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[Analysis of gastric cancer tissues genome methylation by DNA methylation chip].

OBJECTIVE
To detect the methylation status of gastric cancer tissue genome by DNA methylation chip.


METHODS
Methylation status of 6 samples of gastric cancer tissues and their matched adjacent tissues was analyzed using methylated DNA immunoprecipitation(MeDIP) combined with NibleGen chip. Significantly different methylated genes in promoter region and CpG island between two tissues were searched. Functions of these significantly different methylated genes were analyzed by Gene Ontology and Pathway assays.


RESULTS
In gene promoter regions, 113 significantly different methylated genes were identified in gastric cancer tissues, such as SHP1, FGF8 and CSF2RA, while 161 significantly different methylated genes were identified in their matched adjacent tissues, such as TNF, IGF2 and BMP7. In the CpG islands, 123 significantly different methylated genes were identified in gastric cancer tissues, such as WNT2B, JAK2 and TPT1, while 139 significantly different methylated genes were identified in their matched adjacent tissues, such as TNFRSF4, HOXC8 and NFYA. These genes located on different chromosomes. In gastric cancer tissues, the 1st and the 4th chromosomes had the most (both 11), the 18th and the 20th chromosomes had the least(both 1). In matched adjacent normal tissues, the 11th chromosome had the most (17), and no significantly different methylated gene was found on Y chromosome. These genes involved in many functions, such as protein phosphorylation, regulating cellular catabolism, ion transport, enzyme activity, transcriptional regulation, cell division, cell cycle regulation, and signal transduction.


CONCLUSIONS
There are significant differences between gastric cancer tissues and their matched adjacent tissues in DNA methylation. DNA methylation genes locate on different chromosomes, and their number and distribution vary widely. These genes may be associated with many pathways in carcinogenesis.