WWOX Tumor Suppressor Gene Research Articles

WWOX binds MERIT40 and modulates its function in homologous recombination, implications in breast cancer

The tumor suppressor gene WWOX is localized in an unstable chromosomal region and its expression is decreased or absent in several types of cancer. A low expression of WWOX is associated with a poor prognosis in breast cancer (BC). It has recently been shown that WWOX contributes to genome stability through its role in the DNA damage response (DDR). In breast cancer cells, WWOX inhibits homologous recombination (HR), and thus promotes the repair of DNA double-stranded breaks (DSBs) by non-homologous end joining (NHEJ). The fine-tuning modulation of HR activity is crucial. Its under or overstimulation inducing genome alterations that can induce cancer. MERIT40 is a positive regulator of the DDR. This protein is indispensable for the function of the multi-protein complex BRCA1-A, which suppresses excessive HR activity. MERIT40 also recruits Tankyrase, a positive regulator of HR, to the DSBs to stimulate DNA repair. Here, we identified MERIT40 as a new molecular partner of WWOX. We demonstrated that WWOX inhibited excessive HR activity induced by overexpression of MERIT40. We showed that WWOX impaired the MERIT40-Tankyrase interaction preventing the role of the complex on DSBs. Furthermore, we found that MERIT40 is overexpressed in BC and that this overexpression is associated to a poor prognosis. These results strongly suggest that WWOX, through its interaction with MERIT40, prevents the deleterious impact of excessive HR on BC development by inhibiting MERIT40-Tankyrase association. This inhibitory effect of WWOX would oppose MERIT40-dependent BC development.

MiR-187* Enhances SiHa Cervical Cancer Cell Oncogenicity Via Suppression of WWOX.

Cervical cancer is one of the most common cancers worldwide and a major cause of cancer-related mortality among women. Previous studies have reported that microRNA-miR-187*, which is one of the non-coding parts of the genome producing small conserved ribonucleic acids, is associated with various cancers. In this study, we explored the function of miR-187* in cervical cancer cells. miR-187* mimic, WWOX reporter constructs, siRNA and overexpression constructs were transfected into SiHa cells to investigate the function and regulatory mechanisms of miR-187*. Exogenous miR-187* was found to increase the oncogenic phenotypes of SiHa cells. The tumor suppressor gene WWOX is a novel target of miR-187* in SiHa cells. WWOX siRNA suppressed endogenous WWOX expression and increased the oncogenic phenotypes of SiHa cells. Exogenous WWOX expression was able to suppress the oncogenic phenotypes of SiHa cells and rescue cells from miR-187*-induced migration. miR-187* seems to enhance SiHa cervical cancer cell oncogenicity via suppression of the WWOX pathway.

WWOX Tumor Suppressor Gene in Breast Cancer, a Historical Perspective and Future Directions.

The WWOX tumor suppressor gene is located at 16q23. 1–23.2, which covers the region of FRA16D—a common fragile sites. Deletions within the WWOX coding sequence are observed in up to 80% of breast cancer cases, which makes it one of the most common genetic alterations in this tumor type. The WWOX gene is known to play a role in breast cancer: increased expression of WWOX inhibits cell proliferation in suspension, reduces tumor growth rates in xenographic transplants, but also enhances cell migration through the basal membrane and contributes to morphological changes in 3D matrix-based cell cultures. The WWOX protein may act in several ways, as it has three functional domains—two WW domains, responsible for protein-protein interactions and an SDR domain (short dehydrogenase/reductase domain) which catalyzes conversions of low molecular weight ligands, most likely steroids. In epithelial cells, WWOX modulates gene transcription through interaction with p73, AP-2γ, and ERBB4 proteins. In steroid hormone-regulated tissues like mammary gland epithelium, the WWOX SDR domain acts as a steroid dehydrogenase. The relationship between WWOX and hormone receptors was shown in an animal model, where WWOX(C3H)+/–mice exhibited loss of both ER and PR receptors. Moreover, in breast cancer specimens, a positive correlation was observed between WWOX expression and ER status. On the other hand, decreased WWOX expression was associated with worse prognosis, namely higher relapse and mortality rates in BC patients. Recently, it was shown that genomic instability might be driven by the loss of WWOX expression. It was reported that WWOX plays role in DNA damage response (DDR) and DNA repair by regulating ATM activation through physical interaction. A genome caretaker function has also been proposed for WWOX, as it was found that WWOX sufficiency decreases homology directed repair (HDR) and supports non-homologous end-joining (NHEJ) repair as the dominant DSB repair pathway by Brca1-Wwox interaction. In breast cancer cells, WWOX was also found to modulate the expression of glycolysis pathway genes, through hypoxia-inducible transcription factor 1α (HIF1α) regulation. The paper presents the current state of knowledge regarding the WWOX tumor suppressor gene in breast cancer, as well as future research perspectives.

