WT1-AS

Gene Summary


HPRD
Gene:WT1-AS; WT1 antisense RNA
Aliases: WIT1, WIT-1, WT1AS, WT1-AS1
Location:11p13
Summary:This gene is located upstream of the Wilms tumor 1 (WT1) gene; these two genes are bi-directionally transcribed from the same promoter region. This gene is imprinted in kidney, with preferential expression from the paternal allele. Imprinting defects at chromosome 11p13 may contribute to tumorigenesis. [provided by RefSeq, May 2014]
Databases:OMIM, HGNC, GeneCard, Gene
Source:NCBIAccessed: 27 February, 2015

Ontology:

What does this gene/protein do?
WT1-AS is implicated in:
- biological_process
- cellular_component
- molecular_function
Data from Gene Ontology via CGAP

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 27 February 2015 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.

  • Chromosome 11
  • Gene Expression Profiling
  • DNA-Binding Proteins
  • Transcription Factors
  • Genetic Markers
  • Mutation
  • Cell Proliferation
  • Childhood Cancer
  • Gene Expression
  • Genomic Imprinting
  • Leukaemia
  • Western Blotting
  • Promoter Regions
  • WT1
  • Messenger RNA
  • Wilms Tumor Genes
  • Kidney
  • Gene Expression Regulation
  • Cancer Gene Expression Regulation
  • Loss of Heterozygosity
  • Tumor Suppressor Gene
  • Acute Myeloid Leukaemia
  • Molecular Sequence Data
  • Immunohistochemistry
  • RTPCR
  • DNA Methylation
  • Cancer RNA
  • Infant
  • ras Proteins
  • Cell Differentiation
  • Transfection
  • Tumor Markers
  • Apoptosis
  • Neoplasm Proteins
  • p53 Protein
  • Base Sequence
  • Protein Isoforms
  • Kidney Cancer
  • Residual Disease
Tag cloud generated 27 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

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: WT1-AS (cancer-related)

Toska E, Roberts SG
Mechanisms of transcriptional regulation by WT1 (Wilms' tumour 1).
Biochem J. 2014; 461(1):15-32 [PubMed] Related Publications
The WT1 (Wilms' tumour 1) gene encodes a zinc finger transcription factor and RNA-binding protein that direct the development of several organs and tissues. WT1 manifests both tumour suppressor and oncogenic activities, but the reasons behind these opposing functions are still not clear. As a transcriptional regulator, WT1 can either activate or repress numerous target genes resulting in disparate biological effects such as growth, differentiation and apoptosis. The complex nature of WT1 is exemplified by a plethora of isoforms, post-translational modifications and multiple binding partners. How WT1 achieves specificity to regulate a large number of target genes involved in diverse physiological processes is the focus of the present review. We discuss the wealth of the growing molecular information that defines our current understanding of the versatility and utility of WT1 as a master regulator of organ development, a tumour suppressor and an oncogene.

Busch M, Schwindt H, Brandt A, et al.
Classification of a frameshift/extended and a stop mutation in WT1 as gain-of-function mutations that activate cell cycle genes and promote Wilms tumour cell proliferation.
Hum Mol Genet. 2014; 23(15):3958-74 [PubMed] Free Access to Full Article Related Publications
The WT1 gene encodes a zinc finger transcription factor important for normal kidney development. WT1 is a suppressor for Wilms tumour development and an oncogene for diverse malignant tumours. We recently established cell lines from primary Wilms tumours with different WT1 mutations. To investigate the function of mutant WT1 proteins, we performed WT1 knockdown experiments in cell lines with a frameshift/extension (p.V432fsX87 = Wilms3) and a stop mutation (p.P362X = Wilms2) of WT1, followed by genome-wide gene expression analysis. We also expressed wild-type and mutant WT1 proteins in human mesenchymal stem cells and established gene expression profiles. A detailed analysis of gene expression data enabled us to classify the WT1 mutations as gain-of-function mutations. The mutant WT1(Wilms2) and WT1(Wilms3) proteins acquired an ability to modulate the expression of a highly significant number of genes from the G2/M phase of the cell cycle, and WT1 knockdown experiments showed that they are required for Wilms tumour cell proliferation. p53 negatively regulates the activity of a large number of these genes that are also part of a core proliferation cluster in diverse human cancers. Our data strongly suggest that mutant WT1 proteins facilitate expression of these cell cycle genes by antagonizing transcriptional repression mediated by p53. We show that mutant WT1 can physically interact with p53. Together the findings show for the first time that mutant WT1 proteins have a gain-of-function and act as oncogenes for Wilms tumour development by regulating Wilms tumour cell proliferation.

Rauscher J, Beschorner R, Gierke M, et al.
WT1 expression increases with malignancy and indicates unfavourable outcome in astrocytoma.
J Clin Pathol. 2014; 67(7):556-61 [PubMed] Related Publications
AIMS: The zinc finger transcription factor WT1 is expressed in astrocytic neoplasms and therefore is a potential target of immunotherapy in brain tumours. Our aim was to further elucidate the role of WT1 as a diagnostic and prognostic marker in neuropathology, particularly as to the differentiation of astrocytoma from oligodendroglioma as well as to the dependency of WT1 expression on clinically relevant parameters.
METHODS: 829 evaluable brain tumour samples were investigated by WT1 immunohistochemistry on full tissue routine slides, consisting of 442 glioblastomas, 303 astrocytomas, 41 oligodendrogliomas and 43 oligoastrocytomas. In addition public WT1 gene expression data of 351 gliomas were analysed.
RESULTS: Our data show that WT1 expression in diffuse astrocytic tumours increases with WHO tumour grade and is associated with older age, absence of IDH1 mutation but not related to O(6)- methyl guanine methyl transferase (MGMT) promoter methylation status. Univariable, but not multivariable survival analysis indicates that WT1 expression is associated with worse outcome in patients with diffuse astrocytoma but not glioblastoma.
CONCLUSIONS: The significant WT1 expression differences between diffuse astrocytomas, oligoastrocytomas and oligodendrogliomas, which are also present in the Repository for Molecular Brain Neoplasia Data, National Cancer Institute (REMBRANDT, 2005, http://rembrandt.nci.nih.gov) gene database set, provide a rationale for use of WT1 as part of a routine immunohistochemistry panel.

