DEAD-box RNA Helicases: the microRNA managers of breast cancer

The roles of non-coding RNAs in cancers, microRNA (miRNA) especially, have sparked interest in the field of RNA research in recent years. The once widely accepted ‘central dogma of genetics’ describing the flow of cellular protein expression is now being challenged following the discovery of non-coding RNA research. miRNAs belong to the family of non-coding RNAs, in which many have been shown to be involved in cancer progression, including breast cancer. Goh et al. have recently summarized comprehensively, the roles of miRNAs in the hallmarks of breast cancer progression. In this research highlight, we provide a brief summary of these miRNA-associated hallmarks in breast cancer progression and also highlight on a family of proteins known as DEAD-box RNA helicases, many of which have been found to be associated with miRNA-associated tumorigenesis. There are an increasing number of studies on DEAD-box RNA helicases in recent years, with different roles being reported in numerous cancer types. DDX20, a member of the DEAD-box RNA helicase family, was most recently identified by our group to be involved in breast cancer progression and metastasis. New data from our group found a possible novel miRNA-processing role of DDX20 in breast cancer. In an ongoing study, we found miRNA miR-222 expression inversely correlates with DDX20, suggesting a possible tumor suppressor role of miR-222 in invasive breast cancers, contrary to previous reports where miR-222 was associated with invasion in breast cancers. Our work thus provides another dimension to the complexity, where miRNAs and DEAD-box RNA helicases play in breast cancers.