When cellular networks run out of control: global dysregulation of the RNAi machinery in human pathology and therapy.

RNA interference (RNAi) is an evolutionarily conserved fundamental cellular mechanism of potent gene and genome regulation whose misfunction is associated with numerous major human pathologies, from metabolic disorders and viral infections to cancers. Over the past 5 years, compelling evidence has been accumulated that this association is provided by dysregulations of specific mi(cro)RNAs and the ensuing aberrant expression of their target genes. Moreover, a string of interesting reports has now added proof that human disorders are also frequently characterized by global alterations in the RNAi machinery, comprising irregular expression and function of the key protein players Drosha, DGCR8, Exportin-5, Dicer, TRBP, and Argonaute. Here, we comprehensively review these emerging findings in the specific contexts of cancers and infections with viral pathogens and, in addition, describe related observations in preclinical gene/RNAi therapy studies. Finally, we also thoroughly discuss the relevance of these results for future basic RNAi research as well as for the looming clinical translation of RNAi-based technologies and therapeutic concepts.