Expression of Wnt-5a is correlated with aggressiveness of gastric cancer by stimulating cell migration and invasion

Wnt-5a is a representative ligand that activates a beta-catenin-independent pathway in the Wnt signaling. Although abnormal activation of beta-catenin-dependent pathway is often observed in human cancer, the relationship between beta-catenin-independent pathway and tumorigenesis is not clear. We sought to clarify how Wnt-5a is involved in aggressiveness of gastric cancer. Abnormal expression of Wnt-5a was observed in 71 of 237 gastric cancer cases by means of immunohistochemistry. The positivity of Wnt-5a expression was correlated with advanced stages and poor prognosis of gastric cancer. Wnt-5a had the abilities to stimulate cell migration and invasion in gastric cancer cells. Wnt-5a activated focal adhesion kinase and small GTP-binding protein Rac, both of which are known to play a role in cell migration. Cell migration, membrane ruffling, and turnover of paxillin were suppressed in Wnt-5a knockdown cells. Furthermore, anti-Wnt-5a antibody suppressed gastric cancer cell migration. These results suggest that Wnt-5a stimulates cell migration by regulating focal adhesion complexes and that Wnt-5a is not only a prognostic factor but also a good therapeutic target for gastric cancer.

Synergistic action of Wnt and LIF in maintaining pluripotency of mouse ES cells

Leukaemia inhibitory factor (LIF) was the first soluble factor identified as having potential to maintain the pluripotency of mouse embryonic stem (ES) cells. Recently, a second factor, Wnt, with similar activity was found. However, the relationship between these completely different signals mediating the overlapping functions is still unclear. Here, we report that the conditioned medium of L cells expressing Wnt3a maintains ES cells in the undifferentiated state in feeder-free culture, followed by expression of stem cell markers and their ability to generate germline chimaeras. However, although the activity of this conditioned medium is dependent on Wnt3a, recombinant Wnt3a protein cannot maintain ES cells in the undifferentiated state. As supplementation with Wnt3a to the sub-threshold level of LIF alone was not sufficient to maintain ES self-renewal, the results of maintenance of the undifferentiated state indicated the synergistic action of Wnt and LIF. Induction of constitutively activated beta-catenin alone is unable to maintain ES self-renewal but shows a synergistic effect with LIF. These observations indicate that the Wnt signal mediated by the canonical pathway is not sufficient but enhances the effect of LIF to maintain self-renewal of mouse ES cells.

Wnt induction of chondrocyte hypertrophy through the Runx2 transcription factor

We investigated the molecular mechanisms underlying canonical Wnt-mediated regulation of chondrocyte hypertrophy using chick upper sternal chondrocytes. Replication competent avian sarcoma (RCAS) viral over-expression of Wnt8c and Wnt9a, upregulated type X collagen (col10a1) and Runx2 mRNA expression thereby inducing chondrocyte hypertrophy. Wnt8c and Wnt9a strongly inhibited mRNA levels of Sox9 and type II collagen (col2a1). Wnt8c further enhanced canonical bone morphogenetic proteins (BMP-2)-induced expression of Runx2 and col10a1 while Wnt8c and Wnt9a inhibited TGF-beta-induced expression of Sox9 and col2a1. Over-expression of beta-catenin mimics the effect of Wnt8c and Wnt9a by upregulating Runx2, col10a1, and alkaline phosphatase (AP) mRNA levels while it inhibits col2a1 transcription. Western blot analysis shows that Wnt8c and beta-catenin also induces Runx2 protein levels in chondrocytes. Thus, our results indicate that activation of the canonical beta-catenin Wnt signaling pathway induces chondrocyte hypertrophy and maturation. We further investigated the effects of beta-catenin-TCF/Lef on Runx2 promoter. Co-transfection of lymphoid enhancer factor (Lef1) and beta-catenin in chicken upper sternal chondrocytes together with deletion constructs of the Runx2 promoter shows that the proximal region spanning the first 128 base pairs of this promoter is responsible for the Wnt-mediated induction of Runx2. Mutation of the TCF/Lef binding site in the -128 fragment of the Runx2 promoter resulted in loss of its responsiveness to beta-catenin. Additionally, gel-shift assay analyses determined the DNA/protein interaction of the TCF/Lef binding sites on the Runx2 promoter. Finally, our site-directed mutagenesis data demonstrated that the Runx2 site on type X collagen promoter is required for canonical Wnt induction of col10a1. Altogether we demonstrate that Wnt/beta-catenin signaling is regulated by TGF-beta and BMP-2 in chick upper sternal chondrocytes, and mediates chondrocyte hypertrophy at least partly through activation of Runx2 which in turn may induce col10a1 expression.

Importance of P-cadherin, beta-catenin, and Wnt5a/frizzled for progression of melanocytic tumors and prognosis in cutaneous melanoma

PURPOSE

It has been proposed that melanoma cells shift from E-cadherin to N-cadherin expression during tumor development, and recent gene profiling has shown increased expression of Wnt5a/Frizzled in aggressive melanomas possibly by interactions with beta-catenin. We therefore wanted to investigate the role of cadherin subtypes, beta-catenin, and Wnt5a/Frizzled in melanocytic tumors, with focus on prognosis in nodular melanomas.

