1
|
Thapa N, Chen M, Cryns VL, Anderson R. A p85 isoform switch enhances PI3K activation on endosomes by a MAP4- and PI3P-dependent mechanism. Cell Rep 2024; 43:114119. [PMID: 38630589 DOI: 10.1016/j.celrep.2024.114119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 02/21/2024] [Accepted: 03/29/2024] [Indexed: 04/19/2024] Open
Abstract
Phosphatidylinositol 3-kinase α (PI3Kα) is a heterodimer of p110α catalytic and p85 adaptor subunits that is activated by agonist-stimulated receptor tyrosine kinases. Although p85α recruits p110α to activated receptors on membranes, p85α loss, which occurs commonly in cancer, paradoxically promotes agonist-stimulated PI3K/Akt signaling. p110α localizes to microtubules via microtubule-associated protein 4 (MAP4), facilitating its interaction with activated receptor kinases on endosomes to initiate PI3K/Akt signaling. Here, we demonstrate that in response to agonist stimulation and p85α knockdown, the residual p110α, coupled predominantly to p85β, exhibits enhanced recruitment with receptor tyrosine kinases to endosomes. Moreover, the p110α C2 domain binds PI3-phosphate, and this interaction is also required to recruit p110α to endosomes and for PI3K/Akt signaling. Stable knockdown of p85α, which mimics the reduced p85α levels observed in cancer, enhances cell growth and tumorsphere formation, and these effects are abrogated by MAP4 or p85β knockdown, underscoring their role in the tumor-promoting activity of p85α loss.
Collapse
Affiliation(s)
- Narendra Thapa
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Mo Chen
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Vincent L Cryns
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Richard Anderson
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA.
| |
Collapse
|
2
|
Ketcham JM, Harwood SJ, Aranda R, Aloiau AN, Bobek BM, Briere DM, Burns AC, Caddell Haatveit K, Calinisan A, Clarine J, Elliott A, Engstrom LD, Gunn RJ, Ivetac A, Jones B, Kuehler J, Lawson JD, Nguyen N, Parker C, Pearson KE, Rahbaek L, Saechao B, Wang X, Waters A, Waters L, Watkins AH, Olson P, Smith CR, Christensen JG, Marx MA. Discovery of Pyridopyrimidinones that Selectively Inhibit the H1047R PI3Kα Mutant Protein. J Med Chem 2024; 67:4936-4949. [PMID: 38477582 PMCID: PMC10983000 DOI: 10.1021/acs.jmedchem.4c00078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/20/2024] [Accepted: 02/26/2024] [Indexed: 03/14/2024]
Abstract
The H1047R mutation of PIK3CA is highly prevalent in breast cancers and other solid tumors. Selectively targeting PI3KαH1047R over PI3KαWT is crucial due to the role that PI3KαWT plays in normal cellular processes, including glucose homeostasis. Currently, only one PI3KαH1047R-selective inhibitor has progressed into clinical trials, while three pan mutant (H1047R, H1047L, H1047Y, E542K, and E545K) selective PI3Kα inhibitors have also reached the clinical stage. Herein, we report the design and discovery of a series of pyridopyrimidinones that inhibit PI3KαH1047R with high selectivity over PI3KαWT, resulting in the discovery of compound 17. When dosed in the HCC1954 tumor model in mice, 17 provided tumor regressions and a clear pharmacodynamic response. X-ray cocrystal structures from several PI3Kα inhibitors were obtained, revealing three distinct binding modes within PI3KαH1047R including a previously reported cryptic pocket in the C-terminus of the kinase domain wherein we observe a ligand-induced interaction with Arg1047.
Collapse
Affiliation(s)
| | | | - Ruth Aranda
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Athenea N. Aloiau
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Briana M. Bobek
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - David M. Briere
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Aaron C. Burns
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | | | - Andrew Calinisan
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Jeffery Clarine
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Adam Elliott
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Lars D. Engstrom
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Robin J. Gunn
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Anthony Ivetac
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Benjamin Jones
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Jon Kuehler
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - J. David Lawson
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Natalie Nguyen
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Cody Parker
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Kelly E. Pearson
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Lisa Rahbaek
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Barbara Saechao
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Xiaolun Wang
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Anna Waters
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Laura Waters
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Ashlee H. Watkins
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Peter Olson
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Christopher R. Smith
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - James G. Christensen
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| | - Matthew A. Marx
- Mirati Therapeutics, 3545 Cray Court, San Diego, California 92121, United States
| |
Collapse
|
3
|
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, Larivée 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. Discovery and Clinical Proof-of-Concept of RLY-2608, a First-in-Class Mutant-Selective Allosteric PI3Kα Inhibitor That Decouples Antitumor Activity from Hyperinsulinemia. Cancer Discov 2024; 14:240-257. [PMID: 37916956 PMCID: PMC10850943 DOI: 10.1158/2159-8290.cd-23-0944] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/21/2023] [Accepted: 10/27/2023] [Indexed: 11/03/2023]
Abstract
PIK3CA (PI3Kα) 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 PI3Kα inhibitors suffer from poor selectivity leading to undesirable side effects, most prominently hyperglycemia due to inhibition of wild-type (WT) PI3Kα. Here, we used molecular dynamics simulations and cryo-electron microscopy to identify an allosteric network that provides an explanation for how mutations favor PI3Kα 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 PI3Kα. 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 PI3Kα-related toxicities. SIGNIFICANCE Treatments for PIK3CA-mutant cancers are limited by toxicities associated with the inhibition of WT PI3Kα. 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 PI3Kα 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.
