Downregulation of ST6GALNAC1 is associated with esophageal squamous cell carcinoma development

Tylosis is an inherited disorder characterized by abnormal palmoplantar skin thickening and a highly elevated risk of esophageal squamous cell carcinoma (ESCC). Analyses of tylosis in families have localized the responsible gene locus to a region of chromosome 17q25.1. Frequent loss of heterozygosity (LOH) in 17q25.1 was also observed in the sporadic form of ESCC. A putative tumor suppressor gene for ESCC may exist at this locus. We investigated the expression patterns of genes on 17q25.1 in tumor and corresponding normal tissues from patients with sporadic ESCC using RNA sequence analysis. For candidate genes, quantitative real-time reverse transcription-PCR (qRT-PCR), direct sequence, LOH and methylation analyses were performed using 93 clinical ESCC samples and 10 cell lines. A significant downregulation of ST6GALNAC1 was demonstrated in ESCC tissues compared to its expression in normal tissues by qRT-PCR (n=93, p<0.0001). Frequent LOH (17/27, 62.9%) and hyper-methylation in ST6GALNAC1 were also observed in all cell lines. Our results indicated that ST6GALNAC1 was downregulated in sporadic ESCC via hyper-methylation and LOH, and it may be a candidate responsible gene for ESCC. Furthermore, recent studies suggest that multiple genes on chromosome 17q25 are involved in ESCC development.