EXPERIMENTAL DESIGN

The immunohistochemical expression of E-cadherin, N-cadherin, P-cadherin, beta-catenin, and Wnt5a/Frizzled was examined using tissue microarrays of 312 melanocytic tumors.

RESULTS

Cytoplasmic expression of P-cadherin was associated with increasing tumor thickness (P=0.005) and level of invasion (P=0.019), whereas membranous staining was associated with thinner (P=0.012) and more superficial (P=0.018) tumors. Increased cytoplasmic P-cadherin was associated with reduced survival (P=0.047). Lack of nuclear beta-catenin expression was related to increased tumor thickness (P=0.002) and poor patient survival in univariate (P=0.0072) and multivariate (P=0.004) analyses. Membranous expression of N-cadherin was significantly increased from primary tumors to metastatic lesions, whereas E-cadherin staining tended to be decreased. Wnt5a and its receptor Frizzled were highly coexpressed, and nuclear expression of both markers was significantly reduced from benign nevi to melanomas, with a shift from nuclear to cytoplasmic expression in malignant tumors. In addition, Wnt5a expression was significantly associated with nuclear beta-catenin expression.

CONCLUSIONS

Alterations in the expression and subcellular localization of cell adhesion markers are important in the development and progression of melanocytic tumors, and strong cytoplasmic P-cadherin expression and loss of nuclear beta-catenin staining were associated with aggressive melanoma behavior and reduced patient survival.

Dapper 1 Antagonizes Wnt Signaling by Promoting Dishevelled Degradation

Wnt signaling plays pivotal roles in the regulation of embryogenesis and cancer development. Xenopus Dapper (Dpr) was identified as an interacting protein for Dishevelled (Dvl), a Wnt signaling mediator, and modulates Wnt signaling. However, it is largely unclear how Dpr regulates Wnt signaling. Here, we present evidence that human Dpr1, the ortholog of Xenopus Dpr, inhibits Wnt signaling. We have identified the regions responsible for the Dpr-Dvl interaction in both proteins and found that the interaction interface is formed between the DEP (Dishevelled, Egl-10, and pleckstrin) domain of Dvl and the central and the C-terminal regions of Dpr1. The inhibitory function of human Dpr1 requires both its N and C terminus. Overexpression of the C-terminal region corresponding to the last 225 amino acids of Dpr1, in contrast to wild-type Dpr1, enhances Wnt signaling, suggesting a dominant negative function of this region. Furthermore, we have shown that Dpr1 induces Dvl degradation via a lysosome inhibitor-sensitive and proteasome inhibitor-insensitive mechanism. Knockdown of Dpr1 by RNA interference up-regulates endogenous Dvl2 protein. Taken together, our data indicate that the inhibitory activity of Dpr on Wnt signaling is conserved from Xenopus to human and that Dpr1 antagonizes Wnt signaling by inducing Dvl degradation.

Attenuated Wnt signaling perturbs pancreatic growth but not pancreatic function

Mesenchymal-epithelial interactions are pivotal for proper pancreatic growth and development. We have earlier shown that the fibroblast growth factor (FGF) receptor 2 is expressed in pancreatic progenitor cells and that FGF10, the high-affinity ligand of the FGF receptor 2 isoform FGF receptor 2b, promotes expansion of pancreatic progenitors. The Wnt family of ligands, which signal to the Frizzled (Frz) type receptors, have also been shown to mediate mesenchymal-epithelial interactions and cell proliferation in a variety of different systems. Here, we show that Frz3, like FGF receptor 2, is expressed in the pancreatic epithelium during the proliferative phase of the embryonic pancreas in mice and that overexpression of a dominant-negative form of mouse Frz8 in pancreatic progenitors severely perturbs pancreatic growth. Nevertheless, the transgenic mice remain normoglycemic and display normal glucose tolerance and glucose-stimulated insulin secretion when challenged with exogenous glucose. The maintenance of normoglycemia in these mice appears to be the consequence of a relative increase in endocrine cell number per pancreatic area combined with enhanced insulin biosynthesis and insulin secretion. Collectively, our data provide evidence that Wnt signaling is required for pancreatic growth but not adult beta-cell function.

