Background: Due to the poor prognosis of patients suffering malignant brain tumors such as glioblastoma multiforme (GBM), the search for new therapeutic strategies with more efficacy and higher survival rate is of utmost urgency. Growing evidence suggests that alterations in autophagy and metabolism critically contribute to the pathogenesis and progression of GBM. In this context, microRNAs are known to regulate autophagy and associated cellular functions, which point them as promising therapeutic candidates. We previously established the role of miR-7 in regulating relevant metabolic pathways related to insulin signaling and cholesterol homeostasis.
Methods: Bioinformatics analysis was performed to identify miR-7 target genes potentially involved in the regulation of metabolism and cellular processes related to GBM. Ectopic expression of miR-7 was assessed to investigate its role in macroautophagy and energy metabolism. In vivo, miR-7 levels were restored in a mouse GBM xenograft model to
evaluate its potential therapeutic effect in already established tumors. Additional mechanistic approaches, including transcriptomics, bioinformatics, and histopathological analyses, indicate that miR-7 modifies the tumor phenotype by altering key genes involved in extracellular matrix (ECM) remodeling in vivo.
Results: Herein, we unveiled new conceptual and functional pathophysiological avenues in GBM, with potential therapeutic implications, by demonstrating a novel dual role of miR-7 on the regulation of metabolism, through the impairment of the mitochondrial function and glycolysis, and autophagy, by inducing the initiation process through
the regulation of PI3K/AKT/mTORC1 signaling, while blocking later stages via posttranscriptional inhibition of two key SNARE proteins, STX17 and SNAP29. Furthermore, in vivo studies using a preclinical model showed that miR-7 overexpression in already established GBM tumors promotes a significant inhibition of tumor size and progression