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== Function ==
== Function ==
[https://www.uniprot.org/uniprot/PK3CA_HUMAN PK3CA_HUMAN] Phosphoinositide-3-kinase (PI3K) that phosphorylates PtdIns (Phosphatidylinositol), PtdIns4P (Phosphatidylinositol 4-phosphate) and PtdIns(4,5)P2 (Phosphatidylinositol 4,5-bisphosphate) to generate phosphatidylinositol 3,4,5-trisphosphate (PIP3). PIP3 plays a key role by recruiting PH domain-containing proteins to the membrane, including AKT1 and PDPK1, activating signaling cascades involved in cell growth, survival, proliferation, motility and morphology. Participates in cellular signaling in response to various growth factors. Involved in the activation of AKT1 upon stimulation by receptor tyrosine kinases ligands such as EGF, insulin, IGF1, VEGFA and PDGF. Involved in signaling via insulin-receptor substrate (IRS) proteins. Essential in endothelial cell migration during vascular development through VEGFA signaling, possibly by regulating RhoA activity. Required for lymphatic vasculature development, possibly by binding to RAS and by activation by EGF and FGF2, but not by PDGF. Regulates invadopodia formation in breast cancer cells through the PDPK1-AKT1 pathway. Participates in cardiomyogenesis in embryonic stem cells through a AKT1 pathway. Participates in vasculogenesis in embryonic stem cells through PDK1 and protein kinase C pathway. Has also serine-protein kinase activity: phosphorylates PIK3R1 (p85alpha regulatory subunit), EIF4EBP1 and HRAS.<ref>PMID:21708979</ref>  
[https://www.uniprot.org/uniprot/PK3CA_HUMAN PK3CA_HUMAN] Phosphoinositide-3-kinase (PI3K) that phosphorylates PtdIns (Phosphatidylinositol), PtdIns4P (Phosphatidylinositol 4-phosphate) and PtdIns(4,5)P2 (Phosphatidylinositol 4,5-bisphosphate) to generate phosphatidylinositol 3,4,5-trisphosphate (PIP3). PIP3 plays a key role by recruiting PH domain-containing proteins to the membrane, including AKT1 and PDPK1, activating signaling cascades involved in cell growth, survival, proliferation, motility and morphology. Participates in cellular signaling in response to various growth factors. Involved in the activation of AKT1 upon stimulation by receptor tyrosine kinases ligands such as EGF, insulin, IGF1, VEGFA and PDGF. Involved in signaling via insulin-receptor substrate (IRS) proteins. Essential in endothelial cell migration during vascular development through VEGFA signaling, possibly by regulating RhoA activity. Required for lymphatic vasculature development, possibly by binding to RAS and by activation by EGF and FGF2, but not by PDGF. Regulates invadopodia formation in breast cancer cells through the PDPK1-AKT1 pathway. Participates in cardiomyogenesis in embryonic stem cells through a AKT1 pathway. Participates in vasculogenesis in embryonic stem cells through PDK1 and protein kinase C pathway. Has also serine-protein kinase activity: phosphorylates PIK3R1 (p85alpha regulatory subunit), EIF4EBP1 and HRAS.<ref>PMID:21708979</ref>  
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== Publication Abstract from PubMed ==
PIK3CA (PI3Ka) is a lipid kinase commonly mutated in cancer, including ~40% of hormone receptor-positive breast cancer. The most frequently observed mutants occur in the kinase and helical domains. Orthosteric PI3Ka inhibitors suffer from poor selectivity leading to undesirable side effects, most prominently hyperglycemia due to inhibition of wild-type (WT) PI3Ka. Here, we used molecular dynamics simulations and cryo-electron microscopy to identify an allosteric network that provides an explanation for how mutations favor PI3Ka activation. A DNA-encoded library screen leveraging electron microscopy-optimized constructs, differential enrichment, and an orthosteric-blocking compound led to the identification of RLY-2608, a first-in-class allosteric mutant-selective inhibitor of PI3Ka. RLY-2608 inhibited tumor growth in PIK3CA mutant xenograft models with minimal impact on insulin, a marker of dysregulated glucose homeostasis. RLY-2608 elicited objective tumor responses in two patients diagnosed with advanced hormone receptor-positive breast cancer with kinase or helical domain PIK3CA mutations, with no observed WT PI3Ka-related toxicities.
Discovery and clinical proof-of-concept of RLY-2608, a first-in-class mutant-selective allosteric PI3Ka inhibitor that decouples anti-tumor activity from hyperinsulinemia.,Varkaris A, Pazolli E, Gunaydin H, Wang Q, Pierce L, Boezio AA, DiPietro L, Frost A, Giordanetto F, Hamilton EP, Harris K, Holliday M, Hunter TL, Iskandar A, Ji Y, Larivee A, LaRochelle JR, Lescarbeau A, Llambi F, Lormil B, Mader MM, Mar BG, Martin I, McLean TH, Michelsen K, Pechersky Y, Puente-Poushnejad E, Samadani R, Schram AM, Shortsleeves K, Swaminathan S, Tajmir S, Tan G, Tang Y, Valverde R, Wehrenberg B, Wilbur J, Williams BR, Zeng H, Walters WP, Wolf BB, Shaw DE, Bergstrom DA, Watters J, Fraser JS, Fortin PD, Kipp DR Cancer Discov. 2023 Nov 2. doi: 10.1158/2159-8290.CD-23-0944. PMID:37916956<ref>PMID:37916956</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
== References ==
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