ABSTRACT
Phosphoinositide 3-kinase (PI3K)-AKT and androgen receptor (AR) pathways are commonly activated in prostate cancers. Their reciprocal regulation makes advanced prostate cancers difficult to treat. The current study shows that pleckstrin-2 (PLEK2), a proto-oncoprotein involved in the activation and stabilization of AKT, connects these two pathways. Genetic evidence provided herein suggests that Plek2 deficiency largely reverted tumorigenesis in Pten prostate-specific knockout mice and that overexpression of PLEK2 promoted the proliferation and colony formation of prostate cancer cells in vitro. In addition, PLEK2 was negatively regulated by AR, AR transcriptionally repressed PLEK2 through binding to the PLEK2 promoter region, and overexpression of AR reduced PLEK2 expression, which inactivated AKT. Conversely, knockdown of AR in prostate cancer cells increased PLEK2 expression and activated the AKT pathway. This reciprocal inhibitory loop can be pharmacologically targeted using the PLEK2 inhibitor. PLEK2 inhibitor dose-dependently inhibited prostate cancer cell proliferation with the inactivation of AKT. Overall, the current study uncovered a crucial role of PLEK2 in prostate cancer proliferation and provided the rationale for targeting PLEK2 to treat prostate cancers.