Rather MI, Swamy S, Gopinath KS, Kumar A
Transcriptional repression of tumor suppressor CDC73, encoding an RNA polymerase II interactor, by Wilms tumor 1 protein (WT1) promotes cell proliferation: implication for cancer therapeutics.
J Biol Chem. 2014; 289(2):968-76 [PubMed] Free Access to Full Article Related Publications
The Wilms tumor 1 gene (WT1) can either repress or induce the expression of genes. Inconsistent with its tumor suppressor role, elevated WT1 levels have been observed in leukemia and solid tumors. WT1 has also been suggested to act as an oncogene by inducing the expression of MYC and BCL-2. However, these are only the correlational studies, and no functional study has been performed to date. Consistent with its tumor suppressor role, CDC73 binds to RNA polymerase II as part of a PAF1 transcriptional regulatory complex and causes transcriptional repression of oncogenes MYC and CCND1. It also represses β-catenin-mediated transcription. Based on the reduced level of CDC73 in oral squamous cell carcinoma (OSCC) samples in the absence of loss-of-heterozygosity, promoter methylation, and mutations, we speculated that an inhibitory transcription factor is regulating its expression. The bioinformatics analysis predicted WT1 as an inhibitory transcription factor to regulate the CDC73 level. Our results showed that overexpression of WT1 decreased CDC73 levels and promoted proliferation of OSCC cells. ChIP and EMSA results demonstrated binding of WT1 to the CDC73 promoter. The 5-azacytidine treatment of OSCC cells led to an up-regulation of WT1 with a concomitant down-regulation of CDC73, further suggesting regulation of CDC73 by WT1. Exogenous CDC73 attenuated the protumorigenic activity of WT1 by apoptosis induction. An inverse correlation between expression levels of CDC73 and WT1 was observed in OSCC samples. These observations indicated that WT1 functions as an oncogene by repressing the expression of CDC73 in OSCC. We suggest that targeting WT1 could be a therapeutic strategy for cancer, including OSCC.

Israyelyan A, La Rosa C, Tsai W, et al.
Detection and preliminary characterization of CD8+T lymphocytes specific for Wilms' tumor antigen in patients with non-Hodgkin lymphoma.
Leuk Lymphoma. 2013; 54(11):2490-9 [PubMed] Free Access to Full Article Related Publications
Wilms' tumor antigen (WT1) is overexpressed in many different solid tumors and hematologic malignancies. However, little is known about WT1 expression or WT1-specific immune responses in patients with non-Hodgkin lymphoma (NHL). In a cross-sectional survey study, we investigated the immune recognition of WT1 by patients with NHL. Utilizing a WT1 overlapping peptide library, we discovered that a large percentage of patients with NHL of all grades maintain WT1-specific T cells. Ex vivo frequencies of these T cells measured from unfractionated samples by the CD137 activation marker assay were high in many patients (some > 1% CD8+). Using standard in vitro techniques we discovered that they were cytotoxic to WT1 peptide library-loaded T2 cells and WT1 antigen-primed autologous Epstein-Barr virus-transformed B cell lines (EBV-LCLs) and expressed interferon gamma (IFN-γ). In addition, we detected WT1 mRNA transcripts in diseased lymph node tissues of patients with NHL utilizing real-time quantitative polymerase chain reaction (RT-qPCR) technology. These results are the first example of strong T cell reactivity against WT1 in patients with NHL which also demonstrate strong cytotoxicity against peptide-loaded tumor cells. The potential for developing WT1 as a target for immunotherapy in NHL deserves further exploration.

Coosemans A, Van Calster B, Verbist G, et al.
Wilms tumor gene 1 (WT1) is a prognostic marker in high-grade uterine sarcoma.
Int J Gynecol Cancer. 2011; 21(2):302-8 [PubMed] Related Publications
INTRODUCTION: Wilms tumor gene 1 (WT1) contributes to uterine sarcoma tumor biology. In this study, we aimed to clarify the prognostic value of WT1.
METHODS: A retrospective clinical and histopathological review of 71 women with high-grade uterine sarcoma (leiomyosarcoma [n = 24], undifferentiated sarcoma [n = 9]), and carcinosarcoma (n = 38) was performed. Patients were followed up for at least 12 months. Wilms tumor gene 1 expression was determined by immunohistochemistry. Data on recurrence (progression-free survival) and overall survival (OS) were available for all patients. Univariate and multivariate analyses of WT1 expression were carried out using Kaplan-Meier curves and Cox regression, respectively.
RESULTS: Forty-nine (69%) tumors were WT1 positive. Forty-seven (66%) patients died of the disease, with a median OS time of 22 months. Wilms tumor gene 1 was a predictor of survival in the univariate analysis: the hazard ratio of WT1 positivity was 2.44 (95% confidence interval, 1.34-4.71) for progression-free survival and 2.48 (95% confidence interval, 1.26-4.90) for OS. Multivariate analysis including stage, age, tumor size, and sarcoma subtype identified only stage and WT1 positivity as independent prognostic markers for survival.
CONCLUSIONS: The identification of WT1 as a prognostic marker confirms its role in high-grade uterine sarcoma and carcinosarcoma tumor biology.

Vicent S, Chen R, Sayles LC, et al.
Wilms tumor 1 (WT1) regulates KRAS-driven oncogenesis and senescence in mouse and human models.
J Clin Invest. 2010; 120(11):3940-52 [PubMed] Free Access to Full Article Related Publications
KRAS is one of the most frequently mutated human oncogenes. In some settings, oncogenic KRAS can trigger cellular senescence, whereas in others it produces hyperproliferation. Elucidating the mechanisms regulating these 2 drastically distinct outcomes would help identify novel therapeutic approaches in RAS-driven cancers. Using a combination of functional genomics and mouse genetics, we identified a role for the transcription factor Wilms tumor 1 (WT1) as a critical regulator of senescence and proliferation downstream of oncogenic KRAS signaling. Deletion or suppression of Wt1 led to senescence of mouse primary cells expressing physiological levels of oncogenic Kras but had no effect on wild-type cells, and Wt1 loss decreased tumor burden in a mouse model of Kras-driven lung cancer. In human lung cancer cell lines dependent on oncogenic KRAS, WT1 loss decreased proliferation and induced senescence. Furthermore, WT1 inactivation defined a gene expression signature that was prognostic of survival only in lung cancer patients exhibiting evidence of oncogenic KRAS activation. These findings reveal an unexpected role for WT1 as a key regulator of the genetic network of oncogenic KRAS and provide important insight into the mechanisms that regulate proliferation or senescence in response to oncogenic signals.

