Apoptomirs: small molecules have gained the license to kill.

Apoptosis is a tightly regulated form of cell death and represents an important process during normal development. In the past years, the scientific community has produced remarkable advances in our understanding of cancer biology, realizing that apoptosis and the genes that control it have a profound effect on the malignant phenotype. Recently, a new class of non-coding RNA genes, known as microRNA (miRNA or miR), have been demonstrated to play important roles in diverse biological processes, including development, cell differentiation, proliferation, and apoptosis. This suggests that other oncogenic mechanisms are needed to produce selective pressure to override apoptosis during multistage carcinogenesis. Intriguingly, since most cytotoxic anticancer agents induce apoptosis, it is possible that defects in apoptotic programs may contribute to treatment failure. Several studies strongly suggest a role for microRNAs in modulating sensitive/resistant phenotypes to cytotoxic therapy, calling for further investigation and validation of microRNA functions and targets in order to improve sensitivity to cancer treatments, thus ultimately improving prognosis and survival. Here, we review the current findings about microRNAs focusing on their involvement in the apoptotic process.