Engineering a Biodegradable Nanocarrier for Enhancing the Response of T98G Cells to Temozolomide.

Temozolomide (TMZ), the most common DNA alkylating agent, is predominantly mediated by O 6 -methylguanine DNA lesions for the treatment of glioblastoma (GBM). When O 6 -methylguanine-DNA methyltransferase (MGMT) is present, TMZ-induced O 6 -methylguanine lesions are repaired, resulting in the emergence of resistance to chemotherapy. Herein, we attempted to enhance the response of T98G cells to TMZ by gene silencing of MGMT. In this work, we developed transition metal manganese (Mn)-doped mesoporous silica nanoparticles (MSNs) as a carrier system for the co-delivery of TMZ and 10-23 DNAzyme, and realized gene silencing to enhance the TMZ sensitivity in T98G cells. The intelligent theranostic platform based on manganese-doped mesoporous silica nanoparticles (Mn-MSNs) can be decomposed and release chemotherapy drugs under acidic pH and reducing conditions. Meanwhile, the produced Mn 2+ could act as a cofactor of 10-23 DNAzyme to effectively cleave MGMT mRNA, knock down MGMT protein, and sensitize T98G cells to TMZ-induced apoptosis. By co-delivering TMZ and 10-23 DNAzyme employing Mn-MSNs, the concentrations of TMZ that needed to inhibit cell growth by 50% (IC 50 values) decreased (by more than 3.8-fold) compared with free TMZ. This work shows that the designed platform holds great promise for advancing the treatment of drug-resistant cancer.