title: Metformin repositioning as antitumoral agent: selective antiproliferative effects in human glioblastoma stem cells, via inhibition of CLIC1-mediated ion current.
abstract: Epidemiological and preclinical studies propose that metformin, a first-line drug for type-2 diabetes, exerts direct antitumor activity. Although several clinical trials are ongoing, the molecular mechanisms of this effect are unknown. Here we show that chloride intracellular channel-1 (CLIC1) is a direct target of metformin in human glioblastoma cells. Metformin exposure induces antiproliferative effects in cancer stem cell-enriched cultures, isolated from three individual WHO grade IV human glioblastomas. These effects phenocopy metformin-mediated inhibition of a chloride current specifically dependent on CLIC1 functional activity. CLIC1 ion channel is preferentially active during the G1-S transition via transient membrane insertion. Metformin inhibition of CLIC1 activity induces G1 arrest of glioblastoma stem cells. This effect was time-dependent, and prolonged treatments caused antiproliferative effects also for low, clinically significant, metformin concentrations. Furthermore, substitution of Arg29 in the putative CLIC1 pore region impairs metformin modulation of channel activity. The lack of drugs affecting cancer stem cell viability is the main cause of therapy failure and tumor relapse. We identified CLIC1 not only as a modulator of cell cycle progression in human glioblastoma stem cells but also as the main target of metformin's antiproliferative activity, paving the way for novel and needed pharmacological approaches to glioblastoma treatment.
authors.affiliation: Dipartimento di Bioscienze, University of Milano, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Gritti
authors.affiliation: Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Würth
authors.affiliation: Dipartimento di Bioscienze, University of Milano, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Angelini
authors.affiliation: Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Barbieri
authors.affiliation: Dipartimento di Bioscienze, University of Milano, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Peretti
authors.affiliation: Dipartimento di Bioscienze, University of Milano, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Pizzi
authors.affiliation: Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pattarozzi
authors.affiliation: Laboratorio di Trasferimento Genico, IRCCS-AOU San Martino-IST, Genova, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Carra
authors.affiliation: Dipartimento di Ostetricia e Ginecologia, Ospedale Evangelico Internazionale, Genova, Italy.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Sirito
authors.affiliation: Laboratorio di Trasferimento Genico, IRCCS-AOU San Martino-IST, Genova, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Daga
authors.affiliation: School of Physics, University of New South Wales, Sydney, Australia.
authors.forename: Paul M G
authors.initials: PM
authors.lastname: Curmi
authors.affiliation: Dipartimento di Bioscienze, University of Milano, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Mazzanti
authors.affiliation: Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Italy.
authors.forename: Tullio
authors.initials: T
authors.lastname: Florio
mesh_terms: D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D016466:CHO Cells; D018118:Chloride Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003412:Cricetulus; D058492:Drug Repositioning; D005260:Female; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D008875:Middle Aged; D008958:Models, Molecular; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; C501966:CLIC1 protein, human; D018118:Chloride Channels; D007004:Hypoglycemic Agents; D008687:Metformin