The Role Of MiRNA-9 In Lymphatic Metastasis Of Mouse Hepatocarcinoma Cells

Hepatocellular carcinoma (HCC) is one of the common malignant tumors to threat human's health, and there are about 690,000 liver cancer death worldwide each year. WHO has published Cancer Country Profiles in 2014, which point that the incidence of hepatocellular carcinoma no matter in male or female of our country is top the fifth. Metastasis is a main cause of reoccurrence and death, so working on the molecular mechanism of liver cancer metastasis is really urgent.Glycosylation is one of important forms of post-translation modification, which plays a key role in protein synthesis, folding properly, cell recognition and other biological process. Glycosylation is catalyzed by glycosyltrasferases. Aberrant glycosylation including glycosyltransferase gene expression and glycan biosynthesis is a common symbol of tumorrigenesis and tumor metastasis. Sialic acid is a family of acidic sugars with a nine-carbon backbone, normally locates at the terminal of glycan linked to glycoprotein and glycolipid. Sialic acid mediated inflammation, pathogen infection, the tumor development and other pathological process, which closely related to human diseases. ST6Gal1, galactoside ?-2,6-sialyltransferase I which catalyzes sialic acid link to galactose by ?-2,6 glycosidic bond, belongs to sialyltransferase family. Our previous results showed that up-regulation of ST6Gal1 expression and ?-2,6 linked sialic acid enhanced the lymphatic metastasis potential of mouse Hepatocarcinoma cells.miRNAs are short non-coding RNAs which rewcongnize the 3'UTR of the target genes, and act as a potential regulator by silencing or suppressing the target gene expression, hence miRNAs play important roles in cell differentiation, proliferation, and other diverse cellular pathways. There is emerging evidences including our results show that the alterations of miRNAs are involved in changing of cell surface glycosylation modification. However, so far it has not been reported that miRNA modulates ST6Gallexpression and ?-2,6 linked sialic acid biosynthesis.In this study, the role of miRNA-9 in lymphatic metastasis of mouse Hepatocarcinoma cells was investigated. miRNA expression array profiles were obtained previously by our lab from mouse Hepatocarcinoma cell lines Hepal-6, HcaP and HcaF with the none/low/high lymphatic metastasis, respectively. Based on the miRNA expression array profiles and confirmed by qPCR, Western blot and lectin Flow Cytometry analysis, miRNA-9 expression was found to exhibit negatively coincidence with lymphatic metastasis potential, ST6Gall expression and ?-2,6 linked sialic acid biosynthesis, respectively. Dual-luciferase reporter gene assay revealed that miRNA-9 bond to 3'UTR of ST6Gall specifically. Further, when miRNA-9 mimic was transfected with above three cell lines, the expression level of ST6Gall significantly decreased in the mouse Hepatocarcinoma cells, along with reduced the level of a-2,6 linked sialic acid biosynthesis, attenuated the capacity of cell proliferation, migration, invasion and adhesion and FAK signal pathway activity. Conversely, when miRNA-9 inhibitor was transfected with above three mouse Hepatocarcinoma cell lines, the expression level of ST6Gall significantly rose in these cells, along with increased the level of ?-2,6 linked sialic acid biosynthesis, up-regulated the capacity of cell proliferation, migration, invasion and adhesion and FAK signal pathway activity.Together, these results above confirmed that ST6Gall is one of miRNA-9 target genes. miRNA-9 inhibits lymphatic metastasis of mouse Hepatocarcinoma cells by targeting ST6Gall, silencing ?-2,6 linked sialic acid biosynthesis and FAK signal pathway activity. miRNA-9 may be potential target molecule for tumor metastasis therapy.