Vol.:(0123456789) Discover Oncology (2022) 13:87 | https://doi.org/10.1007/s12672-022-00552-8 1 3 Discover Oncology Research Reciprocal regulation of CIP2A and AR expression in prostate cancer cells Hao‑Wen Chuang 1  · Jian‑Hua Pan 2  · Yi‑Xuan Cai 2  · Darius Rupa 2  · Ting‑Syuan Huang 2  · Tzu‑Chien Kuo 2  · Chiao‑Wen Lin 2  · Chi‑Wei Chen 2  · Chia‑Chin Lin 1  · Herng‑Sheng Lee 1  · Ta‑Chun Yuan 2 Received: 14 July 2022 / Accepted: 30 August 2022 © The Author(s) 2022 OPEN Abstract Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein overexpressed in human malignancies, including prostate cancer (PCa). In this study, we aimed to explore the oncogenic function of CIP2A in PCa cells and its underly- ing mechanism. We showed that 63.3% (38/60 cases) of PCa tissues exhibited a high CIP2A immunostaining, compared to 25% (3/12 cases) of BPH samples (p = 0.023). Furthermore, the protein level of CIP2A was positively correlated with patients’ short survival time and nuclear AR levels in PCa tissues. Compared to PZ-HPV-7, an immortalized prostate cell line, androgen-sensitive LNCaP C-33, androgen-independent LNCaP C-81, or 22Rv1 cells exhibited a high CIP2A level, associated with high protein and phosphorylation levels of AR. While AR expression and activity modulated CIP2A expres- sion, manipulating CIP2A expression in PCa cells regulated their AR protein levels and proliferation. The reduction of CIP2A expression also enhanced the sensitivity of PCa cells toward Enzalutamide treatment. Our data further showed that depletion of polo-kinase 1 (PLK1) expression or activity in C-81 or 22Rv1 cells caused reduced protein levels of c-Myc and AR. Notably, inhibition of PLK1 activity could abolish CIP2A-promoted expressions in c-Myc, AR, and prostate-specifc antigen (PSA) in C-33 cells under an androgen-deprived condition, suggesting the role of PLK1 activity in CIP2A-promoted AR expression. In summary, our data showed the existence of a novel regulation between CIP2A and AR protein levels, which is critical for promoting PCa malignancy. Thus, CIP2A could serve as a therapeutic target for PCa. Keywords Prostate cancer · CRPC · CIP2A · AR · PLK1 Abbreviations PCa Prostate cancer BPH Benign prostatic hyperplasia CRPC Castration-resistant prostate cancer AR Androgen receptor CIP2A Cancerous inhibitor of protein phosphatase 2A PP2A Protein phosphatase 2A PLK1 Polo-like kinase 1 RT Room temperature * Ta-Chun Yuan, yuan415@gms.ndhu.edu.tw | 1 Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, No. 386, Dazhong 1st Rd, Zuoying Dist, Kaohsiung 813414, Taiwan, ROC. 2 Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien 974301, Taiwan, ROC.