Gene Summary

Gene:MED1; mediator complex subunit 1
Summary:The activation of gene transcription is a multistep process that is triggered by factors that recognize transcriptional enhancer sites in DNA. These factors work with co-activators to direct transcriptional initiation by the RNA polymerase II apparatus. The protein encoded by this gene is a subunit of the CRSP (cofactor required for SP1 activation) complex, which, along with TFIID, is required for efficient activation by SP1. This protein is also a component of other multisubunit complexes e.g. thyroid hormone receptor-(TR-) associated proteins which interact with TR and facilitate TR function on DNA templates in conjunction with initiation factors and cofactors. It also regulates p53-dependent apoptosis and it is essential for adipogenesis. This protein is known to have the ability to self-oligomerize. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:mediator of RNA polymerase II transcription subunit 1
Source:NCBIAccessed: 30 August, 2019


What does this gene/protein do?
Show (81)
Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • DNA-Binding Proteins
  • p53 Protein
  • Ubiquitin-Conjugating Enzymes
  • DNA Mutational Analysis
  • DNA Repair
  • Prostate Cancer
  • Uterine Cancer
  • Cancer Gene Expression Regulation
  • Transfection
  • Neoplasm Proteins
  • Immunohistochemistry
  • Carcinogenesis
  • Androgen Receptors
  • Receptors, Cytoplasmic and Nuclear
  • Endodeoxyribonucleases
  • Chromosome 17
  • Antineoplastic Agents
  • DNA Methylation
  • Polymerase Chain Reaction
  • Promoter Regions
  • MED1
  • Proto-Oncogene Proteins
  • Messenger RNA
  • Gene Enhancer Elements
  • Base Sequence
  • Nuclear Proteins
  • Up-Regulation
  • bcl-2-Associated X Protein
  • Mediator Complex Subunit 1
  • Western Blotting
  • Gene Expression
  • Mutation
  • Cell Proliferation
  • Colorectal Cancer
  • Transcriptional Activation
  • Breast Cancer
  • Lung Cancer
  • Survival Rate
  • Base Pair Mismatch
  • Carrier Proteins
  • Transcription Factors
Tag cloud generated 30 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MED1 (cancer-related)

Jung AR, Eun YG, Lee YC, et al.
Clinical Significance of CUB and Sushi Multiple Domains 1 Inactivation in Head and Neck Squamous Cell Carcinoma.
Int J Mol Sci. 2018; 19(12) [PubMed] Free Access to Full Article Related Publications
Although the genetic alteration of CUB and Sushi multiple domains 1 (CSMD1) is known to be associated with poor prognosis in several cancers, there is a lack of clinical relevance in head and neck cancer. The aim of this study was to offer insight into the clinical significance of CSMD1, utilizing a multimodal approach that leverages publicly available independent genome-wide expression datasets. CSMD1-related genes were found and analyzed to examine the clinical significance of CSMD1 inactivation in the HNSCC cohort of publicly available databases. We analyzed the frequency of somatic mutations, clinicopathologic characteristics, association with immunotherapy-related gene signatures, and the pathways of gene signatures. We found 363 CSMD1-related genes. The prognosis of the CSMD1-inactivated subgroup was poor.

Ren C, Zhang G, Han F, et al.
Spatially constrained tandem bromodomain inhibition bolsters sustained repression of BRD4 transcriptional activity for TNBC cell growth.
Proc Natl Acad Sci U S A. 2018; 115(31):7949-7954 [PubMed] Free Access to Full Article Related Publications
The importance of BET protein BRD4 in gene transcription is well recognized through the study of chemical modulation of its characteristic tandem bromodomain (BrD) binding to lysine-acetylated histones and transcription factors. However, while monovalent inhibition of BRD4 by BET BrD inhibitors such as JQ1 blocks growth of hematopoietic cancers, it is much less effective generally in solid tumors. Here, we report a thienodiazepine-based bivalent BrD inhibitor, MS645, that affords spatially constrained tandem BrD inhibition and consequently sustained repression of BRD4 transcriptional activity in blocking proliferation of solid-tumor cells including a panel of triple-negative breast cancer (TNBC) cells. MS645 blocks BRD4 binding to transcription enhancer/mediator proteins MED1 and YY1 with potency superior to monovalent BET inhibitors, resulting in down-regulation of proinflammatory cytokines and genes for cell-cycle control and DNA damage repair that are largely unaffected by monovalent BrD inhibition. Our study suggests a therapeutic strategy to maximally control BRD4 activity for rapid growth of solid-tumor TNBC cells.

Jusu S, Presley JF, Williams C, et al.
Examination of VDR/RXR/DRIP205 Interaction, Intranuclear Localization, and DNA Binding in Ras-Transformed Keratinocytes and Its Implication for Designing Optimal Vitamin D Therapy in Cancer.
Endocrinology. 2018; 159(3):1303-1327 [PubMed] Related Publications
Retinoid X receptor (RXR) occupies a central position within the nuclear receptor superfamily, serving as an obligatory partner to numerous other nuclear receptors, including vitamin D receptor (VDR). In the current study, we examined whether phosphorylation of RXRα at serine 260 affects VDR/RXR and VDR interacting protein (DRIP) 205 coactivator recruitment, interactions, and binding of the VDR/human RXRα (hRXRα)/DRIP205 complex to chromatin. Serine 260 is a critical amino acid on the hRXRα that is located in close spatial proximity to regions of coactivator and corepressor interactions. Using fluorescence resonance energy transfer and immunofluorescence studies, we showed that the physical interaction between hRXRα and DRIP205 coactivator was impaired in human keratinocytes with the ras oncogene (HPK1Aras) or transfected with the wild-type hRXRα. Furthermore, the nuclear colocalization of VDR/DRIP205, hRXRα/DRIP205, and VDR/hRXRα/DRIP205 complex binding to chromatin is impaired in the HPK1Aras cells when compared with the normal human keratinocytes (HPK1A cells). However, transfection with the nonphosphorylatable hRXRα (S260A) mutant or treatment with the mitogen-activated protein kinase (MAPK) inhibitor UO126 rescued their nuclear localization, interaction, and binding of the complex to chromatin in the HPK1Aras cells. In summary, we have demonstrated, using highly specific intracellular tagging methods in live and fixed cells, important alterations of the vitamin D signaling system in cancer cells in which the ras-raf-MAPK system is activated, suggesting that specific inhibition of this commonly activated pathway could be targeted therapeutically to enhance vitamin D efficacy.

