Pleckstrin-2 Mediates the Activation of AKT in Prostate Cancer and Is Repressed by Androgen Receptor.

Phosphatidylinositol 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 (PLEK-2, a proto-oncoprotein involved in the activation and stabilization of AKT, connects these two pathways. Genetic evidence is provided that 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, it was found that PLEK2 was negatively regulated by AR, that AR transcriptionally repressed PLEK2 through binding to the PLEK2 promoter region, and that 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. It is shown that the PLEK2 inhibitor dose-dependently inhibited prostate cancer cell proliferation with the inactivation of AKT. Overall, the current study uncovers the crucial role of PLEK2 in prostate cancer proliferation and provides the rationale for targeting PLEK2 to treat prostate cancers.