Gene Summary

Gene:DDX6; DEAD-box helicase 6
Aliases: P54, RCK, HLR2
Summary:This gene encodes a member of the DEAD box protein family. The protein is an RNA helicase found in P-bodies and stress granules, and functions in translation suppression and mRNA degradation. It is required for microRNA-induced gene silencing. Multiple alternatively spliced variants, encoding the same protein, have been identified. [provided by RefSeq, Mar 2012]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:probable ATP-dependent RNA helicase DDX6
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (16)

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.

  • siRNA
  • Proto-Oncogene Proteins c-myc
  • Translocation
  • RNA Helicases
  • Immunohistochemistry
  • Colorectal Cancer
  • RNA Nucleotidyltransferases
  • Genetic Predisposition
  • Two-Hybrid System Techniques
  • Chromosome Aberrations
  • Acute Myeloid Leukaemia
  • DNA Copy Number Variations
  • Stomach Cancer
  • FISH
  • Single Nucleotide Polymorphism
  • Gene Amplification
  • Genome
  • Neoplasm Proteins
  • Western Blotting
  • DDX6
  • Alleles
  • Brain Tumours
  • Xenograft Models
  • Messenger RNA
  • Cytogenetic Analysis
  • Proto-Oncogene Proteins
  • Gene Ontology
  • Computational Biology
  • DNA-Binding Proteins
  • Chromosome 11
  • Sensitivity and Specificity
  • Gene Expression Profiling
  • Up-Regulation
  • DEAD-box RNA Helicases
  • Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein
  • Breast Cancer
  • Loss of Heterozygosity
  • Cancer Gene Expression Regulation
  • Proto-Oncogene Protein c-ets-1
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (1)

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: DDX6 (cancer-related)

Tokumaru Y, Tajirika T, Sugito N, et al.
Synthetic miR-143 Inhibits Growth of HER2-Positive Gastric Cancer Cells by Suppressing KRAS Networks Including DDX6 RNA Helicase.
Int J Mol Sci. 2019; 20(7) [PubMed] Free Access to Full Article Related Publications
Gastric cancer (GC) is one of the most common cancers worldwide. In the clinical setting, the identification of HER2 overexpression in GC was a significant finding, as trastuzumab, an anti-HER2 drug, provides a survival advantage to HER2-positive GC patients. In HER2-postive GC, the dysregulation of PI3K/AKT and MAPK/ERK signaling pathways has been reported, and inhibition of these pathways is an important therapeutic strategy. MiR-143 is known to act as a tumor suppressor in several cancers, such as bladder cancer, breast cancer, colorectal cancer, and gastric cancer. In the current study, we developed a novel chemically-modified miR-143 and explored the functions of this synthetic miR-143 (syn-miR-143) in HER2-positive gastric cancer. The expression level of miR-143 was down-regulated in GC cell lines, including HER2-positive GC cell lines, MKN7, and KATO-III. The ectopic expression of miR-143 in those cell lines suppressed cell growth through systemic silencing of KRAS and its effector signaling molecules, AKT and ERK. Furthermore, syn-miR-143 indirectly down-regulated the expression of HER2, an upstream molecule of KRAS, through silencing DEAD/H-box RNA helicase 6 (DDX6), RNA helicase, which enhanced HER2 protein expression at the translational step in HER2-positive GC cells. These findings suggested that syn-miR-143 acted as a tumor suppressor through the impairment of KRAS networks including the DDX6.

Tajirika T, Tokumaru Y, Taniguchi K, et al.
DEAD-Box Protein RNA-Helicase DDX6 Regulates the Expression of HER2 and FGFR2 at the Post-Transcriptional Step in Gastric Cancer Cells.
Int J Mol Sci. 2018; 19(7) [PubMed] Free Access to Full Article Related Publications
The human DEAD/H-box RNA helicase DDX6 (RCK/p54) is a protein encoded by the fusion gene from the t(11;14)(q23;q32) chromosomal translocation observed in human B-cell lymphoma cell line RC-K8. DDX6 has a variety of functions such as translation initiation, pre-mRNA splicing, and ribosome assembly. However, details of the regulatory mechanism governing DDX6 and the functions of DDX6 are largely unknown. Previously, we reported that DDX6 is overexpressed in most malignant cell lines and clinical colorectal tumor samples and that DDX6 positively contributes to the pathogenesis of various cancers. In the current study, we aimed at revealing the function of DDX6 in HER2 and FGFR2 related human gastric cancer (GC) by using clinical samples and GC cell lines. DDX6 protein was overexpressed in about 60% of the clinical samples; HER2, in 35%; and FGFR2, in 30%, (

Duan Z, Ping P, Wang G, et al.
Imsnc761 and DDX6 synergistically suppress cell proliferation and promote apoptosis via p53 in testicular embryonal carcinoma cells.
Biosci Rep. 2018; 38(4) [PubMed] Free Access to Full Article Related Publications
Intermediate-sized non-coding RNAs (imsncRNAs) have been shown to play important regulatory roles in the development of several eukaryotic organisms. In the present research, we selected imsncRNA 761 (imsnc761) as a research target. Expression analyses in a previous study showed that imsnc761 was down-regulated in maturation-arrested testis tissues as compared with the level in normal controls. In the present study, we found that imsnc761 could interact with DEAD-box helicase 6 (DDX6) to induce NTERA-2 (NT2 (testicular embryonal carcinoma cell)) cell apoptosis and proliferation inhibition via the p53 pathway. This interaction between imsnc761 and DDX6 also inhibited mitochondrial function and specific gene transcription and translation. To facilitate further research, we used label-free quantitation method to analyze the associated differences in Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways and biological processes. This confirmed the changes in several specific pathways, which matched our molecular experimental results.