Terai H, Kitajima S, Potter DS, et al.
ER Stress Signaling Promotes the Survival of Cancer "Persister Cells" Tolerant to EGFR Tyrosine Kinase Inhibitors.
Cancer Res. 2018; 78(4):1044-1057 [PubMed] Free Access to Full Article Related Publications
An increasingly recognized component of resistance to tyrosine kinase inhibitors (TKI) involves persistence of a drug-tolerant subpopulation of cancer cells that survive despite effective eradication of the majority of the cell population. Multiple groups have demonstrated that these drug-tolerant persister cells undergo transcriptional adaptation via an epigenetic state change that promotes cell survival. Because this mode of TKI drug tolerance appears to involve transcriptional addiction to specific genes and pathways, we hypothesized that systematic functional screening of EGFR TKI/transcriptional inhibitor combination therapy would yield important mechanistic insights and alternative drug escape pathways. We therefore performed a genome-wide CRISPR/Cas9 enhancer/suppressor screen in EGFR-dependent lung cancer PC9 cells treated with erlotinib + THZ1 (CDK7/12 inhibitor) combination therapy, a combination previously shown to suppress drug-tolerant cells in this setting. As expected, suppression of multiple genes associated with transcriptional complexes (EP300, CREBBP, and MED1) enhanced erlotinib/THZ1 synergy. Unexpectedly, we uncovered nearly every component of the recently described ufmylation pathway in the synergy suppressor group. Loss of ufmylation did not affect canonical downstream EGFR signaling. Instead, absence of this pathway triggered a protective unfolded protein response associated with STING upregulation, promoting protumorigenic inflammatory signaling but also unique dependence on Bcl-xL. These data reveal that dysregulation of ufmylation and ER stress comprise a previously unrecognized TKI drug tolerance pathway that engages survival signaling, with potentially important therapeutic implications.

Yang Y, Leonard M, Zhang Y, et al.
HER2-Driven Breast Tumorigenesis Relies upon Interactions of the Estrogen Receptor with Coactivator MED1.
Cancer Res. 2018; 78(2):422-435 [PubMed] Free Access to Full Article Related Publications
Studies of the estrogen receptor (ER) coactivator protein Mediator subunit 1 (MED1) have revealed its specific roles in pubertal mammary gland development and potential contributions to breast tumorigenesis, based on coamplification of MED1 and HER2 in certain breast cancers. In this study, we generated a mouse model of mammary tumorigenesis harboring the MMTV-HER2 oncogene and mutation of MED1 to evaluate its role in HER2-driven tumorigenesis. MED1 mutation in its ER-interacting LxxLL motifs was sufficient to delay tumor onset and to impair tumor growth, metastasis, and cancer stem-like cell formation in this model. Mechanistic investigations revealed that MED1 acted directly to regulate ER signaling through the downstream IGF1 pathway but not the AREG pathway. Our findings show that MED1 is critical for HER2-driven breast tumorigenesis, suggesting its candidacy as a disease-selective therapeutic target.

Triki M, Lapierre M, Cavailles V, Mokdad-Gargouri R
Expression and role of nuclear receptor coregulators in colorectal cancer.
World J Gastroenterol. 2017; 23(25):4480-4490 [PubMed] Free Access to Full Article Related Publications
Colorectal cancer (CRC) is one of the most common human cancers and the cause of about 700000 deaths per year worldwide. Deregulation of the WNT/β-catenin pathway is a key event in CRC initiation. This pathway interacts with other nuclear signaling pathways, including members of the nuclear receptor superfamily and their transcription coregulators. In this review, we provide an overview of the literature dealing with the main coactivators (NCoA-1 to 3, NCoA-6, PGC1-α, p300, CREBBP and MED1) and corepressors (N-CoR1 and 2, NRIP1 and MTA1) of nuclear receptors and summarize their links with the WNT/β-catenin signaling cascade, their expression in CRC and their role in intestinal physiopathology.

Jiang M, Zhong T, Zhang W, et al.
Reduced expression of miR‑205‑5p promotes apoptosis and inhibits proliferation and invasion in lung cancer A549 cells by upregulation of ZEB2 and downregulation of erbB3.
Mol Med Rep. 2017; 15(5):3231-3238 [PubMed] Related Publications
Previous studies have demonstrated that microRNA (miR)-205-5p expression is significantly increased in non‑small cell lung cancer tissues and is associated with tumor differentiation grade. The aim of the present study was to explore the effects of miR‑205‑5p on viability, apoptosis and invasion of lung cancer A549 cells. The hsa‑miR‑205‑5p small interfering RNA (siRNA) inhibitor was transfected into A549 cells and expression of miR‑205‑5p was detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). Cell viability, apoptosis and invasion were assayed by Cell Counting kit‑8, Annexin V/propidium iodide double staining and Transwell assay, respectively. Target genes of miR‑205‑5p were predicted using bioinformatics analysis. Expression of mRNA and protein levels of candidate target genes following miR‑205‑5p inhibition were detected using RT‑qPCR and western blot analysis respectively. The results demonstrated that relative survival rates of A549 cells were significantly inhibited in miR‑205‑5p siRNA‑transfected cells at 24 and 48 h compared with control cells. Apoptosis was markedly increased in the miR‑205‑5p siRNA cells compared with control cells. The number of invaded cells following miR‑205‑5p siRNA silencing was significantly decreased compared with control cells. Bioinformatics analysis revealed that erb‑B2 receptor kinase 3 (erbB3), zinc finger E‑box binding homeobox 2 (ZEB2), clathrin heavy chain (CLTC) and mediator complex subunit 1 (MED1) may be potential target genes of miR‑205‑5p. Reduced expression of miR‑205‑5p significantly increased the expression of ZEB2 mRNA and protein, inhibited the expression of erbB3 protein, but had no significant effect on the expression levels of CLTC and MED1. In summary, reduced expression of miR‑205‑5p promoted apoptosis and inhibited proliferation and invasion in lung cancer A549 cells through upregulation of ZEB2 and downregulation of erbB3. The present results suggested that the increased miR‑205‑5p expression observed in non‑small cell lung cancer tissues may contribute to increased proliferation and invasion of lung cancer cells and thus to cancer progression.

