LAUSR

Introduction. Clear cell renal cell carcinoma (ccRCC) is the most frequent type of kidney cancer. These highly vascularized tumors are characterized by mutations that inactivate the von Hippel-Lindau (VHL) tumor suppressor gene. About 30 % of patients present metastasis at diagnosis and 30-40% of patients with localized tumors relapse after surgery. Unfortunately, metastatic ccRCC remains incurable and are resistant to standard therapies. Our studies demonstrated that ccRCC with a loss of VHL can be targeted using a small molecule named STF-62247. This molecule blocks the autophagic flux causing enlargement of endolysosomes leading to cell death. More recently, we identified the lipid kinase PIKfyve as a target of STF-62247. A central complex assuring the functionality of the lysosome is formed by the lipid kinase PIKfyve, the scaffold protein ArPIKfyve (Vac14), and the phosphatase Sac3 (Fig4). Interestingly, PIKfyve has shown to play a role in cell migration but the mechanisms are not well understood. Objectives. Our project aims to i) assess a role for PIKfyve in ccRCC migration/invasion, ii) evaluate the potential of PIKfyve inhibitors on angiogenesis, and iii) assess the effect of PIKfyve inhibitors or genetic knockdown of PIKfyve, Vac14 or Fig4 on tumor growth in vivo. Methods and Results. PIKfyve, Vac14 and Fig4 gene expression were modified using CRISPR/Cas9 (Cr) or the SMARTvectorTM Inducible Lentiviral shRNA system. qRT-PCR and western blot validated our models. Results obtained in Cr.PIKfyve and Cr.Vac14 indicated that loss of Vac14 decreased survival of VHL-deficient ccRCC. Moreover, our recent results show that migration measured by wound healing assay is reduced in CRISPR cells compared to control. To investigate a role for PIKfyve in angiogenesis, tube formation assay was performed in treated cells with PIKfyve inhibitors. Our results indicated a reduction in tube formation in STF-62247 and apilimod treated cells. Furthermore, we will use the proteome profiler human angiogenesis array to identify angiogenic proteins linked to PIKfyve activity. Conclusion. Understanding how PIKfyve is involved in the process of angiogenesis would play a major role in the knowledge for new targeted therapies inkidney cancer. Citation Format: Jolène Cormier, Sandra Turcotte. Investigating a role for PIKfyve in cell migration and invasion of clear cell renal cell carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3617.