Targeting the radiation-induced TR4 nuclear receptor-mediated QKI/circZEB1/miR-141-3p/ZEB1 signaling increases prostate cancer radiosensitivity.

Early studies indicated that the testicular nuclear receptor 4 (TR4) might play key roles in altering prostate cancer (PCa) progression; however, its ability to alter PCa radiosensitivity remains unclear. Here, we found that suppressing TR4 expression promoted radiosensitivity and better suppressed PCa by modulating the protein quaking (QKI)/circZEB1/miR-141-3p/ZEB1 signaling pathway. Mechanism dissection studies revealed that TR4 could transcriptionally increase the RNA-binding protein QKI to increase circZEB1 levels, which then sponges the miR-141-3p to increase the expression of its host gene ZEB1. Preclinical studies with an in vivo mouse model further proved that combining radiation therapy (RT) with metformin promoted radiosensitivity to suppress PCa progression. Together, these results suggest that TR4 may play key roles in altering PCa radiosensitivity and show that targeting this newly identified TR4-mediated QKI/circZEB1/miR-141-3p/ZEB1 signaling pathway may help in the development of a novel RT to better suppress the progression of PCa.