MicroRNA-130b Promotes Tumor Development and Is Associated with Poor Prognosis in Colorectal Cancer

MicroRNA-130b (miR-130b) is involved in several biologic processes; its role in colorectal tumorigenesis has not been addressed so far. Herein, we demonstrate that miR-130b up-regulation exhibits clinical relevance as it is linked to advanced colorectal cancers (CRCs), poor patients' prognosis, and molecular features of enhanced epithelial-mesenchymal transition (EMT) and angiogenesis. miR-130b high-expressing cells develop large, dedifferentiated, and vascularized tumors in mouse xenografts, features that are reverted by intratumor injection of a specific antisense RNA. In contrast, injection of the corresponding mimic in mouse xenografts from miR-130b lowexpressing cells increases tumor growth and angiogenic potential while reduces the epithelial hallmarks. These biologic effects are reproduced in human CRC cell lines. We identify peroxisome proliferator-activated receptor gamma (PPAR gamma) as an miR-130b direct target in CRC in vitro and in vivo. Notably, the effects of PPAR gamma gain-and loss-of-function phenocopy those due tomiR-130b down-regulation or up-regulation, respectively, underscoring their biologic relevance. Furthermore, we provide mechanistic evidences that most of the miR-130b-dependent effects are due to PPAR gamma suppression that in turn deregulates PTEN, E-cadherin, Snail, and vascular endothelial growth factor, key mediators of cell proliferation, EMT, and angiogenesis. Since higher levels of miR-130b are found in advanced tumor stages (III-IV), we propose a novel role of the miR-130b-PPAR gamma axis in fostering the progression toward more invasive CRCs. Detection of onco-miR-130b and its association with PPAR gamma may be useful as a prognostic biomarker. Its targeting in vivo should be evaluated as a novel effective therapeutic tool against CRC.