LncRNAs in Cancer: From garbage to Junk

SIMPLE SUMMARY: Long non-coding RNAs (lncRNAs) are generally defined as transcripts longer than 200 nucleotides and not coding for proteins. This review provides an overview of the main functions of lncRNAs in the cells and their role in tumorigenesis. Additionally, key examples of oncogenic and/or tumor suppressive lncRNAs with a well-established role in tumor development and progression are discussed. Finally, the currently available technological approaches to target lncRNAs (e.g., by modifying their expression, stability, processing and/or binding capacity), with a specific focus on the pros and cons of their use as therapeutic targets are considered. ABSTRACT: Sequencing-based transcriptomics has significantly redefined the concept of genome complexity, leading to the identification of thousands of lncRNA genes identification of thousands of lncRNA genes whose products possess transcriptional and/or post-transcriptional regulatory functions that help to shape cell functionality and fate. Indeed, it is well-established now that lncRNAs play a key role in the regulation of gene expression through epigenetic and posttranscriptional mechanims. The rapid increase of studies reporting lncRNAs alteration in cancers has also highlighted their relevance for tumorigenesis. Herein we describe the most prominent examples of well-established lncRNAs having oncogenic and/or tumor suppressive activity. We also discuss how technical advances have provided new therapeutic strategies based on their targeting, and also report the challenges towards their use in the clinical settings.