Ketorolac modulates Rac-1/HIF-1α/DDX3/β-catenin signalling via a tumor suppressor prostate apoptosis response-4...

Renal cell carcinoma (RCC) is the most difficult-to-treat form of kidney cancer with a median 5-year survival of 10% under metastatic setting. In RCC, although cytoreductive nephrectomy is common, approximately 20-30% of patients will develop recurrent cancer after surgery, which highlights the need for an effective therapy. Rho-GTPases viz, Rac-1 and Cdc42 are the central regulators of cancer cell migration and invasion and thus metastasis in multiple cancer types. Hence, we elucidated the role of Ketorolac, a modulator Rho-GTPases against RCC through potentiation of tumor suppressor Par-4. The effect of Ketorolac alone and in combination on proliferation, apoptosis, cell-cycle progression, migration, tumor inhibition and their related markers were studied. Moreover, Ketorolac's impact on metastasis by influencing Rac-1/HIF-1α/DDX3/β-catenin signalling was studied with respect to its ability to modulate the expression of tumor suppressor Par-4, and this mechanism was confirmed by siRNA knockdown studies. Ketorolac induced cytotoxicity in a panel of renal cells including patient derived tumor cells with IC₅₀ 2.8 to 9.02 mM and 0.28 to 3.8 mM in monolayer and anchorage independent clonogenic assays respectively. Ketorolac caused significant down regulation of proliferation (Ki-67, Cyclin D1, pRB and DDX3), migration/invasion (Rac-1, Cdc42, and Tiam1), and angiogenesis (HIF-1α and VEGF) markers as studied by gene and protein expression. Moreover, it caused a significant upregulation of tumor suppressor Par-4 known to be downregulated in RCC. This mechanism was further confirmed by using siRNA knockdown studies where we could demonstrate a negative relation between the expression of Par-4 and Rac-1/Cdc42. Importantly, Ketorolac alone and in combination with Sunitinib showed tumor growth inhibition (TGI) of 73% and 86% respectively in xenograft model. This anti-tumor activity was further corroborated by down regulation of Rac-1/Cdc42/HIF-1α/DDX3/β-catenin signalling. This is the first report which implicates the role of Ketorolac against RCC by acting as a small molecule secretagogue causing upregulation of Par-4 in autocrine and paracrine manner. Consequently, these findings suggest that Par-4 can serve as a valuable therapeutic target and a prognostic marker for the treatment of RCC.