Taniguchi K, Iwatsuki A, Sugito N, et al.
Oncogene RNA helicase DDX6 promotes the process of c-Myc expression in gastric cancer cells.
Mol Carcinog. 2018; 57(5):579-589 [PubMed] Related Publications
Human DEAD-box RNA helicase gene DDX6 was cloned from B-cell lymphoma cell line RC-K8. Previously, we reported that DDX6 acts as oncogene in several cancers such as colorectal cancer and hepatocellular carcinoma. However, the detailed mechanism of DDX6 action in carcinogenesis is largely unknown. In this study, we examined the functions of DDX6 in clinical gastric cancer (GC) samples and GC cells. DDX6 protein expression levels of cancer samples were higher than those of the adjacent normal tissues in 25 clinical GC samples (median value: 1.4 times higher). Also, the results of an RNA immunoprecipitation-assay (RIP-assay) showed that DDX6 associated with c-Myc mRNA. Moreover, enforced overexpression of DDX6 promoted both mRNA and protein expression of c-Myc in GC cells. On the other hand, the gene silencing of DDX6 induced growth suppression through down-regulation of c-Myc in GC cells grown in either two or three dimensions. Furthermore, c-Myc mRNA expression levels of cancer samples were higher than those of the adjacent normal tissues in DDX6 up-regulated-GC clinical samples. Our findings in this study suggested that DDX6 acted as oncogene in GC cells through promotion of c-Myc expression by association with the mRNA of c-Myc.

Lessel W, Silver A, Jechorek D, et al.
Inactivation of JNK2 as carcinogenic factor in colitis-associated and sporadic colorectal carcinogenesis.
Carcinogenesis. 2017; 38(5):559-569 [PubMed] Related Publications
We recently reported that dysregulated c-Jun N-terminal kinases (JNK) activity causes defective cell cycle checkpoint control, inducing neoplastic transformation in a cellular ulcerative colitis (UC) model. In the quiescent chronic phase of UC, p-p54 JNK was down-regulated and p-p46 JNK was up-regulated. Both were up-regulated in the acute phase. Consequently, increased p21WAF1 and γ-H2AX, two JNK-regulated proteins, induced cell cycle arrest. Their down-regulation led to checkpoint override, causing increased proliferation and undetected DNA damage in quiescent chronic phase, all characteristics of tumorigenesis. We investigated expression of p-JNK2, p-JNK1-3, p21WAF1, γ-H2AX and Ki67 by immunohistochemistry in cases of quiescent UC (QUC), active UC (AUC), UC-dysplasia and UC-related colorectal carcinoma (UC-CRC). Comparison was made to normal healthy colorectal mucosa, sporadic adenoma and colorectal carcinoma (CRC), diverticulitis and Crohns disease (CD). We found p-JNK2 up-regulation in AUC and its early down-regulation in UC-CRC and CRC carcinogenesis. With down-regulated p-JNK2, p21WAF1 was also decreased. Ki67 was inversely expressed, showing increased proliferation early in UC-CRC and CRC carcinogenesis. p-JNK1-3 was increased in AUC and QUC. Less increased γ-H2AX in UC-CRC compared to CRC gave evidence that colitis-triggered inflammation masks DNA damage, thus contributing to neoplastic transformation. We hypothesize that JNK-dependent cell cycle arrest is important in AUC, while chronic inflammation causes dysregulated JNK activity in quiescent phase that may contribute to checkpoint override, promoting UC carcinogenesis. We suggest restoring p-JNK2 expression as a novel therapeutic strategy to early prevent the development of UC-related cancer.

Masuelli L, Benvenuto M, Di Stefano E, et al.
Curcumin blocks autophagy and activates apoptosis of malignant mesothelioma cell lines and increases the survival of mice intraperitoneally transplanted with a malignant mesothelioma cell line.
Oncotarget. 2017; 8(21):34405-34422 [PubMed] Free Access to Full Article Related Publications
Malignant mesothelioma (MM) is a primary tumor arising from the serous membranes. The resistance of MM patients to conventional therapies, and the poor patients' survival, encouraged the identification of molecular targets for MM treatment. Curcumin (CUR) is a "multifunctional drug". We explored the in vitro effects of CUR on cell proliferation, cell cycle regulation, pro-survival signaling pathways, apoptosis, autophagy of human (MM-B1, H-Meso-1, MM-F1), and mouse (#40a) MM cells. In addition, we evaluated the in vivo anti-tumor activities of CUR in C57BL/6 mice intraperitoneally transplanted with #40a cells forming ascites.CUR in vitro inhibited MM cells survival in a dose- and time-dependent manner and increased reactive oxygen species'intracellular production and induced DNA damage. CUR triggered autophagic flux, but the process was then blocked and was coincident with caspase 8 activation which activates apoptosis. CUR-mediated apoptosis was supported by the increase of Bax/Bcl-2 ratio, increase of p53 expression, activation of caspase 9, cleavage of PARP-1, increase of the percentage of cells in the sub G1 phase which was reduced (MM-F1 and #40a) or abolished (MM-B1 and H-Meso-1) after MM cells incubation with the apoptosis inhibitor Z-VAD-FMK. CUR treatment stimulated the phosphorylation of ERK1/2 and p38 MAPK, inhibited that of p54 JNK and AKT, increased c-Jun expression and phosphorylation and prevented NF-κB nuclear translocation. Intraperitoneal administration of CUR increased the median survival of C57BL/6 mice intraperitoneally transplanted with #40a cells and reduced the risk of developing tumors. Our findings may have important implications for the design of MM treatment using CUR.

