Phosphatases of regenerating liver downregulate PTEN to promote tumorigenesis

Abstract

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is one of the most frequently inactivated tumor suppressors in human cancers, serving as a critical negative regulator of phosphatidylinositol 3-kinase (PI3K)–AKT signaling. Although genetic mutation or deletion commonly underlie functional PTEN loss, accumulating evidence indicates that post-transcriptional and post-translational mechanisms also substantially contribute to PTEN suppression. Phosphatases of regenerating liver (PRLs), comprising PRL1, PRL2, and PRL3, are oncogenic phosphatases frequently overexpressed in both solid and hematological malignancies. Emerging studies reveal that PRLs can downregulate PTEN through a post-translational mechanism by direct dephosphorylation of PTEN at Tyr336, therefore promoting PTEN ubiquitination and proteasomal degradation. PRLs can also reduce PTEN expression through a post-transcriptional mechanism by dephosphorylating the inhibitory Tyr570 in JAK2, thereby activating the JAK2/STAT3-mediated miR-21 expression. These coordinated actions collectively amplify PI3K–AKT signaling, consequently promoting proliferation, survival, and metastasis. In the present review, we synthesize current knowledge of PRL structure, evolution, and functional diversity, evaluate genetic, biochemical, and organismal evidence linking PRLs to PTEN regulation, and discuss insights on PRL oncogenicity derived from experimental models. We further examine context-dependent functions of PRLs, unresolved questions regarding catalytic versus scaffold activities, and the therapeutic potential of targeting the PRL–PTEN axis. Understanding how PRLs modulate PTEN activity may reveal new strategies to restore tumor suppressor function in PTEN-deficient cancers.