Mansouri S, Naghavi-Al-Hosseini F, Farahmand L, Majidzadeh-A K
MED1 may explain the interaction between receptor tyrosine kinases and ERα66 in the complicated network of Tamoxifen resistance.
Eur J Pharmacol. 2017; 804:78-81 [PubMed] Related Publications
According to the American Society of Clinical Oncology or ASCO's clinical practice guidelines, administration of Tamoxifen for hormone receptor positive patients improved outcomes. However, many studies have been conducted in this issue, with the rise of Tamoxifen resistance in recent decades. There are many alternative growth cascades that are activated in Tamoxifen resistant cells. The most common and well characterized components of such a resistant network are receptor tyrosine kinases, or RTKs, which can influence many other cellular processes. The interactions between estrogen dependent and independent pathways further complicate the networking. MED1, as a member of a mediator complex, which is activated by RTK growth pathways, plays role in co-activating ERα66 to transcribe genes and enhance cellular proliferation. Herein, we will discuss MED1, a novel biomarker which can explain how RTKs interact with ERα66 which results in Tamoxifen resistance.

Zawistowski JS, Bevill SM, Goulet DR, et al.
Enhancer Remodeling during Adaptive Bypass to MEK Inhibition Is Attenuated by Pharmacologic Targeting of the P-TEFb Complex.
Cancer Discov. 2017; 7(3):302-321 [PubMed] Free Access to Full Article Related Publications
Targeting the dysregulated BRAF-MEK-ERK pathway in cancer has increasingly emerged in clinical trial design. Despite clinical responses in specific cancers using inhibitors targeting BRAF and MEK, resistance develops often involving nongenomic adaptive bypass mechanisms. Inhibition of MEK1/2 by trametinib in patients with triple-negative breast cancer (TNBC) induced dramatic transcriptional responses, including upregulation of receptor tyrosine kinases (RTK) comparing tumor samples before and after one week of treatment. In preclinical models, MEK inhibition induced genome-wide enhancer formation involving the seeding of BRD4, MED1, H3K27 acetylation, and p300 that drives transcriptional adaptation. Inhibition of the P-TEFb-associated proteins BRD4 and CBP/p300 arrested enhancer seeding and RTK upregulation. BRD4 bromodomain inhibitors overcame trametinib resistance, producing sustained growth inhibition in cells, xenografts, and syngeneic mouse TNBC models. Pharmacologic targeting of P-TEFb members in conjunction with MEK inhibition by trametinib is an effective strategy to durably inhibit epigenomic remodeling required for adaptive resistance.

Tanaka S, Maekawa A, Matsubara L, et al.
Periostin supports hematopoietic progenitor cells and niche-dependent myeloblastoma cells in vitro.
Biochem Biophys Res Commun. 2016; 478(4):1706-12 [PubMed] Free Access to Full Article Related Publications
The expression of extracellular matrix protein periostin (POSTN) was attenuated in Med1(-/-) mouse embryonic fibroblasts (MEFs), which exhibited a decreased capability to support hematopoietic progenitor cells (HPCs) in vitro. When bone marrow (BM) cells were cocultured with mitomycin C-treated Med1(+/+) MEFs, or OP-9 or MS-5 BM stromal cells, in the presence of anti-POSTN antibody, the growth of BM cells and number of long-term culture-initiating cells (LTC-ICs) were attenuated. When BM cells were cocultured with Med1(-/-) MEFs in the presence of recombinant POSTN, the growth of BM cells and the number of LTC-ICs were restored. Moreover, antibody-mediated blockage of stromal cells-derived POSTN markedly reduced the growth and cobblestone formation, a leukemic stem cell feature, of stromal cell-dependent MB-1 myeloblastoma cells. POSTN was expressed both in BM cells and variably in different BM stromal cells. Expression in the latter cells was increased by physical interaction with hematopoietic cells. The receptor for POSTN, integrin αvβ3, was expressed abundantly in BM stromal cells. The addition of recombinant POSTN to BM stromal cells induced intracellular signaling downstream of integrin αvβ3. These results suggest that stromal cell POSTN supports both normal HPCs and leukemia-initiating cells in vitro, at least in part, indirectly by acting on stromal cells in an autocrine or paracrine manner.

Alaiya AA, Aljurf M, Shinwari Z, et al.
Protein signatures as potential surrogate biomarkers for stratification and prediction of treatment response in chronic myeloid leukemia patients.
Int J Oncol. 2016; 49(3):913-33 [PubMed] Free Access to Full Article Related Publications
There is unmet need for prediction of treatment response for chronic myeloid leukemia (CML) patients. The present study aims to identify disease-specific/disease-associated protein biomarkers detectable in bone marrow and peripheral blood for objective prediction of individual's best treatment options and prognostic monitoring of CML patients. Bone marrow plasma (BMP) and peripheral blood plasma (PBP) samples from newly-diagnosed chronic-phase CML patients were subjected to expression-proteomics using quantitative two-dimensional gel electrophoresis (2-DE) and label-free liquid chromatography tandem mass spectrometry (LC-MS/MS). Analysis of 2-DE protein fingerprints preceding therapy commencement accurately predicts 13 individuals that achieved major molecular response (MMR) at 6 months from 12 subjects without MMR (No-MMR). Results were independently validated using LC-MS/MS analysis of BMP and PBP from patients that have more than 24 months followed-up. One hundred and sixty-four and 138 proteins with significant differential expression profiles were identified from PBP and BMP, respectively and only 54 proteins overlap between the two datasets. The protein panels also discriminates accurately patients that stay on imatinib treatment from patients ultimately needing alternative treatment. Among the identified proteins are TYRO3, a member of TAM family of receptor tyrosine kinases (RTKs), the S100A8, and MYC and all of which have been implicated in CML. Our findings indicate analyses of a panel of protein signatures is capable of objective prediction of molecular response and therapy choice for CML patients at diagnosis as 'personalized-medicine-model'.

Zhao J, Li X, Yao Q, et al.
RWCFusion: identifying phenotype-specific cancer driver gene fusions based on fusion pair random walk scoring method.
Oncotarget. 2016; 7(38):61054-61068 [PubMed] Free Access to Full Article Related Publications
While gene fusions have been increasingly detected by next-generation sequencing (NGS) technologies based methods in human cancers, these methods have limitations in identifying driver fusions. In addition, the existing methods to identify driver gene fusions ignored the specificity among different cancers or only considered their local rather than global topology features in networks. Here, we proposed a novel network-based method, called RWCFusion, to identify phenotype-specific cancer driver gene fusions. To evaluate its performance, we used leave-one-out cross-validation in 35 cancers and achieved a high AUC value 0.925 for overall cancers and an average 0.929 for signal cancer. Furthermore, we classified 35 cancers into two classes: haematological and solid, of which the haematological got a highly AUC which is up to 0.968. Finally, we applied RWCFusion to breast cancer and found that top 13 gene fusions, such as BCAS3-BCAS4, NOTCH-NUP214, MED13-BCAS3 and CARM-SMARCA4, have been previously proved to be drivers for breast cancer. Additionally, 8 among the top 10 of the remaining candidate gene fusions, such as SULF2-ZNF217, MED1-ACSF2, and ACACA-STAC2, were inferred to be potential driver gene fusions of breast cancer by us.