Amaral CL, Freitas LB, Tamura RE, et al.
S6Ks isoforms contribute to viability, migration, docetaxel resistance and tumor formation of prostate cancer cells.
BMC Cancer. 2016; 16:602 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The S6 Kinase (S6K) proteins are some of the main downstream effectors of the mammalian Target Of Rapamycin (mTOR) and act as key regulators of protein synthesis and cell growth. S6K is overexpressed in a variety of human tumors and is correlated to poor prognosis in prostate cancer. Due to the current urgency to identify factors involved in prostate cancer progression, we aimed to reveal the cellular functions of three S6K isoforms-p70-S6K1, p85-S6K1 and p54-S6K2-in prostate cancer, as well as their potential as therapeutic targets.
METHODS: In this study we performed S6K knockdown and overexpression and investigated its role in prostate cancer cell proliferation, colony formation, viability, migration and resistance to docetaxel treatment. In addition, we measured tumor growth in Nude mice injected with PC3 cells overexpressing S6K isoforms and tested the efficacy of a new available S6K1 inhibitor in vitro.
RESULTS: S6Ks overexpression enhanced PC3-luc cell line viability, migration, resistance to docetaxel and tumor formation in Nude mice. Only S6K2 knockdown rendered prostate cancer cells more sensitive to docetaxel. S6K1 inhibitor PF-4708671 was particularly effective for reducing migration and proliferation of PC3 cell line.
CONCLUSIONS: These findings demonstrate that S6Ks play an important role in prostate cancer progression, enhancing cell viability, migration and chemotherapy resistance, and place both S6K1 and S6K2 as a potential targets in advanced prostate cancer. We also provide evidence that S6K1 inhibitor PF-4708671 may be considered as a potential drug for prostate cancer treatment.

Bradford JR, Wappett M, Beran G, et al.
Whole transcriptome profiling of patient-derived xenograft models as a tool to identify both tumor and stromal specific biomarkers.
Oncotarget. 2016; 7(15):20773-87 [PubMed] Free Access to Full Article Related Publications
The tumor microenvironment is emerging as a key regulator of cancer growth and progression, however the exact mechanisms of interaction with the tumor are poorly understood. Whilst the majority of genomic profiling efforts thus far have focused on the tumor, here we investigate RNA-Seq as a hypothesis-free tool to generate independent tumor and stromal biomarkers, and explore tumor-stroma interactions by exploiting the human-murine compartment specificity of patient-derived xenografts (PDX).Across a pan-cancer cohort of 79 PDX models, we determine that mouse stroma can be separated into distinct clusters, each corresponding to a specific stromal cell type. This implies heterogeneous recruitment of mouse stroma to the xenograft independent of tumor type. We then generate cross-species expression networks to recapitulate a known association between tumor epithelial cells and fibroblast activation, and propose a potentially novel relationship between two hypoxia-associated genes, human MIF and mouse Ddx6. Assessment of disease subtype also reveals MMP12 as a putative stromal marker of triple-negative breast cancer. Finally, we establish that our ability to dissect recruited stroma from trans-differentiated tumor cells is crucial to identifying stem-like poor-prognosis signatures in the tumor compartment.In conclusion, RNA-Seq is a powerful, cost-effective solution to global analysis of human tumor and mouse stroma simultaneously, providing new insights into mouse stromal heterogeneity and compartment-specific disease markers that are otherwise overlooked by alternative technologies. The study represents the first comprehensive analysis of its kind across multiple PDX models, and supports adoption of the approach in pre-clinical drug efficacy studies, and compartment-specific biomarker discovery.

Cho YJ, Kang W, Kim SH, et al.
Involvement of DDX6 gene in radio- and chemoresistance in glioblastoma.
Int J Oncol. 2016; 48(3):1053-62 [PubMed] Related Publications
CCRT (concomitant chemotherapy and radiation therapy) is often used for glioblastoma multiforme (GBM) treatment after surgical therapy, however, patients treated with CCRT undergo poor prognosis due to development of treatment resistant recurrence. Many studies have been performed to overcome these problems and to discover genes influencing treatment resistance. To discover potential genes inducing CCRT resistance in GBM, we used whole genome screening by infecting shRNA pool in patient-derived cell. The cells infected ~8,000 shRNAs were implanted in mouse brain and treated RT/TMZ as in CCRT treated patients. We found DDX6 as the candidate gene for treatment resistance after screening and establishing DDX6 knock down cells for functional validation. Using these cells, we confirmed tumor associated ability of DDX6 in vitro and in vivo. Although proliferation improvement was not found, decreased DDX6 influenced upregulated clonogenic ability and resistant response against radiation treatment in vivo and in vitro. Taken together, we suggest that DDX6 discovered by using whole genome screening was responsible for radio- and chemoresistance in GBM.

Baskin R, Woods NT, Mendoza-Fandiño G, et al.
Functional analysis of the 11q23.3 glioma susceptibility locus implicates PHLDB1 and DDX6 in glioma susceptibility.
Sci Rep. 2015; 5:17367 [PubMed] Free Access to Full Article Related Publications
Glioma is the most common malignant primary brain tumor and is associated with poor prognosis. Genetic factors contributing to glioma risk have recently been investigated through genome-wide association studies (GWAS), implicating seven independent glioma risk loci in six chromosomal regions. Here, we performed an in-depth functional analysis of the risk locus proximal to the PHLDB1 gene on 11q23.3. We retrieved all SNPs in linkage disequilibrium (r(2) ≥ 0.2) with the glioma-associated SNP (rs498872) and performed a comprehensive bioinformatics and experimental functional analysis for the region. After testing candidate SNPs for allele-specific activity in a luciferase-based enhancer scanning assay, we established a subset of 10 functional SNPs in the promoters of PHLDB1 and DDX6, and in a putative enhancer element. Chromatin conformation capture (3C) identified a physical interaction between the enhancer element containing a functional SNP (rs73001406) and the promoter of the DDX6 gene. Knockdown experiments in cell culture and 3D assays to evaluate the role of PHLDB1 and DDX6 suggest that both genes may contribute to the phenotype. These studies reveal the functional landscape of the 11q23.3 glioma susceptibility locus and identify a network of functional SNPs in regulatory elements and two target genes as a possible mechanism driving glioma risk association.

