Therapeutic delivery of microRNAs discovered to target deregulated glioblastoma pathways inhibits tumor growth in mice

Glioblastoma is a fatal primary malignant brain tumor, with an average survival of 15 months despite surgical resection, chemotherapy, and radiation therapy. Due to the concurrent deregulation of numerous genes in glioblastoma, molecular monotherapies have not improved clinical outcomes. Evidence suggests that targeting multiple deregulated molecules is essential for better therapies; however, this is limited by the lack of suitable drugs and increased toxicity of combination therapies. To address this, we hypothesized that miRNAs, small gene-regulatory RNAs that suppress mRNA, could simultaneously inhibit multiple deregulated genes in glioblastoma and be used for more effective therapies. We identified regulatory miRNAs — those that target several deregulated genes in glioblastoma — using a combination of PAR-CLIP screening, TCGA data analyses, and an algorithm to rank target importance and miRNA therapeutic potential. We selected 2 tumor-suppressive miRNAs, miR-340 and miR-382, and 1 oncogenic miRNA, miR-17, and showed that they targeted critical glioblastoma pathways and altered cell growth, survival, invasion, and in vivo tumor growth. We developed and successfully applied a miRNA therapeutic delivery approach using brain-penetrating nanoparticles combined with MRI-guided focused ultrasound and microbubbles, to inhibit established tumor growth and extend animal survival. This strategy offers a promising approach for translating miRNA-based therapies into clinical trials for glioblastoma and other cancers.