The tumor-suppressing role of fibulin-1 has been described in several types of cancers. However, the expression and role of fibulin-1 in the development and progression of gastric cancer (GC) remain largely unknown. In this study, RT-PCR and immunochemistry were used to detect the fibulin-1 expression in GC samples. We have found that the fibulin-1 protein and mRNA levels were downregulated in GC. When investigating the correlation between fibulin-1 expression and clinicopathological characteristics, we have found that low fibulin-1 protein expression was associated with poor tumor differentiation and advanced N stage. Low fibulin-1 protein expression was also an independent prognostic factor for patient survival. To clarify the reason of fibulin-1 downregulation in GC, the mRNA expression and methylation status of fibulin-1 were examined in GC fresh tissue samples (n = 36). We found that the transcriptional expression of fibulin-1 was negatively associated with fibulin-1 promoter hypermethylation, and fibulin-1 hypermethylation was associated with Helicobacter pylori infection. Finally, the effects of fibulin-1 overexpression on cell proliferation and apoptosis were examined. We have found that fibulin-1 overexpression suppressed the growth of GC both in vitro and in vivo and induced apoptosis by increasing cleaved caspase-3 expression. In conclusion, fibulin-1 acts as a tumor suppressor gene, is frequently hypermethylated in GC, and can potentially serve as a useful biomarker for patient prognosis.
Keywords: Epigenetic; Fibulin-1; Gastric carcinogenesis; Prognosis; Tumor suppressor gene.