Arai M, Kawachi T, Kotoku N, et al.
Furospinosulin-1, Marine Spongean Furanosesterterpene, Suppresses the Growth of Hypoxia-Adapted Cancer Cells by Binding to Transcriptional Regulators p54(nrb) and LEDGF/p75.
Chembiochem. 2016; 17(2):181-9 [PubMed] Related Publications
Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. Cancer research has therefore focused on the identification of molecules responsible for hypoxia adaptation in cancer cells, as well as the development of new compounds with action against hypoxia-adapted cancer cells. The marine natural product furospinosulin-1 (1) has displayed hypoxia-selective growth inhibition against cultured cancer cells, and has shown in vivo anti-tumor activity, although its precise mode of action and molecular targets remain unclear. In this study, we found that 1 is selectively effective against hypoxic regions of tumors, and that it directly binds to the transcriptional regulators p54(nrb) and LEDGF/p75, which have not been previously identified as mediators of hypoxia adaptation in cancer cells.

Zhu Z, Zhao X, Zhao L, et al.
p54(nrb)/NONO regulates lipid metabolism and breast cancer growth through SREBP-1A.
Oncogene. 2016; 35(11):1399-410 [PubMed] Related Publications
Dysregulation of lipid metabolism is common in breast cancer. However, the underlying mechanisms remain elusive and the contribution of aberrant lipid metabolism to the malignant phenotypes of breast cancer is poorly understood. Here, we show that the nuclear protein p54(nrb)/Nono is highly expressed in breast cancer tissues as compared with the adjacent normal tissues in human patients. To determine the functions of p54(nrb) in breast cancer, we performed a biochemical screen and identified SREBP-1a, a master activator for genes involved in lipid biosynthesis, as a novel interacting protein of p54(nrb). In human breast cancer tissues, the levels of p54(nrb) and SREBP-1a proteins were positively correlated with each other. Our biochemical analyses showed that the conserved Y267 residue of p54(nrb) was required for its binding to the nuclear form of SREBP-1a. Interestingly, p54(nrb) binding to nuclear SREBP-1a caused an increase of nuclear SREBP-1a protein stability. As a result, p54(nrb) stimulates SREBP-1-meidated transcription of lipogenic genes and lipid production in breast cancer cells. Moreover, both p54(nrb) and SREBP-1a were required for breast cancer cell growth in vitro, and p54(nrb) binding to nuclear SREBP-1a was also critical for breast tumor development in vivo. Together, we conclude that p54(nrb) is a novel regulator of SREBP-1a in the nucleus, and our data suggest that p54(nrb) regulation of SREBP-1a supports the increased cellular demand of lipids for breast cancer growth. Thus, the SREBP pathway may represent a novel target for treating breast cancer.

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.

Rajgor D, Mellad JA, Soong D, et al.
Mammalian microtubule P-body dynamics are mediated by nesprin-1.
J Cell Biol. 2014; 205(4):457-75 [PubMed] Free Access to Full Article Related Publications
Nesprins are a multi-isomeric family of spectrin-repeat (SR) proteins, predominantly known as nuclear envelope scaffolds. However, isoforms that function beyond the nuclear envelope remain poorly examined. Here, we characterize p50(Nesp1), a 50-kD isoform that localizes to processing bodies (PBs), where it acts as a microtubule-associated protein capable of linking mRNP complexes to microtubules. Overexpression of dominant-negative p50(Nesp1) caused Rck/p54, but not GW182, displacement from microtubules, resulting in reduced PB movement and cross talk with stress granules (SGs). These cells disassembled canonical SGs induced by sodium arsenite, but not those induced by hydrogen peroxide, leading to cell death and revealing PB-microtubule attachment is required for hydrogen peroxide-induced SG anti-apoptotic functions. Furthermore, p50(Nesp1) was required for miRNA-mediated silencing and interacted with core miRISC silencers Ago2 and Rck/p54 in an RNA-dependent manner and with GW182 in a microtubule-dependent manner. These data identify p50(Nesp1) as a multi-functional PB component and microtubule scaffold necessary for RNA granule dynamics and provides evidence for PB and SG micro-heterogeneity.

Iio A, Takagi T, Miki K, et al.
DDX6 post-transcriptionally down-regulates miR-143/145 expression through host gene NCR143/145 in cancer cells.
Biochim Biophys Acta. 2013; 1829(10):1102-10 [PubMed] Related Publications
In various human malignancies, widespread dysregulation of microRNA (miRNA) expression is reported to occur and affects various cell growth programs. Recent studies suggest that the expression levels of miRNAs that act as tumor suppressors are frequently reduced in cancers because of chromosome deletions, epigenetical changes, aberrant transcription, and disturbances in miRNA processing. MiR-143 and -145 are well-recognized miRNAs that are highly expressed in several tissues, but down-regulated in most types of cancers. However, the mechanism of this down-regulation has not been investigated in detail. Here, we show that DEAD-box RNA helicase 6, DDX6 (p54/RCK), post-transcriptionally down-regulated miR-143/145 expression by prompting the degradation of its host gene product, NCR143/145 RNA. In human gastric cancer cell line MKN45, DDX6 protein was abundantly expressed and accumulated in processing bodies (P-bodies). DDX6 preferentially increased the instability of non-coding RNA, NCR143/145, which encompasses the miR-143/145 cluster, and down-regulated the expression of mature miR-143/145. In human monocytic cell line THP-1, lipopolysaccharide treatment promoted the assembly of P-bodies and down-regulated the expression of NCR143/145 and its miR-143/145 rapidly. In these cells, cycloheximide treatment led to a loss of P-bodies and to an increase in NCR143/145 RNA stability, thus resulting in up-regulation of miR-143/145 expression. These data demonstrate that DDX6 contributed to the control of NCR143/145 RNA stability in P-bodies and post-transcriptionally regulated miR-143/145 expression in cancer cells.

