title: Acquired resistance to metformin in breast cancer cells triggers transcriptome reprogramming toward a degradome-related metastatic stem-like profile.
abstract: Therapeutic interventions based on metabolic inhibitor-based therapies are expected to be less prone to acquired resistance. However, there has not been any study assessing the possibility that the targeting of the tumor cell metabolism may result in unforeseeable resistance. We recently established a pre-clinical model of estrogen-dependent MCF-7 breast cancer cells that were chronically adapted to grow (> 10 months) in the presence of graded, millimolar concentrations of the anti-diabetic biguanide metformin, an AMPK agonist/mTOR inhibitor that has been evaluated in multiple in vitro and in vivo cancer studies and is now being tested in clinical trials. To assess what impact the phenomenon of resistance might have on the metformin-like "dirty" drugs that are able to simultaneously hit several metabolic pathways, we employed the ingenuity pathway analysis (IPA) software to functionally interpret the data from Agilent whole-human genome arrays in the context of biological processes, networks, and pathways. Our findings establish, for the first time, that a "global" targeting of metabolic reprogramming using metformin certainly imposes a great selective pressure for the emergence of new breast cancer cellular states. Intriguingly, acquired resistance to metformin appears to trigger a transcriptome reprogramming toward a metastatic stem-like profile, as many genes encoding the components of the degradome (KLK11, CTSF, FREM1, BACE-2, CASP, TMPRSS4, MMP16, HTRA1), cancer cell migration and invasion factors (TP63, WISP2, GAS3, DKK1, BCAR3, PABPC1, MUC1, SPARCL1, SEMA3B, SEMA6A), stem cell markers (DCLK1, FAK), and key pro-metastatic lipases (MAGL and Cpla2) were included in the signature. Because this convergent activation of pathways underlying tumor microenvironment interactions occurred in low-proliferative cancer cells exhibiting a notable downregulation of the G 2/M DNA damage checkpoint regulators that maintain genome stability (CCNB1, CCNB2, CDC20, CDC25C, AURKA, AURKB, BUB1, CENP-A, CENP-M) and pro-autophagic features (i.e., TRAIL upregulation and BCL-2 downregulation), it appears that the unique mechanism of acquired resistance to metformin has opposing roles in growth and metastatic dissemination. While refractoriness to metformin limits breast cancer cell growth, likely due to aberrant mitotic/cytokinetic machinery and accelerated autophagy, it notably increases the potential of metastatic dissemination by amplifying the number of pro-migratory and stemness inputs via the activation of a significant number of proteases and EMT regulators. Future studies should elucidate whether our findings using supra-physiological concentrations of metformin mechanistically mimic the ultimate processes that could paradoxically occur in a polyploid, senescent-autophagic scenario triggered by the chronic metabolic stresses that occur during cancer development and after treatment with cancer drugs.
authors.affiliation: Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain; Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Oliveras-Ferraros
authors.affiliation: Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain; Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vazquez-Martin
authors.affiliation: Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain; Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Cuyàs
authors.affiliation: Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain; Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain.
authors.forename: Bruna
authors.initials: B
authors.lastname: Corominas-Faja
authors.affiliation: Unitat de Recerca Biomèdica; Hospital Universitari Sant Joan and Hospital Universitari Joan XXIII; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Rodríguez-Gallego
authors.affiliation: Unitat de Recerca Biomèdica; Hospital Universitari Sant Joan and Hospital Universitari Joan XXIII; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Fernández-Arroyo
authors.affiliation: Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain; Unit of Clinical Research; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Martin-Castillo
authors.affiliation: Unitat de Recerca Biomèdica; Hospital Universitari Sant Joan and Hospital Universitari Joan XXIII; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Joven
authors.affiliation: Metabolism & Cancer Group; Translational Research Laboratory; Catalan Institute of Oncology-Girona (ICO-Girona); Girona, Spain; Molecular Oncology; Girona Biomedical Research Institute (IDIBGI); Girona, Spain.
authors.forename: Javier A
authors.initials: JA
authors.lastname: Menendez
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D020869:Gene Expression Profiling; D006801:Humans; D061986:MCF-7 Cells; D008687:Metformin / Q000494:pharmacology*; D009362:Neoplasm Metastasis; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D059467:Transcriptome
chemical_list: D000970:Antineoplastic Agents; D008687:Metformin; D055372:AMP-Activated Protein Kinases
keywords: AMPK; breast cancer; degradome; metabolism; metastasis; metformin