Inactivation and Promoter Mutation of DPC4 Gene in Gastric Cancer

To investigate the expression level and the mutation status in promoter region of DPC4 gene in gastric cancer, and to analyze the relationship between mutation and expression of DPC4 gene. Methods Using RT-PCR method, we measured the expression of DPC4 in nine gastric cancer cell lines. Cloning and sequencing were performed for detecting the mutation status of DPC4 promoter region. In addition, we used TFSEARCH ver.1.3 to analyze transcription factor binding sites in DPC4 promoter region. Results We found that DPC4 expressed at middle to high level in SNU5, SNU16, SNU484, SNU638 and KATOⅢ cell lines, but low or absent in SNU216, MKN28, MKN74 and AGS cell lines. Sequencing data showed that, except MKN74 cells, there was no mutation of DPC4 promoter region in eight cell lines. There were two substitution mutations of DPC4 promoter region in MKN74 cells. More importantly, we found two mutations might interfere with transcription factors, including MZF-1 and IK-2, to bind to DPC4 promoter. Conclusion Inactivation of DPC4 gene is a frequent event in gastric cancer, and promoter mutation might be one of the inactivation mechanisms of DPC4 gene.