Upregulation of OGT by Caveolin-1 Promotes Mouse Hepatocellular Carcinoma Cells Migration and Invasion / 中国生物化学与分子生物学报

Caveolin-1 (Cav-1), a major structural protein of caveolae, is implicated in the vesicular uptake processes of transcytosis and cell signaling. However, its role in modulating protein glycosylation and tumor metastasis remains to be further elucidated. In the present study, it was shown that Cav-1 promotes the expression of O-GlcNAcylation and O-GlcNAc transferase (OGT), and triggers the invasion and metastasis of hepatocellular carcinoma (HCC) cells. The results of RT-qPCR, Western blot and dual lucif-erase reporter assay showed that Cav-1 negatively regulated the expression of transcription factor RUNX2 in HCC. Subsequently, this results in attenuate RUNX2-induced transcription of miR24. miR24 suppresses mouse HCC cells invasion and metastasis via directly targeting Ogt mRNA 3′UTR. This research provides evidence of Cav-1-mediated OGT expression and O-GlcNAc (O-linked N-acetylglucosamine) elevation. These data give insight into a novel mechanism of HCC occurrence and development.

Glucose-Insulin-Potassium Solution Protects Ventricular Myocytes of Neonatal Rat in an In Vitro Coverslip Ischemia/Reperfusion Model

BACKGROUND AND OBJECTIVES: The benefit of high glucose-insulin-potassium (GIK) solution in clinical applications is controversial. We established a neonatal rat ventricular myocyte (NRVM) in vitro coverslip ischemia/reperfusion (I/R) model and investigated the effects of GIK solution on suppressing reactive oxygen species (ROS) and upregulating O-GlcNacylation, which protects cells from ischemic injury. MATERIALS AND METHODS: NRVMs were isolated from postnatal day 3-4 Sprague-Dawley rat pups and grown in Dulbecco's modified Eagle's medium containing high glucose (4.5 g/L), fetal bovine serum, and penicillin/streptomycin. The effects of the GIK solution on ROS production, apoptosis, and expression of O-GlcNAc and O-GlcNAc transferase (OGT) were investigated in the coverslip I/R model. RESULTS: Covering the 24-well culture plates for 3 hr with 12 mm diameter coverslips resulted in the appropriate ischemic shock. Glucose and insulin synergistically reduced ROS production, protected NRVM dose-dependently from apoptosis, and altered O-GlcNAc and OGT expression. CONCLUSION: The high GIK solution protected NRVM from I/R injury in vitro by reducing ROS and altering O-GlcNacylation.

Immunohistochemical Study of O-GlcNAcylation in Human Skin Tumors / 체질인류학회지

O-linked beta-N-acetylglucosamine modification is an important post-translational modification, emerging as a novel regulatory mechanism in various cellular events. Recently, several studies have shown that O-GlcNAcylation plays an essential role in human breast, lung, and colon cancers. With regard to skin cancers, the role of O-GlcNAcylation has yet to be elucidated. To investigate whether O-GlcNAcylation is linked to human skin tumor development, immunohistochemical analysis was performed to investigate the presence of O-GlcNAcylation in various skin tumors. We evaluated the levels of O-GlcNAcylation, O-GlcNAc transferase, and O-GlcNAcase in 29 benign tumors, 12 premalignant tumors, and 26 malignant tumors in skin. Compared to the benign tumors, premalignant and malignant tumors had increased patterns of O-GlcNAcylation. In addition, the O-GlcNAc transferase and O-GlcNAcase levels were higher in premalignant and malignant tumors than in benign tumors. Interestingly, O-GlcNAcase levels were significantly increased in premalignant tumors compared to benign and malignant tumors. These results suggest that O-GlcNAcylation of proteins may play an important role in the development of human skin tumors.