Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta (PI3Kβ) (PI3Kβ)

Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta (PI3Kβ) is a Class IA PI3K isoform encoded by the PIK3CB gene that plays a pivotal role in cellular signaling by converting phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 3,4,5-trisphosphate (PIP3) (UniProt: P42338). Unlike PI3Kα, which is primarily activated by receptor tyrosine kinases, PI3Kβ can be activated by both receptor tyrosine kinases and G protein-coupled receptors, providing a unique link between different signaling inputs (PubMed: 18418336). In oncology, PI3Kβ is particularly significant in PTEN-deficient tumors, such as certain prostate and breast cancers, where it often serves as the primary driver of the AKT survival pathway (PubMed: 18948945). Beyond its role in cancer, PI3Kβ is essential for platelet activation and stable thrombus formation, making it a potential target for antithrombotic therapy without increasing bleeding risk to the same extent as traditional anticoagulants (PubMed: 15711550). Therapeutic strategies involve small-molecule inhibitors like GSK2636771 and AZD8186, which are designed to selectively target the p110β subunit to minimize off-target effects associated with pan-PI3K inhibition. However, clinical development faces challenges such as managing hyperglycemia and gastrointestinal toxicities, as well as identifying the patient populations most likely to benefit based on PTEN status.

Other names

PIK3CBp110-betap110betaPhosphoinositide 3-kinase betaPI3-kinase subunit beta

Inhibition of the catalytic activity of the p110β subunit, preventing the phosphorylation of PIP2 to PIP3 and subsequent AKT pathway activation.