Schmid R, Meyer K, Spang R, et al.
Melanoma inhibitory activity promotes melanoma development through activation of YBX1.
Pigment Cell Melanoma Res. 2013; 26(5):685-96 [PubMed] Related Publications
Melanoma inhibitory activity (MIA), a small soluble secreted protein, is functionally important for progression of malignant melanoma. We recently revealed that p54(nrb) acts as a mediator of MIA action. In this study, we characterize the transcriptional regulation of p54(nrb) by MIA to explain MIA's molecular action. We identified one highly conserved region in the p54(nrb) promoter that is necessary and sufficient for MIA-dependent activation. Functional promoter analysis identified the transcription factor YBX1 as the mediator of MIA activation of p54(nrb) transcription. We screened the genome for further potential MIA-regulated genes carrying the element in their promoter regions. Integrating our sequence data with expression data from human melanomas identified a list of 23 potential MIA-YBX1 targets in melanomas. In summary, we present for the first time effects of MIA on transcriptional regulation. Uncovering new potential downstream effectors working via activation of YBX1 supports the important role of MIA in melanoma.

Bernhart E, Damm S, Wintersperger A, et al.
Protein kinase D2 regulates migration and invasion of U87MG glioblastoma cells in vitro.
Exp Cell Res. 2013; 319(13):2037-48 [PubMed] Free Access to Full Article Related Publications
Glioblastoma multiforme (GBM) is the most common malignant brain tumor, which, despite combined modality treatment, reoccurs and is invariably fatal for affected patients. Recently, a member of the serine/threonine protein kinase D (PRKD) family, PRKD2, was shown to be a potent mediator of glioblastoma growth. Here we studied the role of PRKD2 in U87MG glioblastoma cell migration and invasion in response to sphingosine-1-phosphate (S1P), an activator of PRKD2 and a GBM mitogen. Time-lapse microscopy demonstrated that random cell migration was significantly diminished in response to PRKD2 silencing. The pharmacological PRKD family inhibitor CRT0066101 decreased chemotactic migration and invasion across uncoated or matrigel-coated Transwell inserts. Silencing of PRKD2 attenuated migration and invasion of U87MG cells even more effectively. In terms of downstream signaling, CRT0066101 prevented PRKD2 autophosphorylation and inhibited p44/42 MAPK and to a smaller extent p54/46 JNK and p38 MAPK activation. PRKD2 silencing impaired activation of p44/42 MAPK and p54/46 JNK, downregulated nuclear c-Jun protein levels and decreased c-Jun(S73) phosphorylation without affecting the NFκB pathway. Finally, qPCR array analyses revealed that silencing of PRKD2 downregulates mRNA levels of integrin alpha-2 and -4 (ITGA2 and -4), plasminogen activator urokinase (PLAU), plasminogen activator urokinase receptor (PLAUR), and matrix metallopeptidase 1 (MMP1). Findings of the present study identify PRKD2 as a potential target to interfere with glioblastoma cell migration and invasion, two major determinants contributing to recurrence of glioblastoma after multimodality treatment.

Stary S, Vinatzer U, Müllauer L, et al.
t(11;14)(q23;q32) involving IGH and DDX6 in nodal marginal zone lymphoma.
Genes Chromosomes Cancer. 2013; 52(1):33-43 [PubMed] Related Publications
Nodal marginal zone lymphoma (NMZL) is a primary nodal B-cell lymphoma that shares morphological and immunophenotypic characteristics with extranodal and splenic marginal zone lymphoma. Data on altered genes and signaling pathways are scarce in this rare tumor entity. To gain further insights into the genetic background of NMZL, seven cases were investigated by microarray analysis, G-banding, and FISH. Chromosomal imbalances were observed in 3/7 cases (43%) with gains of chromosome arms 1q, 8q, and 12q being the most frequent findings. Furthermore, we identified a translocation t(11;14)(q23;q32) involving IGH and DDX6. Chromosomal walking, expression analysis, siRNA-mediated gene knockdown and a yeast two hybrid screen were performed for further characterization of the translocation in vitro. In siRNA experiments, DDX6 appeared not to be involved in NF-κB activation as frequently observed for genes promoting lymphomagenesis but was found to interfere with the expression of BCL6 and BCL2 in an NF-κB independent manner. In conclusion, we identified several unbalanced aberrations and a t(11;14) involving IGH and DDX6 providing evidence for a contribution of DDX6 to lymphomagenesis by deregulation of BCL6 in NMZL.

Wang Y, Lui WY
Transforming growth factor-β1 attenuates junctional adhesion molecule-A and contributes to breast cancer cell invasion.
Eur J Cancer. 2012; 48(18):3475-87 [PubMed] Related Publications
Transforming growth factor-β1 (TGF-β1) is a potent regulator in promoting the invasion and proliferation of breast cancer cells. Junctional adhesion molecule-A (JAM-A) is a tight junction protein that displays an inverse relationship to cell invasiveness in breast cancer cells. Whether TGF-β1 signaling induces alteration of JAM-A expression leading to cell invasion has not been investigated. In this study, we report that TGF-β1 down-regulated JAM-A expression via its effect on both transcriptional and post-translational regulations of JAM-A, thus inducing cell invasion. On exploring whether TGF-β1 might be the upstream regulator of JAM-A expression, we found that knockdown of TGF-β receptors and canonical Smad signaling could upregulate JAM-A level and inhibit cell invasion in MDA-MB-231 cells. TGF-β1 treatment of MCF-7 cells caused a significant reduction of JAM-A mRNA and protein and induced cell invasion. Delineating the signal mechanisms involved in TGF-β1-mediated JAM-A repression, we found that TGF-β1 significantly inhibited JAM-A gene transcription via the activation of Smads. In addition to Smad activation, we found that involvement of p54 JNK is crucial for post-translational modification of TGF-β1-mediated JAM-A protein degradation. Blockage of JNK pathway by inhibitor could attenuate TGF-β1-induced cell invasion. We provide evidences for the first time that TGF-β1 induces breast cancer cell invasion via TGF-β1-mediated control on JAM-A expression. Identification of JAM-A as a downstream target of TGF-β1 represents a crucial mechanism in cancer progression.

