miR-370-3p Is a Therapeutic Tool in Anti-glioblastoma Therapy but Is Not an Intratumoral or Cell-free Circulating Biomarker

In the last decade, microRNAs (miRs) have been described as biomarkers and therapeutic agents. Based on this finding, our aim here is to know if (1) miRNA-370-3p can be used as a biomarker associated with a favorable survival and if (2) miRNA-370-3p can be used as a therapeutic tool that increases the efficiency of standard anti-GBM treatment. A first approach using the data available on the “Prognostic miRNA Database” indicated that the expression level of miRNA-370-3p in GBM (T-miR-370-3p) is not associated with a prognosis value for survival. A second approach quantifying the expression level of cell-free circulating miRNA-370-3p (cfc-miR-370-3p) also indicated that cfc-miR-370-3p is not associated with a prognosis value for survival. To investigate whether miR-370-3p can be used in vivo to increase the anti-GBM effect of TMZ, we then used the model of LN18-induced GBMs in mice. Our data indicated that the miRNA-370-3p/TMZ treatment was two times more efficient than the TMZ treatment for decreasing the tumor volume. In addition, our study correlated the decrease of tumor volume induced by the miRNA-370-3p/TMZ treatment with the decrease in FOXM1 and MGMT (i.e., two targets of miR-370-3p). Our data thus support the idea that miR-370-3p could be used as therapeutic tool for anti-glioblastoma therapy, but not as a biomarker.