A selective Aurora-A 5'-UTR siRNA inhibits tumor growth and metastasis.

Many Aurora-A inhibitors have been developed for cancer therapy; however, the specificity and safety of Aurora-A inhibitors remain uncertain. The Aurora-A mRNA yields nine different 5'-UTR isoforms, which result from mRNA alternative splicing. Interestingly, we found that the exon 2-containing Aurora-A mRNA isoforms are predominantly expressed in cancer cell lines as well as human colorectal cancer tissues, making the Aurora-A mRNA exon 2 a promising treatment target in Aurora-A-overexpressing cancers. In this study, a selective siRNA, siRNA-2, which targets Aurora-A mRNA exon 2, was designed to translationally inhibit the expression of Aurora-A in cancer cells but not normal cells; locked nucleic acid (LNA)-modified siRNA-2 showed improved efficacy in inhibiting Aurora-A mRNA translation and tumor growth. Xenograft animal models combined with noninvasion in vivo imaging system (IVIS) analysis further confirmed the anticancer effect of LNA-siRNA-2 with improved efficiency and safety and reduced side effects. Mice orthotopically injected with colorectal cancer cells, LNA-siRNA-2 treatment not only inhibited the tumor growth but also blocked liver and lung metastasis. The results of our study suggest that LNA-siRNA-2 has the potential to be a novel therapeutic agent for cancer treatment.