View source for 8tu6


==CryoEM structure of PI3Kalpha==
<StructureSection load='8tu6' size='340' side='right'caption='[[8tu6]], [[Resolution|resolution]] 3.12&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8tu6]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8TU6 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8TU6 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.12&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8tu6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8tu6 OCA], [https://pdbe.org/8tu6 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8tu6 RCSB], [https://www.ebi.ac.uk/pdbsum/8tu6 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8tu6 ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/PK3CA_HUMAN PK3CA_HUMAN] Note=Most of the cancer-derived mutations are missense mutations and map to one of the three hotspots: Glu-542; Glu-545 and His-1047. Mutated isoforms participate in cellular transformation and tumorigenesis induced by oncogenic receptor tyrosine kinases (RTKs) and HRAS1/KRAS. Interaction with HRAS1/KRAS is required for Ras-driven tumor formation. Mutations increasing the lipid kinase activity are required for oncogenic signaling. The protein kinase activity may not be required for tumorigenesis.  Defects in PIK3CA are associated with colorectal cancer (CRC) [MIM:[https://omim.org/entry/114500 114500].  Defects in PIK3CA are a cause of susceptibility to breast cancer (BC) [MIM:[https://omim.org/entry/114480 114480]. A common malignancy originating from breast epithelial tissue. Breast neoplasms can be distinguished by their histologic pattern. Invasive ductal carcinoma is by far the most common type. Breast cancer is etiologically and genetically heterogeneous. Important genetic factors have been indicated by familial occurrence and bilateral involvement. Mutations at more than one locus can be involved in different families or even in the same case.  Defects in PIK3CA are a cause of susceptibility to ovarian cancer (OC) [MIM:[https://omim.org/entry/167000 167000]. Ovarian cancer common malignancy originating from ovarian tissue. Although many histologic types of ovarian neoplasms have been described, epithelial ovarian carcinoma is the most common form. Ovarian cancers are often asymptomatic and the recognized signs and symptoms, even of late-stage disease, are vague. Consequently, most patients are diagnosed with advanced disease.  Defects in PIK3CA may underlie hepatocellular carcinoma (HCC) [MIM:[https://omim.org/entry/114550 114550].<ref>PMID:15608678</ref>   Defects in PIK3CA are a cause of keratosis seborrheic (KERSEB) [MIM:[https://omim.org/entry/182000 182000]. A common benign skin tumor. Seborrheic keratoses usually begin with the appearance of one or more sharply defined, light brown, flat macules. The lesions may be sparse or numerous. As they initially grow, they develop a velvety to finely verrucous surface, followed by an uneven warty surface with multiple plugged follicles and a dull or lackluster appearance.<ref>PMID:17673550</ref>   Defects in PIK3CA are the cause of congenital lipomatous overgrowth, vascular malformations, and epidermal nevi (CLOVE) [MIM:[https://omim.org/entry/612918 612918]. CLOVE is a sporadically occurring, non-hereditary disorder characterized by asymmetric somatic hypertrophy and anomalies in multiple organs. It is defined by four main clinical findings: congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and skeletal/spinal abnormalities. The presence of truncal overgrowth and characteristic patterned macrodactyly at birth differentiates CLOVE from other syndromic forms of overgrowth.<ref>PMID:22658544</ref> 
== 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> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
PIK3CA (PI3Kalpha) is a lipid kinase commonly mutated in cancer, including approximately 40% of hormone receptor-positive breast cancer. The most frequently observed mutants occur in the kinase and helical domains. Orthosteric PI3Kalpha inhibitors suffer from poor selectivity leading to undesirable side effects, most prominently hyperglycemia due to inhibition of wild-type (WT) PI3Kalpha. Here, we used molecular dynamics simulations and cryo-electron microscopy to identify an allosteric network that provides an explanation for how mutations favor PI3Kalpha 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 PI3Kalpha. 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 PI3Kalpha-related toxicities. SIGNIFICANCE: Treatments for PIK3CA-mutant cancers are limited by toxicities associated with the inhibition of WT PI3Kalpha. Molecular dynamics, cryo-electron microscopy, and DNA-encoded libraries were used to develop RLY-2608, a first-in-class inhibitor that demonstrates mutant selectivity in patients. This marks the advance of clinical mutant-selective inhibition that overcomes limitations of orthosteric PI3Kalpha inhibitors. See related commentary by Gong and Vanhaesebroeck, p. 204 . See related article by Varkaris et al., p. 227 . This article is featured in Selected Articles from This Issue, p. 201.

Discovery and Clinical Proof-of-Concept of RLY-2608, a First-in-Class Mutant-Selective Allosteric PI3Kalpha Inhibitor That Decouples Antitumor Activity from Hyperinsulinemia.,Varkaris A, Pazolli E, Gunaydin H, Wang Q, Pierce L, Boezio AA, Bulku A, DiPietro L, Fridrich C, 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, Raynor K, Rogala D, Samadani R, Schram AM, Shortsleeves K, Swaminathan S, Tajmir S, Tan G, Tang Y, Valverde R, Wehrenberg B, Wilbur J, Williams BR, Zeng H, Zhang H, Walters WP, Wolf BB, Shaw DE, Bergstrom DA, Watters J, Fraser JS, Fortin PD, Kipp DR Cancer Discov. 2024 Feb 8;14(2):240-257. 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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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Holliday M]]
[[Category: Shi H]]
[[Category: Valverde R]]