Secreted frizzled related protein 1 regulates Wnt signaling for BMP2 induced chondrocyte differentiation

Canonical Wnt signaling (beta-catenin/TCF) has emerged as a key regulator of skeletogenesis. In this study, chondrogenesis is examined in a mouse model in which the Wnt antagonist secreted frizzled related protein 1 (sFRP1) is non-functional and results in a high bone mass phenotype and activation through the canonical pathway of the Runx2 transcription factor that is essential for bone formation. We find during the period of rapid post-natal growth, shortened height of the growth plate and increased calcification of the hypertrophic zone (HZ) in the sFRP1-/- mouse, indicating accelerated endochondral ossification. Using mouse embryo fibroblasts (MEFs) induced into the chondrogenic lineage, increased chondrogenesis and accelerating differentiation of hypertrophic chondrocytes in the sFRP1-/- MEFs was observed compared to WT cells. The induced maturation of hypertrophic chondrocytes in sFRP1(-/-) MEFs was inversely correlated to phospho-beta-catenin levels, indicating involvement of activated canonical Wnt signaling characterized by an increased expression of collagen type 2a1 and Sox 9. However, an absence of Indian hedgehog expression which occurs in WT cells was found. SFRP1-/- cells also exhibited an early induction of collagen type 10a1. Thus, these modifications in gene expression are contributing mechanism(s) for increased chondrocyte differentiation in SFRP1-/- cells. These studies have identified sFRP1 as a critical negative regulator of Wnt signaling for the normal progression of chondrocyte differentiation. Microarray gene profiling provided additional novel insights into the regulatory factors for appropriate Wnt signaling necessary for the control of chondrocyte maturation.

Porcupine-mediated lipid-modification regulates the activity and distribution of Wnt proteins in the chick neural tube

A long-term goal of developmental biology is to understand how morphogens establish gradients that promote proper tissue patterning. A number of reports describe the formation of the Wg (Wnt1) gradient in Drosophila and have shown that Porcupine, a predicted membrane-bound O-acyl transferase, is required for the correct distribution of Wg protein. The discovery that Wnts are palmitoylated on a conserved cysteine residue suggests that porcupine activity and Wnt palmitoylation are important for the generation of Wnt gradients. To establish the role of porcupine in Wnt gradient formation in vertebrates, we tested the role of porcupine/Wnt palmitoylation in human embryonic kidney 293T cells and in the chick neural tube. Our results lead us to conclude that: (1) vertebrate Wnt1 and Wnt3a possess at least one additional site for porcupine-mediated lipid-modification; (2)porcupine-mediated lipid-modification of Wnt proteins promotes their activity in 293T cells and in the chick neural tube; and (3) porcupine-mediated lipid-modification reduces the range of activity of Wnt1 and Wnt3a in the chick neural tube. These findings highlight the importance of porcupine-mediated lipid modifications in the formation of vertebrate Wnt activity gradients.

Multiple gene expression analyses in paraffin-embedded tissues by TaqMan low-density array: Application to hedgehog and Wnt pathway analysis in ovarian endometrioid adenocarcinoma

Recent studies have shown the hedgehog and Wnt families of signaling proteins to be associated with tumor initiation, growth, and survival. However, these pathways remain unexplored in ovarian endometrioid adenocarcinoma (OEA). Here, we describe a novel TaqMan low-density array to examine the expression of 26 and 20 genes in the hedgehog and Wnt pathways, respectively, in six matched snap-frozen and formalin-fixed, paraffin-embedded (FPE) OEA specimens. Expression values were normalized to uninvolved ovarian epithelium. Gene expression in matched frozen and FPE tissues demonstrated significant concordance (r = 0.92, P < 0.0001). However, comparison of amplified and unamplified RNA from frozen OEA tissues revealed an altered molecular profile in amplified RNA. Amplification of RNA from FPE tissues was not successful. The expression of Desert hedgehog (DHH), Indian hedgehog (IHH), Hedge-hog interacting protein (HHIP), Wnt10B, Wnt9B, and Wnt inhibitory factor (WIF1) were tumor-specific with no detectable expression in normal ovarian epithelium. In addition, several genes were significantly (P < 0.025) down-regulated in OEA, including cyclin E2, Porcupine, c-Myc, and Axin 2 (4.8-, 3.6-, 2.9-, and 1.9-fold, respectively). TaqMan low-density array provides an effective multivariate technique for examining gene expression in RNA isolated from either snap-frozen or archival FPE tissues and can identify tumor-specific genes, possibly leading to novel treatments.

Differential expression and localization of WNTs in an animal model of skin wound healing

Wound healing is a dynamic process, and a variety of growth factors have a significant impact on the process. Although the WNT family has a multitude of effects on the state of various physiological pathways, the expression and role of WNT in wounded tissue have remained an enigma. The aim of this study was to assess the expression and localization of WNTs in a murine model of wound healing. RNA isolated from full-thickness cutaneous wounds from day 1 to day 21 postwounding were subjected to reverse transcription-polymerase chain reaction, and expression of WNT3, 4, 5a, and 10b were observed. Immunohistochemistry localized WNT10b to regenerating epithelial cells on day 1 and 3, and WNT4 on day 3 and 5. WNT4 also reacted with fibroblast-like cells beneath the epithelium. The cytoplasmic staining of beta-catenin, a WNT signaling molecule, in the epithelial cells indicates an activation of the WNT signaling pathway. Among target genes downstream of the pathway, matrix metalloproteinases (MMPs) degrade and remodel the extracellular matrix during wound healing. Gelatin zymography showed that MMP9 was expressed from day 1 to day 5. MMP-2 was continuously expressed, but maximally up-regulated at day 5. Activation of MMP-2 coincided with expression of membrane-type 1 MMP, suggesting an involvement of WNTs in this proteolytic cascade. Therefore, WNTs may contribute to the process of wound healing in a spatiotemporal manner.

