Cancer is a disease of aberrant gene expression. While the genetic causes of cancer have been intensively studied, it is becoming evident that a large proportion of cancer susceptibility cannot be attributed to variation in protein-coding sequences. This is highlighted by genome-wide association studies in cancer that reveal that more than 80% of cancer-associated SNPs occur in noncoding regions of the genome. In this review, we posit that a significant fraction of the genetic aetiology of cancer is exacted by noncoding regulatory sequences, particularly by long noncoding RNAs (lncRNAs). Recent studies indicate that several cancer risk loci are transcribed into lncRNAs and these transcripts play key roles in tumorigenesis. We discuss the epigenetic and other mechanisms through which lncRNAs function and how they contribute to each stage of cancer progression, understanding of which will be crucial for realising new opportunities in cancer diagnosis and treatment. Long noncoding RNAs play important roles in almost every aspect of cell biology from nuclear organisation and epigenetic regulation to post-transcriptional regulation and splicing, and we link these processes to the hallmarks and genetics of cancer. Finally, we highlight recent progress and future potential in the application of lncRNAs as therapeutic targets and diagnostic markers.

Highlights d Single-cell genomic analysis of hippocampal neurons reveals a somatic L1 insertion d The donor L1 is slightly 5ʹ truncated and lacks a conserved YY1 binding site d Young L1s with truncated or mutated YY1 binding sites are globally hypomethylated d L1 is able to mobilize in the brain because of locus-specific exceptions to repression

SummaryThe ability to profile transcription and chromatin binding in a cell type-specific manner is a powerful approach for understanding cell fate specification and cellular function in multicellular organisms.We recently developed Targeted DamID (TaDa) to enable genome-wide, cell-type-specific profiling of DNA-and chromatin-binding proteins in vivo without cell isolation. As a Protocol Extension, this article describes substantial modifications to an existing Protocol and offers additional applications.TaDa builds upon DamID, a technique for detecting genome-wide DNA binding profiles of proteins, by coupling it with the GAL4 system in Drosophila to enable both temporal and spatial resolution.TaDa ensures that Dam-fusion proteins are expressed at very low levels, avoiding toxicity and potential artefacts from over-expression. The modifications to the core DamID technique presented here also increase the speed of sample processing and throughput, and adapt the method to Nextgeneration Sequencing technology. TaDa is robust, reproducible, and highly sensitive. Compared to other methods for cell-type specific profiling, the technique requires no cell-sorting, crosslinking or antisera, and binding profiles can be generated from as few as 10,000 total induced cells. By profiling the genome-wide binding of RNA polymerase II, TaDa can also identify transcribed genes in a cell type-specific manner. Here we describe a detailed protocol for carrying out TaDa experiments and preparing the material for next generation sequencing. Although we developed TaDa in Drosophila, it should be easily adapted to other organisms with an inducible expression system. Once transgenic animals are obtained, the entire experimental procedure -from collecting tissue samples to generating sequencing libraries -can be accomplished within 5 days.