Synthetic small inhibiting RNAs:: Efficient tools to inactivate oncogenic mutations and restore p53 pathways

Single base pair mutations that alter the function of tumor suppressor genes and oncogenes occur frequently during oncogenesis. The guardian of the genome, p53, is inactivated by point mutation in more than 50% of human cancers. Synthetic small inhibiting RNAs (siRNAs) can suppress gene expression in mammalian cells, although their degree of selectivity might be compromised by an amplification mechanism. Here, we demonstrate that a single base difference in siRNAs discriminates between mutant and WT p53 in cells expressing both forms, resulting in the restoration of WT protein function. Therefore, siRNAs may be used to suppress expression of point-mutated genes and provide the basis for selective and personalized antitumor therapy.