Abstract PR15: Rho-associated kinase 1 inhibition is synthetically lethal with von Hippel-Lindau deficiency in clear cell renal cell carcinoma

The objective of this study was to identify chemical compounds that are synthetically lethal with VHL deficiency in CC-RCC. An annotated chemical library, the library of pharmacologically active compounds (LOPAC), was screened in parallel on VHL-deficient RCC4 cells and RCC4VHL cells with re-introduced VHL. The ROCK inhibitor, Y-27632, was identified and validated for selective targeting of VHL-deficient CC-RCC in multiple genetic backgrounds by clonogenic assays. Downregulation of ROCK1 by small interfering RNA (siRNA) selectively reduced the colony forming ability of VHL-deficient CC-RCC, thus mimicking the effect of Y-27632 treatment, whereas downregulation of ROCK2 had no effect. In addition, three other ROCK inhibitors, RKI 1447, GSK 429286, AT13148 selectively targeted VHL-deficient CC-RCC. Importantly, we found that mammalian target of rapamycin (mTOR) inhibitor Everolimus synergized with ROCK inhibitor RKI 1447 in targeting VHL-deficient cells. Accordingly, AT13148, an AGC kinase inhibitor blocking S6 kinase (S6K, downstream target of mTOR) in addition to ROCK1&2, showed the most strong synthetic lethality effect out of all ROCK inhibitors tested. CC-RCC treatment with ROCK inhibitors is cytotoxic and cytostatic based on bromodeoxyuridine (BrdU) assay, propidium iodide (PI) staining and growth curves, and blocks cell migration based on transwell assay. On the one hand, knockdown of hypoxia-inducible factor (HIF) β in the VHL-deficient CC-RCC had a protective ...

Source: Molecular Cancer Therapeutics - October 2, 2017 Category: Cancer & Oncology Authors: Thompson, J. M., Nguyen, Q. H., Singh, M., Pavesic, M. W., Nesterenko, I., Nelson, L. J., Liao, A., Razorenova, O. V. Tags: Chemical Biology: Oral Presentations - Proffered Abstracts Source Type: research