Oncolytic adenovirus co-expressing miRNA-34a and IL-24 induces superior antitumor activity in experimental tumor model

It has been demonstrated that numerous microRNAs (miRNAs) have potent tumor-suppressing effects on a variety of cancers, implicating a possible application of miRNA in tumor therapy. Oncolytic adenovirus is a suitable vector to deliver tumor suppressor genes for treatment of cancers. However, it remains unknown whether co-expression of tumor suppressor genes and miRNAs can contribute to a more potent antitumor capacity within an oncolytic adenovirus delivery system. In this study, we found that expression of miRNA-34a was reduced in hepatocellular carcinoma (HCC), and the reduced expression of miRNA-34a was associated with worse outcome of HCC patients. Thus, we developed an oncolytic adenoviral vector, AdCN205, to co-express miRNA-34a and IL-24 driven by an adenovirus endogenous E3 promoter in HCC cells. High levels of miRNA-34a and IL-24 expression were detected in AdCN205-IL-24-miR-34a-infected HCC cells. AdCN205-IL-24-miR-34a significantly induced dramatic antitumor activity, as compared with that induced by AdCN205-IL-24 or AdCN205-miR-34a alone. Transfer of miRNA-34a into HCC cells inhibited the expression of its target genes, Bcl-2 and SIRT1. Treatment of established xenograft HCC tumors with AdCN205-IL-24-miR-34a in a mouse model resulted in complete tumor regression without recurrence. Taken together, our data provide a promising and reasonable delivery strategy of double-aimed cancer therapy, in which miRNAs and tumor-suppressing genes are used simultaneously.