Wnt2 Overexpression Research Articles

WNT2-SOX4 positive feedback loop promotes chemoresistance and tumorigenesis by inducing stem-cell like properties in gastric cancer.

Gastric cancer (GC) is characterized by its vigorous chemoresistance to current therapies, which is attributed to the highly heterogeneous and immature phenotype of cancer stem cells (CSCs) during tumor initiation and progression. The secretory WNT2 ligand regulates multiple cancer pathways and has been demonstrated to be a potential therapeutic target for gastrointestinal tumors; however, its role involved in gastric CSCs (GCSCs) remains unclear. Here, we found that overexpression of WNT2 enhanced stemness properties to promote chemoresistance and tumorigenicity in GCSCs. Mechanistically, WNT2 was positively regulated by its transcription factor SOX4, and in turn, SOX4 was upregulated by the canonical WNT2/FZD8/β-catenin signaling pathway to form an auto-regulatory positive feedback loop, resulting in the maintenance of GCSCs self-renewal and tumorigenicity. Furthermore, simultaneous overexpression of both WNT2 and SOX4 was correlated with poor survival and reduced responsiveness to chemotherapy in clinical GC specimens. Blocking WNT2 using a specific monoclonal antibody significantly disrupted the WNT2-SOX4 positive feedback loop in GCSCs and enhanced the chemotherapeutic efficacy when synergized with the chemo-drugs 5-fluorouracil and oxaliplatin in a GCSC-derived mouse xenograft model. Overall, this study identified a novel WNT2-SOX4 positive feedback loop as a mechanism for GCSCs-induced chemo-drugs resistance and suggested that the WNT2-SOX4 axis may be a potential therapeutic target for gastric cancer treatment.

MicroRNA-627-5p inhibits colorectal cancer cell proliferation, migration and invasion by targeting Wnt2.

microRNA-627-5p (miR-627-5p) dysregulation has been observed in several cancer types, such as hepatocellular carcinoma, oral squamous cell carcinoma, glioblastoma multiforme, and gastric cancer. The biological function of miR-627-5p in colorectal cancer (CRC) growth and metastasis is yet unclear. To investigate the effects of miR-627-5p on the malignant biological properties of colorectal malignant tumour cells by targeting Wnt2. The levels of miR-627-5p in colorectal tumour tissues were assessed in Gene Expression Omnibus datasets. In order to identify Wnt2 transcript expression in CRC tissues, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used. Luciferase reporter tests were used to explore whether miR-627-5p might potentially target Wnt2. Wnt2 transcript and protein levels were detected in CRC cells with high miR-627-5p expression. To learn more about how miR-627-5p affects CRC development, migration, apoptosis, and invasion, functional experiments were conducted. Cotransfection with the overexpression vector of Wnt2 and miR-627-5p mimics was utilized to verify whether overexpression of Wnt2 could cancel the impact of miR-627-5p in CRC. Western blot and qRT-PCR were conducted to investigate the effects of miR-627-5p on the Wnt/β-catenin signalling pathway. miR-627-5p was notably decreased in colorectal tumour tissues, while the gene level of Wnt2 was notably upregulated. A dual luciferase reporter assay revealed that miR-627-5p specifically targets the 3'-untranslated regions of Wnt2 and miR-627-5p upregulation markedly reduced the protein and gene expression of Wnt2 in CRC cells. In vitro gain-of-function assays displayed that miR-627-5p overexpression decreased CRC cells' capabilities to invade, move, and remain viable while increasing apoptosis. Wnt2 overexpression could reverse the suppressive functions of miR-627-5p. Moreover, upregulation of miR-627-5p suppressed the transcript and protein levels of the downstream target factors in the canonical Wnt/β-catenin signalling, such as c-myc, CD44, β-catenin, and cyclinD1. miR-627-5p acts as a critical inhibitory factor in CRC, possibly by directly targeting Wnt2 and negatively modulating the Wnt/β-catenin signalling, revealing that miR-627-5p could be a possible treatment target for CRC.

Overexpression of IL-8 and Wnt2 is associated with prognosis of gastric cancer.

