Expression level and clinical application value of human serum exosomal miR-218-5p in colorectal cancer / 中华检验医学杂志

ABSTRACT

Objective:To explore the expression level of exosomal miR-218-5p in the serum of patients with colorectal cancer (CRC) and its correlation with the clinical pathological characteristics, and evaluate its diagnostic efficacy in CRC.Methods:A group of 78 patients with colorectal cancer diagnosed in Tongji Hospital affiliated to Tongji University from October 2016 to October 2018 were selected. Blood was collected before operation and serum was preserved. Forty cases of healthy people in the same period were selected as the control group. ExoQuick kit was used to extract serum exosomes. Transmission electron microscope, NTA and western blot were used to identify the morphology and molecular phenotype of exosomes. MiRNeasy kit was used to extract total RNA in serum exosomes. Real-time fluorescent quantitative PCR (RT-qPCR) was used to detect the expression level of serum exosomal miR-218-5p in each group. CRC patients were divided into high expression and low expression groups using the median relative expression level of miR-218-5p as the cut off value, and the four-square chi-square test (χ 2 test) was used to judge the relationship between miR-218-5p and clinicopathological features. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficacy of miR-218-5p in colorectal cancer. Results:The exosomes in serum were successfully extracted by kit method. The expression level of serum exosomal miR-218-5p in patients with colorectal cancer was significantly lower than that in normal healthy people [0.566(0.364, 0.850) vs 1.054(0.781, 1.709), P<0.001]. The low expression level was significantly better then the correlated with tumor size, TNM stage, lymph node metastasis and depth of invasion (all P<0.05). Receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) of serum exosomal miR-218-5p for the diagnosis of CRC was 0.827 (95% CI 0.754-0.900), which was significantly better than the conventional tumor marker carcinoembryonic antigen CEA (AUC =0.718, 95% CI 0.626-0.811) and carbohydrate antigen CA199 (AUC = 0.661, 95% CI 0.564-0.758). Conclusions:The down-regulation of miR-218-5p expression in serum exosomes of colorectal cancer patients is associated with a variety of adverse clinicopathological factors, which has the potential to become a diagnostic biomarker for colorectal cancer.