Collapse
Affiliation(s)
- Andreas Varkaris
- Mass General Cancer Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | | | | | - Qi Wang
- D. E. Shaw Research, New York, New York
| | - Levi Pierce
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | | | | | | | | | - Adam Frost
- Altos Labs, Institute of Science, San Francisco, California
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California
- California Institute of Quantitative Biosciences (QB3), University of California San Francisco, San Francisco, California
| | | | - Erika P. Hamilton
- Sarah Cannon Research Institute/Tennessee Oncology, Nashville, Tennessee
| | - Katherine Harris
- MGH/Mass General Cancer Center at Danvers, Danvers, Massachusetts
| | | | | | | | - Yongli Ji
- Hematology/Oncology, Exeter Hospital, Exeter, New Hampshire
| | | | | | | | | | - Brenda Lormil
- Mass General Cancer Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | | | | | - Iain Martin
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | | | | | | | | | - Kevin Raynor
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | | | | | - Alison M. Schram
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | | | | | - Shahein Tajmir
- MGH Radiology, Harvard Medical School, Boston, Massachusetts
| | - Gege Tan
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | - Yong Tang
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | | | | | | | | | - Hongtao Zeng
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | - Hanmo Zhang
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | - W. Patrick Walters
- Mass General Cancer Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Beni B. Wolf
- Relay Therapeutics, Inc., Cambridge, Massachusetts
| | - David E. Shaw
- D. E. Shaw Research, New York, New York
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York
| | | | | | - James S. Fraser
- California Institute of Quantitative Biosciences (QB3), University of California San Francisco, San Francisco, California
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California
| | | | | |
Collapse
|
4
|
Tufail M, Hu JJ, Liang J, He CY, Wan WD, Huang YQ, Jiang CH, Wu H, Li N. Predictive, preventive, and personalized medicine in breast cancer: targeting the PI3K pathway. J Transl Med 2024; 22:15. [PMID: 38172946 PMCID: PMC10765967 DOI: 10.1186/s12967-023-04841-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024] Open
Abstract
Breast cancer (BC) is a multifaceted disease characterized by distinct molecular subtypes and varying responses to treatment. In BC, the phosphatidylinositol 3-kinase (PI3K) pathway has emerged as a crucial contributor to the development, advancement, and resistance to treatment. This review article explores the implications of the PI3K pathway in predictive, preventive, and personalized medicine for BC. It emphasizes the identification of predictive biomarkers, such as PIK3CA mutations, and the utility of molecular profiling in guiding treatment decisions. The review also discusses the potential of targeting the PI3K pathway for preventive strategies and the customization of therapy based on tumor stage, molecular subtypes, and genetic alterations. Overcoming resistance to PI3K inhibitors and exploring combination therapies are addressed as important considerations. While this field holds promise in improving patient outcomes, further research and clinical trials are needed to validate these approaches and translate them into clinical practice.
Collapse
Affiliation(s)
- Muhammad Tufail
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Jia-Ju Hu
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Jie Liang
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Cai-Yun He
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Wen-Dong Wan
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Yu-Qi Huang
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
| | - Can-Hua Jiang
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China
- Institute of Oral Precancerous Lesions, Central South University, Changsha, China
- Research Center of Oral and Maxillofacial Tumor, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Hong Wu
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China
| | - Ning Li
- Department of Oral and Maxillofacial Surgery, Center of Stomatology, Xiangya Hospital, Central South University, Changsha, China.
- Institute of Oral Precancerous Lesions, Central South University, Changsha, China.
