Abstract A031: Androgen deprivation therapy-induced TGFBI signaling promotes EMT and bone metastasis of prostate cancer

Metastatic progression in patients with prostate cancer is common despite pharmacologic inhibition of androgen receptor signaling. This drug resistance is associated with increased signaling through the transforming growth factor-β (TGF-β) signaling pathway. We found the type I/II/IV collagen-binding protein transforming growth factor-β (TGF-β)-induced (TGFBI) is an important factor in the epithelial-to-mesenchymal transition (EMT) and malignant progression of prostate cancer. We identified that an androgen-responsive gene, SPDEF, navigates between AR and TGFβ signaling during prostate cancer progression to metastasis though a physical interaction with the promoter region of the TGFBI gene. We show that loss of AR-regulated SPDEF induces TGFBI expression in prostate cancer cells, leading to drastic and aggressive physiologic changes. Furthermore, we confirmed the negative correlation between SPDEF and TGFβ singling in prostate cancer patients and demonstrated that ADT can reduce SPDEF and increase TGFβ signaling. Our results support an inhibitory role of the AR on TGFβ signaling through SPDEF-mediated suppression of TGFBI, and that disruption of this pathway promotes metastatic progression in prostate cancer. Citation Format: Yen-Nien Liu, Wei-Yu Chen, Yuan-Chin Tsai, Hsiu-Lien Yeh, Florent Suau, Jiaoti Huang. Androgen deprivation therapy-induced TGFBI signaling promotes EMT and bone metastasis of prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A031.