This study is to detect the expression of inflammatory factor or neutrophil-activating factor IL-8 and Wnt2 in gastric cancer (GC) and investigate the involvement of IL-8 and Wnt2 expressions in the clinicopathological indexes and prognosis. We detected the expression of IL-8 and Wnt2 in 100 GC tissues and 40 normal gastric mucosae using immunohistochemistry. The relationships between the IL-8 and Wnt2 expression and the clinicopathological characteristics were explored. The relationship between IL-8 expression, Wnt2 expression, and prognosis of GC was analyzed by survival curve and survival regression. The expression of IL-8 and Wnt2 in GC tissue was 64% and 75% respectively, which was significantly higher than that in adjacent normal gastric mucosa tissues, moreover, expressions of IL-8 and Wnt2 were positively correlated. The positive rate of IL-8 and Wnt2 expressions were correlated with lymph node metastasis and TNM staging （P < 0.01, and Wnt2 was also correlated with infiltration depth (P = 0.021), but there was no difference with age, sex, and differentiation (P > 0.05). The 3-year survival analysis showed that the survival rates of IL-8- and Wnt2-positive patients were 20% and 24%, respectively, which were significantly lower than those of negative patients. Cox regression analysis showed that IL-8 and Wnt2 may be independent factors affecting the prognosis of GC. Our data demonstrated that the overexpression of IL-8 and Wnt2 could be isolated prognostic factors in patients with GC and, possibly, may present new targets for the treatment of GC.

MiR-146a-5p-mediated suppression on trophoblast cell progression and epithelial-mesenchymal transition in preeclampsia

ObjectiveThis study aims to identify the effect of miR-146a-5p on trophoblast cell invasion as well as the mechanism in preeclampsia (PE).MethodsExpression levels of miR-146a-5p and Wnt2 in preeclamptic and normal placentae were quantified. Trophoblast cells (HTR-8) were separately transfected with miR-146a-5p mimic, miR-146a-5p inhibitor, pcDNA3.1-Wnt2 or sh-Wnt2, and then the expression levels of miR-146a-5p, Wnt2, and epithelial-mesenchymal transition (EMT)-related proteins (Vimentin, N-cadherin and E-cadherin) were measured. Moreover, the proliferative, migratory and invasive capacities of trophoblast cells were detected, respectively. Dual luciferase reporter assay determined the binding of miR-146a-5p and Wnt2.ResultsCompared with normal placental tissues, the placentae from PE patients showed higher miR-146a-5p expression and lower Wnt2 expression. Transfection of miR-146a-5p inhibitor or pcDNA3.1-Wnt2 exerted pro-migratory and pro-invasive effects on HTR-8 cells and encouraged EMT in HTR-8 cells; transfection with miR-146a-5p mimic or sh-Wnt2 weakened the proliferative, migratory and invasive capacities as well as reduced EMT process of HTR-8 cells. Moreover, Wnt2 overexpression could partially counteract the suppressive effects of miR-146a-5p overexpression on the progression and EMT of HTR-8 cells.ConclusionmiR-146a-5p mediates trophoblast cell proliferation and invasion through regulating Wnt2 expression.

Downregulation of miR-383 reduces depression-like behavior through targeting Wnt family member 2 (Wnt2) in rats

This study aimed to evaluate the role of miR-383 in the regulation of Wnt-2 signaling in the rat model of chronic stress. The male SD rats with depressive-like behaviors were stimulated with chronic unpredictable mild stress (CUMS) including ice-water swimming for 5 min, food deprivation for 24 h, water deprivation for 24 h, stimulating tail for 1 min, turning night into day, shaking for 15 min (once/s), and wrap restraint (5 min/time) every day for 21 days. The expression levels of miRNAs were detected by qRT-PCR, and the expression levels of Wnt2, depression-impacted proteins (GFAP, BDNF, CREB), brain neurotransmitters (5-HT, NE, DA) and apoptosis-related proteins (Bax and Bcl-2) were evaluated by qRT-PCR and western blot. Bioinformatic analysis and luciferase reporter assay were performed to determine the relationship between miR-383 and Wnt2. Ethological analysis was evaluated by sugar preference test, refuge island test and open field tests. Rescue experiments including knockdown of miR-383, overexpression and silencing of Wnt2 were performed to determine the role of miR-383. High expression levels of miR-383 were observed in the hippocampus of rats submitted to CUMS model. Downregulation of miR-383 significantly inhibited the apoptosis and inflammatory response of hippocampal neurons, and increased the expression levels of GFAP, BDNF and CREB which were impacted in depression, as well as neurotransmitters, then attenuated neural injury in rats induced by CUMS. Furthermore, Wnt family member 2 (Wnt2) was identified as a target of miR-383, and silencing of Wnt2 obviously attenuated the protective effect of miR-383 inhibitor on the apoptosis and inflammatory response in hippocampal neurons, as well as neural injury in CUMS-induced rats. Downregulation of miR-383 ameliorated the behavioral and neurochemical changes induced by chronic stress in rats by directly targeting Wnt2, indicating that the miR-383/Wnt2 axis might be a potential therapeutic target for MDD.

