title: Sulfasalazine intensifies temozolomide cytotoxicity in human glioblastoma cells.
abstract: Temozolomide (TMZ) is an alkylating agent used to treat glioblastoma. This tumor type synthesizes the antioxidant glutathione through system X c (-) , which is inhibited by sulfasalazine (SAS). We exposed A172 and T98G human glioblastoma cells to a presumably clinically relevant concentration of TMZ (25 µM) and/or 0.5 mM SAS for 1, 3, or 5 days and assessed cell viability. For both cell lines, TMZ alone did not alter viability at any time point, while the coadministration of TMZ and SAS significantly reduced cell viability after 5 days. The drug combination exerted a synergistic effect on A172 cells after 3 and 5 days. Therefore, this particular lineage was subjected to complementary analyses on the genetic (transcriptome) and functional (glutathione and proliferating cell nuclear antigen (PCNA) protein) levels. Cellular pathways containing differentially expressed genes related to the cell cycle were modified by TMZ alone. On the other hand, SAS regulated pathways associated with glutathione metabolism and synthesis, irrespective of TMZ. Moreover, SAS, but not TMZ, depleted the total glutathione level. Compared with the vehicle-treated cells, the level of PCNA protein was lower in cells treated with TMZ alone or in combination with SAS. In conclusion, our data showed that the association of TMZ and SAS is cytotoxic to T98G and A172 cells, thus providing useful insights for improving TMZ clinical efficacy through testing this novel drug combination. Moreover, the present study not only reports original information on differential gene expression in glioblastoma cells exposed to TMZ and/or SAS but also describes an antiproliferative effect of TMZ, which has not yet been observed in A172 cells.
authors.affiliation: Department of Anatomical Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: Raffaela Silvestre
authors.initials: RS
authors.lastname: Ignarro
authors.affiliation: Department of Anatomical Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Facchini
authors.affiliation: Department of Medical Genetics, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: André Schwambach
authors.initials: AS
authors.lastname: Vieira
authors.affiliation: Department of Clinical Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: Daniela Rodrigues
authors.initials: DR
authors.lastname: De Melo
authors.affiliation: Department of Medical Genetics, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: Iscia
authors.initials: I
authors.lastname: Lopes-Cendes
authors.affiliation: Department of Clinical Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil.
authors.forename: Roger Frigério
authors.initials: RF
authors.lastname: Castilho
authors.affiliation: Department of Anatomical Pathology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Av. Tessália Vieira De Camargo, 126, Campinas, SP, 13083-887, Brazil. fabio@fcm.unicamp.br.
authors.forename: Fabio
authors.initials: F
authors.lastname: Rogerio
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003603:Cytotoxins / Q000494:pharmacology*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D012460:Sulfasalazine / Q000494:pharmacology*; D000077204:Temozolomide
chemical_list: D003603:Cytotoxins; D012460:Sulfasalazine; D003606:Dacarbazine; D000077204:Temozolomide
keywords: Cell proliferation; Differential gene expression; Glioblastoma; Glutathione