Ward AM, Bidet K, Yinglin A, et al.
Quantitative mass spectrometry of DENV-2 RNA-interacting proteins reveals that the DEAD-box RNA helicase DDX6 binds the DB1 and DB2 3' UTR structures.
RNA Biol. 2011 Nov-Dec; 8(6):1173-86 [PubMed] Free Access to Full Article Related Publications
Dengue virus (DENV) is a rapidly re-emerging flavivirus that causes dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), diseases for which there are no available therapies or vaccines.  The DENV-2 positive-strand RNA genome contains 5' and 3' untranslated regions (UTRs) that have been shown to form secondary structures required for virus replication and interaction with host cell proteins.  In order to comprehensively identify host cell factors that bind the DENV-2 UTRs, we performed RNA chromatography, using the DENV-2 5' and 3' UTRs as "bait", combined with quantitative mass spectrometry.  We identified several proteins, including DDX6, G3BP1, G3BP2, Caprin1, and USP10, implicated in P body (PB) and stress granule (SG) function, and not previously known to bind DENV RNAs.  Indirect immunofluorescence microscopy showed these proteins to colocalize with the DENV replication complex.  Moreover, DDX6 knockdown resulted in reduced amounts of infectious particles and viral RNA in tissue culture supernatants following DENV infection. DDX6 interacted with DENV RNA in vivo during infection and in vitro this interaction was mediated by the DB1 and DB2 structures in the 3' UTR, possibly by formation of a pseudoknot structure.  Additional experiments demonstrate that, in contrast to DDX6, the SG proteins G3BP1, G3BP2, Caprin1 and USP10 bind to the variable region (VR) in the 3' UTR.  These results suggest that the DENV-2 3' UTR is a site for assembly of PB and SG proteins and, for DDX6, assembly on the 3' UTR is required for DENV replication.

Lachance DH, Yang P, Johnson DR, et al.
Associations of high-grade glioma with glioma risk alleles and histories of allergy and smoking.
Am J Epidemiol. 2011; 174(5):574-81 [PubMed] Free Access to Full Article Related Publications
Glioma risk has consistently been inversely associated with allergy history but not with smoking history despite putative biologic plausibility. Data from 855 high-grade glioma cases and 1,160 controls from 4 geographic regions of the United States during 1997-2008 were analyzed for interactions between allergy and smoking histories and inherited variants in 5 established glioma risk regions: 5p15.3 (TERT), 8q24.21 (CCDC26/MLZE), 9p21.3 (CDKN2B), 11q23.3 (PHLDB1/DDX6), and 20q13.3 (RTEL1). The inverse relation between allergy and glioma was stronger among those who did not (odds ratio(allergy-glioma) = 0.40, 95% confidence interval: 0.28, 0.58) versus those who did (odds ratio(allergy-glioma) = 0.76, 95% confidence interval: 0.59, 0.97; P(interaction) = 0.02) carry the 9p21.3 risk allele. However, the inverse association with allergy was stronger among those who carried (odds ratio(allergy-glioma) = 0.44, 95% confidence interval: 0.29, 0.68) versus those who did not carry (odds ratio(allergy-glioma) = 0.68, 95% confidence interval: 0.54, 0.86) the 20q13.3 glioma risk allele, but this interaction was not statistically significant (P = 0.14). No relation was observed between glioma risk and smoking (odds ratio = 0.92, 95% confidence interval: 0.77, 1.10; P = 0.37), and there were no interactions for glioma risk of smoking history with any of the risk alleles. The authors' observations are consistent with a recent report that the inherited glioma risk variants in chromosome regions 9p21.3 and 20q13.3 may modify the inverse association of allergy and glioma.

Schiffner S, Zimara N, Schmid R, Bosserhoff AK
p54nrb is a new regulator of progression of malignant melanoma.
Carcinogenesis. 2011; 32(8):1176-82 [PubMed] Related Publications
Nuclear RNA-binding protein p54(nrb) and its murine homolog NonO are known to be involved in a variety of nuclear processes including transcription and RNA processing. Melanoma inhibitory activity (MIA) has been shown to play an essential role in the progression of malignant melanoma and to influence melanoma-associated molecules and pathways in the early tumor formation steps. Interestingly, recent studies suggest that MIA is a regulator of p54(nrb). Here, we show that p54(nrb) is strongly expressed and localized in the nucleus of both melanoma cell lines and melanoma tissue samples compared with normal human melanocytes or normal skin, respectively. Furthermore, all tested melanoma cell lines revealed strong p54(nrb) promoter activity. Treatment with MIA-specific small interfering RNAs showed an influence of MIA on p54(nrb) expression on both messenger RNA (mRNA) and protein level. Knockdown of p54(nrb) protein in melanoma cell lines led to reduced proliferation rates and to a strong decrease in their migratory potential. In addition, attachment to laminin and poly-l-lysine was significantly increased. We could identify Connexin-43 (Cx-43) as a downstream target molecule of p54(nrb) as knockdown of p54(nrb) resulted in enhanced Cx-43 mRNA and protein levels. As a confirmation of these findings, melanoma cell lines showed very low Cx-43 expression levels compared with melanocytes. Our results demonstrate that p54(nrb) is highly expressed in malignant melanoma and, as a MIA target molecule, it seems to be involved in the development and progression of malignant melanoma.

Desouki MM, Liao S, Conroy J, et al.
The genomic relationship between primary breast carcinomas and their nodal metastases.
Cancer Invest. 2011; 29(4):300-7 [PubMed] Related Publications
We screened the whole tumor genome to identify DNA copy number gains and losses that discriminate between primary breast carcinomas (MP) and their nodal metastases (ML). Six candidate genes were confirmed by quantitative PCR to have differentially distributed copy number changes. Three of the genes (ERRγ, DDX6, and TIAM1) were more commonly amplified in nodal metastases. Principal component analysis revealed that MP-ML pairs varied markedly in their genomic divergence. The latter was larger in PR-negative tumors. Nodal metastases may form early or late in the development of breast carcinomas and PR-negative tumors may metastasize earlier or are genomically less stable.