Clinical Correlation of Wnt2 and COL8A1 With Colon Adenocarcinoma Prognosis.

Wnt2 mRNA is widely expressed in various tumor tissues. Wnt2 overexpression promotes tumor growth, migration, invasion, and metastasis. However, its underlying molecular action mechanisms and clinical implications in colon adenocarcinoma (COAD) remain unclear. mRNA expression data, obtained from tissue samples, and pathophysiological data of 368 COAD patients were obtained from the Cancer Genome Atlas (TCGA) database. Further, Pearson's correlation analysis was performed to explore the correlation between the expression levels of Wnt2 and other genes in the human genome. Subsequently, a protein-protein interaction (PPI) network was constructed for hub gene identification. Overall survival and significance were determined by Kaplan-Meier analysis, and the log-rank test was used to further identify genes with prognostic significance in COAD from GEO datasets (GSE17538 and GSE39582). Subsequently, 158 tissue samples from Affiliated Hospital of Jiangnan University were used for expression verification. Gene set enrichment analysis (GSEA) was performed on high and low Wnt2 expression datasets to identify potential signaling pathways activated in COAD. In all, 10 hub genes associated with Wnt2 were screened by Pearson's correlation analysis and PPI network, with Wnt2 and COL8A1 having significantly poor prognosis by Kaplan-Meier analysis and log-rank test. Furthermore, high expressions of COL8A1 and Wnt2 were associated with poor survival both in TCGA and GEO cohorts. We further found a correlation between the expressions of Wnt2 and COL8A1 in COAD as per immunohistochemical analysis. To further elucidate the underlying molecular mechanisms of Wnt2 in COAD, we searched for pathways enriched in Wnt2 overexpressing datasets by GSEA. Our findings revealed that high Wnt2 levels were significantly associated with extracellular matrix receptor and focal adhesion pathways. Wnt2 expression correlated with COL8A1 expression in COAD; patients with high Wnt2 and COL8A1 expressions had worse survival outcomes. Pathways identified in this study prompt the molecular role of Wnt2 in COAD and provide directions to further elucidate the involved molecular mechanisms in COAD.

Involvement of WNT2 in trophoblast cell behavior in preeclampsia development

ABSTRACT This study aimed to determine the WNT2 expression in patients with severe preeclampsia and to explore the function of WNT2 dysregulation on the biological behaviors of trophoblast cells. The WNT2 and β-catenin expression in the patients with early-onset and late-onset severe preeclampsia and normal controls was determined. Subsequently, WNT2 was overexpressed and knocked down in HTR8 cells and WNT2 signaling pathway in regulating trophoblast cell proliferation, migration, invasion, and apoptosis were evaluated in vitro. The mRNA and protein expression levels of WNT2 and β-catenin were decreased in patients with preeclampsia, especially early-onset severe preeclampsia. Overexpression of WNT2 promoted trophoblast cell proliferation, migration, and invasion and inhibited apoptosis in vitro, whereas knockdown of WNT2 had opposite effects. The findings of this study reveal that WNT2 and β-catenin were decreased expressed in patients with preeclampsia. Decreased expression of WNT2 may inhibit trophoblast cell proliferation, migration, and invasion but induced apoptosis. WNT2 may serve as a promising biomarker for early detection of preeclampsia.

