Promoter analyses of SCC antigen genes.

SCC antigen (SCCA) has been used as a tumor marker for squamous cell carcinoma. Analyses of the SCCA1 and SCCA2 genes, which are almost identical, and their promoters have been reported. Recently it was found that both SCCAs were stimulated by interleukin (IL)-4 and IL-13. Here we analyzed the promoter activity of both SCCAs in the 5'-flanking region, exon 1, and intron 1 to evaluate a putative STAT6 binding site. The addition of intron 1 to the luciferase assay constructs including the 5'-flanking region significantly augmented the promoter activity of both SCCA1 and SCCA2. Furthermore, deletion analyses of intron 1 revealed that a 50-bp fragment of intron 1 that includes putative STAT6 binding site was responsible for the increased promoter activity. Although the sequences of SCCA1 and SCCA2 are very similar in the 5'-flanking region, the analysis of the -337 single nucleotide polymorphism of SCCA2 indicated that this polymorphism may underlie the difference in promoter activity between SCCA1 and SCCA2.