MiR-132-3p boosts caveolae-mediated transcellular transport in glioma endothelial cells by targeting PTEN/PI3K/PKB/Src/Cav-1 signaling pathway

Abstract

Blood-brain tumor barrier (BTB) impedes the transportation of antitumor therapeutic drugs into brain tumors. Its mechanism is still unknown, but learning how to improve the BTB permeability is critical for drug intervention. Recently,microRNAs (miRNAs) have appeared as regulation factors of numerous biologic processes and therapeutic targets of diverse diseases. In this study,we have identified thatmiR-132-3p is an essentialmiRNA by increasing the transcellular transport through the BTB.We found that miR-132-3p expression was significantly up-regulated in glioma endothelial cells (GECs). Furthermore we showed that miR132-3p+ greatly induced the endocytosis of cholera toxin subunit B and FITC-bovine serumalbumin and up-regulated the expression of p-PKB, p-Src and Tyr14 phosphorylation of caveolin-1 (p-Cav-1), while phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression was markedly down-regulated in GECs. Our results identify PTEN as a direct and functional downstreamtarget ofmiR-132-3p, which is involved in the regulation of p-PKB, p-Src, and p-Cav-1. The inhibitors for PI3K and Src significantly reversed the increase of p-Cav-1 induced by miR-132-3p. Moreover, overexpression of PTENgreatly reducedthe endocytosis of cholera toxin subunitBand the up-regulation of p-Cav-1 induced by agomiR132-3p, suggesting that miR132-3p+ increases the endothelial permeability by inhibition of PTEN expression. In addition, miR132-3p+ significantly increased the delivery of doxorubicin across the BTB in vitro and contributed to the accumulation of doxorubicin within the brain tumor tissue. Our results showthat miR-132-3p contributes to the increased permeability of BTB by targeting PTEN/PI3K/PKB/Src/Cav-1, thereby revealing a novel drug target for the treatment ofbrain gliomas.