Wnt2 overexpression protects against PINK1 mutant‑induced mitochondrial dysfunction and oxidative stress.

The PTEN induced putative kinase 1(PINK1) mutation is the second most common cause of autosomal recessive adolescent Parkinson's disease(PD). Furthermore, mitochondrial disorders and oxidative stress are important mechanisms in the pathogenesis of PD. Numerous members of the Wnt family have been found to be associated with neurodegenerative diseases. Therefore, the present study investigated the role of the Wnt2 gene in PINK1B9 transgenic flies, which is a PD model, and its underlying mechanism. It was identified that overexpression of Wnt2 reduced the abnormality rate of PD transgenic Drosophila and improved their flight ability, while other intervention groups had no significant effect. Furthermore, an increase in ATP concentration normalized mitochondrial morphology, and increased the mRNA expression levels of NADH‑ubiquinone oxidoreductase chain 1(ND1), ND42, ND75, succinate dehydrogenase complex subunits B, Cytochrome b and Cyclooxygenase 1, which are associated with Wnt2 overexpression. Moreover, overexpression of Wnt2 in PD transgenic Drosophila resulted in the downregulation of reactive oxygen species and malondialdehyde production, and increased manganese superoxide dismutase(MnSOD), while glutathione was not significantly affected. It was found that overexpression of Wnt2 did not alter the protein expression of β‑catenin in PINK1B9 transgenic Drosophila, but did increase the expression levels of PPARG coactivator 1α(PGC‑1α) and forkhead box sub‑group O(FOXO). Collectively, the present results indicated that the Wnt2 gene may have a protective effect on PD PINK1B9 transgenic Drosophila. Thus, it was speculated that the reduction of oxidative stress and the restoration of mitochondrial function via Wnt2 overexpression may be related to the PGC‑1α/FOXO/MnSOD signaling pathway in PINK1 mutant transgenic Drosophila.

Cancer-associated fibroblast-derived WNT2 increases tumor angiogenesis in colon cancer

WNT2 acts as a pro-angiogenic factor in placental vascularization and increases angiogenesis in liver sinusoidal endothelial cells (ECs) and other ECs. Increased WNT2 expression is detectable in many carcinomas and participates in tumor progression. In human colorectal cancer (CRC), WNT2 is selectively elevated in cancer-associated fibroblasts (CAFs), leading to increased invasion and metastasis. However, if there is a role for WNT2 in colon cancer, angiogenesis was not addressed so far. We demonstrate that WNT2 enhances EC migration/invasion, while it induces canonical WNT signaling in a small subset of cells. Knockdown of WNT2 in CAFs significantly reduced angiogenesis in a physiologically relevant assay, which allows precise assessment of key angiogenic properties. In line with these results, expression of WNT2 in otherwise WNT2-devoid skin fibroblasts led to increased angiogenesis. In CRC xenografts, WNT2 overexpression resulted in enhanced vessel density and tumor volume. Moreover, WNT2 expression correlates with vessel markers in human CRC. Secretome profiling of CAFs by mass spectrometry and cytokine arrays revealed that proteins associated with pro-angiogenic functions are elevated by WNT2. These included extracellular matrix molecules, ANG-2, IL-6, G-CSF, and PGF. The latter three increased angiogenesis. Thus, stromal-derived WNT2 elevates angiogenesis in CRC by shifting the balance towards pro-angiogenic signals.

MicroRNA-199a/b-5p enhance imatinib efficacy via repressing WNT2 signaling-mediated protective autophagy in imatinib-resistant chronic myeloid leukemia cells

