensitive to CCT68127 than were KRAS wild-type cells. Anaphase catastrophe was triggered by CCT68127 treatment. Expression of 180 critical growth-regulatory proteins was studied before and after 6, 24, and 48 hours of CCT68127 or vehicle treatments in murine (LKR13; KRAS mutant and ED1; KRAS wild-type) and human (Hop62; KRAS mutant and H522; KRAS wild-type) lung cancer cells using a reverse phase protein array (RPPA). Regulated species included DNA repair, Hippo, and Rab GTPase proteins. The multifunctional growth regulator PEA15 (phosphoprotein enriched in astrocytes 15), exhibited marked Ser116 phosphorylation inhibition after CCT68127 treatment. This was independently confirmed by immunoblot analysis in murine and human lung cancer cells. When PEA15 was overexpressed in these cells, CCT68127 growth inhibition was antagonized, indicating its direct involvement in these effects. PEA15 knockdown using siRNAs significantly (p<0.05) repressed growth of lung cancer cells and enhanced growth inhibition after CCT68127 treatment. PEA15 immunohistochemical detection was explored in 235 human non-small lung cancers. PEA15 expression was reduced in lung cancers versus adjacent normal lung. Decreased PEA15 expression was significantly (p<0.05) associated with advanced stage and overall survival, establishing the translational importance of PEA15 expression in lung cancer. In summary, the novel CDK2/9 inhibitor, CCT68127, elicits marked antineoplastic effects in lung cancer. This occurs through mechanisms that engage anaphase catastrophe and reduce phosphorylation of the growth regulator PEA15. Citation Format: Masanori Kawakami, Xi Liu, Lisa M. Mustachio, David J. Sekula, Shanhu Hu, Lin Zheng, Jaime Rodriguez-Canales, Barbara Mino, Pamela A. Villalobos, Carmen Behrens, Ignacio I. Wistuba, Sarah J. Freemantle, Ethan Dmitrovsky. Antineoplastic activity of the novel CDK2/9 inhibitor CCT68127 occurs via induced anaphase catastrophe and inhibition of PEA15 phosphorylation in lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2982.