title: The histone demethylase KDM5A is a key factor for the resistance to temozolomide in glioblastoma.
abstract: Notwithstanding current multimodal treatment, including surgery, radiotherapy and chemotherapy with temozolomide (TMZ), median survival of glioblastoma (GBM) patients is about 14 months, due to the rapid emergence of cell clones resistant to treatment. Therefore, understanding the mechanisms underlying chemoresistance is mandatory to improve treatments' outcome. We generated TMZ resistant cells (TMZ-R) from a GBM cell line and from cancer stem cell-enriched cultures isolated from human GBMs. We demonstrated that TMZ resistance is partially reverted by "drug wash-out" suggesting the contribution of epigenetic mechanisms in drug resistance and supporting the possibility of TMZ rechallenge in GBM patients after prior drug exposure. The expression of histone lysine demethylase genes (KDMs) was increased in TMZ-R cells compared to parental cells, and TMZ resistance or restored sensitivity was mimicked by over-expressing or inactivating KDM5A. Methylation and expression of O6-methylguanine-DNA methyltransferase (MGMT) and drug efflux mechanisms were not altered in TMZ-R cells compared to parental TMZ sensitive cells. TMZ-R cells transiently acquired morphologic and molecular characteristics of differentiated tumor cells, features that were lost after drug wash-out. In conclusion, we demonstrated that treatment-induced TMZ resistance in GBM involves epigenetic mechanisms in a subset of slow-cycling and transiently partially differentiated cells that escape drug cytotoxicity, overcome G2 checkpoint and sustain clonal growth. We found that TMZ-R cells are sensitive to histone deacethylase inhibitors (HDACi) that synergize with TMZ. This strong synergism could be exploited to develop novel combined adjuvant therapies for this rapidly progressing and invariably lethal cancer.
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Banelli
authors.affiliation: b Laboratory of Regenerative Medicine; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Carra
authors.affiliation: c Section of Pharmacology ; Department of Internal Medicine and Center of Excellence for Biomedical Research (CEBR); University of Genova ; Genova , Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Barbieri
authors.affiliation: c Section of Pharmacology ; Department of Internal Medicine and Center of Excellence for Biomedical Research (CEBR); University of Genova ; Genova , Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Würth
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Parodi
authors.affiliation: c Section of Pharmacology ; Department of Internal Medicine and Center of Excellence for Biomedical Research (CEBR); University of Genova ; Genova , Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pattarozzi
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Carosio
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Forlani
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Allemanni
authors.affiliation: b Laboratory of Regenerative Medicine; IRCCS AOU San Martino - IST ; Genova , Italy.|d Department of Experimental Medicine (DIMES) ; University of Genova ; Genova , Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Marubbi
authors.affiliation: c Section of Pharmacology ; Department of Internal Medicine and Center of Excellence for Biomedical Research (CEBR); University of Genova ; Genova , Italy.
authors.forename: Tullio
authors.initials: T
authors.lastname: Florio
authors.affiliation: b Laboratory of Regenerative Medicine; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Daga
authors.affiliation: a Laboratory of Tumor Epigenetics; IRCCS AOU San Martino - IST ; Genova , Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Romani
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D004357:Drug Synergism; D044127:Epigenesis, Genetic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005838:Genotype; D005909:Glioblastoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D010641:Phenotype; D034622:RNA Interference; D056485:Retinoblastoma-Binding Protein 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000077204:Temozolomide; D013997:Time Factors; D014162:Transfection
chemical_list: D018906:Antineoplastic Agents, Alkylating; D056572:Histone Deacetylase Inhibitors; D003606:Dacarbazine; C070050:KDM5A protein, human; D056485:Retinoblastoma-Binding Protein 2; D000077204:Temozolomide
keywords: DNA methylation; KDM5A; cancer stem cells; epigenetic; glioblastoma; histone demethylase; temozolomide