title: Sensitivity to PRIMA-1MET is associated with decreased MGMT in human glioblastoma cells and glioblastoma stem cells irrespective of p53 status.
abstract: Alterations of the TP53 tumor suppressor gene occur in ~30% of primary glioblastoma (GBM) with a high frequency of missense mutations associated with the acquisition of oncogenic "gain-of-function" (GOF) mutant (mut)p53 activities. PRIMA-1MET/APR-246, emerged as a promising compound to rescue wild-type (wt)p53 function in different cancer types. Previous studies suggested the role of wtp53 in the negative regulation of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT), a major determinant in resistance to therapy in GBM treatment. The potential role of MGMT in expression of p53 and the efficacy of PRIMA-1MET with respect to TP53 status and expression of MGMT in GBM remain unknown. We investigated response to PRIMA-1MET of wtp53/MGMT-negative (U87MG, A172), mutp53/MGMT-positive U138, LN-18, T98/Empty vector (T98/EV) and its isogenic MGMT/shRNA gene knockdown counterpart (T98/shRNA). We show that MGMT silencing decreased expression of mutp53/GOF in T98/shRNA. PRIMA-1MET further cleared T98/shRNA cells of mutp53, decreased proliferation and clonogenic potential, abrogated the G2 checkpoint control, increased susceptibility to apoptotic cell death, expression of GADD45A and sustained expression of phosphorylated Erk1/2. PRIMA-1MET increased expression of p21 protein in U87MG and A172 and promoted senescence in U87MG cell line. Importantly, PRIMA-1MET decreased relative cell numbers, disrupted the structure of neurospheres of patient-derived GBM stem cells (GSCs) and enabled activation of wtp53 with decreased expression of MGMT in MGMT-positive GSCs or decreased expression of mutp53. Our findings highlight the cell-context dependent effects of PRIMA-1MET irrespective of p53 status and suggest the role of MGMT as a potential molecular target of PRIMA-1MET in MGMT-positive GSCs.
authors.affiliation: Division of Experimental Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Mariia
authors.initials: M
authors.lastname: Patyka
authors.affiliation: Division of Experimental Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Sharifi
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, The Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Petrecca
authors.affiliation: Department of Urologic Oncology Research, McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Jose
authors.initials: J
authors.lastname: Mansure
authors.affiliation: Department of Medicine, Division of Experimental Medicine, McGill University, The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Jean-Claude
authors.affiliation: Department of Oncology, Division of Radiation Oncology, McGill University, Cancer Research Program, The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Siham
authors.initials: S
authors.lastname: Sabri
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015254:DNA Modification Methylases / Q000235:genetics* / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D009154:Mutation; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011812:Quinuclidines / Q000494:pharmacology*; D034622:RNA Interference; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D018797:Cell Cycle Proteins; D015254:DNA Modification Methylases; D045643:DNA Repair Enzymes; D048049:Extracellular Signal-Regulated MAP Kinases; D009687:Nuclear Proteins; D011812:Quinuclidines; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C439070:GADD45A protein, human; D000097642:GADD45 Proteins; C515491:MGMT protein, human; C533410:eprenetapopt
keywords: MGMT; PRIMA-1MET/APR-246; glioblastoma; glioblastoma stem cells; p53 mutation