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Gliomas are the most common primary brain tumors. To date, therapies do not allow curing patients, and glioblastomas (GBMs) are associated with remarkably poor prognosis. This situation is at least partly due to intrinsic or acquired resistance to treatment, especially to chemotherapy. In 2005, temozolomide (TMZ) has become the first chemotherapeutic drug validated for GBM. Nevertheless TMZ efficacy depends on Mgmt status. While the methylation of Mgmt promoter was considered so far as a prognostic marker, its targeting is becoming an effective therapeutic opportunity. Thus, arrival of both TMZ and Mgmt illustrated that considerable progress can still be realized by optimizing adjuvant chemotherapy. A part of this progress could be accomplished in the future by overcoming residual resistance. The aim of the present study was to investigate the involvement of a set of other DNA-repair genes in glioma resistance to temozolomide. We focused on DNA-repair genes located in the commonly deleted chromosomal region in oligodendroglioma (1p/19q) highly correlated with patient response to chemotherapy. We measured effects of inhibition of ten DNA-repair genes expression using siRNAs on astrocytoma cell response to cisplatin (CDDP) and TMZ. SiRNAs targeting ercc1, ercc2, mutyh, and pnkp significantly sensitized cells to chemotherapy, increasing cell death by up to 25%. In vivo we observed a decrease of subcutaneous glioma tumor growth after injection of siRNA in conjunction with absorption of TMZ. We demonstrated in this pre-clinical study that targeting of DNA-repair genes such as Ercc1 could be used as an adjuvant chemosensitization treatment, similarly to Mgmt inhibition.

Original publication

DOI

10.18632/oncotarget.4909

Type

Journal article

Journal

Oncotarget

Publication Date

06/10/2015

Volume

6

Pages

29456 - 29468

Keywords

DNA-repair, Temozolomide (TMZ), chemoresistance, glioma, siRNA, Animals, Antineoplastic Agents, Alkylating, Brain Neoplasms, Cell Death, Cell Line, Tumor, Cell Proliferation, Cisplatin, DNA Modification Methylases, DNA Repair, DNA Repair Enzymes, DNA-Binding Proteins, Dacarbazine, Drug Resistance, Neoplasm, Endonucleases, Gene Expression Regulation, Enzymologic, Gene Expression Regulation, Neoplastic, Glioma, Humans, Mice, Nude, RNA Interference, RNAi Therapeutics, Time Factors, Transfection, Tumor Burden, Tumor Suppressor Proteins, Xenograft Model Antitumor Assays