Relevance of Sp Binding Site Polymorphism in WWOX for Treatment Outcome in Pancreatic Cancer.

Background:A genome-wide association study (GWAS) suggested inherited genetic single-nucleotide polymorphisms (SNPs) affecting overall survival (OS) in advanced pancreatic cancer. To identify robust clinical biomarkers, we tested the strongest reported candidate loci in an independent patient cohort, assessed cellular drug sensitivity, and evaluated molecular effects.Methods:This study comprised 381 patients with histologically verified pancreatic ductal adenocarcinoma treated with gemcitabine-based chemotherapy. The primary outcome was the relationship between germline polymorphisms and OS. Functional assays addressed pharmacological dose-response effects in lymphoblastoid cell lines (LCLs) and pancreatic cancer cell lines (including upon RNAi), gene expression analyses, and allele-specific transcription factor binding. All statistical tests were two-sided.Results:The A allele (26% in Caucasians) at SNP rs11644322 in the putative tumor suppressor gene WWOX conferred worse prognosis. Median OS was 14 months (95% confidence interval [CI] = 12 to 15 months), 13 months (95% CI = 11 to 15 months), and nine months (95% CI = 7 to 12 months) for the GG, GA, and AA genotypes, respectively (P trend < .001 for trend in univariate log-rank assuming a codominant mode of inheritance; advanced disease subgroup P trend < .001). Mean OS was 25 months (95% CI = 21 to 29 months), 19 months (95% CI = 15 to 22 months), and 13 months (95% CI = 10 to 16 months), respectively. This effect held true after adjustment for age, performance status according to Eastern Cooperative Oncology Group classification, TNM, grading, and resection status and was comparable with the strongest established prognostic factors in multivariable analysis. Consistently, reduced responsiveness to gemcitabine, but not 5-fluorouracil, along with lower WWOX expression was demonstrated in LCLs harboring the AA genotype. Likewise, RNAi-mediated WWOX knockdown in pancreatic cancer cells confirmed differential cytostatic drug sensitivity. In electrophoretic mobility shift assays, the A allele exhibited weaker binding of Sp family members Sp1/Sp3.Conclusions: WWOX rs11644322 represents a major predictive factor in gemcitabine-treated pancreatic cancer. Decreased WWOX expression may interfere with gemcitabine sensitivity, and allele-specific binding at rs11644332 might be a causative molecular mechanism behind the observed clinical associations.

Death Receptor-Induced Apoptosis Signalling Regulation by Ezrin Is Cell Type Dependent and Occurs in a DISC-Independent Manner in Colon Cancer Cells.

Ezrin belongs to the ERM (ezrin-radixin-moesin) protein family and has been demonstrated to regulate early steps of Fas receptor signalling in lymphoid cells, but its contribution to TRAIL-induced cell death regulation in adherent cancer cells remains unknown. In this study we report that regulation of FasL and TRAIL-induced cell death by ezrin is cell type dependant. Ezrin is a positive regulator of apoptosis in T-lymphoma cell line Jurkat, but a negative regulator in colon cancer cells. Using ezrin phosphorylation or actin-binding mutants, we provide evidence that negative regulation of death receptor-induced apoptosis by ezrin occurs in a cytoskeleton- and DISC-independent manner, in colon cancer cells. Remarkably, inhibition of apoptosis induced by these ligands was found to be tightly associated with regulation of ezrin phosphorylation on serine 66, the tumor suppressor gene WWOX and activation of PKA. Deficiency in WWOX expression in the liver cancer SK-HEP1 or the pancreatic Mia PaCa-2 cell lines as well as WWOX silencing or modulation of PKA activation by pharmacological regulators, in the colon cancer cell line SW480, abrogated regulation of TRAIL signalling by ezrin. Altogether our results show that death receptor pro-apoptotic signalling regulation by ezrin can occur downstream of the DISC in colon cancer cells.

