title: CoCl2, a mimic of hypoxia, induces formation of polyploid giant cells with stem characteristics in colon cancer.
abstract: The induction of polyploidy is considered the reproductive end of cells, but there is evidence that polyploid giant cancer cells (PGCCs) contribute to cell repopulation during tumor relapse. However, the role of these cells in the development, progression and response to therapy in colon cancer remains undefined. Therefore, the main objective of this study was to investigate the generation of PGCCs in colon cancer cells and identify mechanisms of formation. Treatment of HCT-116 and Caco-2 colon cancer cells with the hypoxia mimic CoCl2 induced the formation of cells with larger cell and nuclear size (PGCCs), while the cells with normal morphology were selectively eliminated. Cytometric analysis showed that CoCl2 treatment induced G2 cell cycle arrest and the generation of a polyploid cell subpopulation with increased cellular DNA content. Polyploidy of hypoxia-induced PGCCs was confirmed by FISH analysis. Furthermore, CoCl2 treatment effectively induced the stabilization of HIF-1α, the differential expression of a truncated form of p53 (p47) and decreased levels of cyclin D1, indicating molecular mechanisms associated with cell cycle arrest at G2. Generation of PGCCs also contributed to expansion of a cell subpopulation with cancer stem cells (CSCs) characteristics, as indicated by colonosphere formation assays, and enhanced chemoresistance to 5-fluorouracil and oxaliplatin. In conclusion, the pharmacological induction of hypoxia in colon cancer cells causes the formation of PGCCs, the expansion of a cell subpopulation with CSC characteristics and chemoresistance. The molecular mechanisms involved, including the stabilization of HIF-1 α, the involvement of p53/p47 isoform and cell cycle arrest at G2, suggest novel targets to prevent tumor relapse and treatment failure in colon cancer.
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Lopez-Sánchez
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Carla
authors.initials: C
authors.lastname: Jimenez
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Araceli
authors.initials: A
authors.lastname: Valverde
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Hernandez
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Jon
authors.initials: J
authors.lastname: Peñarando
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martinez
authors.affiliation: Research Unit, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: Chary
authors.initials: C
authors.lastname: Lopez-Pedrera
authors.affiliation: Research Unit, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Muñoz-Castañeda
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Juan R
authors.initials: JR
authors.lastname: De la Haba-Rodríguez
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Aranda
authors.affiliation: Oncology Department, Maimonides Institute of Biomedical Research (IMIBIC), Reina Sofía Hospital, University of Córdoba, Córdoba, Spain; Spanish Cancer Network (RTICC), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rodriguez-Ariza
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000473:pathology*; D019938:Cyclin D1 / Q000378:metabolism; D004273:DNA, Neoplasm / Q000032:analysis; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000494:pharmacology; D016195:G2 Phase / Q000187:drug effects; D015726:Giant Cells / Q000187:drug effects* / Q000648:ultrastructure; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D009363:Neoplasm Proteins / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D009944:Organoplatinum Compounds / Q000494:pharmacology; D000077150:Oxaliplatin; D011123:Polyploidy; D020033:Protein Isoforms / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism
chemical_list: C530104:CCND1 protein, human; D004273:DNA, Neoplasm; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D009944:Organoplatinum Compounds; D020033:Protein Isoforms; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D000077150:Oxaliplatin; D019938:Cyclin D1; D003035:Cobalt; C018021:cobaltous chloride; D005472:Fluorouracil