Radeva M, Hofmann T, Altenberg B, et al.
The database dbEST correctly predicts gene expression in colon cancer patients.
Curr Pharm Biotechnol. 2008; 9(6):510-5 [PubMed] Related Publications
This study aims to test the predictive power of gene expression data derived from NIH's database dbEST, which collects gene expression results from a large number and variety of DNA array experiments. The motivation of this study is to make comparable experimental studies, which are usually performed only for one or a few tissues or organs, with a wide variety of other tissues. Confirmation of a good predictive power of dbEST would put a number of interesting and partially surprising recent findings, solely based on data mining, on a more solid basis than available so far. The expression of nine genes (eIF4E, DDX6, HAT1, USP28, HSP90(beta, PKM2, PLK1, COX2 and OPN) plus two calibration genes in paired normal and cancer colon tissues of eight individual patients was investigated by quantitative RT-PCR and compared with the predictions made by the data-base. GUS and beta-actin reveal only little variation among different patients, making them good internal calibration standards. In normal colon tissue, data mining correctly predicts the expression of all nine genes, which covers two orders of magnitude. In cancer, dbEST is somewhat less precise, but still valuable for the comparison with clinical results.

Lin F, Wang R, Shen JJ, et al.
Knockdown of RCK/p54 expression by RNAi inhibits proliferation of human colorectal cancer cells in vitro and in vivo.
Cancer Biol Ther. 2008; 7(10):1669-76 [PubMed] Related Publications
Colorectal cancer is the third most common cancer in both men and women around the world. Although much progress of the mechanism of colorectal carcinogenesis has been made, the studies centering on the mechanisms of tumorigenesis are much needed to be further exploited. The overexpression of RCK/p54 gene, a member of the DEAD box protein/RNA helicase family, has been found in this malignancy. Roles of RCK in the development of colon cancer, however, are unknown. In this report, we explored whether RCK/p54 plays a role in maintaining the malignant phenotype and functions in the canonical Wnt signaling pathway of colorectal cancer cells harboring an APC mutation. The ectopic overexpression of RCK/p54 gene in colorectal cancer cells by transfection with RCK/p54 cDNA could lead to a significant increase of Tcf transcriptional activity and expression levels of Wnt target genes. By RNAi assay, we also observed that the Tcf transcriptional activity in LoVo-shRNA cells was significantly decreased by approximately 61.3%, while the mRNA and protein expression levels of Wnt target genes were also obviously decreased. Furthermore, the anti-tumour effects and its possible mechanisms of actions in LoVo cells elicited by a decrease in the level of RCK/p54 by RNAi were examined. Results showed that RCK/p54 downregulation could significantly reduce the viability of LoVo cells, increased cell number of S phase, led to cell apoptosis induction, and inhibited tumor growth in nude mice. Taken together, RCK/ p54 might be a determinant of colorectal cancer proliferation by activating the canonical Wnt pathway and RCK/p54-shRNA might be a potential strategy for colorectal cancer gene therapy.

Mrózek K
Cytogenetic, molecular genetic, and clinical characteristics of acute myeloid leukemia with a complex karyotype.
Semin Oncol. 2008; 35(4):365-77 [PubMed] Free Access to Full Article Related Publications
Patients with acute myeloid leukemia (AML) harboring three or more acquired chromosome aberrations in the absence of the prognostically favorable t(8;21)(q22;q22), inv(16)(p13q22)/t(6;16)(p13;q22), and t(15;17)(q22;q21) aberrations form a separate category - AML with a complex karyotype. They constitute 10% to 12% of all AML patents, with the incidence of complex karyotypes increasing with the more advanced age. Recent studies using molecular-cytogenetic techniques (spectral karyotyping [SKY], multiplex fluorescence in situ hybridization [M-FISH]) and array comparative genomic hybridization (a-CGH) considerably improved characterization of previously unidentified, partially identified, or cryptic chromosome aberrations, and allowed precise delineation of genomic imbalances. The emerging nonrandom pattern of abnormalities includes relative paucity, but not absence, of balanced rearrangements (translocations, insertions, or inversions), predominance of aberrations leading to loss of chromosome material (monosomies, deletions, and unbalanced translocations) that involve, in decreasing order, chromosome arms 5q, 17p, 7q, 18q, 16q, 17q, 12p, 20q, 18p, and 3p, and the presence of recurrent, albeit less frequent and often hidden (in marker chromosomes and unbalanced translocations) aberrations leading to overrepresentation of segments from 8q, 11q, 21q, 22q, 1p, 9p, and 13q. Several candidate genes have been identified as targets of genomic losses, for example, TP53, CTNNA1, NF1, ETV6, and TCF4, and amplifications, for example, ERG, ETS2, APP, ETS1, FLI1, MLL, DDX6, GAB2, MYC, TRIB1, and CDX2. Treatment outcomes of complex karyotype patients receiving chemotherapy are very poor. They can be improved to some extent by allogeneic stem cell transplantation in younger patients. It is hoped that better understanding of genomic alterations will result in identification of novel therapeutic targets and improved prognosis in patients with complex karyotypes.

