Identifying metastasis-initiating miRNA-target regulations of colorectal cancer from expressional changes in primary tumors.

Colorectal cancer (CRC) is prevalent with high mortality, with liver metastasis contributing as a major factor that worsens the survival of patients. The roles of miRNAs in CRC have been elucidated, subsequent to recent studies that suggest the involvement of miRNAs in cancer biology. In this study, we compare the miRNA and gene expression profiles of primary tumors between two groups of patients (with and without liver metastasis) to identify the metastasis-initiating microRNA-target gene regulations. Analysis from 33 patients with metastasis and 14 patients without metastasis revealed that 17 miRNAs and their 198 predicted target genes are differentially expressed, where the target genes showed association with cancer progression and metastasis with statistical significance. In order to evaluate the clinical implications of the findings, we classified CRC patients of independent data into two groups based on the identified miRNA-target regulations, where one group was closer to primary tumors with metastasis than the other group. The comparison of survival showed statistically significant difference, thereby implying the roles of the identified miRNA-target regulations in cancer progression and metastasis. The identification of metastasis-initiating miRNA-target regulations in this study will lead to better understanding of the roles of miRNAs in CRC progression.