HDAC Inhibition Restores Response to HER2-Targeted Therapy in Breast Cancer via PHLDA1 Induction.

The downregulation of Pleckstrin Homology-Like Domain family A member 1 (PHLDA1) expression mediates resistance to targeted therapies in receptor tyrosine kinase-driven cancers. The restoration and maintenance of PHLDA1 levels in cancer cells thus constitutes a potential strategy to circumvent resistance to inhibitors of receptor tyrosine kinases. Through a pharmacological approach, we identify the inhibition of MAPK signalling as a crucial step in PHLDA1 downregulation. Further ChIP-qPCR analysis revealed that MEK1/2 inhibition produces significant epigenetic changes at the PHLDA1 locus, specifically a decrease in the activatory marks H3Kme3 and H3K27ac. In line with this, we show that treatment with the clinically relevant class I histone deacetylase (HDAC) inhibitor 4SC-202 restores PHLDA1 expression in lapatinib-resistant human epidermal growth factor receptor-2 (HER2)+ breast cancer cells. Critically, we show that when given in combination, 4SC-202 and lapatinib exert synergistic effects on 2D cell proliferation and colony formation capacity. We therefore propose that co-treatment with 4SC-202 may prolong the clinical efficacy of lapatinib in HER2+ breast cancer patients.

Precision medicine and lymphoma.

PURPOSE OF REVIEW: The treatment of the germinal center lymphomas, diffuse large B cell (DLBCL) and follicular lymphoma, has changed little beyond the introduction of immunochemotherapies. However, there exists a substantial group of patients within both diseases for which improvements in care will involve appropriate tailoring of treatment. RECENT FINDINGS: DLBCL consists of two major subtypes with striking differences in their clinical outcomes paralleling their underlying genetic heterogeneity. Recent studies have seen advances in the stratification of germinal center lymphomas, through comprehensive profiling of 1001 DLBCLs alongside refinements in the identification of high-risk follicular lymphoma patients using m7-FLIPI and 23G models. A new wave of novel therapeutic agents is now undergoing clinical trials for germinal center lymphomas, with BCR and EZH2 inhibitors demonstrating preferential benefit in subgroups of patients. The emergence of cell-free DNA has raised the possibility of dynamic disease monitoring to potentially mitigate the complexity of spatial and temporal heterogeneity, whilst predicting tumor evolution in real time. SUMMARY: Altogether knowledge of the genomic landscape of germinal center lymphomas is offering welcome opportunities in patient risk stratification and therapeutics. The challenge ahead is to establish how best to combine upfront or dynamic prognostication with precision therapies, while retaining practicality in clinical trials and the real-world setting.

Long non-coding RNAs in the regulation of the immune response.

It is increasingly clear that long non-coding RNAs (lncRNAs) regulate a variety biological responses, and that they do so by a diverse range of mechanisms. In the field of immunology, recent publications have shown widespread changes in the expression of lncRNAs during the activation of the innate immune response and T cell development, differentiation, and activation. These lncRNAs control important aspects of immunity such as production of inflammatory mediators, differentiation, and cell migration through regulating protein-protein interactions or via their ability to basepair with RNA and DNA. We review the current understanding of the mechanism of action of these immune-related lncRNAs, discuss their impact on physiological and pathological processes, and highlight important areas of inquiry at the intersection between immunology and lncRNA biology.

Follicular lymphoma, a B cell malignancy addicted to epigenetic mutations.

While follicular lymphoma (FL) is exquisitely responsive to immuno-chemotherapy, many patients follow a relapsing remitting clinical course driven in part by a common precursor cell (CPC) population. Advances in next generation sequencing have provided valuable insights into the genetic landscape of FL and its clonal evolution in response to therapy, implicating perturbations of epigenetic regulators as a hallmark of the disease. Recurrent mutations of histone modifiers KMT2D, CREBBP, EP300, EZH2, ARIDIA, and linker histones are likely early events arising in the CPC pool, rendering epigenetic based therapies conceptually attractive for treatment of indolent and transformed FL. This review provides a synopsis of the main epigenetic aberrations and the current efforts in development and testing of epigenetic therapies in this B cell malignancy.

Knockdown of Nuclear-Located Enhancer RNAs and Long ncRNAs Using Locked Nucleic Acid GapmeRs.

