Inhibition of USP14 enhances the sensitivity of breast cancer to enzalutamide

BACKGROUND: Androgen receptor (AR) is expressed in approximately 70% of breast tumors. Recent studies increasingly support AR as a potential therapeutic target of AR-positive breast cancer. We have previously reported that deubiquitinase USP14 stabilizes AR proteins by deubiquitination and USP14 inhibition results in inhibition of cell growth and tumor progression in AR-positive prostate cancer and breast cancer. The current study aims to explore the anticancer effect of a treatment combining AR antagonist enzalutamide with USP14 inhibition on breast cancer cells. METHODS: The combining effects of enzalutamide and USP14 inhibition on breast cancer cell proliferation and apoptosis and associated cell signaling were evaluated in vitro and in vivo. RESULTS: USP14 inhibition via administration of IU1 or USP14-specific siRNA/shRNA enhanced cell growth inhibition and apoptosis induction by enzalutamide in breast cancer cell lines in vitro and in vivo. Additionally, the combination of enzalutamide with USP14 inhibition/knockdown induced significant downregulation of AR proteins and suppression of AR-related signaling pathways, including Wnt/β-catenin and PI3K/AKT pathways. Moreover, AKT inhibition via MK2206 increased the antiproliferative and proapoptotic effects of enzalutamide+IU1 combined treatment. CONCLUSION: Collectively, our data suggest that USP14 inhibition in combination with enzalutamide represents a potentially new therapeutic strategy for breast cancer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13046-019-1227-7) contains supplementary material, which is available to authorized users.