Su Hwan Park, Juheon Lee, Hye Jin Yun, Seok-Ho Kim, Jong-Ho Lee
{"title":"Metformin Suppresses Both PD-L1 Expression in Cancer Cells and Cancer-Induced PD-1 Expression in Immune Cells to Promote Antitumor Immunity.","authors":"Su Hwan Park, Juheon Lee, Hye Jin Yun, Seok-Ho Kim, Jong-Ho Lee","doi":"10.3343/alm.2023.0443","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>Metformin, a drug prescribed for patients with type 2 diabetes, has potential efficacy in enhancing antitumor immunity; however, the detailed underlying mechanisms remain to be elucidated. Therefore, we aimed to identify the inhibitory molecular mechanisms of metformin on programmed death ligand 1 (PD-L1) expression in cancer cells and programmed death 1 (PD-1) expression in immune cells.</p><p><strong>Methods: </strong>We employed a luciferase reporter assay, quantitative real-time PCR, immunoblotting analysis, immunoprecipitation and ubiquitylation assays, and a natural killer (NK) cell-mediated tumor cell cytotoxicity assay. A mouse xenograft tumor model was used to evaluate the effect of metformin on tumor growth, followed by flow-cytometric analysis using tumor-derived single-cell suspensions.</p><p><strong>Results: </strong>Metformin decreased AKT-mediated β-catenin S552 phosphorylation and subsequent β-catenin transactivation in an adenosine monophosphate-activated protein kinase (AMPK) activation-dependent manner, resulting in reduced <i>CD274</i> (encoding PD-L1) transcription in cancer cells. Tumor-derived soluble factors enhanced PD-1 protein stability in NK and T cells via dissociation of PD-1 from ubiquitin E3 ligases and reducing PD-1 polyubiquitylation. Metformin inhibited the tumor-derived soluble factor-reduced binding of PD-1 to E3 ligases and PD-1 polyubiquitylation, resulting in PD-1 protein downregulation in an AMPK activation-dependent manner. These inhibitory effects of metformin on both PD-L1 and PD-1 expression ameliorated cancer-reduced cytotoxic activity of immune cells <i>in vitro</i> and decreased tumor immune evasion and growth <i>in vivo</i>.</p><p><strong>Conclusions: </strong>Metformin blocks both PD-L1 and PD-1 within the tumor microenvironment. This study provided a mechanistic insight into the efficacy of metformin in improving immunotherapy in human cancer.</p>","PeriodicalId":8421,"journal":{"name":"Annals of Laboratory Medicine","volume":" ","pages":"426-436"},"PeriodicalIF":4.0000,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11169777/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annals of Laboratory Medicine","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.3343/alm.2023.0443","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/3/26 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"MEDICAL LABORATORY TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Metformin, a drug prescribed for patients with type 2 diabetes, has potential efficacy in enhancing antitumor immunity; however, the detailed underlying mechanisms remain to be elucidated. Therefore, we aimed to identify the inhibitory molecular mechanisms of metformin on programmed death ligand 1 (PD-L1) expression in cancer cells and programmed death 1 (PD-1) expression in immune cells.
Methods: We employed a luciferase reporter assay, quantitative real-time PCR, immunoblotting analysis, immunoprecipitation and ubiquitylation assays, and a natural killer (NK) cell-mediated tumor cell cytotoxicity assay. A mouse xenograft tumor model was used to evaluate the effect of metformin on tumor growth, followed by flow-cytometric analysis using tumor-derived single-cell suspensions.
Results: Metformin decreased AKT-mediated β-catenin S552 phosphorylation and subsequent β-catenin transactivation in an adenosine monophosphate-activated protein kinase (AMPK) activation-dependent manner, resulting in reduced CD274 (encoding PD-L1) transcription in cancer cells. Tumor-derived soluble factors enhanced PD-1 protein stability in NK and T cells via dissociation of PD-1 from ubiquitin E3 ligases and reducing PD-1 polyubiquitylation. Metformin inhibited the tumor-derived soluble factor-reduced binding of PD-1 to E3 ligases and PD-1 polyubiquitylation, resulting in PD-1 protein downregulation in an AMPK activation-dependent manner. These inhibitory effects of metformin on both PD-L1 and PD-1 expression ameliorated cancer-reduced cytotoxic activity of immune cells in vitro and decreased tumor immune evasion and growth in vivo.
Conclusions: Metformin blocks both PD-L1 and PD-1 within the tumor microenvironment. This study provided a mechanistic insight into the efficacy of metformin in improving immunotherapy in human cancer.
Suzanne Rybczynski, Taylor C Ryan, Holly C Wilcox, Kathryn Van Eck, Mary Cwik, Roma A Vasa, Robert L Findling, Keith Slifer, Daniel Kleiner, Paul H Lipkin
Shayla A. Sullivant MD (is Child and Adolescent Psychiatrist, Division of Developmental and Behavioral Health, Children's Mercy Kansas City, Kansas City, Missouri, and Associate Professor of Pediatrics, University of Missouri–Kansas City (UMKC) School of Medicine.), Debby Brookstein MSW, LCSW, LSCSW (is Senior Director of Social Work, Children's Mercy Kansas City.), Michelle Camerer LCSW, LMSW, LSCSW (is Social Work, Manager Children's Mercy Kansas City.), Joan Benson MSN, RN-BC, CPN (is Director, Clinical Informatics and Practice, Children's Mercy Kansas City.), Mark Connelly PhD (is Director of Research, Developmental and Behavioral Health, Children's Mercy Kansas City, and Professor of Pediatrics UMKC School of Medicine.), John Lantos MD (is Director, Bioethics Center, Children's Mercy Kansas City.), Karen Cox PhD, RN, FAAN (is President, Chamberlain University, Chicago, Illinois.), Kathy Goggin PhD (is Director, Division of Health Services and Outcomes Research, Children's Mercy Kansas City, and Professor, UMKC Schools of Medicine and Pharmacy)
期刊介绍:
Annals of Laboratory Medicine is the official journal of Korean Society for Laboratory Medicine. The journal title has been recently changed from the Korean Journal of Laboratory Medicine (ISSN, 1598-6535) from the January issue of 2012. The JCR 2017 Impact factor of Ann Lab Med was 1.916.