Licciulli S, Kissil JL
WT1: a weak spot in KRAS-induced transformation.
J Clin Invest. 2010; 120(11):3804-7 [PubMed] Free Access to Full Article Related Publications
Activating mutations in the Ras alleles are found frequently in tumors, making the proteins they encode highly attractive candidate therapeutic targets. However, Ras proteins have proven difficult to target directly. Recent approaches have therefore focused on identifying indirect targets to inhibit Ras-induced oncogenesis. For example, RNAi-based negative selection screens to identify genes that when silenced in concert with activating Ras mutations are incompatible with cellular proliferation, a concept known as synthetic lethality. In this issue of the JCI, Vicent et al. report on the identification of Wilms tumor 1 (Wt1) as a Kras synthetic-lethal gene in a mouse model of lung adenocarcinoma. Silencing of Wt1 in cells expressing an endogenous allele of activated Kras triggers senescence in vitro and has an impact on tumor progression in vivo. These findings are of significant interest given previous studies suggesting that the ability of oncogenic Kras to induce senescence versus proliferation depends on its levels of expression.

Jahn JE, Best DH, Coleman WB
Exogenous expression of synaptotagmin XIII suppresses the neoplastic phenotype of a rat liver tumor cell line through molecular pathways related to mesenchymal to epithelial transition.
Exp Mol Pathol. 2010; 89(3):209-16 [PubMed] Related Publications
The molecular pathogenesis of hepatocellular carcinoma is well-studied but not completely understood. We utilized a microcell-hybrid model of tumor suppression in rat liver tumor cells to facilitate the identification of liver tumor suppressor genes located on human chromosome 11. These investigations confirmed a liver tumor suppressor locus at human 11p11.2, identified Wt1 as a potential effector of 11p11.2-mediated tumor suppression, and subsequently identified human SYT13 as a strong candidate for the 11p11.2 liver tumor suppressor gene. In the studies presented here, we introduced SYT13 into the GN6TF rat liver tumor cell line to characterize a functional role for SYT13 in this model system. Transfected clones expressing an SDS-resistant dimer form of the SYT13 protein displayed induction of Wt1 gene expression and a significant attenuation of the neoplastic phenotype exhibited by the parental tumor cell line. Saturation densities and anchorage-independent growth of SYT13 dimer-positive cell lines were reduced in vitro, and tumorigenicity was significantly decreased or ablated in syngeneic host rats in vivo. In addition, restoration of the contact-inhibited, epithelioid morphology observed in normal liver epithelial cells accompanied ectopic expression of the SYT13 protein dimer, suggesting that SYT13 may be mediating an epithelial differentiation coordinate with tumor suppression in these cells. Accordingly, the expression of E-cadherin (Cdh1) mRNA was increased >100-fold in SYT13-dimer-positive cell lines and the Cdh1 transcriptional repressor Snail was decreased >3-fold in these cells compared to the parental tumor cells. These studies combine to suggest that SYT13 is a liver tumor suppressor gene and that its function may be mediated through pathways implicated in mesenchymal to epithelial transition.

Bansal H, Bansal S, Rao M, et al.
Heat shock protein 90 regulates the expression of Wilms tumor 1 protein in myeloid leukemias.
Blood. 2010; 116(22):4591-9 [PubMed] Free Access to Full Article Related Publications
The aberrant overexpression of Wilms tumor 1 (WT1) in myeloid leukemia plays an important role in blast cell survival and resistance to chemotherapy. High expression of WT1 is also associated with relapse and shortened disease-free survival in patients. However, the mechanisms by which WT1 expression is regulated in leukemia remain unclear. Here, we report that heat shock protein 90 (Hsp90), which plays a critical role in the folding and maturation of several oncogenic proteins, associates with WT1 protein and stabilizes its expression. Pharmacologic inhibition of Hsp90 resulted in ubiquitination and subsequent proteasome-dependant degradation of WT1. RNAi-mediated silencing of WT1 reduced the survival of leukemia cells and increased the sensitivity of these cells to chemotherapy and Hsp90 inhibition. Furthermore, Hsp90 inhibitors 17-AAG [17-(allylamino)-17-demethoxygeldanamycin] and STA-9090 significantly reduced the growth of myeloid leukemia xenografts in vivo and effectively down-regulated the expression of WT1 and its downstream target proteins, c-Myc and Bcl-2. Collectively, our studies identify WT1 as a novel Hsp90 client and support the crucial role for the WT1-Hsp90 interaction in maintaining leukemia cell survival. These findings have significant implications for developing effective therapies for myeloid leukemias and offer a strategy to inhibit the oncogenic functions of WT1 by clinically available Hsp90 inhibitors.

Essafi A, Hastie ND
WT1 the oncogene: a tale of death and HtrA.
Mol Cell. 2010; 37(2):153-5 [PubMed] Related Publications
Here, Hartkamp et al. (2010) identify WT1 as a novel bona fide substrate of the HtrA2/Omi mitochondrial protease and show that this reaction modulates WT1 antiapoptotic activity under cytotoxic stress. This supports an oncogenic function for WT1, with implications for novel chemotherapeutic avenues.

