Abstract
Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, particularly in developing countries. Despite the achievements in clinical therapeutics, the HCC mortality rate remains high. A number of artificial microRNA (amiRNA)-based HCC gene therapy studies have demonstrated significant inhibition of invasion and induction of apoptosis of HCC cancer cells, indicating that this type of therapy may be a promising alternative to current therapeutics. Since the structure of the amiRNA precursor in the specific intracellular environment is critical for the processing to mature amiRNA, a precursor structure that may be efficiently processed is desired. In this study, we constructed amiRNAs targeting firefly luciferase with the precursor structures of six HCC-abundant microRNAs: miR-18a, miR-21, miR-192, miR-221, miR-222 and miR-224, and evaluated the processing efficiency of these amiRNAs in the HCC cell lines Hep3B and HepG2 using a luciferase reporter system. The results demonstrated that these amiRNA precursors are capable of being expressed in HCC cells, with the miR-221 precursor-based amiRNA exhibiting the most efficient inhibition on firefly luciferase at the levels of mRNA and protein activity. This finding provides a basis for constructing HCC-targeting amiRNAs with potent processing efficiency using the precursor structure of miR-221.