- Research Center of Oral and Maxillofacial Tumor, Xiangya Hospital, Central South University, Changsha, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.
| |
Collapse
|
5
|
Madsen RR, Toker A. PI3K signaling through a biochemical systems lens. J Biol Chem 2023; 299:105224. [PMID: 37673340 PMCID: PMC10570132 DOI: 10.1016/j.jbc.2023.105224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 09/08/2023] Open
Abstract
Following 3 decades of extensive research into PI3K signaling, it is now evidently clear that the underlying network does not equate to a simple ON/OFF switch. This is best illustrated by the multifaceted nature of the many diseases associated with aberrant PI3K signaling, including common cancers, metabolic disease, and rare developmental disorders. However, we are still far from a complete understanding of the fundamental control principles that govern the numerous phenotypic outputs that are elicited by activation of this well-characterized biochemical signaling network, downstream of an equally diverse set of extrinsic inputs. At its core, this is a question on the role of PI3K signaling in cellular information processing and decision making. Here, we review the determinants of accurate encoding and decoding of growth factor signals and discuss outstanding questions in the PI3K signal relay network. We emphasize the importance of quantitative biochemistry, in close integration with advances in single-cell time-resolved signaling measurements and mathematical modeling.
Collapse
Affiliation(s)
- Ralitsa R Madsen
- MRC-Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom.
| | - Alex Toker
- Department of Pathology and Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
| |
Collapse
|
6
|
Vogt PK, Hart JR, Yang S, Zhou Q, Yang D, Wang MW. Structural and mechanistic insights provided by single particle cryo-EM analysis of phosphoinositide 3-kinase (PI3Kα). Biochim Biophys Acta Rev Cancer 2023; 1878:188947. [PMID: 37394020 PMCID: PMC10530483 DOI: 10.1016/j.bbcan.2023.188947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/27/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023]
Abstract
Recent cryo-electron microscopic (cryo-EM) investigations have succeeded in the analysis of various structural conformations and functional states of PI3Kα, a dimer consisting of the catalytic subunit p110α and the regulatory subunit p85α of class IA of phosphoinositide 3-kinase. High resolution structures have been obtained of the unliganded and of BYL-719-bound PI3Kα. The latter provides information on excessively flexible domains of p85α that are then further analyzed with nanobodies and CXMS (chemical cross-linking, digestion and mass spectrometry). Analysis of p110α helical and kinase domain mutations reveals mutant-specific features that can be linked to the gain of function in enzymatic and signaling activities.
Collapse
Affiliation(s)
- Peter K Vogt
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America.
| | - Jonathan R Hart
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Su Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Dehua Yang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ming-Wei Wang
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Research Center for Deepsea Bioresources, Sanya 572025, China; Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| |
Collapse
|
7
|
Zhou Q, Liu X, Neri D, Li W, Favalli N, Bassi G, Yang S, Yang D, Vogt PK, Wang MW. Structural insights into the interaction of three Y-shaped ligands with PI3Kα. Proc Natl Acad Sci U S A 2023; 120:e2304071120. [PMID: 37585458 PMCID: PMC10450665 DOI: 10.1073/pnas.2304071120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/19/2023] [Indexed: 08/18/2023] Open
Abstract
Class IA phosphoinositide 3-kinase alpha (PI3Kα) is an important drug target because it is one of the most frequently mutated proteins in human cancers. However, small molecule inhibitors currently on the market or under development have safety concerns due to a lack of selectivity. Therefore, other chemical scaffolds or unique mechanisms of catalytic kinase inhibition are needed. Here, we report the cryo-electron microscopy structures of wild-type PI3Kα, the dimer of p110α and p85α, in complex with three Y-shaped ligands [cpd16 (compound 16), cpd17 (compound 17), and cpd18 (compound 18)] of different affinities and no inhibitory effect on the kinase activity. Unlike ATP-competitive inhibitors, cpd17 adopts a Y-shaped conformation with one arm inserted into a binding pocket formed by R770 and W780 and the other arm lodged in the ATP-binding pocket at an angle that is different from that of the ATP phosphate tail. Such a special interaction induces a conformation of PI3Kα resembling that of the unliganded protein. These observations were confirmed with two isomers (cpd16 and cpd18). Further analysis of these Y-shaped ligands revealed the structural basis of differential binding affinities caused by stereo- or regiochemical modifications. Our results may offer a different direction toward the design of therapeutic agents against PI3Kα.