Imatinib (IM) is a first-line therapeutic drug for chronic myeloid leukemia (CML), a hematological disease. Mutations in the BCR-ABL domain increase formation of IM resistance in CML. However, not all patients are BCR-ABL domain-mutant dependent. Investigating non-mutant mechanisms in the development of acquired IM resistance is a critical issue. We explored the mechanisms which influence IM efficacy and resistance in CML. Higher protective autophagy was identified in IM-resistant K562 (K562R) cells. Inhibition of autophagy by the inhibitors, chloroquine and 3-methyladenine, enhanced IM's efficacy in K562R cells. In addition, microRNA (miR)-199a/b-5p were downregulated in K562R cells compared to parent cells. Overexpression of miR-199a/b-5p reduced autophagy and induced cell apoptosis, resulting in enhanced IM's efficacy in K562R cells. Moreover, expression levels of the Wingless-type MMTV integration site family member 2 (WNT2), a positive regulator of autophagy, were significantly higher in K562R cells, and it was validated as a direct target gene of miR-199a/b-5p. Overexpressions of miR-199a/b-5p inhibited WNT2 downstream signaling. Furthermore, overexpression and knockdown of WNT2 influenced autophagy formation and CML drug sensitivity to IM. Overexpression of WNT2 could also reverse miR-199a/b-5p-enhanced IM efficacy in K562R cells. These results emphasized that miR-199a/b-5p inhibited autophagy via repressing WNT2 signaling and might provide novel therapeutic strategies for future IM-resistant CML therapy and drug development.

Deregulated Mucosal Immune Surveillance through Gut-Associated Regulatory T Cells and PD-1+ T Cells in Human Colorectal Cancer.

Disturbed balance between immune surveillance and tolerance may lead to poor clinical outcomes in some malignancies. In paired analyses of adenocarcinoma and normal mucosa from 142 patients, we found a significant increase of the CD4/CD8 ratio and accumulation of regulatory T cells (Tregs) within the adenocarcinoma. The increased frequency of Tregs correlated with the local infiltration and extension of the tumor. There was concurrent maturation arrest, upregulation of programmed death-1 expression, and functional impairment in CD8+ T cells (CTLs) isolated from the adenocarcinoma. Adenocarcinoma-associated Tregs directly inhibit the function of normal human CTLs in vitro. With histopathological analysis, Foxp3+ Tregs were preferentially located in stroma. Concurrent transcriptome analysis of epithelial cells, stromal cells, and T cell subsets obtained from carcinomatous and normal intestinal samples from patients revealed a distinct gene expression signature in colorectal adenocarcinoma-associated Tregs, with overexpression of CCR1, CCR8, and TNFRSF9, whereas their ligands CCL4 and TNFSF9 were found upregulated in cancerous epithelium. Overexpression of WNT2 and CADM1, associated with carcinogenesis and metastasis, in cancer-associated stromal cells suggests that both cancer cells and stromal cells play important roles in the development and progression of colorectal cancer through the formation of a tumor microenvironment. The identification of CTL anergy by Tregs and the unique gene expression signature of human Tregs and stromal cells in colorectal cancer patients may facilitate the development of new therapeutics against malignancies.

The antidepressant roles of Wnt2 and Wnt3 in stress-induced depression-like behaviors.

Wnts-related signaling pathways have been reported to play roles in the pathogenesis of stress-induced depression-like behaviors. However, there is relatively few direct evidence to indicate the effect of Wnt ligands on this process. Here, we investigated the role of Wnts in mediating chronic restraint stress (CRS)-induced depression-like behaviors. We found that CRS induced a significant decrease in the expression of Wnt2 and Wnt3 in the ventral hippocampus (VH) but not in the dorsal hippocampus. Knocking down Wnt2 or Wnt3 in the VH led to impaired Wnt/β-catenin signaling, neurogenesis deficits and depression-like behaviors. In contrast, overexpression of Wnt2 or Wnt3 reversed CRS-induced depression-like behaviors. Moreover, Wnt2 and Wnt3 activated cAMP response element-binding protein (CREB) and there was CREB-dependent positive feedback between Wnt2 and Wnt3. Finally, fluoxetine treatment increased Wnt2 and Wnt3 levels in the VH and knocking down Wnt2 or Wnt3 abolished the antidepressant effect of fluoxetine. Taken together, our study indicates essential roles for Wnt2 and Wnt3 in CRS-induced depression-like behaviors and antidepressant.

Transient Expression of WNT2 Promotes Somatic Cell Reprogramming by Inducing β-Catenin Nuclear Accumulation.

