WWP1 inactivation enhances efficacy of PI3K inhibitors while suppressing their toxicities in breast cancer models.

Activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway is a pervasive event in tumorigenesis due to PI3K mutation and dysfunction of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Pharmacological inhibition of PI3K has resulted in variable clinical outcomes, however, raising questions regarding the possible mechanisms of unresponsiveness and resistance to treatment. WWP1 is an oncogenic HECT-type ubiquitin E3 ligase frequently amplified and mutated in multiple cancers, as well as in the germ lines of patients predisposed to cancer, and was recently found to activate PI3K signaling through PTEN inactivation.

WWP1 Gain-of-Function Inactivation of PTEN in Cancer Predisposition.

Background: Patients with hamartoma tumor syndrome (PHTS) have germline mutations in the tumor-suppressor gene encoding phosphatase and tensin homologue (). Such mutations have been associated with a hereditary predisposition to multiple types of cancer, including the Cowden syndrome. However, a majority of patients who have PHTS-related phenotypes have tested negative for mutations.