title: Cigarette smoke induces promoter methylation of single-stranded DNA-binding protein 2 in human esophageal squamous cell carcinoma.
abstract: Esophageal squamous cell carcinoma (ESCC) is the sixth most frequent cause of cancer death in the world, and cigarette smoke is a key factor in esophageal carcinogenesis. To identify molecular changes during cigarette smoke-induced ESCC, we examined the methylation status of 13 gene promoters in the human immortalized, nontumorigenic esophageal epithelial cell line (Het-1A) that were exposed to mainstream (MSE) or sidestream cigarette smoke extract (SSE) for 6 months in culture. The promoter of sequence-specific single-stranded DNA-binding protein 2 (SSBP2) was methylated in the Het-1A cells exposed to MSE (MSE-Het-1A). Promoter methylation (86%, 56/70) and downregulation of SSBP2 expression were frequently detected in tumor tissues from ESCC patients. In addition, reintroduction of SSBP2 in an ESCC cell line (TE1) that does not express SSBP2 and in the MSE-Het-1A cells inhibited expression of LRP6 and Dvl3, which are mediators of the Wnt signaling pathway. SSBP2 expression markedly decreased the colony-forming ability of ESCC cell lines and significantly inhibited cell growth of the MSE-Het-1A cells. Our results indicate that cigarette smoking is a cause of SSBP2 promoter methylation and that SSBP2 harbors a tumor suppressive role in ESCC through inhibition of the Wnt signaling pathway.
authors.affiliation: Department of Dermatology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Chang
authors.forename: Juna
authors.initials: J
authors.lastname: Lee
authors.forename: Yong Gu
authors.initials: YG
authors.lastname: Cho
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhong
authors.forename: Il-Seok
authors.initials: IS
authors.lastname: Park
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Liu
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Califano
authors.forename: Edward A
authors.initials: EA
authors.lastname: Ratovitski
authors.forename: David
authors.initials: D
authors.lastname: Sidransky
authors.forename: Myoung Sook
authors.initials: MS
authors.lastname: Kim
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D002461:Cell Line, Transformed; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics*; D004938:Esophageal Neoplasms / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012906:Smoke; D014026:Nicotiana
chemical_list: D004268:DNA-Binding Proteins; C477058:SSBP2 protein, human; D012906:Smoke