The role of WWOX tumor suppressor gene in the regulation of EMT process via regulation of CDH1-ZEB1-VIM expression in endometrial cancer.

This study defines the role of WWOX in the regulation of epithelial to mesenchymal transition. A group of 164 endometrial adenocarcinoma patients was studied as well as an ECC1 well-differentiated steroid-responsive endometrial cell line, which was transducted with WWOX cDNA by a retroviral system. The relationship between WWOX gene and EMT marker (CDH1, VIM, ZEB1, SNAI1) expression on mRNA (RT-qPCR) and protein levels (western blotting) was evaluated. The EMT processes were also analysed in vitro by adhesion of cells to extracellular matrix proteins, migration through a basement membrane, anchorage-independent growth and MMP activity assay. DNA microarrays (HumanOneArray™) were used to determine WWOX-dependent pathways in an ECC1 cell line. A positive correlation was observed between WWOX and ZEB1, and a negative correlation between CDH1 and VIM. WWOX expression was found to inversely correlate with the risk of recurrence of tumors in patients. However, in the WWOX-expressing ECC1 cell line, WWOX expression was found to be inversely related with VIM and positively with CDH1. The ECC1/WWOX cell line variant demonstrated increased migratory capacity, with increased expression of metalloproteinases MMP2/MMP9. However, these cells were not able to form colonies in suspension and revealed decreased adhesion to fibronectin and fibrinogen. Microarray analysis demonstrated that WWOX has an impact on the variety of cellular pathways including the cadherin and integrin signalling pathways. Our results suggest that the WWOX gene plays a role in the regulation of EMT processes in endometrial cancer by controlling the expression of proteins associated with cell motility, thus influencing tissue remodeling, with the suppression of mesenchymal markers.

Immunohistochemical assessment of tumor suppressor gene Wwox in relation to proliferative marker KI67 proteins expression in giant cell lesions of the jaws and giant cell tumor of long bones

Background: Peripheral giant cell lesion (PGCL) and central giant cell lesion (CGCL) of the jaws have a distinct clinical behavior.Giant cell tumour (GCT) is a benign locally aggressive neoplasm affects the long bones. Both lesions are characterized histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. The WW domain-containing oxidoreductase (WWOX) gene is located at 16q23.1–16q23.2, a region that spans the second most common human fragile site, FRA16D, at 16q23.2.The Ki-67 antigen is a nuclear protein that is associated with and may be necessary for cellular proliferation.Ki-67 protein is present during all active phases of the cell cycle (G1, S, G2, and mitosis), but is absent from resting cells (G0). This study aimed to evaluate and compare immunohistochemical expression of tumor suppressor gene (WWOX) and proliferative marker (ki67) in giant cell lesions (GCLs) of the jaws and long bones. Materials and methods: Forty five retrospective paraffin embedded tissue blocks of giant cell lesions of the jaw and long bones were included in this study.Sections were stained immunohistochemically with anti WWOX and anti ki67 monoclonal antibodies. Results: Positive WWOX expression was found in 12 cases (80%), 14cases (93.3%)and12 (80%) of CGCG, PGCG and GCT studied cases respectively, with thehighest strong positive expression observed in PGCG.Positive Ki67 expression was found in 12 cases (80% ), 13cases ( 86.7 % )and10(66.7%) of CGCG,PGCG and GCT studied cases respectively with the high proliferative expression score has been recorded in PGCG .Statistically highly significant difference was found in the Ki67expression among different giant lesion types (p=0.006), whilenon-significant difference was found in WWOX expression. Non-significant correlation was found between expression of WWOXand Ki67 in CGCG, PGCG and GCT studied cases. Conclusions: Similar immunohistochemical expression of WWOX and Ki67 ingiant cell lesions of the jaw and GCT of long boneswith non-significant correlation between them in different studied lesionssuggests that those lesions may be the same disease but with different clinical behavior. Keywords: Wwox, KI67.