Michiels JF, Perrin C, Leccia N, et al.
PPARbeta activation inhibits melanoma cell proliferation involving repression of the Wilms' tumour suppressor WT1.
Pflugers Arch. 2010; 459(5):689-703 [PubMed] Free Access to Full Article Related Publications
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that strongly influence molecular signalling in normal and cancer cells. Although increasing evidence suggests a role of PPARs in skin carcinogenesis, only expression of PPARgamma has been investigated in human melanoma tissues. Activation of PPARalpha has been shown to inhibit the metastatic potential, whereas stimulation of PPARgamma decreased melanoma cell proliferation. We show here that the third member of the PPAR family, PPARbeta/delta is expressed in human melanoma samples. Specific pharmacological activation of PPARbeta using GW0742 or GW501516 in low concentrations inhibits proliferation of human and murine melanoma cells. Inhibition of proliferation is accompanied by decreased expression of the Wilms' tumour suppressor 1 (WT1), which is implicated in melanoma proliferation. We demonstrate that PPARbeta directly represses WT1 as (1) PPARbeta activation represses WT1 promoter activity; (2) in chromatin immunoprecipitation and electrophoretic mobility shift assays, we identified a binding element for PPARbeta in the WT1 promoter; (3) deletion of this binding element abolishes repression by PPARbeta and (4) the WT1 downstream molecules nestin and zyxin are down-regulated upon PPARbeta activation. Our findings elucidate a novel mechanism of signalling by ligands of PPARbeta, which leads to suppression of melanoma cell growth through direct repression of WT1.

Madore J, Ren F, Filali-Mouhim A, et al.
Characterization of the molecular differences between ovarian endometrioid carcinoma and ovarian serous carcinoma.
J Pathol. 2010; 220(3):392-400 [PubMed] Related Publications
The histopathological diagnosis of high-grade endometrioid and serous carcinoma of the ovary is poorly reproducible under the current morphology based classification system, especially for anaplastic, high-grade tumours. The transcription factor Wilms' tumour-1 (WT1) is differentially expressed among the gynaecological epithelia from which epithelial ovarian cancers (EOCs) are believed to originate. In EOCs, WT1 protein is observed in the majority of serous carcinomas and in up to 30% of endometrioid carcinomas. It is unclear whether the latter is a reflection of the actual incidence of WT1 protein expression in endometrioid carcinomas, or whether a significant number of high-grade serous carcinomas have been misclassified as endometrioid carcinoma. Several genetic aberrations are reported to occur in EOCs. These include mutation of the TP53 gene, aberrant activation of beta-catenin signalling and loss of PTEN protein expression, among others. It is unclear whether these aberrations are histotype-specific. The aim of this study was to better define the molecular characteristics of serous and endometrioid carcinomas in an attempt to address the problems with the current histopathological classification methods. Gene expression profiles were analysed to identify reproducible gene expression phenotypes for endometrioid and serous carcinomas. Tissue microarrays (TMA) were used to assess the incidence of TP53, beta-catenin and PTEN aberrations in order to correlate their occurrence with WT1 as an immunohistochemistry based biomarker of serous histotype. It was found that nuclear WT1 protein expression can identify misclassified high-grade endometrioid carcinomas and these tumours should be reassigned to serous histotype. Although low-grade endometrioid carcinomas rarely progress to high-grade carcinomas, a combined WT1-negative, TP53-positive immunophenotype may identify an uncommon high-grade subtype of ovarian endometrioid carcinoma. GEO database: array data accession number GSE6008.

Glienke W, Maute L, Wicht J, Bergmann L
Wilms' tumour gene 1 (WT1) as a target in curcumin treatment of pancreatic cancer cells.
Eur J Cancer. 2009; 45(5):874-80 [PubMed] Related Publications
The transcription factor WT1 plays an important role in cellular proliferation and survival of various cancer cells, and is frequently expressed in pancreatic cancer. Curcumin has been shown to be a potentially effective agent in pancreatic cancer. In this context, the purpose of this study was to determine the role of WT1 in a curcumin-treated pancreatic cancer cell line. To study the effect of curcumin on the expression of WT1, we incubated the pancreatic cancer cell line PANC-1 with different amounts of curcumin. The expression of WT1 on mRNA and protein level was measured with real-time RT-PCR and Western blot analysis. The incubation of the pancreatic cancer cell line PANC-1 with curcumin resulted in an inhibition of cellular proliferation as measured with MTT assay. The expression of WT1 on mRNA and protein level was significantly down-regulated in a concentration-dependent manner after treatment with curcumin. The WT1 mRNA levels were decreased by 20%, 25%, 40%, 78% and 88% in response to 10, 20, 30, 40 and 50 microM curcumin. The use of small inhibitory RNA (siRNA) targeting WT1 down-regulated the expression of WT1 about 90%. Combined treatment with curcumin and siRNA targeting WT1 resulted in a significant inhibition of cell proliferation compared to curcumin-treated cells alone. In conclusion, WT1 is involved in cellular proliferation of PANC-1 cells. Targeting WT1 gene expression with siRNA may enhance the efficacy of curcumin to inhibit cell proliferation.

Li H, Smolen GA, Beers LF, et al.
Adenosine transporter ENT4 is a direct target of EWS/WT1 translocation product and is highly expressed in desmoplastic small round cell tumor.
PLoS One. 2008; 3(6):e2353 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Desmoplastic Small Round Cell Tumor (DSRCT) is a highly aggressive malignancy that affects mainly adolescents and young adults. A defining characteristic of DSRCT is a specific chromosomal translocation, t(11;22)(p13;q12), that fuses EWS with WT1, leading to a production of two isoforms of chimeric transcription factor, EWS/WT1(-KTS) and EWS/WT1(+KTS). The chimeric proteins are thought to play critical roles in various stages of oncogenesis through aberrant transcription of different genes, but only a few of these genes have been identified.
METHODOLOGY/PRINCIPAL FINDINGS: We report the identification of a new target of EWS/WT1, ENT4 (equilibrative nucleoside transporter 4) which encodes a pH-dependent adenosine transporter. ENT4 is transcriptionally activated by both isoforms of EWS/WT1 as evidenced by promoter-reporter and chromatin immunoprecipitation (ChIP) analyses. Furthermore, ENT4 is highly and specifically expressed in primary tumors of DSRCT as well as in a DSRCT cell line, JN-DSRCT-1. Treatment of JN-DSRCT-1 cells with adenosine analogs, such as 2-chloro-2'-deoxyadenosine (2-CdA), resulted in an increased cytotoxic response in dose- and pH-dependent manner.
CONCLUSIONS/SIGNIFICANCE: Our detailed analyses of a novel target of EWS/WT1 in DSRCT reveal an insight into the oncogenic mechanism of EWS-fusion chromosomal translocation gene products and provide a new marker for DSRCT. Furthermore, identification of ENT4 as a highly expressed transcript in DSRCT may represent an attractive pathway for targeting chemotherapeutic drugs into DSRCT.