Solid pseudopapillary neoplasms of the pancreas show an interruption of the Wnt-signaling pathway and express gene products of 11q

Solid pseudopapillary neoplasms of the pancreas almost consistently show a beta-catenin mutation activating the Wnt-signaling pathway, resulting in overexpression of cyclin D1, but not in overt malignancy of this tumor. Besides cyclin D1, a set of markers (ie FLI-1, CD56 and progesterone receptor), whose genes map to chromosome 11q, are frequently expressed in solid pseudopapillary neoplasms. Chromosome 11q is a region that is also often affected in pancreatic neuroendocrine tumors. This immunohistochemical study was undertaken to gain insights into the downstream regulation of the Wnt-signaling pathway and the significance of overexpressed gene products belonging to chromosome 11q for the tumorigenesis in solid pseudopapillary neoplasms. Fourteen solid pseudopapillary neoplasms were analyzed for the expression of cyclin-dependent kinase inhibitors p21, p27, p16 and hyperphosphorylated retinoblastoma (pRb) proteins. In an extended series of 93 solid pseudopapillary neoplasms, beta-catenin, cyclin D1, FLI-1 and CD56 expression was examined and compared with that in 22 pancreatic neuroendocrine tumors. Solid pseudopapillary neoplasms (98%) showed aberrant expression of beta-catenin with a concomitant cyclin D1 expression in 69% of the cases, but no expression of pRb (0%) was found. p27 and p21 were expressed in 100% (14/14) and 86% (12/14) of the cases, but only 2/14 (14%) were positive for p16. FLI-1 was expressed in 63% of solid pseudopapillary neoplasms, but only in 1/22 pancreatic neuroendocrine tumors (5%), cyclin D1 expression was present in 14% of the latter. We conclude that in solid pseudopapillary neoplasms the activated Wnt-signaling pathway is disrupted, and that p21 and p27 are contributing to this fact by blocking of the hyperphosphorylation of the Rb protein, thus causing the very low proliferation rate characterizing the solid pseudopapillary neoplasms. The accumulation of high expression of proteins whose genes are located on chromosome 11q is characteristic of solid pseudopapillary neoplasms, but not of pancreatic neuroendocrine tumors.

Gli3 is required for the specification and differentiation of preplate neurons

During corticogenesis, the cerebral cortex develops a laminated structure which is essential for its function. Early born neurons of the preplate and its derivatives, the marginal zone (MZ) and the subplate (SP), serve as a framework during the cortical lamination process. Here, I report on defects in the generation and specification of these early born cortical neurons in extra-toes (Xt(J)) mice which are defective for the Gli3 zinc finger transcription factor. The Gli3 mutation dramatically disrupts early steps in the cortical lamination process. The MZ, SP and the cortical plate (CP) do not form layers but cortical neurons are arranged in clusters. These defects start to become evident at E12.5 when the cortex forms several protrusions and the ventricular zone becomes undulated. At this stage, cortical progenitor cells start to loose their apical/basal cell polarity correlating with an ectopic expression of Wnt7b in the ventricular zone. In addition, the cellular composition of the preplate is severely altered. Cajal-Retzius cells are reduced in numbers while early born Calretinin(+) neurons are overproduced. These results show that multiple aspects of corticogenesis including the organization of the venticular zone, the apical/basal cell polarity of cortical progenitors and the differentiation of early born cortical neurons are affected in the Gli3 mutant.

PPARgamma and Wnt/beta-Catenin pathway in human breast cancer: expression pattern, molecular interaction and clinical/prognostic correlations

PURPOSE

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor expressed in a large number of human cancers and plays important roles in breast cancer cell proliferation. Its association with clinicopathologic features and Wnt/beta-Catenin signaling pathway, a crucial factor in embryonic and malignant development, in breast cancer has not been reported systematically. In the present study, expression patterns, interaction and the correlations with clinical/prognostic factors of PPARgamma and beta-Catenin were investigated among patients with breast cancer.

METHODS

Using immunohistochemistry, we performed a study on 70 patient-derived human breast tumors and compared the protein expression levels of PPARgamma, beta-Catenin and Ki-67. Correlations were then analyzed between IHC-assessed level of these molecules and major clinicopathologic variables and survival. Furthermore, western blot (WB) analysis before and after immunoprecipitation with PPARgamma and beta-Catenin were performed on breast cancer tissues and cell lines to evaluate their protein level and molecular interaction.