Alternating expression levels of WWOX tumor suppressor and cancer-related genes in patients with bladder cancer.

The aim of the present study was to determine the roles of the WWOX tumor suppressor and cancer-related genes in bladder tumor carcinogenesis. Reverse transcription-quantitative polymerase chain reaction was used to analyze the status of WWOX promoter methylation (using MethylScreen™ technology) and loss of heterozygosity (LOH) in papillary urothelial cancer tissues. The associations between the expression levels of the following tumorigenesis-related genes were also assessed: The WWOX tumor suppressor gene, the MKI67 proliferation gene, the BAX, BCL2 and BIRC5 apoptotic genes, the EGFR signal transduction gene, the VEGF vascular endothelial growth factor gene, and the CCND1 and CCNE1 cell cycle genes. The results reveal a high frequency of LOH in intron 1 in the WWOX gene, as well as an association between reduced WWOX expression levels and increased promoter methylation. In addition, the present study demonstrates that in bladder tumors, apoptosis is inhibited by increased expression levels of the BCL2 gene. A correlation between the proliferation indices of the MKI67 and the BIRC5 genes was also revealed. Furthermore, the expression levels of VEGF were identified to be positively associated with those of the EGFR gene.

The supposed tumor suppressor gene WWOX is mutated in an early lethal microcephaly syndrome with epilepsy, growth retardation and retinal degeneration

BackgroundWWOX, encoding WW domain-containing oxidoreductase, spans FRA16D, the second most common chromosomal fragile site frequently altered in cancers. It is therefore considered a tumor suppressor gene, but its direct implication in cancerogenesis remains controversial.Methods and resultsBy whole-exome sequencing, we identified a homozygous WWOX nonsense mutation, p.Arg54*, in a girl from a consanguineous family with a severe syndrome of growth retardation, microcephaly, epileptic seizures, retinopathy and early death, a phenotype highly similar to the abormalities reported in lde/lde rats with a spontaneous functional null mutation of Wwox. As in rats, no tumors were observed in the patient or heterozygous mutation carriers.ConclusionsOur finding, a homozygous loss-of-function germline mutation in WWOX in a patient with a lethal autosomal recessive syndrome, supports an alternative role of WWOX and indicates its importance for human viability.

The correlation analysis of WWOX expression and cancer related genes in neuroblastoma- a real time RT-PCR study.

Neuroblastoma is one of the most common paediatric cancers, described as unpredictable due to diverse patterns of behaviour. WWOX is a tumour suppressor gene whose expression is reduced in many tumour types. Loss of its expression was shown to correlate with more aggressive disease stage and mortality rate. The aim of this study was to investigate the role of the WWOX tumour suppressor gene in neuroblastoma formation. We performed real-time RT-PCR to analyse levels of WWOX expression in 22 neuroblastic tumour samples in correlation with genes involved in cell cycle regulation (CCNE1, CCND1), proliferation (MKI67), apoptosis (BCL2, BIRC5, BAX) and signal transduction (EGFR, ERBB4). We also evaluated two potential mechanisms - promoter methylation (MethylScreen method) and loss of heterozygosity (LOH) status, which could be connected with regulation of WWOX gene expression. We found a positive correlation between WWOX gene and BCL2 and HER4 JM-a and negative with cyclin D1 and E1. Our observations are consistent with previous findings and emphasise the role of WWOX in cell cycle and apoptosis regulation. Moreover, strong positive association with HER4 JM-a in this tumour type may indicate a role for WWOX in neuroblastoma cell differentiation. The presented results indicate that LOH in locus D16S3096 (located in intron 8) may be involved in the regulation of WWOX mRNAexpression. However, no association between methylation status of WWOX promoter and its expression was observed.

