Background and Aim: Glioblastoma (GBM) is the most aggressive glioma which have poor prognosis. GBM patients die within a few months if they don’t treat. Temozolomide (TMZ) has been first line GBM treatment for over a decade, but benefit of this treatment is limited by MGMT (O6-methylguanine- DNA methyltransferase). epigenetic modification of MGMT promoter and enhancer can result in complete attenuation of MGMT expression and eventually sensitization of tumor cells to TMZ cytotoxic effects. In this study we used CRISPR-Cas system to inducing MGMT promoter and enhancer methylation. Methods: sgRNAs were designed for promotor and enhancer regions of the MGMT gene. sgRNAs were cloned into pdCas9- DNMT3A-PuroR (ANV)_v2 separately. recombinant vector which called Dn-sg was transfected into the T98g cell line. recombinant cells which express sgRNA and dCas-dnmt3a protein were selected using puromycin treatment. These cells were treated with TMZ and cell survival was estimated by MTT test. Results: Results were illustrated epigenetic modification of promotor and enhancer MGMT leading to sensitization of T98G cells to TMZ. Conclusion: MGMT expression suppression using CRISPR based chromatin remodeling can be a promising tool as new adjuvant therapy drug in treatment of glioblastoma.

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