The microproteome of cancer: From invisibility to relevance

Recent findings have revealed that many genomic regions previously annotated as non-protein coding actually contain small open reading frames, smaller that 300 bp, that are transcribed and translated into evolutionary conserved microproteins. To date, only a small subset of them have been functionally characterized, but they play key functions in fundamental processes such as DNA repair, RNA processing and metabolism regulation. This emergent field seems to hide a new category of molecular regulators with clinical potential. In this review, we focus on its relevance for cancer. Following Hanahan and Weinberg's classification of the hallmarks of cancer, we provide an overview of those microproteins known to be implicated in cancer or those that, based on their function, are likely to play a role in cancer. The resulting picture is that while we are at the very early times of this field, it holds the promise to provide crucial information to understand cancer biology.