Preliminary Exploration Of The Relation Between GnT-IVa And Adhesion Molecules With Invasion And Migration Of Hepatoma Cell

As the fourth biomacromolecule after DNA, RNA and protein, glycan plays an extremely important role in the organism. Large number of studies have shown that sugar is not only an important energy material for the organism, glycan, which has diverse structure, is also involved in a series of important biological processes, such as the cell recognition, immunoprotection, metabolismnregulation, morphological development, and so on.Researches show that the abnormity of glycan chain structure is associated with oncogenesis, and some glycan chains with specific structure can also be used as biomarkers of cancer diagnosis. The synthesis of glycan chain is dependent on the glycosyltransferase, about whose reseach is rapidly rising in recent years. Reports show that N-glycan structure reshape, which is catalyzed by Gn T-III and Gn T–V, regulated cell adhesion and migration, which is mediated by cadherin and integrin. But reports about Gn T-IVa on cadherin and integrin is few. Our study showed that the expression of Gn T-IVa in hepatocellular carcinoma cell(HCC) is higher than adjacent tissues. This showed that Gn T-IVa has certain effect on the formation of hepatocarcinogenesis. When using si RNA silences mgat4 a gene, the transfer ability of liver cancer cell BEl-7402 changed. This shows that the Gn T-IVa is associated with hepatocarcinogenesis.On the basis of early study, we hypothesized that in HCC, the Gn T-IVa changes the glycan chain structure, leading to the glycosylation abnormity of cell adhesion factor(cadherin and integrin), causing their function changes, resulting in the adjustment of the downstream signaling pathways, ultimately affectting the BEl-7402 cell invasion and migration ability. According to the assumption, we use RNAi tecnology to study the change of cell surface integrin beta 1 glycan chain after down-regulating Gn T-IVa in BEl-7402 cells, then compare the adhesion ability change of BEl-7402 cells, last but not least, explore the effect of Gn T-IVa change on downstream signaling pathways of HCC. RT-PCR and Western Blot results show that Gn T-IVa expression is down-regulated about 65% in hepatocellular carcinoma cell BEL-7402 after RNAi. Then using immunoprecipitation to obtain integrin beta 1, and glycan analysis showed that integrin beta 1 glycan chain changed after Gn T-IVa down-regulated. Immunofluorescence results show that the location of integrin beta 1 did not change significantly after the Gn T-IVa down-regulation. The following experiments use cell adhesion assay and apoptosis flow test to study BEL-7402 cell biology function change after Gn T-IVa down-regulation. Results show that cell adhesion ability is enhanced, but no obvious signs of apoptosis after silencing Gn T-Iva. Finally, the experiment analyzed the effect of Gn T-IVa on the invasion and migration associated signaling molecules. Results show that the expression of beta-catenin is enhanced, and the expression of P-ERK2 is decreased after Gn T-IVa down-regulation. Therefore, Gn T-IVa plays a role in Hepatic carcinoma signaling pathways.This issue uses integrin beta 1 as the pointcut to analysis the effect of Gn T-IVa changes on the molecular mechanism of cell movement ability. Results show that cell adhesion molecule integrin beta 1 glycan chain changed after Gn T-IVa down-regulation. And the cell adhesion ability is enhanced. Expression of some signaling molecules of the signaling pathways is also changed. This issue preliminary clarified the invasion and migration mechanism of hepatoma carcinoma cells, providing a new thought to the reseach of the glycan chain and Gn T-IVa biology function.