Klisovic RB, Stock W, Cataland S, et al.
A phase I biological study of MG98, an oligodeoxynucleotide antisense to DNA methyltransferase 1, in patients with high-risk myelodysplasia and acute myeloid leukemia.
Clin Cancer Res. 2008; 14(8):2444-9 [PubMed] Related Publications
PURPOSE: Epigenetic silencing via aberrant promoter DNA hypermethylation of normal genes has been described as a leukemogenic mechanism in myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML). We hypothesized that MG98, an oligonucleotide antisense to DNA methyltransferase 1 (DNMT1), could reverse malignant phenotypes by down-regulating DNMT1 and inducing reexpression of hypermethylated genes. This phase I study was conducted to determine a biologically effective dose and describe the safety of MG98 in MDS/AML.
EXPERIMENTAL DESIGN: Twenty-three patients with MDS (n = 11) and AML (n = 12) were enrolled. Biologically effective dose was defined as the dose at which > or =50% of patients experienced >50% reduction in DNMT1 expression with acceptable toxicity. Escalating doses of MG98 were administered according to two schedules (2-hour i.v. bolus followed by 5-day continuous i.v. infusion every 14 days, or 14-day continuous i.v. infusion every 21 days).
RESULTS: DNMT1 down-regulation was observed in 8 patients. However, biologically effective dose was not reached. Reexpression of target genes (P15, WIT1, and ER) was observed in 12 patients but did not correlate with DNMT1 down-regulation. Escalation was stopped due to dose-limiting toxicities (bone pain, nausea, and fever). No objective clinical response was observed. Disease stabilization occurred in 6 (26%) patients.
CONCLUSIONS: No pharmacodynamic or clinical activity was observed at MG98 doses and schedules administered. Despite this, pursuing DNMT1 down-regulation remains a sound approach for targeting aberrant epigenetics in AML/MDS. Future studies with different formulation and/or doses and schedules will be required to ensure efficient MG98 intracellular uptake and fully evaluate its therapeutic potential.

Ommen HB, Nyvold CG, Braendstrup K, et al.
Relapse prediction in acute myeloid leukaemia patients in complete remission using WT1 as a molecular marker: development of a mathematical model to predict time from molecular to clinical relapse and define optimal sampling intervals.
Br J Haematol. 2008; 141(6):782-91 [PubMed] Related Publications
We hypothesized that Wilms tumour 1 gene (WT1) expression levels in acute myeloid leukaemia (AML) patients might have predictive value and reveal molecular relapse kinetics. WT1 level was determined at diagnosis, during therapy and post-therapy follow-up in 89 patients who reached first complete remission (CR1) (952 samples, median 8 samples/patient, range 2-38). CR1 bone marrow (BM) WT1 level above normal (based on 39 healthy donors) was an independent adverse prognostic factor regarding both disease-free survival [hazard ratio (HR) 4.46, P = 0.001] and overall survival (HR 2.62, P = 0.019). By grouping 34 BM and 99 peripheral blood (PB) complete remission samples in monthly intervals prior to clinical relapse, disease development was delineated and a simple mathematical model constructed, that allowed for the prediction of relapse detection rates (RDRs) as well as median times [t(m)s] from WT1 positivity to clinical relapse. BM sampling was required to obtain RDRs above 93% and t(m)s above 67 d. Acceptable RDRs and t(m)s (81% and 44 d, respectively) could be acquired by bimonthly PB sampling. In conclusion, CR1 WT1 expression is an independent prognostic factor in AML. According to our model, BM is superior for relapse prediction, but PB samples are useful when shorter sampling intervals are possible.

Hämäläinen MM, Kairisto V, Juvonen V, et al.
Wilms tumour gene 1 overexpression in bone marrow as a marker for minimal residual disease in acute myeloid leukaemia.
Eur J Haematol. 2008; 80(3):201-7 [PubMed] Related Publications
OBJECTIVES: Wilms tumour gene 1 (WT1) is overexpressed in leucocytes of most acute myeloid leukaemia (AML) patients. However, the clinical relevance of WT1 gene expression as minimal residual disease (MRD) marker in AML has been questioned.
METHODS: We determined the expression of WT1 gene in bone marrow (BM) mononuclear cells of 100 AML patients at diagnosis and compared it with other MRD markers during follow up in 16 patients using quantitative reverse transcription-polymerase chain reaction.
RESULTS: The median WT1 gene expression was 9.7% of K562 cell line WT1 expression (lower quartile 1.5%, upper quartile 29.9%, n = 100) at diagnosis and, 0.053% (lower quartile 0.022%, upper quartile 0.125%, n = 87) in molecular or immunophenotypic remission. Median WT1 expression in control BM was 0.029% (lower quartile 0.013%, upper quartile 0.061%, n = 22). The upper 99% percentile of remission samples was 0.3%, which was regarded as the cut-off of increased WT1 gene expression in AML and was exceeded in 87% of all AML patients at diagnosis. WT1 and the other MRD markers showed only minor differences in profiles during follow-up. WT1 expression at diagnosis with median value 9.7% as the cut-off level or as a continuous variable had no prognostic significance for 2-yr survival.
CONCLUSIONS: The sensitivity of WT1 as a MRD marker was low due to the relatively high background WT1 gene expression in BM cells at remission and in subjects without haematological malignancies. Therefore, WT1 gene expression analysis would be beneficial only in those patients who do not have a more specific and sensitive MRD marker.

