Phosphoinositide 3-kinase–protein kinase B pathway (PI3K-Akt pathway)

The Phosphoinositide 3-kinase (PI3K)–protein kinase B (Akt) pathway is a critical intracellular signaling cascade that regulates a wide array of cellular processes including growth, proliferation, motility, and survival. It is typically activated by the binding of extracellular signals, such as growth factors or insulin, to receptor tyrosine kinases (RTKs) or G protein-coupled receptors (GPCRs), which then recruit and activate PI3K. PI3K generates phosphatidylinositol (3,4,5)-trisphosphate (PIP3) at the plasma membrane, which serves as a docking site for Akt and its activating kinase PDK1. Once activated, Akt phosphorylates numerous downstream targets, including mTOR, to promote anabolic metabolism and inhibit apoptosis. (Source: StatPearls, NCBI, 2023; Nature Reviews Cancer, 2021). Dysregulation of this pathway is one of the most frequent events in human oncology, often driven by gain-of-function mutations in the PIK3CA gene or loss of the tumor suppressor PTEN, which normally antagonizes PI3K activity. Because of its central role in promoting tumor cell fitness and resistance to therapy, the pathway is a major focus of drug development. Therapeutic strategies include isoform-specific PI3K inhibitors, pan-PI3K inhibitors, Akt inhibitors, and mTOR inhibitors. However, clinical utility is often limited by feedback loops and significant systemic toxicities, such as hyperglycemia, due to the pathway's essential role in normal glucose metabolism and insulin signaling. (Source: PubMed, PMC, 2022; Wikipedia, 2024).

Other names

PI3K/Akt signaling pathwayPI3K-Akt-mTOR pathwayPhosphatidylinositol 3-kinase-Akt pathway

Drugs targeting this pathway typically act as competitive inhibitors of the ATP-binding site of PI3K isoforms, Akt, or mTOR, thereby blocking the phosphorylation cascade that leads to downstream signaling for cell growth and survival.