title: Effect of lomeguatrib-temozolomide combination on MGMT promoter methylation and expression in primary glioblastoma tumor cells.
abstract: Temozolomide (TMZ) is commonly used in the treatment of glioblastoma (GBM). The MGMT repair enzyme (O (6)-methylguanine-DNA methyltransferase) is an important factor causing chemotherapeutic resistance. MGMT prevents the formation of toxic effects of alkyl adducts by removing them from the DNA. Therefore, MGMT inhibition is an interesting therapeutic approach to circumvent TMZ resistance. The aim of the study was to investigate the effect of the combination of lomeguatrib (an MGMT inactivator) with TMZ, on MGMT expression and methylation. Primary cell cultures were obtained from GBM tumor tissues. The sensitivity of primary GBM cell cultures and GBM cell lines to TMZ, and to the combination of TMZ and lomeguatrib, was determined by a cytotoxicity assay (MTT). MGMT and p53 expression, and MGMT methylation were investigated after drug application. In addition, the proportion of apoptotic cells and DNA fragmentation was analyzed. The combination of TMZ and lomeguatrib in primary GBM cell cultures and glioma cell lines decreased MGMT expression, increased p53 expression, and did not change MGMT methylation. Moreover, apoptosis was induced and DNA fragmentation was increased in cells. In addition, we also showed that lomeguatrib-TMZ combination did not have any effect on the cell cycle. Finally, we determined that the sensitivity of each primary GBM cells and glioma cell lines to the lomeguatrib-TMZ combination was different and significantly associated with the structure of MGMT methylation. Our study suggests that lomeguatrib can be used with TMZ for GBM treatment, although further clinical studies will be needed so as to determine the feasibility of this therapeutic approach.
authors.affiliation: Department of Medical Biology, Ankara University School of Medicine, Ankara, Turkey. mtaspinartr@gmail.com
authors.forename: Mehmet
authors.initials: M
authors.lastname: Taspinar
authors.forename: Seda
authors.initials: S
authors.lastname: Ilgaz
authors.forename: Mevci
authors.initials: M
authors.lastname: Ozdemir
authors.forename: Tulin
authors.initials: T
authors.lastname: Ozkan
authors.forename: Derya
authors.initials: D
authors.lastname: Oztuna
authors.forename: Hande
authors.initials: H
authors.lastname: Canpinar
authors.forename: Juan A
authors.initials: JA
authors.lastname: Rey
authors.forename: Asuman
authors.initials: A
authors.lastname: Sunguroğlu
authors.forename: Javier S
authors.initials: JS
authors.lastname: Castresana
authors.forename: Hasan Caglar
authors.initials: HC
authors.lastname: Ugur
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D020552:Comet Assay; D019175:DNA Methylation / Q000187:drug effects*; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005909:Glioblastoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D011687:Purines / Q000494:pharmacology*; D000077204:Temozolomide; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D018906:Antineoplastic Agents, Alkylating; D004273:DNA, Neoplasm; D011687:Purines; D025521:Tumor Suppressor Proteins; D003606:Dacarbazine; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes; C521206:lomeguatrib; D000077204:Temozolomide