SummaryTreatment with several Wnt/β-catenin signaling pathway regulators can change the cellular reprogramming efficiency; however, the dynamics and role of endogenous Wnt/β-catenin signaling in reprogramming remain largely unanswered. Here we identify the upregulation of WNT2 and subsequent β-catenin nuclear accumulation as key events in reprogramming. Transient nuclear accumulation of β-catenin occurs early in MEF reprogramming. Wnt2 is strongly expressed in the early stage of reprogramming. Wnt2 knockdown suppresses the nuclear accumulation of β-catenin and reduces the reprogramming efficiency. WNT2 overexpression promotes β-catenin nuclear accumulation and enhances the reprogramming efficiency. WNT2 contributes to the promotion of cell proliferation. Experiments with several drugs that control the Wnt pathway also indicate the importance of β-catenin nuclear accumulation in reprogramming. Our findings reveal the role of WNT2/β-catenin signaling in reprogramming.

Characterization of Wnt2 Overexpression in a Rat Granulosa Cell Line (DC3): Effects on CTNNB1 Activation1

WNTs comprise a family of secreted glycoproteins that are essential for normal embryonic development of the female reproductive system. The functional role that WNTs play in the postnatal ovary is poorly defined. We have shown previously that Wnt2 and Fzd4 mRNAs are expressed in granulosa cells of the postnatal rat ovary. Here we examine the effects of Wnt2 overexpression in a rat granulosa cell line (DC3) that displays characteristics of granulosa cells at an early stage of follicular development. We show that DC3 cells express a 7.7-kb Fzd4 mRNA transcript similar in size to that detected in the rat and human ovary. Our results demonstrate that Wnt2 overexpression in DC3 promotes cytosolic and nuclear accumulation of beta-catenin (CTNNB1), but does not stimulate CTNNB1/TCF-dependent (pGL3-OT) transcriptional activity. We show that chibby (CBY1), a nuclear CTNNB1-associated antagonist of the WNT pathway, is expressed in DC3 cells and associates with CTNNB1 in the presence and absence of Wnt2 overexpression, suggesting that Cby1 contributes to suppression of CTNNB1/TCF-dependent transcription in these cells. Our results show that Wnt2 overexpression in DC3 cells increases follistatin (Fst) mRNA expression and promotes resistance to activin-induced cell deletion. Taken together, our results suggest that WNT2 opposes activin activity in granulosa cells by up-regulating expression of the activin antagonist Fst in a CTNNB1/TCF-independent manner, and that rat granulosa cells express factors, including Cby1, that suppress CTNNB1/TCF-dependent signal transduction in the presence of a WNT signal.

Abstract 3238: Frizzled-8 receptor is activated by the Wnt-2 ligant in non-small cell lung cancer

Abstract Introduction: Lung cancer is the leading cause of cancer-associated mortality throughout the world. We previously showed that the Wnt signaling pathway is aberrantly activated in lung cancer. In this report, we investigated the role of interactions between different Frizzled receptors and the Wnt-2 ligant in non-small cell lung cancer (NSCLC). Methods: Quantitative RT-PCR was used to measure expression of Frz-8 and Wnt-2 from fifty freshly resected lung tumors and matched normal lung tissue. A human dominant-negative Wnt-2 mutant (dnhWnt-2) was designed to target the interactions between Fzd-8 and Wnt-2 in vitro and in vivo. pTOPflash/pFOPflash luciferase activity assay was used to detect TCF/β-catenine transcription activity. Crystal violet staining assay was used to determine the colony formation. A mouse xenogrant model using A549 cells transfected with dnhWnt-2 vector or control vector was used to detect tumorigenic effects. Results: RT-PCR analysis showed that Wnt-2 overexpression is in correlation with overexpression of Fzd-8 in 45/50 (90%) tumor samples analyzed. Coexpression of the dnhWnt-2 construct together with Wnt-2 and Fzd8 expression vectors in 293T, 293 and A549 cells strongly reduced TCF-dependent transcriptional activity (TOPflash assay) as compared with cells transfected with control vectors. In lung cancer cell line A549, naturally overexpressing both Wnt-2 and Fzd8, the dnhWnt-2 construct induced cell death, inhibited cell proliferation. Results from colony formation assay showed 50% reduction in colonies formed from the dnhWnt-2 transfected cells as compared to control vector. A tumor xenograft model of A549 cells expressing the dnhWnt-2 mutant, demonstrated a marked reduction in tumor formation 43 days after cell inoculation (p&amp;lt;0.02) with reduced Wnt downstream target gene expressions (Survivin, c-Myc, Dvl-3 and Cyclin- D1) compared to control tumors. Conclusion: This report demonstrated a novel interaction between Frz-8 receptor and Wnt-2 ligant in non-small cell lung cancer. Inhibition of this interaction may provide a new therapeutic avenue in targeting the Wnt pathway in lung cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3238. doi:1538-7445.AM2012-3238

