Self-assembling nanoparticles for delivery of miR-603 and miR-221 in glioblastoma as a new strategy to overcome resistance to temozolomide

Glioblastoma (GBM) is a highly aggressive brain cancer with poor clinical outcome. Unfortunately, chemotherapy with temozolomide (TMZ) has a limited efficacy due to resistance mainly attributed to O6-methylguanine methyl transferase (MGMT) activity. Recently, miR-603 and miR-221 have been identified to target MGMT, thus improving the efficacy of temozolomide (TMZ) in the treatment of GBM. Previously, self-assembling nanoparticles (SANPs) have been proposed to deliver miRNAs into the brain. Here, SANP co-encapsulating miRNA-603 (miR-603) and miRNA-221 (miR-221) have been developed to enhance the efficacy of TMZ in the treatment of GBM by preventing the occurrence of chemoresistance. Preliminarily, SANPs encapsulating miRNAs were optimized in terms of lipid composition to assure physical stability and no hemolytic activity. Subsequently, SANPs with the lowest cytotoxicity and excellent internalization efficiency of miRNAs were selected through MTT assay and real-time PCR, respectively. To evaluate a potential synergistic effect between TMZ and miRNAs, MTT and clonogenic assays were performed. In our biological model, miRNA delivery via SANPs in combination with TMZ treatment strongly reduced cell viability and tumorigenic potential. Finally, in vivo assays were carried out on orthotopic xenograft mouse models. The treatment with SANPs encapsulating both miRNAs in combination with TMZ greatly decreased tumour growth, and even more significantly increased animal survival. In conclusion, this strategy provides the rationale for the development of new therapeutic approaches based on SANP technology to deliver miRNAs that play a key role in suppressing tumour. [Display omitted] •Glioblastoma (GBM) treatment with temozolomide (TMZ) has a limited efficacy due to resistance mainly attributed to O6-methylguanine methyl transferase (MGMT) activity.•miRNAs, actually miR603 and miR221, control MGMT activity.•Self-assembling nanoparticles (SANP) with optimal physical-chemical and biological properties have been designed for efficient delivery of miR603 and miR221 into glioblastoma cells.•GBM treatment with SANP encapsulating both miR603 and 221, combined with TMZ, resulted in decreased tumor growth and increased mice survival, without occurrence of chemoresistance.