The Next-Generation Cdk2/9 Inhibitor Cyc065 Elicits Marked Antineoplastic Effects In Lung Cancer By Engaging Antimetastatic Pathways

We previously reported CDK2 antagonism with the first generation CDK2/9/7 inhibitor seliciclib (CYC202; Cyclacel) triggered anaphase catastrophe. This occurred when genomically unstable cancer cells with supernumerary centrosomes (a hallmark of cancer) fail to cluster excessive centrosomes at mitosis. This causes multipolar cell division and apoptotic death. Anaphase catastrophe is conferred after CDK2 antagonism of aneuploid cancer cells, sparing bipolar normal cells with two centrosomes. CYC065 (Cyclacel) is a next-generation CDK2/9 inhibitor that is undergoing clinical trial. Here, we explored CYC065 activity against lung cancer cells, some with known high metastatic potential. CYC065 substantially inhibited growth, triggered apoptosis, and induced anaphase catastrophe in murine (ED1, LKR13, and 393P) and human (Hop62, A549, and H1299) lung cancer cells. In marked contrast, these effects were largely unseen in bipolar immortalized pulmonary epithelial (murine C10 and human BEAS-2B) cells. We sought to explore whether CYC065 antineoplastic effects engaged antimetastatic pathways. In vitro migration and invasion assays were performed. CYC065 markedly inhibited migration and invasion of lung cancer cells (murine: 344SQ and KC2; human: A549 and H1299). Reverse Phase Protein Arrays (RPPAs) interrogated nearly 300 growth-regulatory proteins in murine (344SQ and KC2) and human (A549 and H1299) lung cancer cells over time (6, 12, 24, and 48 hours) after CYC065 or vehicle treatments. These lung cancer cells have high metastatic as well migration or invasive potentials. When highlighted proteins were clustered after CYC065 treatment, some species were clustered as significantly up-regulated or down-regulated in all cells over studied time points. Not surprisingly, up-regulated proteins included those involved in DNA damage or apoptosis. In addition to known CDK targets like phosphorylated retinoblastoma protein, novel proteins were markedly down-regulated, including mTOR pathway and integrin pathway proteins such as FAK phosphorylation and Src phosphorylation. Affected pathways were identified using Ingenuity Pathway Analysis (IPA). IPA revealed up-regulation of pathways that engaged ATM signaling, G2/M DNA damage checkpoint regulation, or apoptosis signaling. Down-regulated pathways affected mTOR signaling, cyclins, cell cycle regulation, or integrin pathways. Mouse studies will be presented that examine in vivo effects of CYC065 in reducing metastases. Taken together, the next-generation CDK2/9 inhibitor, CYC065, elicits marked antineoplastic effects by antagonizing migration and invasion of lung cancer cells. Comprehensive RPPA and IPA studies found that distinct pathways trigger these effects. Citation Format: Masanori Kawakami, Jason Roszik, Lin Zheng, Jonathan Kurie, Lisa Maria Mustachio, Xi Liu, Ethan Dmitrovsky. The next-generation CDK2/9 inhibitor CYC065 elicits marked antineoplastic effects in lung cancer by engaging antimetastatic pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 128. doi:10.1158/1538-7445.AM2017-128