Role of fibulin-1 gene promoter methylation in the carcinogenesis and development of tongue squamous cell carcinoma

Objective. Recently, fibulin-1 (FBLN1) has been shown to be downregulated in various cancers via promoter hypermethylation. Our study aimed to determine the expression and methylation status of FBLN1 in tongue squamous cell carcinoma (TSCC) tissues and cells. Methods. Methylation-specific polymerase chain reaction was implemented to detect the methylation status of the FBLN1 gene in TSCC tissues and Western blot analysis was used to detect the expression of FBLN1 protein. The human TSCC cell lines CAL27 and SCC9 were cultured in vitro and treated with 5-aza-deoxycytidine (5-Aza-dC). CCK-8, colony formation, and Transwell assays were performed to test TSCC cell proliferation, migration, and invasion following 5-Aza-dC treatment or overexpression of FBLN1, which was further verified in in vivo experiments. Results. FBLN1 was hypermethylated and the protein expression was reduced in TSCC tissues. After human TSCC cell lines (CAL27 and SCC9) were treated with 5-Aza-dC or overexpressed FBLN1, FBLN1 expression was upregulated and the TSCC cell proliferation, migration, and invasion abilities were suppressed. In vivo experiments further showed that demethylation or overexpression of FBLN1 slowed tumor growth in nude mice. Conclusion. This study demonstrated that 5-Aza-dC treatment or overexpression of FBLN1 inhibited the growth of human TSCC.