The human genome is widely transcribed outside of protein-coding genes, producing thousands of noncoding RNAs from different subfamilies including enhancer RNAs. Functional studies to determine the role of individual genes are challenging with noncoding RNAs appearing to be more difficult to knockdown than mRNAs. One factor that may have hindered progress is that the majority of noncoding RNAs are thought to be located within the nucleus, where the efficiency of traditional RNA interference techniques is debatable. Here we present an alternative RNA interference technique utilizing Locked Nucleic Acids, which is able to efficiently knockdown noncoding RNAs irrespective of intracellular location.

Catalog of Differentially Expressed Long Non-Coding RNA following Activation of Human and Mouse Innate Immune Response.

Despite increasing evidence to indicate that long non-coding RNAs (lncRNAs) are novel regulators of immunity, there has been no systematic attempt to identify and characterize the lncRNAs whose expression is changed following the induction of the innate immune response. To address this issue, we have employed next-generation sequencing data to determine the changes in the lncRNA profile in four human (monocytes, macrophages, epithelium, and chondrocytes) and four mouse cell types (RAW 264.7 macrophages, bone marrow-derived macrophages, peritoneal macrophages, and splenic dendritic cells) following exposure to the pro-inflammatory mediators, lipopolysaccharides (LPS), or interleukin-1ß. We show differential expression of 204 human and 210 mouse lncRNAs, with positional analysis demonstrating correlation with immune-related genes. These lncRNAs are predominantly cell-type specific, composed of large regions of repeat sequences, and show poor evolutionary conservation. Comparison within the human and mouse sequences showed less than 1% sequence conservation, although we identified multiple conserved motifs. Of the 204 human lncRNAs, 21 overlapped with syntenic mouse lncRNAs, of which five were differentially expressed in both species. Among these syntenic lncRNA was IL7-AS (antisense), which was induced in multiple cell types and shown to regulate the production of the pro-inflammatory mediator interleukin-6 in both human and mouse cells. In summary, we have identified and characterized those lncRNAs that are differentially expressed following activation of the human and mouse innate immune responses and believe that these catalogs will provide the foundation for the future analysis of the role of lncRNAs in immune and inflammatory responses.

Transcriptional profiling identifies differential expression of long non-coding RNAs in Jo-1 associated and inclusion body myositis.

Myositis is characterised by muscle inflammation and weakness. Although generally thought to be driven by a systemic autoimmune response, increasing evidence suggests that intrinsic changes in the muscle might also contribute to the pathogenesis. Long non-coding RNAs (lncRNAs) are a family of novel genes that regulate gene transcription and translation. To determine the potential role of lncRNAs, we employed next generation sequencing to examine the transcriptome in muscle biopsies obtained from two histologically distinct patient populations, inclusion body myositis (IBM) and anti-Jo-1-associated myositis (Jo-1). 1287 mRNAs and 1068 mRNAs were differentially expressed in the muscle from Jo-1 and IBM patients, respectively. Pathway analysis showed the top canonical pathway in both Jo-1 and IBM was oxidative phosphorylation and mitochondrial dysfunction. We identified 731 known and 325 novel lncRNAs in the muscles biopsies. Comparison with controls showed 55 and 46 lncRNAs were differentially expressed in IBM and Jo-1 myositis, respectively. Of these, 16 lncRNAs were differentially expressed in both IBM and Jo-1 myositis and included upregulated H19, lncMyoD and MALAT1. Given that these are known to regulate muscle proliferation and differentiation, we speculate that changes in lncRNAs might contribute to the phenotypic changes in Jo-1 and IBM myositis.

Long Intergenic Noncoding RNAs Mediate the Human Chondrocyte Inflammatory Response and Are Differentially Expressed in Osteoarthritis Cartilage.

