Abstract 1162: Multiple genes on chromosome 17q25 were involved in sporadic esophageal squamous cell carcinoma development

Abstract

[Background] Tylosis is an autosomal dominant skin disorder that is associated with the early onset of esophageal squamous cell carcinoma (ESCC) in several families. The tylosis esophageal cancer (TOC) gene locus has been mapped to chromosome 17q25.1 using linkage analyses. This region is also frequently lost in sporadic ESCC. [Materials and Methods] Gene expression profiles on 17q25 in tumor samples from 3 ESCC patients were analyzed using RNA-seq. We validated the expression status of candidate genes in samples from 90 ESCC patients using qRT-PCR. Direct sequence, microsatellite LOH analysis, and methylation assay were also performed in the candidate gene, ST6GALNAC1. Mutation profiles of genes on 17q were also evaluated by exome sequence analysis from 144 ESCC patients. [Result] EVPL and ST6GALNAC1 were found to be significantly downregulated in tumor samples using RNA-seq. Significant downregulation of ST6GALNAC1 and EVPL expression in cancer tissues was confirmed by qRT-PCR in 90 ESCC samples. Although direct sequence of ST6GALNAC1 demonstrated missense mutations in 7 out of 46 (15%) cases, these mutations were not tumor specific. ST6GALNAC1 expression was significantly upregulated in 5-aza-dC treatment groups compared with control in the 5 ESCC cell lines. LOH in ST6GALNAC1 gene locus were identified 18 of 27 informative cases (67%). On chromosome 17q, exome sequence revealed that recurrent mutations were observed only in ZNF750 (14.5%) on 7q25.3. Recently, missense mutations in RHBDF2 were identified tylosis familys. However, RHBDF2 mutation was not observed in sporadic ESC samples by exome sequence analysis. [Conclusion] Our results suggest that ST6GALNAC1 is a putative tumor suppressor gene for ESCC. Furthermore, recent studies on tylosis families and our results on sporadic ESC suggest that multiple genes on chromosome 17q25 are involved in ESCC development. Citation Format: Takeshi Iwaya, Suburu Amano, Fumitaka Endo, Yuji Akiyama, Yoshihiro Shioi, Kohei Kume, Satoshi Nishizuka, Chie Ito, Akira Sasaki, Koshi Mimori. Multiple genes on chromosome 17q25 were involved in sporadic esophageal squamous cell carcinoma development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1162.