Inhibition of miR-21 regulates mutant KRAS effector pathways and intercepts pancreatic ductal adenocarcinoma development [miRNA]. Inhibition of miR-21 regulates mutant KRAS effector pathways and intercepts pancreatic ductal adenocarcinoma development [miRNA]

We identified miR-21 and miR-224 as cell-specific and compartment-specific regulators in PanINs and PDA. miR-21 is overexpressed in tumor epithelial cells of premalignant ducts, while miR-224 is overexpressed in cancer-associated fibroblasts in PDA stroma. Inhibition of miR-21 reverted pro-tumorigenic functionalities to baseline levels. Overexpression of miR-224 induced activated phenotypes in normal fibroblasts. miR-21 inhibition downregulated MAPK, mTOR and actin cytoskeleton pathways downstream of KRAS activation in tumor cells. In vivo miR-21 inhibition improved survival in established PDA, while early systemic miR-21 inhibition intercepted premalignant progression. Overall design: TaqMan OpenArray Rodent MicroRNA Panel. We conducted a comprehensive miRNA profiling study of multiple PanIN stages and PDA using KPC mice. We performed microdissections on increasing grades of PanINs from sections of KPC pancreata followed by a miRNA microarray analysis utilizing the Taqman OpenArray platform to quantify the levels of 750 known murine miRNAs.

我们鉴定出微小RNA-21（miR-21）与微小RNA-224（miR-224）可作为胰腺上皮内瘤变（PanIN）及胰腺导管腺癌（PDA）中细胞特异性与区域特异性的调控因子。miR-21在癌前导管的肿瘤上皮细胞中过表达，而miR-224则在PDA间质的癌症相关成纤维细胞内呈过表达状态。抑制miR-21可将肿瘤细胞的促瘤生成功能恢复至基线水平；过表达miR-224则可诱导正常成纤维细胞产生活化表型。在肿瘤细胞中，抑制miR-21可下调KRAS激活下游的丝裂原活化蛋白激酶（MAPK）、哺乳动物雷帕霉素靶蛋白（mTOR）及肌动蛋白细胞骨架通路。体内实验显示，抑制miR-21可改善已建立的PDA模型小鼠的存活情况，而早期全身性抑制miR-21能够阻断癌前病变的进展。总体实验设计：本研究采用TaqMan OpenArray啮齿类微小RNA检测板（TaqMan OpenArray Rodent MicroRNA Panel）。我们借助KPC小鼠对多阶段PanIN及PDA样本开展了全面的微小RNA表达谱分析：先从KPC小鼠胰腺组织切片中获取不同分级的PanIN并进行显微切割，随后采用Taqman OpenArray平台完成微小RNA微阵列分析，以定量750种已知小鼠微小RNA的表达水平。