OBJECTIVE: To identify long noncoding RNAs (lncRNAs), including long intergenic noncoding RNAs (lincRNAs), antisense RNAs, and pseudogenes, associated with the inflammatory response in human primary osteoarthritis (OA) chondrocytes and to explore their expression and function in OA. METHODS: OA cartilage was obtained from patients with hip or knee OA following joint replacement surgery. Non-OA cartilage was obtained from postmortem donors and patients with fracture of the neck of the femur. Primary OA chondrocytes were isolated by collagenase digestion. LncRNA expression analysis was performed by RNA sequencing (RNAseq) and quantitative reverse transcriptase-polymerase chain reaction. Modulation of lncRNA chondrocyte expression was achieved using LNA longRNA GapmeRs (Exiqon). Cytokine production was measured with Luminex. RESULTS: RNAseq identified 983 lncRNAs in primary human hip OA chondrocytes, 183 of which had not previously been identified. Following interleukin-1ß (IL-1ß) stimulation, we identified 125 lincRNAs that were differentially expressed. The lincRNA p50-associated cyclooxygenase 2-extragenic RNA (PACER) and 2 novel chondrocyte inflammation-associated lincRNAs (CILinc01 and CILinc02) were differentially expressed in both knee and hip OA cartilage compared to non-OA cartilage. In primary OA chondrocytes, these lincRNAs were rapidly and transiently induced in response to multiple proinflammatory cytokines. Knockdown of CILinc01 and CILinc02 expression in human chondrocytes significantly enhanced the IL-1-stimulated secretion of proinflammatory cytokines. CONCLUSION: The inflammatory response in human OA chondrocytes is associated with widespread changes in the profile of lncRNAs, including PACER, CILinc01, and CILinc02. Differential expression of CILinc01 and CIinc02 in hip and knee OA cartilage, and their role in modulating cytokine production during the chondrocyte inflammatory response, suggest that they may play an important role in mediating inflammation-driven cartilage degeneration in OA.

Reduced Expression of Histone Methyltransferases KMT2C and KMT2D Correlates with Improved Outcome in Pancreatic Ductal Adenocarcinoma.

Genes encoding the histone H3 lysine 4 methyltransferases KMT2C and KMT2D are subject to deletion and mutation in pancreatic ductal adenocarcinoma (PDAC), where these lesions identify a group of patients with a more favorable prognosis. In this study, we demonstrate that low KMT2C and KMT2D expression in biopsies also defines better outcome groups, with median survivals of 15.9 versus 9.2 months (P = 0.029) and 19.9 versus 11.8 months (P = 0.001), respectively. Experiments with eight human pancreatic cell lines showed attenuated cell proliferation when these methyltransferases were depleted, suggesting that this improved outcome may reflect a cell-cycle block with diminished progression from G0-G1 RNA-seq analysis of PDAC cell lines following KMT2C or KMT2D knockdown identified 31 and 124 differentially expressed genes, respectively, with 19 genes in common. Gene-set enrichment analysis revealed significant downregulation of genes related to cell-cycle and growth. These data were corroborated independently by examining KMT2C/D signatures extracted from the International Cancer Genome Consortium and The Cancer Genome Atlas datasets. Furthermore, these experiments highlighted a potential role for NCAPD3, a condensin II complex subunit, as an outcome predictor in PDAC using existing gene expression series. Kmt2d depletion in KC/KPC cell lines also led to an increased response to the nucleoside analogue 5-fluorouracil, suggesting that lower levels of this methyltransferase may mediate the sensitivity of PDAC to particular treatments. Therefore, it may also be therapeutically beneficial to target these methyltransferases in PDAC, especially in those patients demonstrating higher KTM2C/D expression. Cancer Res; 76(16); 4861-71. ©2016 AACR.

Divergent signalling pathways regulate lipopolysaccharide-induced eRNA expression in human monocytic THP1 cells.

Recent studies have indicated that non-coding RNAs transcribed from enhancer regions are important regulators of enhancer function and gene expression. In this report, we have characterised the expression of six enhancer RNAs (eRNAs) induced in human monocytic THP1 cells following activation of the innate immune response by lipopolysaccharide (LPS). Specifically, we have demonstrated that LPS-induced expression of individual eRNAs is mediated through divergent intracellular signalling pathways that includes NF-κB and the mitogen activated protein kinases, extracellular regulated kinase-1/2 and p38.

Long non-coding RNAs and enhancer RNAs regulate the lipopolysaccharide-induced inflammatory response in human monocytes.

Early reports indicate that long non-coding RNAs (lncRNAs) are novel regulators of biological responses. However, their role in the human innate immune response, which provides the initial defence against infection, is largely unexplored. To address this issue, here we characterize the long non-coding RNA transcriptome in primary human monocytes using RNA sequencing. We identify 76 enhancer RNAs (eRNAs), 40 canonical lncRNAs, 65 antisense lncRNAs and 35 regions of bidirectional transcription (RBT) that are differentially expressed in response to bacterial lipopolysaccharide (LPS). Crucially, we demonstrate that knockdown of nuclear-localized, NF-κB-regulated, eRNAs (IL1ß-eRNA) and RBT (IL1ß-RBT46) surrounding the IL1ß locus, attenuates LPS-induced messenger RNA transcription and release of the proinflammatory mediators, IL1ß and CXCL8. We predict that lncRNAs can be important regulators of the human innate immune response.