OBJECTIVETo study the difference of gene expression profile among colorectal cancer tissue, pericancerous mucosa and normal mucosa, and to screen associated novel genes in colorectal carcinogenesis by DNA microarray.

METHODScDNA chip containing approximate 8000 genes was used to detect differentially expressed genes in colorectal cancer tissues, pericancerous mucosa and normal mucosa, and to screen associated novel genes in colorectal carcinogenesis by DNA microarray.

RESULTSAs compared with normal mucosa, 769 genes differentially expressed in cancerous tissue were identified, which included 363 up-regulated and 406 down-regulated genes. In pericancerous mucosa 3 cm away from cancerous tissues, 155 genes differentially expressed were identified, of whom 52 genes were up-regulated and 103 were down-regulated. In pericancerous mucosa 5 cm away from cancerous tissues, 230 genes differentially expressed were identified, of whom 46 genes were up-regulated and 184 genes were down-regulated. The genes expressed differentially were associated with several functional types. According to the primary results, the differentially expressed genes with prominent functions included tumor-related genes, genes regulating cell proliferation and apoptosis, transcriptional control genes, and construction and degradation of extracellular matrix-associated genes. The cancerous mucosa was obviously different from the normal mucosa(about 20%, 769/3944). The differences between the normal mucosa and pericancerous mucosa were relatively small (3.9%,5.8%).

CONCLUSIONSDifferent tissues have their own biological property. Several genes play roles in the development of colorectal carcinogenesis. Genes in adjacent non-cancerous tissues are also expressed differentially, leading to a malignant change.