To explore the correlation between miR-122 and postoperative colorectal liver metastases.

Clinical data of 186 patients with postoperative liver metastases from colorectal cancer who were admitted in the 909^th Hospital of Joint Logistics Support Force of PLA from January 2008 to January 2014 were retrospectively analyzed. The informed consents of all patients were obtained and the local ethical committee approval was received. Among them, 112 patients were male and 74 female, aged 33-76 years old and with a median age of 52. 43 cases were with left-sided colon cancer, 79 cases with right-sided colon cancer and 64 cases with rectal cancer. The relative expression of miR-122 in cancerous and paraneoplastic tissues was quantified by qRT-PCR. Comparison of miR-122 relative expression between two groups was performed using t test. The correlation between miR-122 expression and time to postoperative liver metastasis was analyzed by linear correlation analysis.

The average relative expression of miR-122 in colorectal cancer tissues was 1.28±0.14, which was significantly higher than 0.83±0.09 in paraneoplastic tissues (t=124.00, P<0.05). miR-122 relative expression was associated with tumor diameter, tumor differentiation, and lymph node metastasis in patients with postoperative liver metastases from colorectal cancer (t=-7.17, 4.16, -8.69; P<0.05). Time to postoperative liver metastasis from colorectal cancer was (23±9) months. The miR-122 relative expression in cancer tissues was negatively correlated with the time to postoperative liver metastasis (r=-0.67, P<0.05).

miR-122 is highly expressed in colorectal cancer tissue. The miR-122 expression was negatively correlated with the time to postoperative liver metastasis. The higher expression is, the earlier liver metastasis occurs.