title: KCa3.1 inhibition switches the phenotype of glioma-infiltrating microglia/macrophages.
abstract: Among the strategies adopted by glioma to successfully invade the brain parenchyma is turning the infiltrating microglia/macrophages (M/MΦ) into allies, by shifting them toward an anti-inflammatory, pro-tumor phenotype. Both glioma and infiltrating M/MΦ cells express the Ca(2+)-activated K(+) channel (KCa3.1), and the inhibition of KCa3.1 activity on glioma cells reduces tumor infiltration in the healthy brain parenchyma. We wondered whether KCa3.1 inhibition could prevent the acquisition of a pro-tumor phenotype by M/MΦ cells, thus contributing to reduce glioma development. With this aim, we studied microglia cultured in glioma-conditioned medium or treated with IL-4, as well as M/MΦ cells acutely isolated from glioma-bearing mice and from human glioma biopsies. Under these different conditions, M/MΦ were always polarized toward an anti-inflammatory state, and preventing KCa3.1 activation by 1-[(2-Chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), we observed a switch toward a pro-inflammatory, antitumor phenotype. We identified FAK and PI3K/AKT as the molecular mechanisms involved in this phenotype switch, activated in sequence after KCa3.1. Anti-inflammatory M/MΦ have higher expression levels of KCa3.1 mRNA (kcnn4) that are reduced by KCa3.1 inhibition. In line with these findings, TRAM-34 treatment, in vivo, significantly reduced the size of tumors in glioma-bearing mice. Our data indicate that KCa3.1 channels are involved in the inhibitory effects exerted by the glioma microenvironment on infiltrating M/MΦ, suggesting a possible role as therapeutic targets in glioma.
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Grimaldi
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.|IRCCS Neuromed, Via Atinense 18, Pozzilli 86077, Italy.
authors.forename: G
authors.initials: G
authors.lastname: D'Alessandro
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.
authors.forename: M T
authors.initials: MT
authors.lastname: Golia
authors.affiliation: Department of Pharmacology, University of California, 451 Health Sciences Drive, GBSF3502, Davis, CA 95616, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Grössinger
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.|Center for Life Nanoscience Istituto Italiano di Tecnologia@Sapienza, Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Di Angelantonio
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.|IRCCS Neuromed, Via Atinense 18, Pozzilli 86077, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Ragozzino
authors.affiliation: Department of Neurology and Psychiatry, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Santoro
authors.affiliation: IRCCS Neuromed, Via Atinense 18, Pozzilli 86077, Italy.|Department of Neurology and Psychiatry, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Esposito
authors.affiliation: Department of Pharmacology, University of California, 451 Health Sciences Drive, GBSF3502, Davis, CA 95616, USA.
authors.forename: H
authors.initials: H
authors.lastname: Wulff
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.|IRCCS Neuromed, Via Atinense 18, Pozzilli 86077, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Catalano
authors.affiliation: IRCCS Neuromed, Via Atinense 18, Pozzilli 86077, Italy.|Pasteur Institute-Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Moro 5, Rome 00185, Italy.
authors.forename: C
authors.identifier: http://orcid.org/0000-0001-7504-8197
authors.initials: C
authors.lastname: Limatola
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000166:cytology / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D002867:Chromones; D051417:Focal Adhesion Kinase 1; D015847:Interleukin-4; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011720:Pyrazoles; D012333:RNA, Messenger; C496925:Kcnn4 protein, mouse; C411671:TRAM 34; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C496051:Ptk2 protein, mouse