Dallosso AR, Hancock AL, Malik S, et al.
Alternately spliced WT1 antisense transcripts interact with WT1 sense RNA and show epigenetic and splicing defects in cancer.
RNA. 2007; 13(12):2287-99 [PubMed] Free Access to Full Article Related Publications
Many mammalian genes contain overlapping antisense RNAs, but the functions and mechanisms of action of these transcripts are mostly unknown. WT1 is a well-characterized developmental gene that is mutated in Wilms' tumor (WT) and acute myeloid leukaemia (AML) and has an antisense transcript (WT1-AS), which we have previously found to regulate WT1 protein levels. In this study, we show that WT1-AS is present in multiple spliceoforms that are usually expressed in parallel with WT1 RNA in human and mouse tissues. We demonstrate that the expression of WT1-AS correlates with methylation of the antisense regulatory region (ARR) in WT1 intron 1, displaying imprinted monoallelic expression in normal kidney and loss of imprinting in WT. However, we find no evidence for imprinting of mouse Wt1-as. WT1-AS transcripts are exported into the cytoplasm and form heteroduplexes with WT1 mRNA in the overlapping region in WT1 exon 1. In AML, there is often abnormal splicing of WT1-AS, which may play a role in the development of this malignancy. These results show that WT1 encodes conserved antisense RNAs that may have an important regulatory role in WT1 expression via RNA:RNA interactions, and which can become deregulated by a variety of mechanisms in cancer.

Iwasaki T, Sugisaki C, Nagata K, et al.
Wilms' tumor 1 message and protein expression in bone marrow failure syndrome and acute leukemia.
Pathol Int. 2007; 57(10):645-51 [PubMed] Related Publications
Wilms' tumor 1 (WT1) is a useful marker for the diagnosis of acute leukemia and myelodysplastic syndromes (MDS). In the current study quantitative reverse transcription-polymerase chain reaction and immunostaining were used simultaneously to examine the relationship between WT1 RNA and protein level and also to evaluate WT1 as a tool to differentiate aplastic anemia (AA) and MDS refractory anemia (RA). Three types of WT1 messages (total, exon 5(+) and KTS(+)) and WT1 immunostaining of these diseases were analyzed. An increase of all three WT1 messages in high-grade MDS and acute leukemia was observed as compared with the normal control, whereas there was no significant difference in WT1 message between AA and RA, suggesting that WT1 message is not a good tool to discriminate AA and RA. No significant difference was observed between normal and RA, except for exon 5 message. Three WT1 message levels had a significant correlation, suggesting that the total WT1 message is sufficient for clinical practice. Positive immunostaining of WT1 was observed only in the portion of acute leukemia and overt leukemia (OL) transformed from MDS with a high WT1 message level, suggesting the relatively high detection threshold of WT1 protein with the immunostaining method.

Yang L, Han Y, Suarez Saiz F, et al.
A tumor suppressor and oncogene: the WT1 story.
Leukemia. 2007; 21(5):868-76 [PubMed] Related Publications
The Wilms' tumor 1 (WT1) gene encodes a transcription factor important for normal cellular development and cell survival. The initial discovery of WT1 as the causative gene in an autosomal-recessive condition identified it as a tumor suppressor gene whose mutations are associated with urogenital disease and the development of kidney tumors. However, this view is not in keeping with the frequent finding of wild-type, full-length WT1 in human leukemia, breast cancer and several other cancers including the majority of Wilms' tumors. Rather, these observations suggest that in those conditions, WT1 has an oncogenic role in tumor formation. In this review, we explore the literature supporting both views of WT1 in human cancer and in particular human leukemias. To understand the mechanism by which WT1 can do this, we will also examine its functional activity as a transcription factor and the influence of protein partners on its dual behavior.

Hancock AL, Brown KW, Moorwood K, et al.
A CTCF-binding silencer regulates the imprinted genes AWT1 and WT1-AS and exhibits sequential epigenetic defects during Wilms' tumourigenesis.
Hum Mol Genet. 2007; 16(3):343-54 [PubMed] Related Publications
We have shown previously that AWT1 and WT1-AS are functionally imprinted in human kidney. In the adult kidney, expression of both transcripts is restricted to the paternal allele, with the silent maternal allele retaining methylation at the WT1 antisense regulatory region (WT1 ARR). Here, we report characterization of the WT1 ARR differentially methylated region and show that it contains a transcriptional silencer element acting on both the AWT1 and WT1-AS promoters. DNA methylation of the silencer results in increased transcriptional repression, and the silencer is also shown to be an in vitro and in vivo target site for the imprinting regulator protein CTCF. Binding of CTCF is methylation-sensitive and limited to the unmethylated silencer. Potentiation of the silencer activity is demonstrated after CTCF protein is knocked down, suggesting a novel silencer-blocking activity for CTCF. We also report assessment of WT1 ARR methylation in developmental and tumour tissues, including the first analysis of Wilms' tumour precursor lesions, nephrogenic rests. Nephrogenic rests show increases in methylation levels relative to foetal kidney and reductions relative to the adult kidney, together with biallelic expression of AWT1 and WT1-AS. Notably, the methylation status of CpG residues within the CTCF target site appears to distinguish monoallelic and biallelic expression states. Our data suggest that failure of methylation spreading at the WT1 ARR early in renal development, followed by imprint erasure, occurs during Wilms' tumourigenesis. We propose a model wherein imprinting defects at chromosome 11p13 may contribute to Wilms' tumourigenesis.

