Objective The purpose of this study was to explore serum miR-135a-5p expression in colorectal cancer and examine the potential usefulness of this molecule as a biomarker for diagnosis in colorectal cancer. Methods Serum samples were collected from 60 patients with primary colorectal cancer, 40 patients with colorectal polyps and 50 healthy controls. Serum miR-135a-5p expression levels were detected by reverse transcription quantitative real-time quantitative polymerase chain reaction. Serum carcinoembryonic antigen and carbohydrate antigen 199 concentrations were detected by MODULAR ANALYTICS E170. Results The relative expression level of serum miR-135a-5p in colorectal cancer patients, colorectal polyps patients and healthy controls was 2.451 (1.107, 4.413), 0.946 (0.401, 1.942) and 0.949 (0.194, 1.415), respectively, indicating that it was significantly higher in colorectal cancer patients than that in the other two groups ( U = 351.0, 313.0, both P < 0.001). Additionally, it was significantly correlated with different degrees of tumour differentiation ( U = 215.0, P = 0.029) and different tumour stages ( U = 202.0, P = 0.013). There was no significant correlation between the relative expression of serum miR-135a-5p and carcinoembryonic antigen ( r2 = 0.023, P = 0.293) or carbohydrate antigen 199 ( r2 = 0.067, P = 0.068) in colorectal cancer patients. Compared with colorectal polyps group, AUCROC of serum miR-135a-5p in colorectal cancer group was 0.832 with 95% CI 0.73-0.93; compared with healthy control group, AUCROC was 0.875 with 95% CI 0.80-0.95. Conclusion Serum miR-135a-5p expression in colorectal cancer patients was higher than that in patients with colorectal polyps and healthy controls, suggesting that serum miR-135a-5p may prove to be an important biomarker for auxiliary diagnosis of colorectal cancer.
Keywords: Colorectal cancer; auxiliary diagnosis; miR-135a-5p; reverse transcription quantitative real-time polymerase chain reaction.