Zhou B, Wang L, Zhang S, et al.
INO80 governs superenhancer-mediated oncogenic transcription and tumor growth in melanoma.
Genes Dev. 2016; 30(12):1440-53 [PubMed] Free Access to Full Article Related Publications
Superenhancers (SEs) are large genomic regions with a high density of enhancer marks. In cancer, SEs are found near oncogenes and dictate cancer gene expression. However, how oncogenic SEs are regulated remains poorly understood. Here, we show that INO80, a chromatin remodeling complex, is required for SE-mediated oncogenic transcription and tumor growth in melanoma. The expression of Ino80, the SWI/SNF ATPase, is elevated in melanoma cells and patient melanomas compared with normal melanocytes and benign nevi. Furthermore, Ino80 silencing selectively inhibits melanoma cell proliferation, anchorage-independent growth, tumorigenesis, and tumor maintenance in mouse xenografts. Mechanistically, Ino80 occupies >90% of SEs, and its occupancy is dependent on transcription factors such as MITF and Sox9. Ino80 binding reduces nucleosome occupancy and facilitates Mediator recruitment, thus promoting oncogenic transcription. Consistently, genes co-occupied by Ino80 and Med1 are selectively expressed in melanomas compared with melanocytes. Together, our results reveal an essential role of INO80-dependent chromatin remodeling in SE function and suggest a novel strategy for disrupting SEs in cancer treatment.

Kowalczewska M, Piotrowski J, Jędrzejewski T, Kozak W
Polysaccharide peptides from Coriolus versicolor exert differential immunomodulatory effects on blood lymphocytes and breast cancer cell line MCF-7 in vitro.
Immunol Lett. 2016; 174:37-44 [PubMed] Related Publications
The protein-bound polysaccharides (PBP), isolated from Coriolus versicolor (CV) fungus, are considered as natural compounds with potential therapeutic applications. The immunopotentiating and antitumor activity of polysaccharopeptides has been previously examined, however similar findings could not be achieved. The source of PBP, variations in extraction process as well as environmental factors seems to affect the biological properties of these active CV components. Since further analysis are needed to draw more definite conclusion, the present study aimed to investigate the immunomodulatory properties of the PBP extract, isolated from commercially available capsules of C. versicolor. Our results revealed that the effect mediated by PBP extract depends on the target cells. We reported that the polysaccharopeptides induced a significant decrease in breast cancer MCF-7 cells growth, which was TNF-α-dependent phenomenon. Interestingly, the level of two others cytokines, IL-1β and IL-6 was not affected. On the other hand, in this study we noticed that protein-bound polysaccharides extracted from CV significantly augmented the proliferative response of blood lymphocytes in a time-dependent manner, which was associated with IL-6 and IL-1β mRNA upregulation. Moreover we found that the cells response to PBP stimuli might be inversely related to its concentration.

Genrich G, Kruppa M, Lenk L, et al.
The anti-oxidative transcription factor Nuclear factor E2 related factor-2 (Nrf2) counteracts TGF-β1 mediated growth inhibition of pancreatic ductal epithelial cells -Nrf2 as determinant of pro-tumorigenic functions of TGF-β1.
BMC Cancer. 2016; 16:155 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Nuclear factor E2 related factor-2 (Nrf2) is an oxidative stress inducible transcription factor being essential in regulating cell homeostasis. Thus, acute induction of Nrf2 in epithelial cells exposed to inflammation confers protection from oxidative cell damage and mutagenesis supporting an anti-tumorigenic role for Nrf2. However, pancreatic ductal adenocarcinoma (PDAC) is characterized by persistent Nrf2 activity conferring therapy resistance which points to a pro-tumorigenic role of Nrf2. A similar dichotomous role in tumorigenesis is described for the Transforming Growth Factor-beta 1 (TGF-β1). The present study therefore aimed at elucidating whether the switch of Nrf2 function towards a tumor promoting one relates to the modulation of TGF-β1 induced cell responses and whether this might occur early in PDAC development.
METHODS: In situ analysis comprised immunohistochemical stainings of activated (phosphorylated) Nrf2 and Ki67 in pancreatic tissues containing normal ducts and pancreatic intraepithelial neoplasia (PanINs). In vitro, Nrf2 levels in benign (H6c7-pBp), premalignant (H6c7-kras) and malignant (Colo357) pancreatic ductal epithelial cells were modulated by Nrf2 specific siRNA or Nrf2 overexpression. Then, the effect of Nrf2 alone and in combination with TGF-β1 on cell growth and survival was investigated by cell counting, Ki67 staining and apoptosis assays. The underlying cell signaling was investigated by western blotting. Statistical analysis was performed by Shapiro-Wilk test for normal distribution. Parametric data were analyzed by one-way ANOVA, while non-parametric data were analyzed by Kruskal-Wallis one-way ANOVA on ranks.
RESULTS: Significantly elevated expression of activated Nrf2 and Ki67 could be detected in PanINs but not in normal pancreatic ductal epithelium. While the effect of Nrf2 on basal cell growth of H6c7-pBp, H6c7-kras and Colo357 cells was minor, it clearly attenuated the growth inhibiting effects of TGF-β1 in all cell lines. This enhanced Nrf2-mediated cell survival was predominantly based on an enhanced proliferative activity. Accordingly, expression of p21 expression along with expression of phospho-p38 and phospho-Smad3 was diminished whereas Erk-phosphorylation was enhanced under these conditions.
CONCLUSIONS: Overall, our data demonstrate that Nrf2 being elevated in early precursor lesions counteracts the growth inhibiting function of TGF-β1 already in benign and premalignant pancreatic ductal epithelial cells. This could represent one fundamental mechanism underlying the functional switch of both- TGF-β1 and Nrf2 - which may manifest already in early stages of PDAC development.

