Reinforcement of the Tumor Suppressing Properties of microRNA-1 by Substitution at the C2' Position of Varying Ribose Residues in Chemically Synthesized microRNA-1 Molecules

Background/aim: Tumor suppressive microRNAs (miR) are frequently down-regulated during cancer development. The application of synthetic miR molecules restoring suppressed miR, therefore, opens up innovative possibilities in future anticancer therapy. The potential application, however, is limited by the instability of RNA molecules. The presented proof-of-principle study evaluates the potential of using synthetic chemically modified miR molecules as anticancer drugs.

Materials and methods: Chemically synthesized miR-1 molecules containing two 2'-O-RNA modifications, 2'-O-methyl- and 2'-fluoro-derivatives, introduced at different positions of the 3'-terminus, were transfected into prostate cancer (PC) cells (LNCaP, PC-3). Detectability was measured by quantitative RT-PCR. The effect of modifications regarding the growth inhibitory activity of miR-1 was investigated by cell growth kinetics with transfected PC cells.

Results: All variants of synthetic modified miR-1 could be transfected into PC cells and were detectable by RT-PCR. Depending on the chemical modification, but especially on the position of the modification, the growth inhibitory activity of synthetic modified miR-1 was increased compared to synthetic unmodified miR-1.

Conclusion: Synthetic miR-1 can be enhanced in its biological activity by modification of the C2'-OH group. This depends on the chemical substituent, the position and number of substituted nucleotides. The molecular fine-tuning of tumor suppressive miR like miR-1 may represent a promising approach for the development of multi-targeting nucleic acid-based drugs for cancer therapy.