Preliminary study on microRNA expression profiles of colonic cancer without lymph node metastasis

Objective To investigate microRNA expression profiles of colonic cancer without lymph node metastasis and identify the specific microRNAs associated with carcinogenesis of colon.Methods Cancerous and para-cancerous tissues (5 cm from cancer tissues of the colon) confirmed without lymph node metastasis were collected from 3 patients. The microRNAs were extracted and isolated by mirVana RNA kit. Hybridizations were made by applying the microRNAs to Agilent microRNA microarray. Data analysis was done by software of Feacture Extraction. The discovered microRNAs were confirmed by real time PCR assay. Results Twelve out of 14 microRNAs associated with colonic cancer were up-regulated in colonic tissues. They were miR-106b, miR-135b,miR-18a,miR-18b,miR-196b, miR-19a, miR-224, miR-335, miR-424, miR-20a' , miR-301b and miR-374a. The rest two of miR-378 and miR 378* were down-regulated. Two up-regulated microRNAs (miR-18a and miR-135b) were detected in 3 pairs of cancerous and para-cancerous tissues. The expression level of miR-18a and miR-135b were accordant with the results of real time PCR.Conclusions microRNA.such as miR-106b,miR-135b.miR-18a.miR-18b,miR-196b,ect,were differentially expressed between cancerous and para-cancerous tissues.Many of these target genes are supposed to participate in the process of multiple tunmorgenesis.These microRNAs play an important role in the carcinogenesis of colon. Key words: Colonic neoplasms; MicroRNAs; Microchip analytical procedures