Osteogenic potency of stem cell-based genetic engineering targeting Wnt3a and Wnt9a

Abstract Bone engineering is a promising therapeutic approach to correct skeletal defects, and genetically-modified stem cells have been implicated in engineering new bone. However, the use of genetically-modified human mesenchymal stem cells targeting an osteogenic growth factor Wnt is not yet investigated. In the present study, a proliferation assay and the alkaline phosphatase (ALP) activity and expression of runt-related transcription factor 2 (Runx2) and osteocalcin (OC) transcripts were investigated to examine the effect of Wnt2 overexpression, Wnt3a overexpression, and Wnt9a knockdown on cell proliferation and osteoblast differentiation of bone marrowderived mesenchymal stem cells (BMSCs). The results showed that the expression of Wnt2 and Wnt3a was up-regulated throughout the osteoblast differentiation period of BMSCs, whereas that of Wnt9a was down-regulated. Overexpression of Wnt3a stimulated cell proliferation while knockdown of Wnt9a increased the ALP activity and the expression of Runx2 and OC. Double transfection producing Wnt3a overexpression and Wnt9a knockdown simultaneously resulted in up-regulation of osteoblast differentiation markers, i.e., the ALP activity and the Runx2 expression. In conclusion, simultaneous genetic modification of Wnt3a overexpression and Wnt9a knockdown enhances osteoblast differentiation of BMSCs, suggesting its osteogenic potency to regenerate new bone in vivo.

WNT2 Regulates DNA Synthesis in Mouse Granulosa Cells Through Beta-Catenin1

WNTs are secreted extracellular signaling molecules that transduce their signals by binding to G protein-coupled receptors of the frizzled (FZD) family. They control diverse developmental processes, such as cell fate specification, cell proliferation, cell differentiation, and apoptosis. Although WNT signaling has been shown to be essential for development of the ovary, its mechanistic role in folliculogenesis within the adult ovary has not been studied extensively. Therefore, the objective of this study was to investigate the regulation and function of WNT2 signaling in mouse granulosa cells. Immunostaining identified WNT2 as being expressed in granulosa cells throughout folliculogenesis, but with varying signal strength: in sequential sections, WNT2 immunoreactivity was strongest in healthy antral follicles but weak in atretic follicles. Knockdown of WNT2 expression using transfected short interfering RNA decreased DNA synthesis in granulosa cells, whereas WNT2 overexpression using a recombinant viral vector enhanced it. WNT2 knockdown led to accumulation of glycogen synthase kinase-3beta (GSK3B) in the cytoplasm but reduced the expression of beta-catenin. Conversely, WNT2 overexpression reduced the expression of GSK3B in the cytoplasm and induced beta-catenin translocation from the membrane into the nucleus. Beta-catenin knockdown also inhibited DNA synthesis in granulosa cells and neutralized the effect of WNT2 overexpression. WNT2/beta-catenin signaling had a slight effect on the apoptosis of granulosa cells. Taken together, the data indicate that WNT2 regulates beta-catenin localization in granulosa cells, and WNT2/beta-catenin signaling contributes to regulating their proliferation.

