Combined Inhibition of PI3K and STAT3 Signaling is Effective in Bladder Cancer Treatment

Abstract Bladder cancer is characterized by aberrant activation of the phosphatidylinositol-3-OH kinase (PI3K) signaling, underscoring the significance of directing therapeutic efforts toward the PI3K pathway as a promising strategy. In this study, we discovered that PI3K serves as a potent therapeutic target for bladder cancer through a high-throughput screening of inhibitory molecules. The PI3K inhibitor demonstrated a robust anti-tumor efficacy, validated both in vitro and in vivo settings. Nevertheless, the feedback activation of JAK1-STAT3 signaling reinstated cell and organoid survival, leading to resistance against the PI3K inhibitor. Mechanistically, the PI3K inhibitor suppresses PTPN11 expression, a negative regulator of the JAK-STAT pathway, thereby activating STAT3. Conversely, restoration of PTPN11 enhances the sensitivity of cancer cells to the PI3K inhibitor. Simultaneous inhibition of both PI3K and STAT3 with small-molecule inhibitors resulted in sustained tumor regression in patient-derived bladder cancer xenografts. These findings advocate for a combinational therapeutic approach targeting both PI3K and STAT3 pathways to achieve enduring cancer eradication in vitro and in vivo, underscoring their promising therapeutic efficacy for treating bladder cancer.