RESULTS

We showed that PPARgamma expression was of significant prognostic value in the outcome of breast carcinomas, which positively correlated with ER status (P = 0.012) and inversely associated with histologic grade (P = 0.012), tumor size (P = 0.007), axillary lymph node status (P = 0.044), TNM stage (P = 0.026), Ki-67 (P = 0.006) and abnormal beta-Catenin expression (P = 0.023), whereas no correlation was seen between PPARgamma and age (P = 0.513), histology (P = 0.764), PR (P = 0.099) or HER-2 status (P = 0.175). Kaplan-Meier survival curves of the study population showed that high expression level of PPARgamma significantly correlated with long-term survival. Molecular interaction could also be demonstrated between PPARgamma and beta-Catenin both in breast cancer cell lines and tissue samples.

CONCLUSIONS

On the basis of these results, we suggested that PPARgamma might serve as a future target for the development of novel treatments in breast cancer.

Presence of ghost cells and the Wnt signaling pathway in odontomas

BACKGROUND

Although it has been reported that ghost cells are present in odontomas, the generation mechanism of these cells is unclear. To evaluate the presence of ghost cells and involvement of the Wnt signaling pathway, we examined the expression of hard keratins, beta-catenin and Lef-1 in odontomas.

METHODS

Sixty-nine cases of odontoma were examined immunohistochemically with the use of antibodies against human hair proteins, beta-catenin and Lef-1.

RESULTS

Expression of hard keratins was found only in the cytoplasm of ghost cells in 46 (66.7%) of the 69 odontomas. Compound odontomas (78.8%) showed a higher incidence of ghost cells than complex odontomas (29.4%). Histopathologically, ghost cells were found within odontogenic epithelium adjacent to immature enamel and in the centre of Liesegang-ring-like calcified materials. Expression of beta-catenin and Lef-1 was observed in the cytoplasm and nucleus of odontogenic epithelial cells adjacent to the ghost cells in immature odontomas.

CONCLUSION

These findings suggest that odontoma is a hard keratin-expressing tumor-like lesion, and that the Wnt signaling pathway may be involved in the formation of ghost cells in odontomas.

Beta-catenin overexpression in Dupuytren's disease is unrelated to disease recurrence

Recurrence of Dupuytren's contracture is common yet unpredictable, compromising surgical outcome. The alpha-smooth muscle actin-containing myofibroblast is the active contractile cellular component. Based on recent reports on beta-catenin accumulation in Dupuytren's disease, we investigated a possible relation with disease recurrence. We divided a collection of 143 nodules into those from patients with recurrent or nonrecurrent nodules and with a minimal 3-year followup. We randomly selected 12 and 11 samples of each group, respectively. We looked at Dupuytren's diathesis, immunohistologic staining for beta-catenin and alpha-smooth muscle actin, and Luck's histologic stages (zones). The expression of selected Wnt genes was examined with TaqMan PCR in separate histologic zones. All samples showed cytoplasmic and nuclear beta-catenin accumulation in myofibroblasts in involutional zones. The risk score of Abe et al. and Dupuytren's diathesis were greater in the recurrent group. Greater Wnt5a expression in the beta-catenin-accumulating involutional zone was seen. We conclude intracellular beta-catenin accumulation, possibly regulated by upstream Wnt signaling pathway activation and confined in myofibroblasts in the involutional zone of Dupuytren's diathesis, is unrelated to disease recurrence. Clinical parameters for Dupuytren's diathesis remain the best way to predict recurrence risk.

Immunolocalization of Wnt5a during the hair cycle and its role in hair shaft growth in mice

Previous studies have shown that the Wnt signaling pathway plays an important role in the growth and development of hair follicles. It has been generally accepted that Wnt5a, a non-canonical Wnt gene, inhibits the Wnt/β-catenin signaling pathway. Several reports have addressed its mRNA expression in embryonic and postnatal hair follicles, but its exact role in the growth of hair follicles is currently unknown. In this study, we investigated the immunolocalization of Wnt5a protein in pelages of the dorsal skin and whisker follicles of mice. We found that in the anagen phase, dermal papilla cells showed the highest staining levels of Wnt5a protein, while in the catagen and the telogen phases the staining levels were lower. During the growth stage, Wnt5a protein was prominently located in the matrix and precortex cells in addition to the inner root sheath, outer root sheath and the dermal papilla. As the hair cycle progresses, the immunostaining of Wnt5a was gradually decreased in the catagen phase and was located in the bulge and secondary hair germ in the telogen phase. This Wnt5a immunostaining profile was consistent between dorsal skin pelages and whisker follicles. Furthermore, in an in vitro study using whisker follicle organ culture, we demonstrated that the growth of the hair shaft was significantly inhibited by adenovirus Wnt5a. Our findings suggest that Wnt5a is a dynamic factor in the hair cycle and it is important for the regulation of hair shaft growth.

Expression of Wnt3a, Wnt10b, β-catenin and DKK1 in periodontium during orthodontic tooth movement in rats

OBJECTIVE

To investigate the expression of Wnt3a, Wnt10b, β-catenin and DKK1 in the periodontal ligament (PDL) during orthodontic tooth movement (OTM) in rats.

