| Choriocarcinoma, a malignant trophoblastic tumor, with highlymetastatic ability and invasion capacity, is a common carcinoma in normalor abnormal pregnant women which mainly arise in the uterus andcharacterized by early hematogenous spread to the lungs. Thus there is anurgent need to clarify mechanism of choriocarcinoma metastasis and screeneffective targets for inhibition of choriocarcinoma metastasis. Currently,researches of tumor metastatic ability focus gradually on the proteinpost-translational modification, especially protein glycosylation, in whichsaccharides are selectively added to specific protein residues via variouskinds of glycosyltransferases. Different sugar residues attaching to proteinsperform different function to control various biological effects. In our study,the effect of O-GlcNAcylation on choriocarcinoma cells metastasis and themolecular mechanism were detected.O-GlcNAcylation is a post-translational modification which occurs inserine or threonine residues of nucleocytoplasmic proteins widely. O-linkedN-acetylglucosamine transferase (OGT) catalyzes the addition of a singleβ-O-linked GlcNAc (O-GlcNAc) to serine or threonine residues, and thecleavage of it from modified proteins is performed by theenzyme O-GlcNAcase (OGA). O-GlcNAcylation is a reversible processwhich was balanced by OGT and OGA. O-GlcNAcylation of functional protein could affect their structure and activity, which involve multiplecellular biological processes, such as cell migration, adhesion, invasion andso on.In our study, the objects were human choriocarcinoma cell lines (JAR).Cell modes expressing higher O-GlcNAcylation levels were established byOGA inhibitor. Transwell assay was used to examine JAR cells migrationability. The preliminary study suggested that O-GlcNAcylation promotedJAR cells migration, furthermore adhesion assay demonstrated thatO-GlcNAcylation enhanced JAR cells adhesion to EA.hy926cells, whichindicated that O-GlcNAcylation might be involved in regulating humanchoriocarcinoma cells metastasis. Down-regulation of OGT in JAR cells bysiRNA interference suspended the capacity of JAR cells migration andadhesion ability of JAR cells to EA.hy926cells, which verified the positivecorrelation between O-GlcNAcylation and JAR cells metastasis.Meanwhile, the O-GlcNAcylation level of β-catenin was analyzed byimmunoprecipitation after JAR cells treatment with OGA inhibitor.Upregulation of O-GlcNAcylation levels in cells, the O-GlcNAcylation ofβ-catenin was up-regulated apparently without altering its protein level.Moreover, qRT-PCR and western blot analysis were involved to detect theexpression of OGT and O-GlcNAcylation in JAR cell after the treatment ofIL-8(100ng/ml) for24h. Nevertheless, neither OGT nor O-GlcNAcylationchanged after IL-8treatment, which suggested that O-GlcNAcylation didnot participate in the process of IL-8-induced JAR cells migration. Insummary, OGT up-regulates the O-GlcNAcylation of β-catenin, leading toincrease of human choriocarcinoma cells metastasis. Our research mayprovide an effective target for the diagnosis and therapy ofchoriocarcinoma. |