Overexpression of Wnt-2 in colorectal cancers

The binding of the Wnt ligand to its receptor Frizzled, activates the Wnt canonical signaling pathway in carcinogenesis as well as many cellular processes, including cellular proliferation and differentiation. Wnt-2, one of 19 members of the <em>Wnt</em> gene family, is frequently overexpressed in malignant tissues. Here, in order to investigate the role of Wnt-2 in colorectal carcinogenesis, we examined the expression of the Wnt-2 protein in 120 colorectal cancers by immunohistochemistry. Wnt-2 protein was expressed in the cell membrane and cytoplasm and up-regulated in 74 (61.7%) of 120 colorectal cancers. Statistically, overexpression of Wnt-2 protein was not associated with the clinical and pathological parameters studied, including tumor location, tumor size, clinical stage, lymph node metastasis, and 5-year survival (<em>P > </em>0.05). These results indicate that up-regulation of the Wnt-2 protein might play a role in the development of colorectal cancers, as an early event of carcinogenesis. Wnt-2 protein, expression, immunohistochemistry, tissue microarray, colon cancer.

Infrequent COX-2 expression due to promoter hypermethylation in gastric cancers in Dalian, China

Cyclooxygenase-2 (COX-2) has been shown to play oncogenic roles during stepwise gastrocarcinogenesis, and its expression is correlated with Helicobacter pylori infection, tumor necrosis factor alpha-mediated nuclear factor (NF)-kappaB activation, and Wnt signaling. To examine COX-2 expression and the status of its regulatory factors, we examined 49 gastric cancers (GCs), 21 premalignant tissues, and 10 noncancerous gastric mucosa from residents of Dalian, China. Unexpectedly, it was found that COX-2 expression was infrequent in the gastric samples (18.8%, 15/80) regardless of the type of lesion or morphological phenotype. H pylori infection was detected in 19 of 35 tested GC cases. Tumor necrosis factor alpha expression, NF-kappaB nuclear translocation, or Wnt2 overexpression was observed in 56 (82.3%) of 68, 40 (50.0%) of 80, and 62 (77.5%) of 80 of the gastric tissue samples, respectively. Methylation-sensitive restriction enzyme digestion followed by polymerase chain reaction of COX-2 promoter regions revealed a remarkably high hypermethylation rate (100%, 20/20) among the COX-2-negative GCs, which was associated with the overexpression of DNA methyltransferase (DNMT) 1 (r = 0.587, P < .01). These results indicate that (1) in contrast to previous findings using other GC sources, our results show that COX-2 activity may not be a critical molecular event during GC formation, (2) the tumor-promoting effects of H pylori infection and Wnt and NF-kappaB activities may be mediated by COX-2-independent pathways, and (3) promoter hypermethylation is the major cause of COX-2 silencing in Dalian GCs, apparently because of increased expression of DNMTs (especially DNMT1). Consequently, a COX-2-oriented preventive or therapeutic strategy is not practical for Dalian GCs. The frequent COX-2 hypermethylation observed in Dalian GCs could have insightful epigenetic and epidemiologic implications.

061 Wnt2 as a new therapeutic target in malignant pleural mesothelioma

Malignant mesothelioma of the pleura (MPM) is a highly aggressive neoplasm with a poor prognosis and limited treat-ment options. A better understanding of its pathogenesis is essential to developing alternative therapeutic stratégies. We previously demonstrated that the Wnt signaling pathway is activated in MPM through the overexpression of dishevelled proteins. To extend our knowledge of Wnt signaling activation in MPM, we performed Wnt spécifie microarrays in normal pleura and MPM. We inhibited Wnt2 by siRNA and a monoclonal anti-Wnt2 antibody and analyzed their effects on apoptosis and downs-tream signaling effectors. We then assessed the anti-proliferative effects of the Wnt2 antibody and Alimta ® , one of the current standard treatments of MPM. We found that the most common event in MPM was the upregulation of Wnt2. We confirmed Wnt2 overexpression at the mRNA and protein level in MPM cell lines and tissues. We then demonstrated that inhibition of Wnt2 by siRNA or a monoclonal antibody induces programmed-cell death in MPM cells. We next analyzed the effects of the anti-Wnt2 antibody and of Alimta on MPM cell prolifération. We found that although Wnt2 antibody by itself had less anti-proliferative potency than Alimta ® , the two in combination had substantially more activity than Alimta ® alone. We thus propose that inhibition of Wnt2 is of the rapeutic interest in the development of more effective treatments for MPM.