With the advent of new and improved high-throughput sequencing technologies in the last few years, a growing number of novel classes of small RNA, other than miRNAs or siRNA, has emerged, which appear as new actors in gene expression regulation. tRNA-derived small RNAs represent one of these novel members that are, surprisingly, among the most conserved class of small RNAs throughout evolution. They could represent the most primitive small RNA pathways from which the well-known canonical RNA silencing pathways reported in higher eukaryotes evolved. This review aims to make a compilation of the most relevant research literature in this field with the purpose of shedding light on the relation of these primitive tRNA-derived molecules with the gene silencing machinery.

SummarySmall noncoding RNAs are key controllers of cellular function, and their deregulation can lead to cancer development and metastatic evolution. This review summarizes the most important examples of small RNAs involved in human cancer and discusses their clinical use as biomarkers and drug targets for diagnosis, prognosis, and treatment of cancer. We also describe the possible mechanisms underlying small RNA-mediated transformation and outline the future describing new small RNA families with great potential in cancer biology.

The complete understanding of the growing catalog of regulatory non-coding RNAs is going to shed light in different aspects of a wide range of pathogenic mechanisms in human diseases. This review was aimed to highlight recent advances in the small non- coding RNA world that could have implications in the development of new strategies in medical sciences. Among the diverse group of small non-coding RNAs, we highlight the group of tRNA-derived fragments as molecules known for a long time which have recently emerged as novel regulators influencing several aspects of cell biology. We describe here recent advances in the field of tRNA-derived fragments playing key roles in the biology of some infectious agents, including E. coli, A. fumigatus, G. lamblia, Ascaris, T. cruzi, Virus, Prions and a brief overview linking them to cancer biology. Additionally, we focus on the potential implications of these molecules in future biotechnological applications in the development of new biomarkers and as new therapeutic targets.

No abstract