Phosphoinositide 3-kinase class I alpha and delta isoforms (PI3Kα and PI3Kδ)

Phosphoinositide 3-kinase class I alpha and delta isoforms are lipid kinases (enzymes that phosphorylate phosphatidylinositol lipids) involved in intracellular signal transduction. Each isoform consists of a catalytic (p110α or p110δ) and a regulatory (often p85) subunit. PI3Kα is widely expressed across tissues and frequently mutated in human cancers, driving oncogenic signaling, cell growth, and survival[2][5][6][7]. PI3Kδ is predominantly expressed in leukocytes and plays a key role in immune cell development and function, particularly B cell maturation and survival[1][5]. Both serve as major nodes in the PI3K/AKT/mTOR pathway, which regulates cell proliferation, survival, metabolism, and other essential cellular processes[4][5][6]. Activating mutations (especially in PIK3CA, the gene coding for p110α) and inappropriate pathway activation have been implicated in cancers and immune disorders, making these isoforms important drug targets. Multiple approved drugs act as isoform-selective inhibitors, with ongoing research addressing efficacy and safety challenges[3][5][6].

Other names

PI3K class I alpha (PI3Kα)PI3K class I delta (PI3Kδ)phosphatidylinositol 3-kinase alphaphosphatidylinositol 3-kinase deltap110αp110δ

Inhibition of PI3Kα or PI3Kδ catalytic activity halting downstream PI3K/AKT/mTOR pathway signaling Suppression of cellular proliferation and survival in tumor or immune cells