title: Fascin overexpression is regulated by the transactivation of the promoter but not by its hypomethylation in esophageal squamous cell carcinoma.
abstract: Fascin 1 (fascin) is known to be overexpressed in esophageal squamous cell carcinoma (ESCC); however, the mechanisms of this overexpression are unclear. In this study, the FSCN1 core promoter was isolated and the transcriptional regulatory mechanism of fascin overexpression in ESCC was investigated. By combining the use of progressive 5' deletions and dual-luciferase reporter assays, the FSCN1 core promoter was identified within the -74/-41 region in esophageal carcinoma EC109 cells harboring a GC box and a composite CRE/AP-1 binding site. Further analysis demonstrated that only the GC box was essential for transcription. No methylated CpG sites were found within the FSCN1 promoter in normal and tumor cells or tissues examined by methylation-specific PCR (MSP) and bisulfite genomic sequencing (BGS), which suggested that hypomethylation did not contribute to the overexpression of fascin in ESCC. Furthermore, the region of +168/+2838 was found to inhibit promoter activity. Additional BGS analysis indicated that the region of +560/+859 (in exon 1) was hypermethylated in normal and tumor cells or tissues. Unexpectedly, demethylation did not eliminate the suppression, suggesting that a silencer caused this suppression, and not DNA methylation in exon 1. Taken together, the results indicate that fascin overexpression in ESCC is regulated by the transactivation of the fascin promoter, but not by its hypomethylation.
authors.affiliation: Institute of Oncologic Pathology, College of Medicine, Shantou University, Shantou 515041, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hou
authors.forename: Zhang-Yan
authors.initials: ZY
authors.lastname: Guo
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Xie
authors.forename: En-Min
authors.initials: EM
authors.lastname: Li
authors.forename: Li-Yan
authors.initials: LY
authors.lastname: Xu