Previous studies have shown that hST6GaI I mRNA is overexpressed in colorectal cancer tissues compared with non-malignant or benign tissue. Moreover, Form I (hepatic form) mRNA isoform had a marked tendency to accumulate in colon cancer [Int. J. Cancer 88 (2000) 58-65]. These findings suggest that the transcriptional regulation of Form I is altered during malignant transformation. We report here transcriptional regulation of the hST6GaI I gene in colon adenocarcinoma cell lines. We characterized PI promoter region, which regulates Form 1 mRNA expression, using luciferase assays. The result indicates that the nt-156 to -1 region is important for transcriptional activity of hST6GaI I gene in colon adenocarcinoma cell lines. The nt-156 to -1 region contains HNF1 recognition element. Mutation of the HNF1 site reduced luciferase activity by about 80% compared with the wild-type construct, suggesting that HNF1 site is involved in the transcription of Form 1 mRNA in colon cancer cells. (C) 2003 Elsevier Inc. All rights reserved.