MicroRNAs in biological processes and carcinogenesis.

MicroRNAs (miRNAs) encoding small non-coding RNAs have been recognized as a very large gene family present in most organisms. The precise biological effects of miRNAs are yet to be elucidated in detail, partly because each miRNA is believed to negatively regulate the expression of hundreds of target genes. Nevertheless, recent findings indicate that carcinogenic processes are associated with alterations in the expression of several miRNAs, suggesting that some function as oncogenes or tumor suppressor genes. The present review focuses on recent findings in this exciting new area of research, with special emphasis on the involvement of miRNAs in cancer development and progression. Further studies are clearly warranted to elucidate the molecular and biological roles of miRNAs, which may ultimately provide both a better understanding of disease development, as well as a foundation for novel strategies for cancer diagnosis and therapy.