Regulation of the GnT-V Promoter by Transcription Factor Ets-1 in Various Cancer Cell Lines

Abstract

Although the precise role of oligosaccharides in metastasis is presently unknown, numerous studies suggest that the ␤1-6 branching structure of N-linked oligosaccharides plays a role in tumor metastasis. N-Acetylglucosaminyltransferase V (GnT-V), which catalyzes the formation of the ␤1-6 branch, therefore appears to play a crucial role in tumor metastasis. Recently, we demonstrated that the expression of the GnT-V gene is regulated by a transcriptional factor, Ets-1 (Kang, R., Saito, H., Ihara, Y., Miyoshi, E., Koyama, N., Sheng, Y., and Taniguchi, N. (1996) J. Biol. Chem. 271, 26706 -26712). In this study, we report an investigation of the general requirement for Ets-1 in the expression of GnT-V in cancer cell lines. In 16 cancer cell lines, the levels of GnT-V mRNA were closely correlated with ets-1 expression (r ‫؍‬ 0.97; p < 0.0001). An increase in ets-1 levels by transfection of its cDNA led to an enhancement in GnT-V expression in cells that normally expressed low levels of ets-1. In contrast, the transfection of dominant negative ets-1 into cells that express high levels of ets-1 resulted in a decrease in GnT-V expression. Although Ets-1 cooperates with c-Jun in certain gene expressions, this was not the case in the regulation of the GnT-V gene. These results suggest that Ets-1 plays a significant role in regulating the expression of GnT-V in a variety of cancers and might be involved in the potential for malignancy via the action of GnT-V.The glycosylation of cell surface glycoproteins is thought to play a critical role in a variety of specific biological interactions (1). Numerous studies have concluded that alterations of cell surface glycoprotein oligosaccharides cause significant changes in the adhesive or migratory behavior of a cell (2). The high degree of branching of N-glycans, in particular, the ␤1-6 branching type, appears to be related to a potential for the development of malignancy (3). UDP-GlcNAc, ␣-mannoside ␤-1,6-N-acetylglucosaminyltransferase V (GnT-V), 1 represents an enzyme that catalyzes such branching. To understand the molecular basis of this oligosaccharide structure in terms of tumor metastasis, we and other groups have purified GnT-V from rat kidney (4) and from a human lung cancer cell line QG (5) and cloned the gene. The expression of GnT-V is enhanced by malignant transformation through the ras oncogene (6), by cell proliferation (7), and by hepatocarcinogenesis (8). However, GnT-V is also highly expressed in normal tissues, suggesting that the synthesis of oligosaccharides by GnT-V might be different in normal cells versus cancer cells (9). The most important issue, however, is how GnT-V modifies the metastatic potential of tumor cells.When the GnT-V gene was transfected into a lung epithelioid cell, the transfectant showed an increased tumorigenicity, as evidenced by an assay involving the subcutaneous injection of the cells into nude mice (10). Interestingly, this cell showed an altered transformed cell morphology, as is often observed for oncogenically transformed cells. ...

Functional glycomics and evidence for gain- and loss-of-functions of target proteins for glycosyltransferases involved in <i>N</i>-glycan biosynthesis: their pivotal roles in growth and development, cancer metastasis and antibody therapy against cancer

“…A dominant negative form of Ets-1 was reported to suppress GnT-V expression. 34) These data confirm that the GnT-V gene is generally regulated by Ets-1. It has recently been reported that several glycosyltransferase genes are regulated by Ets-1 and some other glycosyltransferases appear to be regulated by a similar mechanism.…”

N-Acetylglucosaminyltransferase V (Mgat5)-Mediated N-Glycosylation Negatively Regulates Th1 Cytokine Production by T Cells

“…1g). Because the Mgat5 promoter has Ets and AP-1 binding sites and is responsive to the Ras signaling pathway (21,22), these data suggest that Mgat5 expression is directly induced by TCR and CD28 signaling. Furthermore, the data indicate that ␤1,6GlcNAc-branched N-glycan expression is tightly regulated during T cell activation and subsequent cell divisions.…”

“…Mgat5 gene transcription is positively regulated by Ras-Raf-Ets (21,22), a pathway commonly activated in cancer cells as well as activated T cells. Mgat5-modified glycans in human breast and colorectal carcinomas correlate with progression (34) and reduced patient survival time (37).…”

Hepatitis B virus-X protein upregulates the expression of p21wafl/cipl and prolongs G1→S transition via a p53-independent pathway in human hepatoma cells

“…Two other ets-related genes, the Spi-1/PU.1 and the ERBG/Fli-1, were also shown to have a direct role in neoplasia, since these two genes were found to be activated by spleen focusforming virus (SFFV) and murine leukemia virus (MULV) proviral integration in erythroleukemias (Moreau-Gachelin et al, 1989;Ben-David et al, 1991). Recently, it is reported that regulation of the N-acetyl glucosaminyl transferase V (Gn T-V) gene which appears to play a crucial role in tumor metastasis, is mediated by ets transcription factors in a cell-speci®c manner in human and murine cancer cells (Ko et al, 1999). These ®ndings suggest that Ets-1 is a multifunctional transcription factor.…”