The WWOX tumor suppressor gene in endometrial adenocarcinoma

Endometrial cancer is a lethal malignancy, the causes of which remain to be determined. The aim of the present study, carried out on tumor samples from 79 patients, was to evaluate the role of the WWOX tumor suppressor gene in endometrial adenocarcinoma. The expression levels of WWOX and its protein content were assessed in normal endometrium and cancer samples. Quantitative PCR was used to assess the correlation between the expression levels of WWOX and the genes involved in the proliferation (MKI67), apoptosis (BAX, BCL2), signal transduction (EGFR), cell cycle (CCNE1, CCND1), cell adhesion (CDH1) and transcription regulation (TP73, NCOR1). The relationship between loss of hetero-zygosity (LOH) and WWOX mRNA levels was also investigated using high resolution melting. Results of the present study demonstrated a positive correlation of WWOX expression with BCL2 and CCND1 and a negative correlation with BAX, CDH1, NCOR1 and BCL2/BAX ratio. The results also showed that loss of heterozygosity at two analyzed loci of the WWOX gene is frequent in patients with endometrial cancer and that WWOX expression levels are lower in tumor samples than in normal tissue. In conclusion, WWOX may be involved in endometrial cancer.

129 The molecular mechanism of breakage at fragile site FRA16D

Replication stress induces physical breakage at discrete loci in chromosomes, which can be visualized on a metaphase chromosome spread. These common fragile sites (CFS) are conserved across species and are hotspots for sister chromatid recombination, viral integration, rearrangements, translocations, and deletions (Glover et al 2005). Despite multiple theories, the molecular mechanisms of CFS expression and genomic instability are still not well understood. The fragile site FRA16D is of special interest because it is the second most highly expressed fragile site and is located within the WWOX tumor suppressor gene. Previous data identified a polymorphic AT repeat within a FRA16D subregion called F1 that causes chromosome fragility and replication fork stalling in a yeast model (Zhang and Freudenreich 2007). Recently, we have found that breakage increases in an AT repeat length-dependent manner. Our results suggest that the AT repeat in the context of F1 forms a secondary structure, making the region more vulnerable to breakage.

Genetic alterations of WWOX in Wilms’ tumor are involved in its carcinogenesis

Loss of heterozygosity (LOH) in 16q appears in ~20-30% cases of Wilms' tumor. Within this region, known as common fragile site FRA16D, the WWOX tumor suppressor gene is located. Abnormalities of WWOX gene expression levels were observed in many tumor types and were associated with worse prognosis. The purpose of this study was to investigate the role of the WWOX tumor suppressor gene in Wilms' tumor samples. We evaluated the correlation between expression of WWOX and genes involved in proliferation (Ki67), apoptosis (BCL2, BAX), signal transduction (ERBB4, ERBB2, EGFR), cell cycle (CCNE1, CCND1), cell adhesion (CDH1) and transcription (TP73) using real-time RT-PCR in 23 tumor samples. We also analyzed the potential causes of WWOX gene expression reduction i.e., promoter methylation status (MethylScreen method) and loss of heterozygosity (LOH) status. We revealed a positive correlation between WWOX expression and BCL2, BCL2/BAX ratio, EGFR, ERBB4 isoform JM-a, TP73 and negative correlation with both cyclins. Loss of heterozygosity of the WWOX gene was observed only at intron 8, however, it had no influence on the reduction of its expression levels. Contrary to LOH, methylation of the region covering the 3' end of the promoter and part of exon 1 was associated with statistically significant reduction of WWOX gene expression levels. In the present study we reveal that in Wilms' tumors the WWOX expression levels are positively associated with the process of apoptosis, signal transduction through the ErbB4 pathway and EGFR and negatively with the regulation of the cell cycle (by cyclin E1 and D1). Moreover, our analysis indicates that in this type of tumor the expression of the WWOX gene can be regulated by an epigenetic mechanism--its promoter methylation.