Budczies J, Pfarr N, Stenzinger A, et al.
Ioncopy: a novel method for calling copy number alterations in amplicon sequencing data including significance assessment.
Oncotarget. 2016; 7(11):13236-47 [PubMed] Free Access to Full Article Related Publications
Recently, it has been demonstrated that calling of copy number alterations (CNAs) from amplicon sequencing (AS) data is feasible. Most approaches, however, require non-tumor (germline) DNA for data normalization. Here, we present the method Ioncopy for CNA detection which requires no normal controls and includes a significance assessment for each detected alteration.Ioncopy was evaluated in a cohort of 184 clinically annotated breast carcinomas. A total number of 252 amplifications were detected, of which 183 (72.6%) could be validated by a call of an additional amplicon interrogating the same gene. Moreover, a total number of 33 deletions were found, whereof 27 (81.8%) could be validated. Analyzing the 16 most frequently amplified genes, validation rates of over 89% could be achieved for 11 of these genes. 11 of the top 16 genes showed significant overexpression in the amplified tumors. 89.5% of the HER2-amplified tumors were GRB7 and STARD3 co-amplified, whereas 68.4% of the HER2-amplified tumors had additional MED1 amplifications. Correlations between CNAs measured by amplicons in HER2 exons 19, 20 and 21 were strong (all R > 0.93). AS based detection of HER2 amplifications had a sensitivity of 90.0% and a specificity of 98.8% compared to the gold standard of HER2 immunohistochemistry combined with in situ hybridization.In summary, we developed and validated a novel method for detection and significance assessment of CNAs in amplicon sequencing data. Using Ioncopy, AS offers a straightforward and efficient approach to simultaneously analyze gene amplifications and gene deletions together with simple somatic mutations in a single assay.

Sunkel B, Wu D, Chen Z, et al.
Integrative analysis identifies targetable CREB1/FoxA1 transcriptional co-regulation as a predictor of prostate cancer recurrence.
Nucleic Acids Res. 2016; 44(9):4105-22 [PubMed] Free Access to Full Article Related Publications
Identifying prostate cancer-driving transcription factors (TFs) in addition to the androgen receptor promises to improve our ability to effectively diagnose and treat this disease. We employed an integrative genomics analysis of master TFs CREB1 and FoxA1 in androgen-dependent prostate cancer (ADPC) and castration-resistant prostate cancer (CRPC) cell lines, primary prostate cancer tissues and circulating tumor cells (CTCs) to investigate their role in defining prostate cancer gene expression profiles. Combining genome-wide binding site and gene expression profiles we define CREB1 as a critical driver of pro-survival, cell cycle and metabolic transcription programs. We show that CREB1 and FoxA1 co-localize and mutually influence each other's binding to define disease-driving transcription profiles associated with advanced prostate cancer. Gene expression analysis in human prostate cancer samples found that CREB1/FoxA1 target gene panels predict prostate cancer recurrence. Finally, we showed that this signaling pathway is sensitive to compounds that inhibit the transcription co-regulatory factor MED1. These findings not only reveal a novel, global transcriptional co-regulatory function of CREB1 and FoxA1, but also suggest CREB1/FoxA1 signaling is a targetable driver of prostate cancer progression and serves as a biomarker of poor clinical outcomes.

Shu S, Lin CY, He HH, et al.
Response and resistance to BET bromodomain inhibitors in triple-negative breast cancer.
Nature. 2016; 529(7586):413-417 [PubMed] Free Access to Full Article Related Publications
Triple-negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease for which there is no targeted therapy. BET bromodomain inhibitors, which have shown efficacy in several models of cancer, have not been evaluated in TNBC. These inhibitors displace BET bromodomain proteins such as BRD4 from chromatin by competing with their acetyl-lysine recognition modules, leading to inhibition of oncogenic transcriptional programs. Here we report the preferential sensitivity of TNBCs to BET bromodomain inhibition in vitro and in vivo, establishing a rationale for clinical investigation and further motivation to understand mechanisms of resistance. In paired cell lines selected for acquired resistance to BET inhibition from previously sensitive TNBCs, we failed to identify gatekeeper mutations, new driver events or drug pump activation. BET-resistant TNBC cells remain dependent on wild-type BRD4, which supports transcription and cell proliferation in a bromodomain-independent manner. Proteomic studies of resistant TNBC identify strong association with MED1 and hyper-phosphorylation of BRD4 attributable to decreased activity of PP2A, identified here as a principal BRD4 serine phosphatase. Together, these studies provide a rationale for BET inhibition in TNBC and present mechanism-based combination strategies to anticipate clinical drug resistance.

Tricarico R, Cortellino S, Riccio A, et al.
Involvement of MBD4 inactivation in mismatch repair-deficient tumorigenesis.
Oncotarget. 2015; 6(40):42892-904 [PubMed] Free Access to Full Article Related Publications
The DNA glycosylase gene MBD4 safeguards genomic stability at CpG sites and is frequently mutated at coding poly-A tracks in mismatch repair (MMR)-defective colorectal tumors (CRC). Mbd4 biallelic inactivation in mice provided conflicting results as to its role in tumorigenesis. Thus, it is unclear whether MBD4 alterations are only secondary to MMR defects without functional consequences or can contribute to the mutator phenotype. We investigated MBD4 variants in a large series of hereditary/familial and sporadic CRC cases. Whereas MBD4 frameshifts were only detected in tumors, missense variants were found in both normal and tumor DNA. In CRC with double-MBD4/MMR and single-MBD4 variants, transition mutation frequency was increased, indicating that MBD4 defects may affect the mutational landscape independently of MMR defect. Mbd4-deficient mice showed reduced survival when combined with Mlh1-/- genotype. Taken together, these data suggest that MBD4 inactivation may contribute to tumorigenesis, acting as a modifier of MMR-deficient cancer phenotype.

Nilsson EM, Laursen KB, Whitchurch J, et al.
MiR137 is an androgen regulated repressor of an extended network of transcriptional coregulators.
Oncotarget. 2015; 6(34):35710-25 [PubMed] Free Access to Full Article Related Publications
Androgens and the androgen receptor (AR) play crucial roles in male development and the pathogenesis and progression of prostate cancer (PCa). The AR functions as a ligand dependent transcription factor which recruits multiple enzymatically distinct epigenetic coregulators to facilitate transcriptional regulation in response to androgens. Over-expression of AR coregulators is implicated in cancer. We have shown that over-expression of KDM1A, an AR coregulator, contributes to PCa recurrence by promoting VEGFA expression. However the mechanism(s) whereby AR coregulators are increased in PCa remain poorly understood. In this study we show that the microRNA hsa-miR-137 (miR137) tumor suppressor regulates expression of an extended network of transcriptional coregulators including KDM1A/LSD1/AOF1, KDM2A/JHDM1A/FBXL11, KDM4A/JMJD2A, KDM5B JARID1B/PLU1, KDM7A/JHDM1D/PHF8, MED1/TRAP220/DRIP205 and NCoA2/SRC2/TIF2. We show that expression of miR137 is increased by androgen in LnCaP androgen PCa responsive cells and that the miR137 locus is epigenetically silenced in androgen LnCaP:C4-2 and PC3 independent PCa cells. In addition, we found that restoration of miR137 expression down-regulates expression of VEGFA, an AR target gene, which suggests a role of miR137 loss also in cancer angiogenesis. Finally we show functional inhibition of miR137 function enhanced androgen induction of PSA/KLK3 expression. Our data indicate that miR137 functions as an androgen regulated suppressor of androgen signaling by modulating expression of an extended network of transcriptional coregulators. Therefore, we propose that epigenetic silencing of miR137 is an important event in promoting androgen signaling during prostate carcinogenesis and progression.

