MicroRNA control of apoptotic programs in cancer

MicroRNAs (miRNAs) are small noncoding regulatory RNAs that are involved in diverse cellular functions, including control of cell growth, differentiation, and apoptosis. Expression of miRNAs is deregulated in most cancers and plays a significant role in all aspects of cancer development. Evasion of apoptosis, or programmed cell death, is one of the hallmarks of cancer. Apoptosis is a well-orchestrated, conserved, irreversible cellular mechanism that balances the effects of cell proliferation and cell death. Although the complex role of miRNAs in the regulation of cellular apoptosis is not fully understood, recent data strongly suggest that miRNAs play a key role in regulating apoptosis and downstream signaling pathways associated with it. Many of the apoptotic genes, irrespective of their proapoptotic or antiapoptotic functions, are regulated by miRNAs. Thus, the miRNAs involved in apoptotic pathways can be broadly classified as proapoptotic and antiapoptotic miRNAs. In this chapter, we discuss the emerging role of miRNAs in regulating cellular apoptosis in cancer.