Cannon GM, Balasudramani M, Getzenberg RH
Characterization of nuclear matrix protein alterations associated with renal cell carcinoma.
Urology. 2007; 69(6):1227-30 [PubMed] Related Publications
OBJECTIVES: Nuclear matrix proteins (NMPs), which constitute the nuclear skeleton, play a role in regulating gene expression and are thought to play an important role in carcinogenesis. Five NMPs specific to renal cell carcinoma (RCC) have been previously identified, RCCA 1 to 5. Our aim was to identify the sequence of these novel NMPs that are associated with RCC.
METHODS: NMPs were extracted from five conventional clear cell RCC specimens from patients undergoing surgical excision for presumed RCC. The RCCA proteins identified were analyzed by matrix-assisted light desorption ionization mass spectrometry to determine their peptide mass fingerprint. This fingerprint was then analyzed by searching the Mascot and National Institutes of Health BLAST (basic local alignment search tool) databases to determine protein identification.
RESULTS: Only RCCA-1 and RCCA-2 were able to be consistently identified from each tumor specimen by the reverse staining method necessary to perform mass spectrometry. Mass spectrometry peptide mass fingerprinting revealed that RCCA-1 appears to be a differentially spliced form of nucleoporin p54 that has been identified in endometrial carcinoma. RCCA-2 was identified as an albumin-like protein.
CONCLUSIONS: This is the first report of nucleoporin p54 and albumin alterations in RCC. The identification of an abnormal nucleoporin in RCC suggests that alterations in nuclear transport might play a role in the development of this disease. The alterations in these NMPs suggest future areas for investigation in identifying diagnostic markers of, or therapeutic targets for, RCC.

Poppe B, De Paepe A, Speleman F
Acquired chromosomal rearrangements targeting selected transcription factors: contribution of molecular cytogenetic and expression analyses to the identification of clinically and biologically relevant subgroups in hematological malignancies.
Verh K Acad Geneeskd Belg. 2007; 69(1):47-64 [PubMed] Related Publications
In leukemias chromosomal aberrations, balanced translocations in particular, play a critical role in the oncogenic process. The characterization of these chromosomal alterations was crucial to the discovery of the genes implicated in leukemogenesis, as the chromosomal breakpoints indicated their genomic localization. In addition, these molecular defects may serve as targets for diagnostic essays and can have a major prognostic value. Finally, the characterization of the deregulated cellular pathways potentially identifies targets for therapeutic intervention. In this paper we summarize our efforts to expand the current knowledge of the diagnostic, prognostic or biological significance of selected chromosomal aberrations identified in M-FISH studies. First, we illustrated the power of M-FISH in dissecting complex chromosomal aberrations in myeloid neoplasms. MLL amplification was defined as a clinical entity characterized by adverse prognosis and within the multitude and variety of chromosomal rearrangements a pattern of a limited number of cytogenetic subclasses was discerned. In leukemias characterized by 11q23 amplification, we described the amplicon and confirmed MLL, in addition to DDX6, as a principal amplification target. Molecular characterization of a large series of unselected sporadic and recurrent 3q26 rearranged leukemias confirmed the decisive role of ectopic EVI1 expression in these malignancies. We contributed to an extensive analysis of the phenotypical and prognostic features of T-ALL characterized by HOX11L2 expression and identified HOX11L2 overexpression as one of the most frequent genetic defects in childhood T-ALL, associated with intermediate prognosis. Finally, we designed and validated diagnostic tools for the detection of the t(9;14) (p13;q34) resulting in PAX5 overexpression and convincingly associated the presence of this rearrangement to high-grade morphology and karyotype complexity. In conclusion, the series of investigations presented here clearly illustrate the benefits of M-FISH as molecular tool for the dissection and characterization of complex and cryptic rearrangements. The subsequent reports demonstrate the utility of molecular cytogenetics and expression analyses to the clinical management of patients diagnosed with hematological malignancies.

Hisada-Ishii S, Ebihara M, Kobayashi N, Kitagawa Y
Bipartite nuclear localization signal of matrin 3 is essential for vertebrate cells.
Biochem Biophys Res Commun. 2007; 354(1):72-6 [PubMed] Related Publications
Matrin 3, a nuclear matrix protein has potential (1) to withhold promiscuously edited RNAs within the nucleus in cooperation with p54(nrb) and PSF, (2) to mediate NMDA-induced neuronal death, and (3) to modulate promoter activity of genes proximal to matrix/scaffold attachment region (MAR/SAR). We identified a bipartite nuclear localization signal (NLS) of chicken matrin 3 (cmatr3) at residues 583-602. By expressing green fluorescent protein (GFP) fused to the NLS mutant in chicken DT40 cells, we showed an essential role of the NLS for cell proliferation. Furthermore, we showed that both clusters of basic amino acids and a linker of the bipartite NLS were essential and sufficient for the nuclear import of GFP. Exogenous cmatr3 rescued the HeLa cells where human matrin 3 was suppressed by RNA interference, but cmatr3 containing deletions at either of the basic amino acid clusters or the linker could not.

Terenzi F, Hui DJ, Merrick WC, Sen GC
Distinct induction patterns and functions of two closely related interferon-inducible human genes, ISG54 and ISG56.
J Biol Chem. 2006; 281(45):34064-71 [PubMed] Related Publications
Human P54 and P56 proteins are tetratricopeptide proteins that are encoded by two closely related genes, ISG54 and ISG56. These genes are induced strongly but transiently when cells are treated with interferons or double-stranded RNA or infected with a variety of viruses. We observed that, although double-stranded RNA or Sendai virus infection induced the two genes with similar kinetics, their induction kinetics in response to interferon-beta were quite different. The induction kinetics by virus infection were also different between two cell lines. Functionally the two proteins were similar. Like P56, P54 bound to the translation initiation factor eIF3 and inhibited translation. However, unlike P56, P54 bound to both the "e" and the "c" subunits of eIF3. Consequently, P54 inhibited two functions of eIF3. Like P56, it inhibited the ability of eIF3 to stabilize the eIF2 x GTP x Met-tRNA(i) ternary complex. But in addition, it also inhibited the formation of the 48 S pre-initiation complex between the 40 S ribosomal subunit and the 20 S complex composed of eIF3, ternary complex, eIF4F, and mRNA. Thus, although similar in structure, the human P54 and P56 proteins are induced differently and function differently.

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