Transcriptional Mechanism of the β4-Galactosyltransferase 4 Gene in SW480 Human Colon Cancer Cell Line

Increased expression of beta 4-galactosyltransferase (beta 4GalT) 4 has been shown to be associated with meta-static ability and poor prognosis of colon cancer cells. To solve the up-regulation of beta 4GalT4 in colon cancer cells at transcriptional level, we examined the transcriptional mechanism of the beta 4GalT4 gene in SW480 human colon cancer cell line. Luciferase assay using the deletion constructs revealed that the promoter activity of the beta 4GalT4 gene is associated with the region between nucleotides -122 and -55 relative to the transcriptional start site, which contained one Specificity protein 1 (Spl)-binding site. The mutation into the Spl-binding site resulted in dramatic decreased promoter activity. Meanwhile, ectopic Spl expression stimulated the promoter activity significantly. The present study suggests that the expression of the beta 4GalT4 gene is controlled by Spl, and Spl plays a key role in the activation of the beta 4GalT4 gene in colon cancer cells.