MATERIALS AND METHODS

Nickel-titanium closed-coil springs were used to deliver an initial 50 g mesial force to the left maxillary first molars in 30 rats. The force was kept constant for 1, 3, 5, 7, 10 and 14 days until the animals were sacrificed. The right maxillary molars without force application served as control. Paraffin-embedded sections of the upper jaws were prepared for histological and immunohistochemical analyses to detect Wnt3a, Wnt10b, β-catenin and DKK1 expression in PDL.

RESULTS

Wnt3a, Wnt10b, β-catenin and DKK1 were expressed on both the ipsilateral and contralateral sides of PDL in each group. After the application of orthodontic force, the expression of β-catenin and DKK1 was initially increased and then decreased on both sides, with maximal levels of expression at day 7 and day 10, respectively. On the compression side, Wnt3a and Wnt10b levels started to increase at day 5, while on the tension side, these two molecules began to increase at day 1. Furthermore, the expression levels of Wnt3a, Wnt10b, and β-catenin were much stronger on the tension side than on the compression side at any of the observation points, while DKK1 level was much higher on the compression side.

CONCLUSION

Wnt3a, Wnt10b, β-catenin and DKK1 expression may be related to the periodontal tissue remodeling following the application of an orthodontic force in rats. These observations suggest that the Wnt/β-catenin signaling pathway may play a crucial role in periodontal tissue remodeling during OTM.

Regulator of g protein signaling 3 modulates wnt5b calcium dynamics and somite patterning

Vertebrate development requires communication among cells of the embryo in order to define the body axis, and the Wnt-signaling network plays a key role in axis formation as well as in a vast array of other cellular processes. One arm of the Wnt-signaling network, the non-canonical Wnt pathway, mediates intracellular calcium release via activation of heterotrimeric G proteins. Regulator of G protein Signaling (RGS) proteins can accelerate inactivation of G proteins by acting as G protein GTPase-activating proteins (GAPs), however, the possible role of RGS proteins in non-canonical Wnt signaling and development is not known. Here, we identify rgs3 as having an overlapping expression pattern with wnt5b in zebrafish and reveal that individual knockdown of either rgs3 or wnt5b gene function produces similar somite patterning defects. Additionally, we describe endogenous calcium release dynamics in developing zebrafish somites and determine that both rgs3 and wnt5b function are required for appropriate frequency and amplitude of calcium release activity. Using rescue of gene knockdown and in vivo calcium imaging assays, we demonstrate that the activity of Rgs3 requires its ability to interact with Gα subunits and function as a G protein GAP. Thus, Rgs3 function is necessary for appropriate frequency and amplitude of calcium release during somitogenesis and is downstream of Wnt5 activity. These results provide the first evidence for an essential developmental role of RGS proteins in modulating the duration of non-canonical Wnt signaling.

Vertebrate development requires communication among cells in order to define the body axis (front/back, head/tail, or left/right). Secreted factors such as Wnts play key roles in a vast array of cellular processes, including patterning of the body axis. One arm of the Wnt-signaling network, the non-canonical pathway, mediates intracellular calcium release via activation of heterotrimeric G proteins. Regulator of G protein Signaling (RGS) proteins can accelerate inactivation of G proteins by acting as G protein GAPs and are uniquely situated to control the amplitude of a Wnt signal. Here, we combine cellular, molecular, and genetic analyses with high resolution calcium imaging to identify a role for RGS modulation of Wnt-mediated calcium release dynamics and developmental patterning events. We find that loss of rgs3 gene function produced body patterning defects like those observed with loss of wnt5b gene function. Analysis of endogenous calcium release dynamics in developing zebrafish revealed that both rgs3 and wnt5b are required for appropriate frequency and amplitude of calcium release. Our results provide new evidence that a member of the RGS protein family is essential for modulating the non-canonical Wnt network to assure normal tissue patterning during development.

The Emergence of Pattern in Embryogenesis: Regulation of beta-Catenin Localization During Early Sea Urchin Development

The accumulation of beta-catenin in the nuclei of blastomeres at one pole of the early embryo is a highly conserved and essential feature of animal development. In the sea urchin, beta-catenin accumulates in the nuclei of vegetal blastomeres during early cleavage and activates gene regulatory networks that drive mesoderm and endoderm formation. Measurements of beta-catenin half-life in vivo have demonstrated a gradient in stability along the animal-vegetal axis. Dishevelled (Dsh), a protein that regulates beta-catenin turnover, is localized in the vegetal cortex, where it has an essential role in stabilizing beta-catenin and activating endomesodermal gene networks. Two motifs of Dsh are required for targeting to the vegetal cortex. Overexpression of Dsh in animal blastomeres does not alter their fate, which suggests that a localized activator of Dsh may be missing in these cells. Wnt signaling may be localized in the early sea urchin embryo, as it is in Xenopus, but findings point to possible differences in the initial polarizing signal in amphibians and echinoderms. Further studies will be required to determine the extent to which mechanisms that control beta-catenin nuclearization in early embryogenesis have been conserved during animal evolution.

