Upregulation of OGT by Caveolin-1 promotes hepatocellular carcinoma cell migration and invasion.

Caveolin-1 (CAV1), a major structural protein of caveolae, is reported to exert a positive regulatory effect on tumor growth and to play a crucial role in hepatocellular carcinoma (HCC) cell metastasis by regulating glycosyltransferase expression and cellular glycosylation. However, the role of CAV1 in modulating protein glycosylation and tumor metastasis remains to be further elucidated. In the present study, we showed that CAV1 promoted the expression of O-GlcNAc transferase (OGT), which catalyzed the addition of O-GlcNAc residues to a variety of nuclear and cytoplasmic proteins. In human HCC cell lines with different metastatic potentials, high levels of OGT and cellular O-GlcNAcylation were associated with CAV1 expression and cell metastasis. Overexpression of CAV1 increased the levels of OGT and O-GlcNAcylation, and cell migration was also increased. Furthermore, CAV1 was found to reduce the expression of Runt-related transcription factor 2 (RUNX2) in HCC cells. Subsequently, this effect resulted in the attenuation of the RUNX2-induced transcription of microRNA24 (miR24), a microRNA previously shown to suppress OGT mRNA expression by targeting its 3' untranslated regions (UTR). Finally, we demonstrated that CAV1 induced cellular O-GlcNAcylation and HCC cell invasion. This study provides evidence of CAV1-mediated increases in OGT expression and O-GlcNAcylation. These data provide insight into a novel mechanism underlying HCC metastasis and suggest a novel strategy for the treatment of HCC.