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

Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta isoform (PI3Kβ) is a Class IA PI3K enzyme encoded by the PIK3CB gene that plays a pivotal role in cellular signaling by generating the second messenger phosphatidylinositol 3,4,5-trisphosphate (PIP3) [1]. Unlike the alpha isoform, PI3Kβ is uniquely regulated by both receptor tyrosine kinases and G protein-coupled receptors, allowing it to integrate diverse extracellular signals [2]. It is a critical mediator of platelet function and thrombus formation, making it a potential target for antithrombotic therapies [3]. In oncology, PI3Kβ is particularly significant in cancers characterized by the loss of the PTEN tumor suppressor, such as prostate, breast, and endometrial cancers, where it often becomes the dominant driver of the PI3K/AKT/mTOR survival pathway [4]. Therapeutic strategies involve the use of selective inhibitors, such as GSK2636771 and AZD8186, to disrupt this signaling in PTEN-null tumors while potentially minimizing the metabolic side effects, like severe hyperglycemia, often associated with pan-PI3K or alpha-selective inhibition [5]. Clinical development focuses on identifying patients with specific genomic alterations, primarily PTEN loss, to maximize the efficacy of these targeted agents [6]. Sources: [1] UniProt P42338; [2] PMID: 18418338; [3] PMID: 22921223; [4] PMID: 19164905; [5] PMID: 25104311; [6] PMID: 29133389.

Other names

PIK3CBp110-betap110βPhosphoinositide 3-kinase catalytic beta polypeptideP110BETAPI3Kbeta

Selective or pan-inhibition of the catalytic activity of the p110β subunit, preventing the phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 3,4,5-trisphosphate (PIP3) and subsequent AKT pathway activation [1, 5].