Collapse
Affiliation(s)
- Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai200032, China
| | - Xiao Liu
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai200032, China
| | - Dario Neri
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zurich), Zurich8093, Switzerland
| | - Wenxin Li
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai200032, China
| | - Nicholas Favalli
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zurich), Zurich8093, Switzerland
| | - Gabriele Bassi
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zurich), Zurich8093, Switzerland
| | - Su Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA92037
| | - Dehua Yang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai201203, China
| | - Peter K. Vogt
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA92037
| | - Ming-Wei Wang
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai200032, China
- Research Center for Deepsea Bioresources, Sanya572025, China
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo113-0033, Japan
- School of Pharmacy, Hainan Medical College, Haikou570228, China
| |
Collapse
|
8
|
Harris NJ, Jenkins ML, Nam SE, Rathinaswamy MK, Parson MA, Ranga-Prasad H, Dalwadi U, Moeller BE, Sheekey E, Hansen SD, Yip CK, Burke JE. Allosteric activation or inhibition of PI3Kγ mediated through conformational changes in the p110γ helical domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536585. [PMID: 37090531 PMCID: PMC10120615 DOI: 10.1101/2023.04.12.536585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
PI3Kγ is a critical immune signaling enzyme activated downstream of diverse cell surface molecules, including Ras, PKCβ activated by the IgE receptor, and Gβγ subunits released from activated GPCRs. PI3Kγ can form two distinct complexes, with the p110γ catalytic subunit binding to either a p101 or p84 regulatory subunit, with these complexes being differentially activated by upstream stimuli. Here using a combination of Cryo electron microscopy, HDX-MS, and biochemical assays we have identified novel roles of the helical domain of p110γ in regulating lipid kinase activity of distinct PI3Kγ complexes. We defined the molecular basis for how an allosteric inhibitory nanobody potently inhibits kinase activity through rigidifying the helical domain and regulatory motif of the kinase domain. The nanobody did not block either p110γ membrane recruitment or Ras/Gβγ binding, but instead decreased ATP turnover. We also identified that p110γ can be activated by dual PKCβ helical domain phosphorylation leading to partial unfolding of an N-terminal region of the helical domain. PKCβ phosphorylation is selective for p110γ-p84 compared to p110γ-p101, driven by differential dynamics of the helical domain of these different complexes. Nanobody binding prevented PKCβ mediated phosphorylation. Overall, this works shows an unexpected allosteric regulatory role of the helical domain of p110γ that is distinct between p110γ-p84 and p110γ-p101, and reveals how this can be modulated by either phosphorylation or allosteric inhibitory binding partners. This opens possibilities of future allosteric inhibitor development for therapeutic intervention.
Collapse
|
9
|
Sivakumar S, Jin DX, Rathod R, Ross J, Cantley LC, Scaltriti M, Chen JW, Hutchinson KE, Wilson TR, Sokol ES, Vasan N. Genetic Heterogeneity and Tissue-specific Patterns of Tumors with Multiple PIK3CA Mutations. Clin Cancer Res 2023; 29:1125-1136. [PMID: 36595567 PMCID: PMC10011881 DOI: 10.1158/1078-0432.ccr-22-2270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/02/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023]
Abstract
PURPOSE To comprehensively characterize tissue-specific and molecular subclasses of multiple PIK3CA (multi-PIK3CA) mutations and assess their impact on potential therapeutic outcomes. EXPERIMENTAL DESIGN We profiled a pan-cancer cohort comprised of 352,392 samples across 66 tumor types using a targeted hybrid capture-based next-generation sequencing panel covering at least 324 cancer-related genes. Molecularly defined subgroups, allelic configuration, clonality, and mutational signatures were identified and tested for association with PI3K inhibitor therapeutic response. RESULTS Multi-PIK3CA mutations are found in 11% of all PIK3CA-mutant tumors, including 9% of low tumor mutational burden (TMB) PIK3CA-mutant tumors, and are enriched in breast and gynecologic cancers. Multi-PIK3CA mutations are frequently clonal and in cis on the same allele and occur at characteristic positions across tumor types. These mutations tend to be mutually exclusive of mutations in other driver genes, and of genes in the PI3K pathway. Among PIK3CA-mutant tumors with a high TMB, 18% are multi-PIK3CA mutant and often harbor an apolipoprotein B mRNA-editing enzyme, catalytic polypeptide (APOBEC) mutational signature. Despite large differences in specific allele combinations comprising multi-PIK3CA mutant tumors, especially across cancer types, patients with different classes of multi-PIK3CA mutant estrogen receptor-positive, HER2-negative breast cancers respond similarly to PI3K inhibition. CONCLUSIONS Our pan-tumor study provides biological insights into the genetic heterogeneity and tissue specificities of multi-PIK3CA mutations, with potential clinical utility to guide PI3K inhibition strategies.
Collapse
Affiliation(s)
| | | | - Ruchita Rathod
- Department of Medicine, Division of Hematology/Oncology, Columbia University Irving Medical Center, New York, New York
| | - Jeffrey Ross
- Foundation Medicine, Cambridge, Massachusetts.,Departments of Pathology and Urology, Upstate Medical University, Syracuse, New York
| | | | | | - Jessica W Chen
- Oncology Biomarker Development, Genentech, South San Francisco, California
| | | | - Timothy R Wilson
- Oncology Biomarker Development, Genentech, South San Francisco, California
| | | | - Neil Vasan
- Department of Medicine, Division of Hematology/Oncology, Columbia University Irving Medical Center, New York, New York.,Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York
| |
Collapse
|