title: Development of resistance to antiglioma agents in rat C6 cells caused collateral sensitivity to doxorubicin.
abstract: Chemoresistance is a severe limitation to glioblastoma (GBM) therapy and there is a strong need to understand the underlying mechanisms that determine its response to different chemotherapeutics. Therefore, we induced resistance in C6 rat glioma cell line, which considerably resembles the characteristics of human GBM. The resistant phenotype was developed by 3-bis (2-chloroethyl)-1-nitrosourea (BCNU), one of the most commonly used therapeutic drug in the course of GBM treatment. After confirmation of the cross-resistance to cisplatin (CPt) and temozolomide (TMZ) in newly established RC6 cell line, we examined cell death induction and DNA damage by these drugs. Resistance to apoptosis and deficiency in forming DNA double-strand breaks was followed by significant decrease in the mRNA expression of pro-apoptotic and anti-apoptotic genes. The development of drug resistance was associated with significant increase in reactive oxygen species (ROS) and decrease in oxidized to reduced gluthatione ratio in RC6 cell line indicating a reduced level of oxidative stress. The mRNA expression levels of manganese superoxid dismutase (MnSOD), inducible nitric oxide synthase (iNOS) and gluthatione peroxidase (GPx) were increased while hypoxia-inducible factor 1-α (HIF-1α) was decreased in RC6 compared to C6 cells. This was in line with obtained changes in ROS content and increased antioxidative capacity of RC6 cells. Importantly, RC6 cells demonstrated collateral sensitivity to doxorubicin (DOX). The analysis of this phenomenon revealed increased accumulation of DOX in RC6 cells due to their adaptation to high ROS content and acidification of cytoplasm. In conclusion, newly established RC6 rat glioma cell line could be used as a starting material for the development of allogenic animal model and preclinical evaluation of new antiglioma agents. Collateral sensitivity to DOX obtained after BCNU treatment may prompt new studies aimed to find efficient delivery of DOX to the glioma site in brain.
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Sonja
authors.initials: S
authors.lastname: Stojković
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Ana
authors.initials: A
authors.lastname: Podolski-Renić
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Dinić
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Tijana
authors.initials: T
authors.lastname: Stanković
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Jasna
authors.initials: J
authors.lastname: Banković
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hadžić
authors.affiliation: Faculty of Medicine, University of Belgrade, Doktora Subotića 8, Belgrade, Serbia.
authors.forename: Verica
authors.initials: V
authors.lastname: Paunović
authors.affiliation: Faculty of Medicine, University of Belgrade, Doktora Subotića 8, Belgrade, Serbia.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Isaković
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia.
authors.forename: Nikola
authors.initials: N
authors.lastname: Tanić
authors.affiliation: Institute for Biological Research "Siniša Stanković", University of Belgrade, Despota Stefana 142, 11060 Belgrade, Serbia. Electronic address: camala@ibiss.bg.ac.rs.
authors.forename: Milica
authors.initials: M
authors.lastname: Pešić
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002330:Carmustine / Q000494:pharmacology*; D004249:DNA Damage; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D005910:Glioma; D020128:Inhibitory Concentration 50; D018384:Oxidative Stress; D051381:Rats; D000077204:Temozolomide
chemical_list: D000903:Antibiotics, Antineoplastic; D018906:Antineoplastic Agents, Alkylating; D051017:Apoptosis Regulatory Proteins; D003606:Dacarbazine; D004317:Doxorubicin; D002330:Carmustine; D000077204:Temozolomide
keywords: Antioxidant capacity; Carmustine; Collateral sensitivity; Doxorubicin; Drug resistance; Glioma