ABSTRACT
Temozolomide (TMZ) is a chemotherapeutic used for the treatment of glioblastoma. The MGMT repair enzyme (O'-(6)-methyl guanine-DNA-methyltransferase) promoter methylation is a predictive biomarker to TMZ response; interferons (IFNs) type I can downregulate MGMT expression improving survival in patients with unmethylated MGMT promoter. HeberFERON is a co-formulation of IFNs type I and II with higher antiproliferative effect over glioblastoma cell lines than individual IFNs. We investigated the proliferative response of patient-derived glioblastoma cultures to HeberFERON and its combination with TMZ in relation to MGMT promoter methylation and the regulation of MGMT transcript after HeberFERON treatment. Eleven glioblastoma-derived cultures, molecularly classified according to TCGA and MGMT promoter methylation, were assayed for proliferation inhibition with HeberFERON at low doses (1-25 IU/mL) [alone or combined with TMZ] or at higher doses (50-200 IU/mL) using CellTiter-Glo Luminescent Cell Viability Assay (Promega). Eight cultures were further treated with 100 IU/mL of HeberFERON for 72 h, total RNA purified (Qiagen) and converted to cDNA (Superscript III kit, Invitrogen) as quantitative PCR templates. Changes of MGMT&P53 transcripts level were monitored. Response of cultures to HeberFERON is variable, dose-dependent and apparently independent from TCGA classification and MGMT methylation status, based on the eight Classical cultures data. When combining HeberFERON with TMZ there was an increase in cell death for cultures, 2/4 with methylated and 5/5 with unmethylated MGMT promoter. In two out five cultures with unmethylated MGMT status, we observed a decrease of MGMT gene levels and an increase in P53 encoding gene levels. HeberFERON and TMZ combination should be further assayed in glioblastoma, mainly for those with unmethylated MGMT promoter.
Subject(s)
Brain Neoplasms/genetics , DNA Methylation , DNA Modification Methylases/genetics , DNA Repair Enzymes/genetics , Glioblastoma/genetics , Interferon Type I/pharmacology , Interferon-gamma/pharmacology , Temozolomide/pharmacology , Tumor Suppressor Proteins/genetics , Antineoplastic Agents, Alkylating/pharmacology , Brain Neoplasms/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Resistance, Neoplasm , Drug Synergism , Glioblastoma/metabolism , Humans , Promoter Regions, Genetic , Tumor Cells, CulturedABSTRACT
BACKGROUND: Incidence of type 1 diabetes varies widely around the world, probably due to ethnic differences across populations among other factors. AIMS: To determine whether there is an association between disease and ancestry proportions; and to control disease-HLA associations for possible confounding by admixture or population stratification. SUBJECTS AND METHODS: 100 cases and 129 controls participated in the study. Ancestry informative markers, which have considerable differences in frequency between European, West African and Native American populations were used. Type 1 diabetes associated HLA susceptibility/protection alleles were ascertained by PCR using specific primers. Statistical analyses were conducted using STRUCTURE 2.1, ADMIXMAP 3.7, SPSS 16.0 and STRAT 1.0 packages. RESULTS: The results of logistic regression implemented in ADMIXMAP 3.7 indicated that European ancestry was associated with type 1 diabetes mellitus with an odds ratio of 5.7 corresponding to one unit change in European admixture proportion. Association was found between HLA alleles and disease, DQA1*0501, *0301 DQB1*0201 and DRB1*0301, *0401 being susceptibility alleles and DRB1*1501, DQA1*0102/3 and DQB1*0602 being protective alleles. CONCLUSIONS: We found an association between European ancestry and type 1 diabetes in our sample, indicating the contribution of ethnicity to incidence differences. Previously reported associations of HLA DR/DQ alleles with disease are confirmed for the admixed Cuban population.
