<i>SETD2</i> loss sensitizes cells to PI3Kβ and AKT inhibition

Abstract

Upregulation of the PI3K pathway has been implicated in the initiation and progression of several types of cancer, including renal cell carcinoma (RCC). Although several targeted therapies have been developed for RCC, durable and complete responses are exceptional. Thus, advanced RCC remains a lethal disease, underscoring the need of robust biomarker-based strategies to treat RCC. We report a synthetic lethal interaction between inhibition of phosphatidylinositol 3-kinase beta (PI3Kβ) and loss of <i>SETD2</i> methyltransferase. Clear cell RCC (ccRCC)-derived <i>SETD2</i> knockout 786-0 and <i>SETD2</i> mutant A498 cells treated with TGX221 (PI3Kβ-specific) and AZD8186 (PI3Kβ- and δ-specific) inhibitors displayed decreased cell viability, cell growth, and migration compared to <i>SETD2</i> proficient 786-0 cells. Inhibition of the p110 δ and α isoforms alone had modest (δ) and no (α) effect on ccRCC cell viability, growth, and migration. <i>In vivo</i>, treatment of <i>SETD2</i> mutant A498 cells, but not <i>SETD2</i> proficient 786-0 cells, with AZD8186 significantly decreased tumor growth. Interestingly, inhibition of the downstream effector AKT (MK2206) recapitulated the effects observed in AZD8186-treated <i>SETD2</i> deficient cells. Our data show that specific inhibition of PI3Kβ causes synthetic lethality with <i>SETD2</i> loss and suggest targeting of the AKT downstream effector pathway offers a rationale for further translational and clinical investigation of PI3Kβ-specific inhibitors in ccRCC.