Srivastava A, Fuchs B, Zhang K, et al.
High WT1 expression is associated with very poor survival of patients with osteogenic sarcoma metastasis.
Clin Cancer Res. 2006; 12(14 Pt 1):4237-43 [PubMed] Related Publications
PURPOSE: Although metastasis is the primary determinant of poor survival of patients with osteogenic sarcoma, some patients live much longer than others, indicating metastatic heterogeneity underlying survival outcome. The purpose of the investigation was to identify genes underlying survival outcome of patients with osteogenic sarcoma metastasis.
EXPERIMENTAL DESIGN: We have used microarray to first compare mRNA expression between normal bone and osteogenic sarcoma specimens, identified genes overexpressed in osteogenic sarcoma, and compared expression of the selected gene between a poorly metastatic (SAOS) and two highly metastatic cell lines (LM8 and 143B). Finally, expression of the selected gene was assessed by immunostaining of osteogenic sarcoma samples with known survival outcome.
RESULTS: Microarray analysis revealed 5.3-fold more expression of WT1 mRNA in osteogenic sarcoma compared with normal bone and >2-fold overexpression in 143B and LM8 cells compared with SAOS. Furthermore, WT1 mRNA was absent in normal bone (10 of 10) by reverse transcription-PCR but present in osteogenic sarcoma-derived cell lines (5 of 8). One hundred percent (42 of 42) of low-grade osteogenic sarcoma specimens expressed no WT1 as determined by immunostaining; however, 24% (12 of 49) of the high-grade specimens showed intense staining. Mean survival of patients with high-grade metastatic osteogenic sarcoma but low WT1 staining (27 of 37) was 96.5 +/- 129.3 months, whereas mean survival of patients with high-grade metastatic osteogenic sarcoma having intense staining (10 of 37) was 18.3 +/- 12.3 months (P > 0.0143). All splice variants of WT1 mRNA, including a hitherto unknown variant (lacking exons 4 and 5), were found to be expressed in osteogenic sarcoma.
CONCLUSION: WT1 seems to be associated with very poor survival of patients with osteogenic sarcoma metastasis.

Wang Y, Yu Q, Cho AH, et al.
Survey of differentially methylated promoters in prostate cancer cell lines.
Neoplasia. 2005; 7(8):748-60 [PubMed] Free Access to Full Article Related Publications
DNA methylation and copy number in the genomes of three immortalized prostate epithelial and five cancer cell lines (LNCaP, PC3, PC3M, PC3M-Pro4, and PC3M-LN4) were compared using a microarray-based technique. Genomic DNA is cut with a methylation-sensitive enzyme HpaII, followed by linker ligation, polymerase chain reaction (PCR) amplification, labeling, and hybridization to an array of promoter sequences. Only those parts of the genomic DNA that have unmethylated restriction sites within a few hundred base pairs generate PCR products detectable on an array. Of 2732 promoter sequences on a test array, 504 (18.5%) showed differential hybridization between immortalized prostate epithelial and cancer cell lines. Among candidate hypermethylated genes in cancer-derived lines, there were eight (CD44, CDKN1A, ESR1, PLAU, RARB, SFN, TNFRSF6, and TSPY) previously observed in prostate cancer and 13 previously known methylation targets in other cancers (ARHI, bcl-2, BRCA1, CDKN2C, GADD45A, MTAP, PGR, SLC26A4, SPARC, SYK, TJP2, UCHL1, and WIT-1). The majority of genes that appear to be both differentially methylated and differentially regulated between prostate epithelial and cancer cell lines are novel methylation targets, including PAK6, RAD50, TLX3, PIR51, MAP2K5, INSR, FBN1, and GG2-1, representing a rich new source of candidate genes used to study the role of DNA methylation in prostate tumors.

Kaneuchi M, Sasaki M, Tanaka Y, et al.
WT1 and WT1-AS genes are inactivated by promoter methylation in ovarian clear cell adenocarcinoma.
Cancer. 2005; 104(9):1924-30 [PubMed] Related Publications
BACKGROUND: Ovarian clear cell adenocarcinoma is associated with one of the poorest prognoses among human epithelial ovarian cancers. The authors hypothesized that Wilms tumor suppressor 1 gene (WT1) sense and antisense (WT1-AS) expression and their promoter methylation status could characterize ovarian clear cell adenocarcinoma from ovarian serous adenocarcinoma.
METHODS: To test this hypothesis, ovarian cancer cell lines and 42 cancer tissues (17 clear cell and 25 serous adenocarcinoma) were analyzed for expression and methylation of WT1 and WT1-AS genes.
RESULTS: These experiments demonstrated that all serous adenocarcinoma tissues expressed both WT1 and WT1-AS genes, although expression of these genes was lacking in clear cell adenocarcinoma. The WT1 and WT1-AS promoter were significantly methylated in clear cell adenocarcinoma (88.2% and 88.2%, respectively) compared with serous adenocarcinoma (24.0% and 20.0%, respectively). Significant correlation between methylation and mRNA expression status was observed for each gene. Also in agreement with these data, WT1 and WT1-AS negative ovarian cancer cell lines reexpressed these genes after treatment with the demethylating agent, 5-aza-2'-deoxycytidine.
CONCLUSIONS: The current study shows that CpG hypermethylation is an important mechanism of WT1 and WT1-AS gene inactivation in ovarian clear cell adenocarcinoma. This is the first report that has demonstrated differential expression and methylation of WT1-AS in ovarian clear cell and serous adenocarcinomas. This study presents new molecular characterizations between these two types of adenocarcinoma and may provide insight as to why clear cell adenocarcinoma has a poorer prognosis than serous adenocarcinoma of the ovary.

Orloff MS, Iyengar SK, Winkler CA, et al.
Variants in the Wilms' tumor gene are associated with focal segmental glomerulosclerosis in the African American population.
Physiol Genomics. 2005; 21(2):212-21 [PubMed] Related Publications
Wilms' tumor gene (WT1) is important for nephrogenesis and gonadal growth. WT1 mutations cause Denys-Drash and Frasier syndromes, which are characterized by glomerular scarring. To test whether genetic variations in WT1 and WIT1 (gene immediately 5' to WT1) associate with focal segmental glomerulosclerosis (FSGS), patients with biopsy-proven idiopathic and HIV-1-associated FSGS were enrolled in a multicenter study. We genotyped SNP rs6508 located in WIT1 exon 1, three SNPs (rs2301250, rs2301252, rs2301254) in the promoter shared by WT1 and WIT1, rs2234590 in exon 6, rs2234591 in intron 6, rs16754 in exon 7, and rs1799937 in intron 9 of WT1. Cases (n = 218) and controls (n = 281) were compared in the African American population. Stratification by HIV-1 infection status showed that SNPs rs6508, rs2301254, and rs1799937 were significantly associated with FSGS [rs6508 odds ratio (OR) 1.82, P = 0.006; rs2301254 OR 1.65, P = 0.049; rs1799937 OR 1.91, P = 0.005] in the non-HIV-1 group and rs2234591 (OR 0.234, P = 0.011) in the HIV-1 group. Haplotype analyses in the population revealed that seven SNPs were associated with FSGS; five SNPs had the highest contingency score [-log10(P value) = 13.57] in the HIV-1 group. This association could not be explained by population substructure. We conclude that SNPs in WT1 and WIT1 genes are significantly associated with FSGS, suggesting that variants in these genes may mediate pathogenesis by altering WT1 function. Furthermore, HIV-1 infection status interacts with genetic variations in both genes to influence this phenotype. We speculate that nephropathy liability alleles in WT1 pathway genes cause podocyte dysfunction and glomerular scarring.

