Abstract 338: Unexpected activity of multiple targeted cancer drugs in regulating ciliary dynamics (2017)

Abstract The primary cilium is an antenna-like structure protruding from the cell surface, which provides a platform for receptors for signaling systems including PDGF-alpha, Hedgehog, Wnt, and others that influence cell differentiation and proliferation decisions. Under normal physiological growth conditions, the cilium forms after mitosis and in quiescent cells, extending from a basal body centered at a centriole, with timed resorption in G0 or early G1. Cancer cells have altered ciliary dynamics, with some (medulloblastomas and basal cell carcinomas) often dependent on cilia, and other tumor types downregulating them. In prior work, we defined Aurora-A, an oncogenic kinase typically thought of as a mitotic regulator, as transiently activated at the basal body, and absolutely required for resorption of cilia at the G0/G1 boundary, and we showed the targeted Aurora-A inhibitor entirely blocked ciliary resorption. In subsequent work, we found that a second drug, the EGFR inhibitor erlotinib, also affected ciliary resorption, positioning erlotinib and alisertib to influence cilia-dependent signaling. In this study, we broadly assessed the activity of a panel of targeted preclinical and clinical agents of known specificity for action in controlling ciliary dynamics. For this, we developed stable hTERT-RPE1 cell line models with integrated Arl13b-GFP reporters to visualize cilia, and performed a mid-throughput screen of 180 drugs for activity in 1) independently inducing ciliary resorption in quiescent G0 cells, or 2) blocking ciliary resorption in cells induced to cycle by serum treatment. With a ~5% hit rate overall, we identified 9 compounds inducing, and 7 compounds blocking resorption. This included some agents commonly used in the clinic, such as sunitinib, which had never previously been linked to control of the ciliary protrusion/resorption cycle. Mechanistic analysis confirmed these compounds controlled activation of Aurora-A at the basal body; in vivo testing demonstrated sunitinib resulted in loss of cilia not only in vitro, but also in normal kidney, kidney tumors, and in renal cysts associated with polycystic kidney disease (PKD), a disease dependent on defective signaling from intact cilia. Further, sunitinib was successful in controlling PKD-dependent cyst development, as predicted by current models for this ciliopathy. These data for the first time suggest new mechanisms for activity of sunitinib and other drugs, in which they can influence activity of lateral signaling pathways such as Wnt and PDGFa by regulating the availability of receptors on a ciliary signaling platform. Citation Format: Anna Kiseleva, Vladislav Korobeynikov, Anna Nikonova, Alexander Deneka, Margret Einarson, Emmanuelle Nicolas, Petr Makhov, Vladimir Kolenko, Jeffrey Peterson, Zeng-jie Yang, Erica Golemis. Unexpected activity of multiple targeted cancer drugs in regulating ciliary dynamics [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 338. doi:10.1158/1538-7445.AM2017-338