407002

MIR219A1

MIR219-1|MIRN219-1|MRI219-1|hsa-mir-219a-1|mir-219;microRNA 219a-1;MIR219A1;microRNA 219a-1

hsa-mir-219-1|microRNA 219-1

6p21.32

ncRNA

microRNAs (miRNAs) have been linked to the molecular pathogenesis of many cancers. In this study, we found that miR-219-5p was significantly downregulated in 83 HCC tissues and three HCC cell lines, compared to their non-tumor counterparts. MiR-219-5p expression correlated with tumor size, histological differentiation, and overall survival time in HCC patients. We also found that miR-219-5p could inhibit cell proliferation in vitro and arrest cell cycle at the G1 to S transition. Further studies identified that miR-219-5p reduced both the mRNA and protein levels of glypican-3 (GPC3). These findings indicate that miR-219-5p exerts tumor-suppressive effects in hepatic carcinogenesis through negative regulation of GPC3 expression.

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal cancers in the world with one of the worst outcome. The oncogenic mucin MUC4 has been identified as an actor of pancreatic carcinogenesis as it is involved in many processes regulating pancreatic cancer cell biology. MUC4 is not expressed in healthy pancreas whereas it is expressed very early in pancreatic carcinogenesis. Targeting MUC4 in these early steps may thus appear as a promising strategy to slow-down pancreatic tumorigenesis. miRNA negative regulation of MUC4 could be one mechanism to efficiently downregulate MUC4 gene expression in early pancreatic neoplastic lesions. Using in silico studies, we found two putative binding sites for miR-219-1-3p in the 3-UTR of MUC4 and showed that miR-219-1-3p expression is downregulated both in PDAC-derived cell lines and human PDAC tissues compared with their normal counterparts. We then showed that miR-219-1-3p negatively regulates MUC4 mucin expression via its direct binding to MUC4 3-UTR. MiR-219-1-3p overexpression (transient and stable) in pancreatic cancer cell lines induced a decrease of cell proliferation associated with a decrease of cyclin D1 and a decrease of Akt and Erk pathway activation. MiR-219-1-3p overexpression also decreased cell migration. Furthermore, miR-219-1-3p expression was found to be conversely correlated with Muc4 expression in early pancreatic intraepithelial neoplasia lesions of Pdx1-Cre;LSL-Kras(G12D) mice. Most interestingly, in vivo studies showed that miR-219-1-3p injection in xenografted pancreatic tumors in mice decreased both tumor growth and MUC4 mucin expression. Altogether, these results identify miR-219-1-3p as a new negative regulator of MUC4 oncomucin that possesses tumor-suppressor activity in PDAC.