title: AMPK activators inhibit the proliferation of human melanomas bearing the activated MAPK pathway.
abstract: Raf/MEK/ERK signaling can inhibit the liver kinase B1-AMP-activated protein kinase (LKB1-AMPK) pathway, thus rendering melanoma cells resistant to energy stress conditions. We evaluated whether pharmacological reactivation of the AMPK function could exert antitumor effects on melanoma cells bearing this pathway constitutively active because of a mutation in NRAS or BRAF genes. Nine melanoma cell lines were treated with the AMPK activators 5-aminoimidazole-4-carboxamide-ribonucleoside (AICAR) and phenformin. The activation of AMPK enzymatic activity, phosphorylation of AMPK and acetyl-CoA carboxylase kinase, in-vitro proliferation, cell cycle, and in-vivo growth of xenografts in nude mice were evaluated. AICAR and phenformin promoted phosphorylation and enzymatic activity of AMPK, as well as phosphorylation of the AMPK downstream target acetyl-CoA carboxylase. Drug treatment of either BRAF-mutant or NRAS-mutant melanomas, at doses not inducing cell death, was accompanied by a dose-dependent decrease in melanoma cell proliferation because of cell cycle arrest in either the G0/G1 or the S phase, associated with an increased expression of the p21 cell cycle inhibitor. Melanomas isolated from subcutaneously implanted mice, 25 days from treatment with AICAR, showed increased staining of the senescence-associated marker β-galactosidase, high p21 expression, and evidence of necrosis. Altogether, these results indicate that pharmacological activators of AMPK-dependent pathways inhibit the cell growth of melanoma cells with active Raf/MEK/ERK signaling and provide a rationale for further investigation on their use in combination therapies.
authors.affiliation: Unit of Immunobiology of Human Tumors, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Petti
authors.forename: Claudia
authors.initials: C
authors.lastname: Vegetti
authors.forename: Alessandra
authors.initials: A
authors.lastname: Molla
authors.forename: Ilaria
authors.initials: I
authors.lastname: Bersani
authors.forename: Loredana
authors.initials: L
authors.lastname: Cleris
authors.forename: Kirsty J
authors.initials: KJ
authors.lastname: Mustard
authors.forename: Franca
authors.initials: F
authors.lastname: Formelli
authors.forename: Grahame D
authors.initials: GD
authors.lastname: Hardie
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Sensi
authors.forename: Andrea
authors.initials: A
authors.lastname: Anichini
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D020536:Enzyme Activators / Q000494:pharmacology*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D010629:Phenformin / Q000494:pharmacology; D010766:Phosphorylation; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics
chemical_list: D020536:Enzyme Activators; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D010629:Phenformin; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide