Differential expression of microRNAs in colorectal cancer: Different patterns between isolated cancer gland and stromal cells

Although microRNAs (miRNAs) play an important role in invasive tumor lesions, which involve cancer tissues mixed with stromal tissues, the differences in miRNA expression between cancer and stromal cells remain unclear. We selected 13 miRNAs and examined their differential expression patterns in cancer gland cells and surrounding stromal cells isolated from 24 colorectal cancer (CRC) specimens using a crypt isolation method. Although six miRNAs were upregulated in gland cells, only three were upregulated in the corresponding stromal cells, in the cancer compared with non-cancer specimens. Next, we examined the differences in miRNA expression between isolated cancer gland and stromal cells. Five miRNAs showed statistical differences in their cancer-related differential expression patterns between isolated cancer gland and stromal cells. We then compared these miRNA expression patterns in isolated cancer gland and stromal cells with those in fresh intact tumor tissues, consisting of cancer nests and stromal tissue, obtained from the 24 CRCs. The expression patterns of three miRNAs in the intact cancer tissue samples did not correspond with those in the isolated components. Identification of the expression patterns of miRNAs in both the cancer gland and stromal cell components of the tumor microenvironment greatly contributes to evaluating epigenetic regulation in CRC.