Role of WNT10A-expressing kidney fibroblasts in acute interstitial nephritis

WNT signaling mediates various physiological and pathological processes. We previously showed that WNT10A is a novel angio/stromagenic factor involved in such processes as tumor growth, wound healing and tissue fibrosis. In this study, we investigated the role of WNT10A in promoting the fibrosis that is central to the pathology of acute interstitial nephritis (AIN). We initially asked whether there is an association between kidney function (estimated glomerular filtration rate; eGFR) and WNT10A expression using kidney biopsies from 20 patients with AIN. Interestingly, patients with WNT10A expression had significantly lower eGFR than WNT10A-negative patients. However, changes in kidney function were not related to the level of expression of other WNT family members. Furthermore, there was positive correlation between WNT10A and α-SMA expression. We next investigated the involvement of WNT10A in kidney fibrosis processes using COS1 cells, a kidney fibroblast cell line. WNT10A overexpression increased the level of expression of fibronectin and peroxiredoxin 5. Furthermore, WNT10A overexpression renders cells resistant to apoptosis induced by hydrogen peroxide and high glucose. Collectively, WNT10A may induce kidney fibrosis and associate with kidney dysfunction in AIN.

A SERM increasing the expression of the osteoblastogenesis and mineralization-related proteins and improving quality of bone tissue in an experimental model of osteoporosis

Raloxifene is an antiresorptive drug, selective estrogen receptor modulator (SERM) used in the treatment of osteoporosis. Objective To evaluate proteins related to bone repair at the peri-implant bone in a rat model of osteoporosis treated with raloxifene. Material and Methods 72 rats were divided into three groups: SHAM (healthy animals), OVX (ovariectomized animals), and RLX (ovariectomized animals treated with raloxifene). Raloxifene was administered by gavage (1 mg/kg/day). Tibial implantation was performed 30 days after ovariectomy, and animals were euthanized at 14, 42, and 60 days postoperatively. Samples were collected and analyzed by immunohistochemical reactions, molecular analysis, and microtomographic parameters. Results RLX showed intense staining of all investigated proteins at both time points except for RUNX2. These results were similar to SHAM and opposite to OVX, showing mild staining. The PCR gene expression of OC and ALP values for RLX (P<0.05) followed by SHAM and OVX groups. For BSP data, the highest expression was observed in the RLX groups and the lowest expression was observed in the OVX groups (P<0.05). For RUNX2 data, RLX and SHAM groups showed greater values compared to OVX (P<0.05). At 60 days postoperatively, microtomography parameters, related to closed porosity, showed higher values for (Po.N), (Po.V), and (Po) in RLX and SHAM groups, whereas OVX groups showed lower results (P<0.05); (BV) values (P=0.009); regarding total porosity (Po.tot), RLX group had statistically significant lower values than OVX and SHAM groups (P=0.009). Regarding the open porosity (Po.V and Po), the SHAM group presented the highest values, followed by OVX and RLX groups (P<0.05). The Structural Model Index (SMI), RLX group showed a value closer to zero than SHAM group (P<0.05). Conclusions Raloxifene had a positive effect on the expression of osteoblastogenesis/mineralization-related proteins and on micro-CT parameters related to peri-implant bone healing.

The role of WNT10B in normal prostate gland development and prostate cancer

BACKGROUND

WNT signaling is implicated in embryonic development, and in adult tissue homeostasis, while its deregulation is evident in disease. This study investigates the unique roles of canonical WNT10B in both normal prostate development and prostate cancer (PCa) progression.

METHODS

Organ culture and rat ventral prostates (VPs) were used to study Wnt10b ontogeny and growth effect of WNT10B protein. PB-SV40 LTag rat VPs were utilized for Wnt expression polymerase chain reaction (PCR) array and immunohistochemistry. Human localized PCa tissue microarrays (TMAs) were investigated for differential WNT10B expression. Human RNA-seq data sets were queried for differential expression of WNT10B in metastatic and localized PCa. Knockdown of WNT10B in PC3 cells was utilized to study its effects on proliferation, stemness, epithelial to mesenchymal transition (EMT), and xenograft propagation.

RESULTS

Wnt10b expression was highest at birth and rapidly declined in the postnatal rat VP. Exogenous WNT10B addition to culture developing VPs decreased growth suggesting an antiproliferative role. VPs from PB-SV40 LTag rats with localized PCa showed a 25-fold reduction in Wnt10b messenger RNA (mRNA) expession, confirmed at the protein level. Human PCa TMAs revealed elevated WNT10B protein in prostate intraepithelial neoplasia compared with normal prostates but reduced levels in localized PCa specimens. In contrast, RNA-seq data set of annotated human PCa metastasis found a significant increase in WNT10B mRNA expression compared with localized tumors suggesting stage-specific functions of WNT10B. Similarly, WNT10B mRNA levels were increased in metastatic cell lines PC3, PC3M, as well as in HuSLC, a PCa stem-like cell line, as compared with disease-free primary prostate epithelial cells. WNT10B knockdown in PC3 cells reduced expression of EMT genes, MMP9 and stemness genes NANOG and SOX2 and markedly reduced the stem cell-like side population. Furthermore, loss of WNT10B abrogated the ability of PC3 cells to propagate tumors via serial transplantation.

