The miRNAs are differentially expressed between colonic tumor tissues and para-cancerous tissues. Many of these miRNAs are expected to participate in the process of multiple tumorigenesis. These miRNAs could play an important role in the carcinogenesis of colon. These results provide new insights in human colorectal cancer genesis.

OBJECTIVE:To identify microRNA expression patterns associated with the lymph node metastasis of colon cancer. METHODS:MicroRNA were isolated from six frozen non-cancerous surrounding colonic tissues derived from stage II-III colon cancer patients with (n = 3) and without (n = 3) lymph node metastasis. We compared the microRNA expression profiles of the six non-cancerous colonic tissues from two colon cancer patient groups; those with confirmed lymph node metastasis, termed the lymph node positive group, and those without detectable lymph node metastasis, termed the lymph node negative group. MicroRNA expression was analyzed with Agilent microarrays containing 723 human microRNA probes. We validated the expression level of differentially expressed microRNA using quantitative real-time PCR analysis. RESULTS:Two microRNA (hsa-miR-129*, hsa-miR-137) were differentially expressed in the lymph node positive group compared with the lymph node negative group. The expression level of hsa-miR-137 was quantified via quantitative real-time PCR analysis for validation. Hsa-miR-137 expression was significantly upregulated nearly 6.6-fold in lymph node positive specimens (P = 0.036). The quantitative real-time PCR result correlates with the microarray finding. CONCLUSION:The non-cancerous colonic tissues from colon cancer patients with lymph node metastasis have a significantly different microRNA expression profile compared to that from colon cancer patients without lymph node metastasis. The differentially expressed microRNA could have relevance to the lymph node metastasis of colon cancer and may provide a simple profiling method to assist in identifying patients with lymph node metastasis. Besides, these data might offer new ideas for preventing and controlling lymphatic metastasis in colon cancer.KEY WORDS: adjacent non-cancerous colonic tissue, colon cancer, hsa-miR-137, lymph node metastasis, microRNA expression profile.