Association of insulin-like growth factor binding protein-7 promoter methylation with esophageal cancer in peripheral blood

The insulin-like growth factor (IGF) signaling pathway has an important role in many cancers, including esophageal cancer (EC). IGF-binding protein 7 (IGFBP7) is one of the proteins in this signaling pathway, and its role in cancer has not yet been fully clarified. In the present study, we evaluated the clinical relevance of IGFBP7 methylation status and mRNA expression in EC patients compared to healthy controls. We also investigated whether IGFBP7 methylation status affects mRNA expression. The study comprised 100 EC patients and 105 healthy controls. Methylation specific PCR (MSP) was used to examine IGFBP7's promoter methylation and real-time quantitative reverse transcription PCR (qRT-PCR) was used to assess IGFBP7 mRNA expression. The IGFBP7 promoter methylation was significantly higher in controls than in EC patients (p < 0.05). IGFBP7 mRNA expression was significantly lower in EC patients compared to controls, especially in those over 55 years old (p < 0.0001). The globulin level and reflux were significantly higher in IGFBP7-unmethylated patients compared to IGFBP7 methylated patients (p = 0.01). In EC patients, however, there was no significant relationship between IGFBP7 mRNA expression and methylation in the peripheral blood (p = 0.33). In addition, neither IGFBP7 mRNA expression nor methylation were shown to be linked with survival (p > 0.05). Our study indicated that promoter unmethylation and mRNA expression of the IGFBP7 promoter in peripheral blood could be different biomarkers for EC. Furthermore, unmethylation of the IGFBP7 promoter in EC patients was associated with reflux and elevated globulin levels. More studies with a larger number of cases is needed to confirm this association.