Long non-coding RNAs (lncRNAs) are emerging as important regulators of tissue physiology and disease processes including cancer. In order to delineate genome-wide lncRNA expression, we curated 7,256 RNA-Seq libraries from tumors, normal tissues, and cell lines comprising over 43 terabases of sequence from 25 independent studies. We applied ab initio assembly methodology to this dataset, yielding a consensus human transcriptome of 91,013 expressed genes. Over 68% (58,648) of genes were classified as lncRNAs, of which 79% (48,952) were previously unannotated. About 1% (597) of the lncRNAs harbored ultraconserved elements and 7% (3,900) overlapped disease-associated single nucleotide polymorphisms (SNPs). To prioritize lineage-specific, disease-associated lncRNA expression we employed non-parametric differential expression testing and nominated 7,942 lineage- or cancer-associated lncRNA genes. The lncRNA landscape characterized here may shed light into normal biology and cancer pathogenesis, and be valuable for future biomarker development.

While mutations affecting protein-coding regions have been examined across many cancers, structural variants at the genome-wide level are still poorly defined. Through integrative deep whole-genome and -transcriptome analysis of 101 castration-resistant prostate cancer metastases (109X tumor/38X normal coverage), we identified structural variants altering critical regulators of tumorigenesis and progression not detectable by exome approaches. Notably, we observed amplification of an intergenic enhancer region 624 kb upstream of the androgen receptor (AR) in 81% of patients, correlating with increased AR expression. Tandem duplication hotspots also occur near MYC, in lncRNAs associated with post-translational MYC regulation. Classes of structural variations were linked to distinct DNA repair deficiencies, suggesting their etiology, including associations of CDK12 mutation with tandem duplications, TP53 inactivation with inverted rearrangements and chromothripsis, and BRCA2 inactivation with deletions. Together, these observations provide a comprehensive view of how structural variations affect critical regulators in metastatic prostate cancer.

Luminal- and basal-like prostate cancers demonstrate divergent clinical behavior, and patients with luminal B tumors respond better to postoperative ADT than do patients with non–luminal B tumors. These findings contribute novel insight into prostate cancer biology, providing a potential clinical tool to personalize ADT treatment for prostate cancer by predicting which men may benefit from ADT after surgery.

Alternative RNA splicing plays an important role in cancer. To determine which factors involved in RNA processing are essential in prostate cancer, we performed a genome-wide CRISPR/Cas9 knockout screen to identify the genes that are required for prostate cancer growth. Functional annotation defined a set of essential spliceosome and RNA binding protein (RBP) genes, including most notably heterogeneous nuclear ribonucleoprotein L (HNRNPL). We defined the HNRNPL-bound RNA landscape by RNA immunoprecipitation coupled with next-generation sequencing and linked these RBP-RNA interactions to changes in RNA processing. HNRNPL directly regulates the alternative splicing of a set of RNAs, including those encoding the androgen receptor, the key lineage-specific prostate cancer oncogene. HNRNPL also regulates circular RNA formation via back splicing. Importantly, both HNRNPL and its RNA targets are aberrantly expressed in human prostate tumors, supporting their clinical relevance. Collectively, our data reveal HNRNPL and its RNA clients as players in prostate cancer growth and potential therapeutic targets.CRISPR screen | HNRNPL | prostate cancer | RNA binding protein | alternative splicing P rostate cancer is among the most prevalent adult malignancies in developed countries. The principal treatment for prostate cancer once it is no longer amenable to surgery or radiation treatment is androgen deprivation therapy, which targets androgen or androgen receptor (AR) signaling. However, resistance to androgen deprivation therapy often develops and leads to a state termed "castration-resistant prostate cancer," which still lacks an effective cure (1-3). Therefore, significant efforts have been devoted to better understand the mechanism of oncogenesis and to develop additional effective therapeutics targeting pivotal oncogenes, cancer-related signal transduction pathways, and epigenetic regulators (4, 5).Alternative RNA splicing is a fundamental cellular process by which a single gene can give rise to multiple different transcripts and proteins. This process is tightly regulated by core spliceosomes and other splicing factors, such as the serine/ arginine-rich family of proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs) (6, 7). Multiple studies indicate that deregulation of alternative splicing is implicated in cancer progression and that the splicing machinery may be targeted therapeutically (8-10). In addition to RNA splicing, the physical interactions between RNAs and RNA binding proteins (RBPs) underlie multiple RNA processing steps, such as capping, polyadenylation, transport, localization, modification, and translation, thereby regulating many aspects of RNA fate (11).Which RBPs and their related RNA processing steps are functionally important, especially in prostate cancer, remains elusive.The recent implementation of the clustered regularly interspaced short palindromic repeats (CRISPR)-associated nuclease Cas9 genome editing system has proved effective in high-throughput lossof-function screens (12)(13)(14)...