Kämpjärvi K, Kim NH, Keskitalo S, et al.
Somatic MED12 mutations in prostate cancer and uterine leiomyomas promote tumorigenesis through distinct mechanisms.
Prostate. 2016; 76(1):22-31 [PubMed] Related Publications
BACKGROUND: Mediator is a multiprotein interface between eukaryotic gene-specific transcription factors and RNA polymerase II. Mutations in exon 2 of the gene encoding MED12, a key subunit of the regulatory kinase module in Mediator, are extremely frequent in uterine leiomyomas, breast fibroadenomas, and phyllodes tumors. These mutations disrupt kinase module interactions and lead to diminished Mediator-associated kinase activity. MED12 mutations in exon 26, resulting in a substitution of leucine 1224 to phenylalanine (L1224F), have been recurrently observed in prostate cancer.
METHODS: To elucidate the molecular mechanisms leading to tumorigenesis in prostate cancer, we analyzed global interaction profiles of wild-type and L1224F mutant MED12 with quantitative affinity purification-mass spectrometry (AP-MS). Immunoprecipitation and kinase activity assay were used to further assess the interactions between Mediator complex subunits and kinase activity. The presence of L1224F mutation was analyzed in altogether 877 samples representing prostate hyperplasia, prostate cancer, and various tumor types in which somatic MED12 mutations have previously been observed.
RESULTS: In contrast to N-terminal MED12 mutations observed in uterine leiomyomas, the L1224F mutation compromises neither the interaction of MED12 with kinase module subunits Cyclin C and CDK8/19 nor Mediator-associated CDK activity. Instead, the L1224F mutation was shown to affect interactions between MED12 and other Mediator components (MED1, MED13, MED13L, MED14, MED15, MED17, and MED24). Mutation screening revealed one mutation in a Finnish (Caucasian) prostate cancer patient, whereas no mutations in any other tumor type were observed.
CONCLUSIONS: Specific somatic MED12 mutations in prostate cancer and uterine leiomyomas accumulate in two separate regions of the gene and promote tumorigenesis through clearly distinct mechanisms.

Ma R, Wang C, Wang J, et al.
miRNA-mRNA Interaction Network in Non-small Cell Lung Cancer.
Interdiscip Sci. 2016; 8(3):209-19 [PubMed] Related Publications
MicroRNAs (miRNAs) are small RNA molecules, about 20-25 nucleotides in length. They repress or degrade messenger RNA (mRNA) translation, which are involved in human cancer. In this study based on paired miRNA and mRNA expression profiles of non-small cell lung cancer samples, we constructed and analyzed miRNA-mRNA interaction network via several bioinformatics softwares and platforms. This integrative network is comprised of 249 nodes for mRNA, 90 nodes for miRNA and 290 edges that show regulations between target genes and miRNAs. The three miR-1207-5p, miR-1228* and miR-939 are the most connected miRNA that regulated a large number of genes. ST8SIA2, MED1 and HDAC4, SPN, which are targeted by multiple miRNAs and located in the center of the network, are involved in both lung cancer and nervous system via functional annotation analysis. Such a global interaction network of miRNA-mRNA in lung cancer will contribute to refining miRNA target predictions and developing novel therapeutic candidates.

Hensel J, Duex JE, Owens C, et al.
Patient Mutation Directed shRNA Screen Uncovers Novel Bladder Tumor Growth Suppressors.
Mol Cancer Res. 2015; 13(9):1306-15 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Next-generation sequencing (NGS) of human bladder cancer has revealed many gene alterations compared with normal tissue, with most being predicted to be "loss of function." However, given the high number of alterations, evaluating the functional impact of each is impractical. Here, we develop and use a high-throughput, in vivo strategy to determine which alterations are loss of function in tumor growth suppressors. Genes reported as altered by NGS in bladder cancer patients were bioinformatically processed by MutationTaster and MutationAssessor, with 283 predicted as loss of function. An shRNA lentiviral library targeting these genes was transduced into T24 cells, a nontumorigenic human bladder cancer cell line, followed by injection into mice. Tumors that arose were sequenced and the dominant shRNA constructs were found to target IQGAP1, SAMD9L, PCIF1, MED1, and KATNAL1 genes. In vitro validation experiments revealed that shRNA molecules directed at IQGAP1 showed the most profound increase in anchorage-independent growth of T24 cells. The clinical relevance of IQGAP1 as a tumor growth suppressor is supported by the finding that its expression is lower in bladder cancer compared with benign patient urothelium in multiple independent datasets. Lower IQGAP1 protein expression associated with higher tumor grade and decreased patient survival. Finally, depletion of IQGAP1 leads to increased TGFBR2 with TGFβ signaling, explaining in part how reduced IQGAP1 promotes tumor growth. These findings suggest IQGAP1 is a bladder tumor growth suppressor that works via modulating TGFβ signaling and is a potentially clinically useful biomarker.
IMPLICATIONS: This study used gene mutation information from patient-derived bladder tumor specimens to inform the development of a screen used to identify novel tumor growth suppressors. This included identification of the protein IQGAP1 as a potent bladder cancer growth suppressor.