CONCLUSIONS

Taken together, these results suggest a dual role for WNT10B in normal development and in PCa progression with opposing functions depending on disease stage. We propose that decreased WNT10B levels in localized cancer allow for a hyperproliferative state, whereas increased levels in advanced disease confer a stemness and malignant propensity which is mitigated by knocking down WNT10B levels. This raises the potential for WNT10B as a novel target for therapeutic intervention in metastatic PCa.

Mutational analyses of WNT7A and HDAC11 as candidate tumour suppressor genes in sporadic malignant pancreatic endocrine tumours

OBJECTIVE

We and others have reported loss of heterozygosity (LOH) on chromosome 3p25 in sporadic malignant pancreatic endocrine tumours (PETs). A common region of deletion on chromosome 3p25 contains numerous genes, including VHL and PPARgamma, that have been excluded previously as candidate tumour suppressor genes by DNA sequencing analysis. We have analysed whether WNT7A or HDAC11 was biallelically inactivated in a group of well-characterized PETs.

PATIENTS AND DESIGN

Ten PETs from eight patients were selected from a previous study, where LOH on chromosome 3p25 was found in 11 out of 22 sporadic PETs. These tumours were examined for inactivating mutations of WNT7A and HDAC11 by direct sequencing of all exons and intron-exon boundaries. Inactivation of WNT7A expression by aberrant CpG island methylation and WNT7A protein expression were evaluated by methylation-specific polymerase chain reaction (PCR) and immunohistochemistry, respectively. HDAC11 protein expression was also examined.

RESULTS

No point mutations, deletion or insertions were detected in either WNT7A or HDAC11 in any of the PETs. Two polymorphisms were identified in the third exon of the WNT7A gene. CpG methylation of the WNT7A gene was not detected and the WNT7A and HDAC11 proteins were normally expressed.

CONCLUSION

The absence of tumour-specific somatic events in WNT7A and HDAC11 suggests that these genes are unlikely to have a classical tumour suppressor gene role in sporadic malignant PETs. The putative 3p25 tumour suppressor remains to be identified.

Wnt Family Member 9b (Wnt9b) Is a New Sensitive and Specific Marker for Breast Cancer

Confirming the tumor origin is often a diagnostic challenge in pathology and carries significant therapeutic impacts. Cytokeratin 7, estrogen receptor, and GATA binding protein 3 (GATA3) are well-established diagnostic markers frequently used to support a tumor's breast origin. However, their specificities still have room to improve. Many nonbreast tumors express cytokeratin 7 and estrogen receptor, and urothelial tumors frequently express GATA3. There is a practical need for a new breast lineage marker that is sensitive and specific. Wnt family member proteins play critical roles in embryo development, tissue homeostasis and tumor development through β-catenin dependent and independent pathways. The current study evaluated Wnt9b and GATA3 expression in 163 primary breast cancers, 63 metastatic breast cancers, and 525 nonbreast epithelial tumors. The positive rates of Wnt9b and GATA3 in primary breast cancer were both 98.7%. The positive rates in metastatic breast cancer were 87.3% for Wnt9b and 96.8% for GATA3. For nonbreast tumors, including 64 cases of urothelial carcinoma, Wnt9b was negative in all except salivary gland carcinomas. The study demonstrated that Wnt9b is a breast cancer marker with similar sensitivity as GATA3 but with greater specificity than GATA3 and may ultimately become a useful diagnostic tool in routine surgical pathology practice.

Canonical and noncanonical Wnt pathways: a comparison between endometrial cancer type I and atrophic endometrium in Brazil

CONTEXT AND OBJECTIVE

The Wnt pathway is involved in tumorigenesis of several tissues. For this reason, we proposed to evaluate Wnt gene expression in endometrial cancer type I.

DESIGN AND SETTING

Cross-sectional study on materials gathered from the tissue bank of the Department of Pathology, Universidade Federal de São Paulo.

METHODS

Endometrial specimens were obtained from surgeries performed between 1995 and 2005 at São Paulo Hospital, Universidade Federal de São Paulo. The material was divided into two groups according to tissue type: Group A, atrophic endometrium (n = 15); and Group B, endometrial adenocarcinoma (n = 45). We compared the immunohistochemical expression of Wnt1, Frizzled-1 (FZD1), Wnt5a, Frizzled-5 (FZD5) and beta-catenin between endometrial cancer type I and atrophic endometrium.

RESULTS

Regarding Wnt1, FZD1 and Wnt5a expression, no significant association was observed between the groups. A significant association was observed between the groups in relation to FZD5 expression (P = 0.001). The proportion of FZD5-positive samples was significantly higher in group A (80.0%) than in group B (31.1%). Regarding the survival curve for FZD5 in group B, we did not find any significant association between atrophic endometrium and endometrial adenocarcinoma. We also did not find any significant association regarding beta-catenin expression (P = 1.000).

CONCLUSION

FZD5 is downregulated in endometrial adenocarcinoma, in comparison with atrophic endometrium.