An expression analysis of miR-200a in serum and liver tissue during the process of liver cancer development in rats

Abstract

To explore whether microRNA-200a (miR-200a) could be used as a novel biomarker of liver cancer using a rat model system. Diethylnitrosamine abdominal injection was applied to induce liver cancer in the F344 rat strain (n =40); ten unmodeled rats served as controls. In addition, human subjects with normal healthy liver (n =10), liver cirrhosis (n =10), and liver cancer (n =10) were enrolled in the study. Blood samples from both rats and patients and rats' livers were collected for analysis. Real-time quantitative PCR and enzyme-linked immunosorbent assay were used respectively to measure the expressions of serum miR-200a and alpha-fetoprotein (AFP) for all rat and human subjects. In situ hybridization was used to detect the miR-200a expression in the rats' livers. Comparison of normal rats and the liver cancer modeled rats showed that the latter had significantly lower expression of miR-200a (P less than 0.05), with decreasing expression following the progression of liver injury to cancer (liver cirrhosis rats less than early liver cancer rats less than advanced liver cancer rats); in contrast, the AFP levels were significantly higher in the liver cancer modeled rats only at the early and advanced stages of the liver cancer (P less than 0.05). These suggested that miR-200a expression decreases during the developmental process of liver cancer, while AFP expression increases distinctly at the stage of tumor formation. Analysis of the human subjects' clinical samples showed that miR-200a expression was decreased in both liver cirrhosis patients and liver cancer patients (vs. normal liver subjects, P less than 0.05), while AFP showed abnormal expression only in the patients with liver cancer. Comparison of the normal rats and modeled rats using in situ hybridization showed the positive rates for miR-200a expression were 1.00% +/- 0.01% in rats with normal liver, 0.37% +/- 0.03% in rats with fibrotic liver, 0.14% +/- 0.01% in rats with cirrhotic liver, 0.05% +/- 0.00% in rats with early stage liver cancer, and 0.01% +/- 0.00% in rats with advanced stage liver cancer. MiR-200a may play an important role in liver cancer development and may have diagnostic value for indicating early liver cancer.