Lehmann R, Childs L, Thomas P, et al.
Assembly of a comprehensive regulatory network for the mammalian circadian clock: a bioinformatics approach.
PLoS One. 2015; 10(5):e0126283 [PubMed] Free Access to Full Article Related Publications
By regulating the timing of cellular processes, the circadian clock provides a way to adapt physiology and behaviour to the geophysical time. In mammals, a light-entrainable master clock located in the suprachiasmatic nucleus (SCN) controls peripheral clocks that are present in virtually every body cell. Defective circadian timing is associated with several pathologies such as cancer and metabolic and sleep disorders. To better understand the circadian regulation of cellular processes, we developed a bioinformatics pipeline encompassing the analysis of high-throughput data sets and the exploitation of published knowledge by text-mining. We identified 118 novel potential clock-regulated genes and integrated them into an existing high-quality circadian network, generating the to-date most comprehensive network of circadian regulated genes (NCRG). To validate particular elements in our network, we assessed publicly available ChIP-seq data for BMAL1, REV-ERBα/β and RORα/γ proteins and found strong evidence for circadian regulation of Elavl1, Nme1, Dhx6, Med1 and Rbbp7 all of which are involved in the regulation of tumourigenesis. Furthermore, we identified Ncl and Ddx6, as targets of RORγ and REV-ERBα, β, respectively. Most interestingly, these genes were also reported to be involved in miRNA regulation; in particular, NCL regulates several miRNAs, all involved in cancer aggressiveness. Thus, NCL represents a novel potential link via which the circadian clock, and specifically RORγ, regulates the expression of miRNAs, with particular consequences in breast cancer progression. Our findings bring us one step forward towards a mechanistic understanding of mammalian circadian regulation, and provide further evidence of the influence of circadian deregulation in cancer.

Liu G, Sprenger C, Wu PJ, et al.
MED1 mediates androgen receptor splice variant induced gene expression in the absence of ligand.
Oncotarget. 2015; 6(1):288-304 [PubMed] Free Access to Full Article Related Publications
The appearance of constitutively active androgen receptor splice variants (AR-Vs) has been proposed as one of the causes of castration-resistant prostate cancer (CRPC). However, the underlying mechanism of AR-Vs in CRPC transcriptional regulation has not been defined. A distinct transcriptome enriched with cell cycle genes, e.g. UBE2C, has been associated with AR-Vs, which indicates the possibility of an altered transcriptional mechanism when compared to full-length wild-type AR (ARfl). Importantly, a recent study reported the critical role of p-MED1 in enhancing UBE2C expression through a locus looping pattern, which only occurs in CRPC but not in androgen-dependent prostate cancer (ADPC). To investigate the potential correlation between AR-V and MED1, in the present study we performed protein co-immunoprecipitation, chromatin immunoprecipitation, and cell proliferation assays and found that MED1 is necessary for ARv567es induced UBE2C up-regulation and subsequent prostate cancer cell growth. Furthermore, p-MED1 is bound to ARv567es independent of full-length AR; p-MED1 has higher recruitment to UBE2C promoter and enhancer regions in the presence of ARv567es. Our data indicate that p-MED1 serves as a key mediator in ARv567es induced gene expression and suggests a mechanism by which AR-Vs promote the development and progression of CRPC.

Fidalgo F, Rodrigues TC, Pinilla M, et al.
Lymphovascular invasion and histologic grade are associated with specific genomic profiles in invasive carcinomas of the breast.
Tumour Biol. 2015; 36(3):1835-48 [PubMed] Free Access to Full Article Related Publications
Lymphovascular invasion (LVI) and histologic grade are clinical parameters of high prognostic value in breast cancer and indicate the level of tumor aggressiveness. Many studies have focused on the association of breast cancer subtypes with gene expression and chromosomal profiles, but considerably less genomic information is available regarding traditional prognostic factors such as histologic grade and LVI. We studied by array-CGH a group of 57 invasive ductal carcinomas of the breast to outline the DNA copy number aberration (CNA) profile linked to high histologic grades and LVI. Selected CNAs were validated using real-time quantitative PCR (qPCR). Furthermore, gene expression analysis was performed in a subset of 32 of these tumors, and findings were integrated with array-CGH data. Our findings indicated an accumulation of genomic alterations in high-grade breast tumors compared to low-grade samples. Grade III tumors showed higher number of CNAs and larger aberrations than low-grade tumors and displayed a wide range of chromosomal aberrations, which were mainly 5p, 8q, 10p, 17q12, and 19 gains, and 3p, 4, 5q proximal, 9p, 11p, 18q, and 21 losses. The presence of LVI, a well-established prognostic marker, was not significantly associated with increased genomic instability in comparison to breast tumors negative for LVI, considering the total number of chromosomal alterations. However, a slightly increase in the frequency of specific alterations could be detected in LVI-positive group, such as gains at 5p, 16p, 17q12, and 19, and losses at 8p, 11q, 18q, and 21. Three newly reported small-scale rearrangements were detected in high-risk tumors (LVI-positive grade III) harboring putative breast cancer genes (amplicons at 4q13.3 and 11p11.2, and a deletion at 12p12.3). Furthermore, gene expression analysis uncovered networks highlighting S100A8, MMP1, and MED1 as promising candidate genes involved in high-grade and LVI-positive tumors. In summary, a group of genomic regions could be associated with high-risk tumors, and expression analysis pinpointed candidate genes deserving further investigation. The data has shed some light on the molecular players involved in two highly relevant prognostic factors and may further add to the understanding of the mechanisms of breast cancer aggressiveness.

Jiang C, Chen H, Shao L, Wang Q
MicroRNA-1 functions as a potential tumor suppressor in osteosarcoma by targeting Med1 and Med31.
Oncol Rep. 2014; 32(3):1249-56 [PubMed] Related Publications
MicroRNA-1 (miR-1) has been shown to function as a critical gene regulator in multiple types of cancers. However, the role of miR-1 in osteosarcoma has not been totally clarified. In the present study, we investigated the effects of miR-1 on osteosarcoma and the underlying mechanism. We found that miR-1 was downregulated in osteosarcoma tissues and osteosarcoma cell lines. Restoration of miR-1 significantly suppressed osteosarcoma cell proliferation by inhibiting cell cycle progression. Mediator complex subunit 1 (Med1) and 31 (Med31) were validated as targets of miR-1 in osteosarcoma by luciferase reporter assay. Downregulation of Med1 and Med31 suppressed the proliferation of osteosarcoma cells, and overexpression of Med1 and Med31 abrogated the effects of miR-1 on cell proliferation. Furthermore, both miR-1 and knockdown of Med1 or Med31 reduced the expression of met proto-oncogene (MET) and blocked the downstream signaling of MET responding to hepatocyte growth factor (HGF). Taken together, the findings of this study suggest that Med1 and Med31 serve as potential gene therapeutic targets in osteosarcoma and miR-1 may prove to be a promising agent.