Wagner N, Wagner KD, Xing Y, et al.
The major podocyte protein nephrin is transcriptionally activated by the Wilms' tumor suppressor WT1.
J Am Soc Nephrol. 2004; 15(12):3044-51 [PubMed] Related Publications
NPHS1 encodes the structural protein nephrin, which has a crucial role in the filtration barrier of the glomerular podocyte. Mutations or deregulation of NPHS1 are associated with a variety of renal diseases, including the Finnish type congenital nephrotic syndrome. This study analyzed a potential regulation of nephrin by the Wilms' tumor protein, Wt1. Using an inducible U2OS osteosarcoma cell line, it is shown that upon Wt1 induction, endogenous nephrin mRNA becomes highly upregulated. Co-transfection studies demonstrate that Wt1 can activate the nephrin promoter >10-fold. DNase footprinting and mutation analysis identify a Wt1 responsive element in the nephrin promoter, which is required for the binding of Wt1 protein. Mutations or deletion of this Wt1 responsive element completely abolished transactivation of the nephrin promoter by Wt1. Moreover, transgenic analysis demonstrates the requirement of the identified binding site to direct podocyte-specific expression of a reporter gene in transgenic mice, thus confirming the importance of this site for the regulation of nephrin in vivo. Finally, it is shown that nephrin expression is lowest in kidneys of mice that lack specifically the Wt1(-KTS) splice variant, but in comparison with wild-type littermates, it is also reduced in animals with disruption of the Wt1(+KTS) splice variant. Taken together, these data identify nephrin as a direct transcriptional target for Wt1 and underline the importance of Wt1 as a key regulator in podocyte function.

Wagner KJ, Roberts SG
Transcriptional regulation by the Wilms' tumour suppressor protein WT1.
Biochem Soc Trans. 2004; 32(Pt 6):932-5 [PubMed] Related Publications
Wilms' tumour is a paediatric malignancy of the kidneys and is the most common solid tumour found in children. The Wilms' tumour suppressor protein WT1 is mutated in approximately 15% of Wilms' tumours, and is aberrantly expressed in many others. WT1 can manifest both tumour suppressor and oncogenic activities, but the reasons for this are not yet clear. The Wilms' tumour suppressor protein WT1 is a transcriptional activator, the function of which is under cell-context-specific control. We have previously described a small region at the N-terminus of WT1 (suppression domain) that inhibits the transcriptional activation domain by contacting a co-suppressor protein. We recently identified BASP1 as one of the components of the co-suppressor. Here, we analyse the mechanism of action of the WT1 suppression domain, and discuss its function in the context of the role of WT1 as a regulator of development.

Siehl JM, Reinwald M, Heufelder K, et al.
Expression of Wilms' tumor gene 1 at different stages of acute myeloid leukemia and analysis of its major splice variants.
Ann Hematol. 2004; 83(12):745-50 [PubMed] Related Publications
WT1 is a transcription factor involved in differentiation and proliferation of acute myeloid leukemia (AML) blasts and is expressed in 90% of cases, as determined by nested reverse transcription polymerase chain reaction (RT-PCR). It is proposed to be a key molecule in leukemia promotion. To assess the relevance of WT1 expression, we analyzed blood and bone marrow samples from 58 AML patients (37 at diagnosis, 8 in hematological remission, and 13 at relapse) for the level of WT1 expression, using quantitative real-time RT-PCR. In addition, 21 randomly chosen samples were also analyzed for the quantitative expression of the main WT1 splice variants. As expected, samples from patients at the time of diagnosis or relapse showed significantly higher WT1 expression compared to samples from patients in remission or control samples. No striking difference in expression levels was found between various French-American-British (FAB) subtypes. The level of WT1 expression observed in patients at the time of initial diagnosis was similarly high in patients at relapse. Expression of the four main isoforms (E5+/KTS+, E5-/KTS+, E5+/KTS-, and E5-/KTS-) was found in all samples with significantly higher expression levels of the E5+ variants. Together, these findings support the potential of WT1 as a target for novel treatment approaches in AML.

Dupont J, Wang X, Marshall DS, et al.
Wilms Tumor Gene (WT1) and p53 expression in endometrial carcinomas: a study of 130 cases using a tissue microarray.
Gynecol Oncol. 2004; 94(2):449-55 [PubMed] Related Publications
OBJECTIVE: With the exception of ovarian serous carcinoma, Wilms tumor suppressor gene (WT1) expression in common gynecologic carcinomas has not been described in detail. We studied a large number of endometrial carcinomas to determine the range of tumors that express WT1; this could have prognostic and therapeutic significance.
METHODS: We studied the immunohistochemical expression of WT1 and p53 in 130 primary human endometrial carcinomas of various histological subtypes, grades, and stages using a tissue microarray. The clinical data were retrieved from the medical records.
RESULTS: WT1 was expressed in a wide variety of endometrial cancers and was most marked in malignant mixed Mullerian tumors (MMMTs) (70% positive). WT1 expression was significantly correlated with high histological grade, and there was a trend toward a worse clinical outcome for patients whose tumors expressed WT1. An association between expression of WT1 and p53 and between these and outcome was noted in a univariate analysis, but only stage and p53 status remained prognostically significant independent variables.
CONCLUSION: WT1 is expressed in appreciable numbers of endometrial cancers, particularly MMMTs. These findings support further investigation of WT1 as a possible therapeutic target in gynecologic malignancies.

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