707 Biological Characteristics of the WWOX Tumour Suppressor Gene Transduced MDA-MD-231 Breast Cancer Cell Line

707 Biological Characteristics of the WWOX Tumour Suppressor Gene Transduced MDA-MD-231 Breast Cancer Cell Line

Immunology in Israel: Society and research

Immunology in Israel: Society and research

Coordination of the canonical and noncanonical IKK/NF-κB signaling pathways in HTLV-I Tax-mediated tumorigenesis

Although the mechanisms by which the HTLV-I Tax oncoprotein activates the two NF-κB signaling pathways have been well studied, there is still no convincing evidence demonstrating a functional role for NF-κB in the Tax-mediated tumorigenesis or HTLV-I-mediated adult T-cell leukemia/lymphoma (ATL). Moreover, how Tax is negatively regulated by cellular factors has not yet been explored. Using various transgenic mice and cells deficient in different key IKK/NF-κB signaling components, we have defined the differential but cooperative roles of the canonical and noncanonical NF-κB pathways in Tax-mediated tumorigenesis. One function of non-canonical NF-κB activation is to repress expression of the wwox tumor suppressor gene, which in turn facilitates Tax-induced canonical NF-κB activation. Mechanistic studies indicate that WWOX blocks Tax-induced IKKalpha recruitment and subsequent RelA phosphorylation. Furthermore, we have identified PDLIM2, an essential terminator of canonical NF-κB activation, as a negative regulator of Tax. PDLIM2 directly binds to and shuttles Tax from its activation sites to the nuclear matrix for ubiquitination-mediated degradation, thereby suppressing the tumorigenicities of HTLV-I- or Tax-transduced cells. Interestingly, PDLIM2 expression is epigenetically downregulated in HTLV-I-transformed T cells and primary ATL cells. These studies suggest that the counterbalance between PDLIM2 and HTLV-I may determine the ATL leukemogenesis and provide the first line of genetic evidence demonstrating the functional significance of NF-κB in Tax-mediated tumorigenesis. These studies also define, for the first time, a delicate cooperation of the two pro-oncogenic NF-κB pathways in tumorigenesis and a functional role of the WWOX tumor suppressor in NF-κB regulation and viral tumorigenesis.

Evidences that the polymorphism Pro‐282‐Ala within the tumor suppressor gene WWOX is a new risk factor for differentiated thyroid carcinoma

We report a hypothesis-driven study aimed to detect genetic markers of susceptibility to differentiated thyroid carcinomas (DTC). A large number of candidate genes were first selected through literature search (genome-wide studies were also included). To restrict the analysis to single nucleotide polymorphisms (SNPs) with a high likelihood to be associated with increased risk, each SNP must comply with several a priori hypotheses. Only one SNP, the rs3764340 encoding for the aminoacidic substitution proline-to-alanine at codon 282 of the tumor suppressor gene WWOX, passed the selection. A case-control association study was carried out, involving a total of 1,741 cases and 1,042 controls. The logistic regression analysis revealed an increased risk of DTC for the carriers of the G-allele (crude odds ratio, OR = 1.53; 95% confidence interval, CI = 1.18-1.99; p = 1.38 × 10(-3) ). When we controlled for covariates, the adjusted OR was 1.48 with a 95% CI of 1.08-2.03 (p = 8.0 × 10(-3) ). The association was confirmed after stratification for histology (for papillary thyroid carcinoma the adjusted OR was 1.43; 95% CI 1.02-2.00; p = 0.037), incident cases and smokers, but was also at the limit of statistical significance in all the other categories considered. In silico analyses showed that when alanine substitutes proline, subtle changes of the proteic structure can be predicted. These findings together with other observations from literature on human cancers and the fact that the proline at codon 282 is extremely conserved in phylogenetically distant organisms (including Drosophila) suggest that the variant allele-282 could affect the biological function of WWOX, thereby predisposing individuals to thyroid cancer.