Davidov T, Nagar M, Kierson M, et al.
Carbonic anhydrase 4 and crystallin α-B immunoreactivity may distinguish benign from malignant thyroid nodules in patients with indeterminate thyroid cytology.
J Surg Res. 2014; 190(2):565-74 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Thyroid nodules are present in 19%-67% of the population and carry a 5%-10% risk of malignancy. Unfortunately, fine-needle aspiration biopsies are indeterminate in 20%-30% of patients, often necessitating thyroid surgery for diagnosis. Numerous DNA microarray studies including a recently commercialized molecular classifier have helped to better distinguish benign from malignant thyroid nodules. Unfortunately, these assays often require probes for >100 genes, are expensive, and only available at a few laboratories. We sought to validate these DNA microarray assays at the protein level and determine whether simple and widely available immunohistochemical biomarkers alone could distinguish benign from malignant thyroid nodules.
METHODS: A tissue microarray (TMA) composed of 26 follicular thyroid carcinomas (FTCs) and 53 follicular adenomas (FAs) from patients with indeterminate thyroid nodules was stained with 17 immunohistochemical biomarkers selected based on prior DNA microarray studies. Antibodies used included galectin 3, growth and differentiation factor 15, protein convertase 2, cluster of differentiation 44 (CD44), glutamic oxaloacetic transaminase 1 (GOT1), trefoil factor 3 (TFF3), Friedreich Ataxia gene (X123), fibroblast growth factor 13 (FGF13), carbonic anhydrase 4 (CA4), crystallin alpha-B (CRYAB), peptidylprolyl isomerase F (PPIF), asparagine synthase (ASNS), sodium channel, non-voltage gated, 1 alpha subunit (SCNN1A), frizzled homolog 1 (FZD1), tyrosine related protein 1 (TYRP1), E cadherin, type 1 (ECAD), and thyroid hormone receptor associated protein 220 (TRAP220). Of note, two of these biomarkers (GOT1 and CD44) are now used in the Afirma classifier assay. We chose to compare specifically FTC versus FA rather than include all histologic categories to create a more uniform immunohistochemical comparison. In addition, we have found that most papillary thyroid carcinoma could often be reasonably distinguished from benign disease by morphological cytology findings alone.
RESULTS: Increased immunoreactivity of CRYAB was associated with thyroid malignancy (c-statistic, 0.644; negative predictive value [NPV], 0.90) and loss of immunoreactivity of CA4 was also associated with malignancy (c-statistic, 0.715; NPV, 0.90) in indeterminate thyroid specimens. The combination of CA4 and CRYAB for discriminating FTC from FA resulted in a better c-statistic of 0.75, sensitivity of 0.76, specificity of 0.59, positive predictive value (PPV) of 0.32, and NPV of 0.91. When comparing widely angioinvasive FTC from FA, the resultant c-statistic improved to 0.84, sensitivity of 0.75, specificity of 0.76, PPV of 0.11, and NPV of 0.99.
CONCLUSIONS: Loss of CA4 and increase in CRYAB immunoreactivity distinguish FTC from FA in indeterminate thyroid nodules on a thyroid TMA with an NPV of 91%. Further studies in preoperative patient fine needle aspiration (FNAs) are needed to validate these results.

Jia Y, Viswakarma N, Reddy JK
Med1 subunit of the mediator complex in nuclear receptor-regulated energy metabolism, liver regeneration, and hepatocarcinogenesis.
Gene Expr. 2014; 16(2):63-75 [PubMed] Free Access to Full Article Related Publications
Several nuclear receptors regulate diverse metabolic functions that impact on critical biological processes, such as development, differentiation, cellular regeneration, and neoplastic conversion. In the liver, some members of the nuclear receptor family, such as peroxisome proliferator-activated receptors (PPARs), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), liver X receptor (LXR), pregnane X receptor (PXR), glucocorticoid receptor (GR), and others, regulate energy homeostasis, the formation and excretion of bile acids, and detoxification of xenobiotics. Excess energy burning resulting from increases in fatty acid oxidation systems in liver generates reactive oxygen species, and the resulting oxidative damage influences liver regeneration and liver tumor development. These nuclear receptors are important sensors of exogenous activators as well as receptor-specific endogenous ligands. In this regard, gene knockout mouse models revealed that some lipid-metabolizing enzymes generate PPARα-activating ligands, while others such as ACOX1 (fatty acyl-CoA oxidase1) inactivate these endogenous PPARα activators. In the absence of ACOX1, the unmetabolized ACOX1 substrates cause sustained activation of PPARα, and the resulting increase in energy burning leads to hepatocarcinogenesis. Ligand-activated nuclear receptors recruit the multisubunit Mediator complex for RNA polymerase II-dependent gene transcription. Evidence indicates that the Med1 subunit of the Mediator is essential for PPARα, PPARγ, CAR, and GR signaling in liver. Med1 null hepatocytes fail to respond to PPARα activators in that these cells do not show induction of peroxisome proliferation and increases in fatty acid oxidation enzymes. Med1-deficient hepatocytes show no increase in cell proliferation and do not give rise to liver tumors. Identification of nuclear receptor-specific coactivators and Mediator subunits should further our understanding of the complexities of metabolic diseases associated with increased energy combustion in liver.

Hsieh CL, Fei T, Chen Y, et al.
Enhancer RNAs participate in androgen receptor-driven looping that selectively enhances gene activation.
Proc Natl Acad Sci U S A. 2014; 111(20):7319-24 [PubMed] Free Access to Full Article Related Publications
The androgen receptor (AR) is a key factor that regulates the behavior and fate of prostate cancer cells. The AR-regulated network is activated when AR binds enhancer elements and modulates specific enhancer-promoter looping. Kallikrein-related peptidase 3 (KLK3), which codes for prostate-specific antigen (PSA), is a well-known AR-regulated gene and its upstream enhancers produce bidirectional enhancer RNAs (eRNAs), termed KLK3e. Here, we demonstrate that KLK3e facilitates the spatial interaction of the KLK3 enhancer and the KLK2 promoter and enhances long-distance KLK2 transcriptional activation. KLK3e carries the core enhancer element derived from the androgen response element III (ARE III), which is required for the interaction of AR and Mediator 1 (Med1). Furthermore, we show that KLK3e processes RNA-dependent enhancer activity depending on the integrity of core enhancer elements. The transcription of KLK3e was detectable and its expression is significantly correlated with KLK3 (R(2) = 0.6213, P < 5 × 10(-11)) and KLK2 (R(2) = 0.5893, P < 5 × 10(-10)) in human prostate tissues. Interestingly, RNAi silencing of KLK3e resulted in a modest negative effect on prostate cancer cell proliferation. Accordingly, we report that an androgen-induced eRNA scaffolds the AR-associated protein complex that modulates chromosomal architecture and selectively enhances AR-dependent gene expression.

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