Abstract: 【Objective】 The expression of pancreatic-duodenal homeobox 1 (PDX1) is aberrantly reduced in gastric cancer. This study aimed to determine the regulation of DNA methylation and histone acetylation on the expression of PDX1 in gastric cancer. 【Methods】 The expression of PDX1

Dnmt1 and HDAC was detected in human gastric cancer tissue chips by immunohistochemistry

and its correlations were analyzed. PDX1 expression in response to demethylation (5’-aza-dC) and acetylation (TSA) was assessed in human gastric cancer cells by reverse transcription-polymerase chain reaction (RT-PCR). Six PDX1 promoter fragments were cloned into pGL3 vector and the transcription activity of promoters in response to demethylation and acetylation was detected by dual luciferase assay. In gastric cancer cell lines

promoter DNA methylation was evaluated by methylation-specific PCR(MSP) and bisulfite DNA sequencing PCR (BSP) while histone acetylation was detected by chromatin immunoprecipitation (ChIP) assay. 【Results】 Compared to gastric normal tissues

the expression of PDX1 protein was weak but the expression of Dnmt1 and HDAC was upregulated. Our results also showed that PDX1 is negatively correlated with Dnmt1 and HDAC. PDX1 expression was restored by 5’-aza-dC and by TSA in gastric cancer cells. F383 (-22063 ~ -21681nt) wihich displayed significant promoter transcript activity

which was increased by 5’-aza-dC and TSA but decreased by SssI methylase. F383 was completely methylated in gastric cancer cells by MSP and more than 80% of 17 single CpG sites located at F383 were methylated compared with gastric normal tissues by BSP (P < 0.01). F383 had also lower acetylation level of histone H3 and H4 in gastric cancer cells by ChIP assay. 【Conclusion】 PDX1 silencing was resulted by promoter hyper-methylation and histone hypo-acetylation in gastric cancer.