Transcribed Ultraconserved Regions (T-UCR) as a Missing Puzzle in Cancer Research

The ultraconserved regions (UCRs) of the DNA are highly similar across different organisms due to the negative selection of these DNA regions. The UCRs are transcribed into non-coding RNAs, named transcribed UCRs (T-UCRs). The current review on T-UCRs has identified the most significant T-UCRs for cancer, and it argues that there should be a focus on these T-UCRs to better understand their molecular mechanism in different cancers. Most of T-UCRs have an oncogenic role, with uc.63+, uc.338, uc.339, and uc.147 being the most commonly mentioned. At the same time, uc.160 and uc.454 have a tumor suppressor role. Uc.138 and uc.238+A have dual roles depending on the cancer type, probably through the modulation of different molecular pathways. Interestingly, there are T-UCRs with high specificity, such as uc.300A in neuroblastoma or uc.112 in B-ALL. Future research should acknowledge the current limitations and further improve the scientific approach.