Correlation between miR-21 and miR-145 and the incidence and prognosis of colorectal cancer.

PURPOSE: The purpose of this study was to investigate the expression of microRNA (miR)-21 and miR-145 in serum and tumor tissues of patients with colorectal cancer (CRC), and to explore the correlation between the expression of these miRs and the clinicopathological parameters and prognosis of CRC patients. METHODS: Serum specimens, frozen tumor tissue and adjacent normal tissue of 50 CRC patients who were hospitalized in our hospital from February 2009 to February 2011 were collected, along with serum specimens of 30 healthy people (control). The expression levels of miR-21 and miR-145 in serum, tumor tissues and adjacent normal tissues were detected by quantitative real time polymerase chain reaction (qRT-PCR). The correlation between the expression of the two miRs in serum was analyzed by Spearman method. The relationship between the expression of miR- 21 and miR-145 in serum and the pathological parameters and prognosis of patients with CRC were analyzed using clinical data. RESULTS: The expression level of miR-21 in CRC tissue was significantly higher than that in adjacent normal tissues, while the expression of miR-145 in CRC tissue was significantly lower than that in adjacent normal tissues. The expression level of miR-21 in the serum of CRC patients was significantly higher compared with healthy people, while the expression of miR-145 in the serum of CRC patients was significantly lower than that in healthy people. The expression of miR-21 and miR-145 in the serum was positively correlated with their expression in tumor tissue. High expression level of miR-21 in the serum was correlated with tumor size, grade of differentiation, invasion, metastasis and clinical stage, and low expression level of miR-145 in the serum was correlated with tumor size, grade of differentiation, invasion, metastasis and clinical stage. The 5-year overall survival (OS) was 52% (26/50). Single factor survival analysis showed that miR-21 and miR-145 were the influencing factors of OS of patients with CRC. CONCLUSIONS: High expression of miR-21 and low expression of miR-145 are closely related to the development and progression of CRC, especially with the grade of differentiation, invasion, metastasis and clinical stage. MiR-21 and miR-145 in the serum can be used as markers for early screening of CRC and indicators for prognosis prediction.