# An Enterovirus-Like RNA Construct for Colon Cancer Suicide Gene Therapy

## TL;DR

Researchers designed an RNA construct for colon cancer therapy that can express a suicide gene, but its activity is controlled by microRNAs, which are often downregulated in cancer.

## Contribution

A novel enterovirus-like RNA construct is proposed for suicide gene therapy, regulated by miRNA targeting.

## Key findings

- Enterovirus-like RNA effectively expressed both reporter and suicide genes in colon cancer cells.
- Restoring hsa-miR-143 in cancer cells significantly repressed the expression of the RNA construct's genes.
- RNA constructs with miRNA target sequences may have reduced activity in cancer tissues with downregulated miRNAs.

## Abstract

In gene therapy, the use of RNA molecules as therapeutic agents has shown advantages over plasmid DNA, including higher levels of safety. However, transient nature of RNA has been a major obstacle in application of RNA in gene therapy.

Here, we used the internal ribosomal entry site of encephalomyocarditis virus and the 3’ non-translated region of Poliovirus to design an enterovirus-like RNA for the expression of a reporter gene (enhanced green fluorescent protein) and a suicide gene (thymidine kinase of herpes simplex virus). The expression of these genes was evaluated by flow cytometry and cytotoxicity assay in human colorectal adenocarcinoma cell line (SW480). We then armed RNA molecules with a target sequence for hsa-miR-143 to regulate their expression by microRNA (miRNA) mimics.

The results showed effective expression of both genes by Entrovirus-like RNA constructs. The data also showed that the restoration of hsa-miR-143 expression in SW480 leads to a significant translation repression of the introduced reporter and suicide genes.

Collectively, our data suggest the potential use of Entrovirus-like RNA molecules in suicide gene therapy. Additionally, as a consequence of the possible downregulated miRNA expression in cancerous tissues, a decreased expression of gene therapy constructs armed with target sequences for such miRNA in cancer tissue is expected.