Wwox inactivation enhances mammary tumorigenesis

Breast cancer is the leading cause of cancer-related death in women worldwide. Expression of the WWOX tumor suppressor is absent or reduced in a large proportion of breast tumors suggesting that loss of WWOX may contribute to breast tumorigenesis. Wwox-deficient mice die by 3-4 weeks of age precluding adult tumor analysis. To evaluate the effect of WWOX-altered expression on mammary tumor formation, the Wwox-heterozygous allele was back crossed onto the C3H mammary tumor-susceptible genetic background (Wwox(C3H)+/-) and incidence of mammary tumor formation was evaluated. Although 50% of the female Wwox(C3H)+/- mice developed mammary carcinomas, only 7% of Wwox(C3H)+/+ mice did. Intriguingly, mammary tumors in Wwox(C3H)+/- mice frequently lost WWOX protein expression suggesting a genetic predisposition toward mammary tumorigenesis. Immunohistochemical staining of hormone receptors revealed loss of estrogen receptor-α (ER) and progesterone receptor in the majority of these tumors. In vitro, depletion of WWOX in MCF7 ER-positive cells led to reduced ER expression and reduced sensitivity to tamoxifen and estrogen treatment and was associated with enhanced survival and anchorage-independent growth. Finally, cDNA array analyses of murine normal mammary epithelial cells and mammary tumors identified 163 significantly downreguated and 129 upregulated genes in the tumors. The majority of differentially expressed genes were part of pathways involved in cellular movement, cell-to-cell signaling and interaction, cellular development, cellular growth and proliferation and cell death. These changes in gene expression of mouse mammary tumors in Wwox(C3H)+/- mice resemble, at least in part, human breast cancer development. Our findings demonstrate the critical role that the WWOX tumor suppressor gene has in preventing tumorigenesis in breast cancer.

The tumor suppressor gene WWOX links the canonical and noncanonical NF-κB pathways in HTLV-I Tax-mediated tumorigenesis

AbstractBoth the canonical and noncanonical nuclear factor κB (NF-κB) pathways have been linked to tumorigenesis. However, it remains unknown whether and how the 2 signaling pathways cooperate during tumorigenesis. We report that inhibition of the noncanonical NF-κB pathway significantly delays tumorigenesis mediated by the viral oncoprotein Tax. One function of noncanonical NF-κB activation was to repress expression of the WWOX tumor suppressor gene. Notably, WWOX specifically inhibited Tax-induced activation of the canonical, but not the noncanonical NF-κB pathway. Mechanistic studies indicated that WWOX blocked Tax-induced inhibitors of κB kinaseα (IKKα) recruitment to RelA and subsequent RelA phosphorylation at S536. In contrast, WWOX Y33R, a mutant unable to block the IKKα recruitment and RelA phosphorylation, lost the ability to inhibit Tax-mediated tumorigenesis. These data provide one important mechanism by which Tax coordinates the 2 NF-κB pathways for tumorigenesis. These data also suggest a novel role of WWOX in NF-κB regulation and viral tumorigenesis.

736 The expression of WWOX tumour suppressor gene in colorectal cancer

Ecological studies in Taiwan, Chile, Argentina, Bangladesh, and Mexico have confirmed significant dose-dependent associations between ingestion of arsenic-contaminated drinking water and the risk of various human malignancies. The FHIT and WWOX genes are active in common fragile sites FRA3B and FRA16D, respectively. Reduced expression of FHIT or WWOX is known to be an early indicator of carcinogen-induced cancers. However, the effect of arsenite on the expressions and molecular mechanisms of these markers is still unclear. The aims of this study were (i) to observe the expression of ATR, WWOX and FHIT proteins in urothelial carcinoma (UC) between endemic and non-endemic areas of blackfoot disease (BFD) by immunohistochemical analyses; (ii) to compare expression of these genes between arsenite-treated SV-HUC-1 human epithelial cells and rat uroepithelial cells; and (iii) to determine the role of DNMT and MEK inhibitors on expressions of WWOX and FHIT in response to arsenite in SV-HUC-1. The experiments revealed that expressions of ATR, WWOX and FHIT in UC significantly differed between BFD areas and non-BFD areas (p = 0.003, 0.009 and 0.021, respectively). In fact, the results for the arsenite-treated groups showed that ATR, WWOX and FHIT are downregulated by arsenite in SV-HUC-1. However, the inhibitors suppressed the effects of arsenite on WWOX and FHIT proteins and mRNA expression. In conclusion, arsenite decreased expressions of ATR, WWOX and FHIT via ERK1/2 activation in SV-HUC-1 cells. These findings confirm that dysregulations of these markers may contribute to arsenite-induced carcinogenesis.