Relationship between promoter methylation of homeobox D10 gene and clinical prognosis of patients with cholangiocarcinoma

Objective: To investigate the methylated status of homeobox D10 (HOXD10) gene promoter in human cholangiocarcinoma tissues, and to explore the relationship between the promoter methylation of HOXD10 gene and the clinical prognosis of patients with cholangiocarcinoma. Methods: The methylation of HOXD10 gene promoter in 87 human cholangiocarcinoma tissues and 30 para-cancerous tissues was determined by methylation-specific PCR. Additionally, the methylation status of 27 cytosine-phosphate-guanosine (CpG) loci in HOXD10 gene promoter was detected by bisulfite genomic sequencing PCR. Then the correlation between the protein expression and the promoter methylation of HOXD10 gene was assessed by Spearman correlation test. Furthermore, the association of the number of methylated CpG loci with the survival of cholangiocarcinoma patients was examined by cut-point survival analysis and Kaplan-Meier test.  Results: The positive methylation rate of HOXD10 gene promoter in cholangiocarcinoma tissues was significantly higher than that in para-cancerous tissues (P < 0.05). The number of methylated CpG loci in para-cancerous tissues was less than that in cholangiocarcinoma tissues. The expression of HOXD10 protein was negatively correlated with the methylation status of HOXD10 gene promoter (r = －0.82, P < 0.000 1). Methylation of seven CpG loci in HOXD10 gene promoter was the optimal cut-off value for the survival analysis of cholangiocarcinoma patients (P < 0.001). The survival time of cholangiocarcinoma patients with 0-6 methylated CpG loci of HOXD10 gene promoter was significantly longer than that of the patients with more than 7 methylated CpG loci (P < 0.01). Conclusion: The methylation of gene promoter is closely correlated with the inactivation of HOXD10 protein expression, and the methylation of ≥7 CpG loci in HOXD10 gene promoter may be a potential predictor of poor prognosis in the patients with cholangiocarcinoma. DOI:10.3781/j.issn.1000-7431.2018.33.054