Expression and methylation of Iroquois homeobox protein 1 in pancreatic cancer / 中华胰腺病杂志

ABSTRACT

Objective To investigate the expression of Iroquois homeobox protein 1 ( IRX1 ) gene and the hypermethylation status of its promoter in pancreatic cancer,and their relationship.Methods Real-time PCR was used to quantitatively detect IRX1 gene expression level of 12 sets of resected pancreatic cancer tissue and 6 sets of pancreatic cancer cell lines; gene sequences analysis was used to detect the structure of IRX1 promoter; DNA methylation inhibitor 5-Aza-2′-deoxycytidine (5-Aza-dC) was used in pancreatic cancer cell lines,and then the methylation of IRX 1 was measured by methylation-specific PCR (MSP) and unmethylation sequence-PCR (USP) methods.Results Expression of IRX1 mRNA in pancreatic cancer tissue was 0.31 ± 0.11,which were significantly lower than that in normal pancreatic tissue ( 1.05 ±0.32,P ＜0.01 ).IRX1 mRNA expression of AsPCl,BxPC3,Capan 2,PANCl,PaTu8988 and SW1990 were 0.36 ± 0.08,0.34 ±0.16,0.37 ±0.11,0.25 ±0.06,0.31 ±0.04,0.36 ±0.02,which were significantly lower than that in human kidney epithelial 293 cells ( 1.03 ± 0.28,P ＜ 0.05 or ＜ 0.01 ).Analysis of IRX1 gene sequence showed abundant CpG islands in promoter.Hypermethylation of IRX1 promoter site was found in all pancreatic cancer cell lines.However,its methylation status could be reversed by 5-Aza-dC,and the IRX1 expression was also restored.Conclusions IRX1 mRNA expression is down-regulated in pancreatic cancer,and it is related with promoter CpG islands hypermethylation.