The WNT signaling pathway from ligand secretion to gene transcription: molecular mechanisms and pharmacological targets. Pharmacol Ther. 2013;138:66-83. [PMID: 23328704 DOI: 10.1016/j.pharmthera.2013.01.002]

Contribution of the Wnt Pathway to Defining Biology of Glioblastoma

Glioblastoma (GBM), a highly lethal brain tumor, has been comprehensively characterized at the molecular level with the identification of several potential treatment targets. Data concerning the Wnt pathway are relatively sparse, but apparently very important in defining several aspects of tumor biology. The Wnt ligands are involved in numerous basic biological processes including regulation of embryogenic development, cell fate determination, and organogenesis, but growing amount of data also support the roles of Wnt pathways in the formation of many tumors, including gliomas. Two main Wnt pathways are distinguished: the canonical (β-catenin) and non-canonical (planar cell polarity, Wnt/Ca²⁺) routes. Wnt signaling regulates glioma stem cells (GSCs), thereby defining invasive potential, recurrence, and treatment resistance of GBM. Some observations suggest that the Wnt pathways are differentially active in molecular subtypes of this tumor, thereby may also guide prognostication and novel therapeutic decisions. In this review, we highlight main elements and biological relevance of the Wnt pathways, primarily focusing on the pathogenesis and subtypes of GBM. Finally, we briefly summarize newer therapeutic strategies targeting networks of the Wnt signaling cascades and their molecular associates that appear to be marked contributors to GBM aggressiveness.

Expression Analysis of Platinum Sensitive and Resistant Epithelial Ovarian Cancer Patient Samples Reveals New Candidates for Targeted Therapies

Ovarian cancer has the highest mortality rate of all gynecologic malignancies. Identification of new biomarkers is highly needed due to its late diagnosis and high recurrence rate. The objective of this study was to identify mechanisms of therapy resistance and potential biomarkers by analyzing mRNA and protein expression from samples derived from patients with platinum-sensitive and -resistant ovarian cancer (total cohort n = 53). The data revealed new candidates for targeted therapies, such as GREB1 and ROR2. We showed that the development of platinum resistance correlated with upregulation of ROR2, whereas GREB1 was downregulated. Moreover, we demonstrated that high levels of ROR2 in platinum-resistant samples were associated with upregulation of Wnt5a, STAT3 and NF-kB levels, suggesting that a crosstalk between the non-canonical Wnt5a-ROR2 and STAT3/NF-kB signaling pathways. Upregulation of ROR2, Wnt5a, STAT3 and NF-kB was further detected in a platinum-resistant cell-line model. The results of the present study provided insight into molecular mechanisms associated with platinum resistance that could be further investigated to improve treatment strategies in this clinically challenging gynecological cancer.

Opposite Roles of Wnt7a and Sfrp1 in Modulating Proper Development of Neural Progenitors in the Mouse Cerebral Cortex

The Wingless (Wnt)-mediated signals are involved in many important aspects of development of the mammalian cerebral cortex. How Wnts interact with their modulators in cortical development is still unclear. Here, we show that Wnt7a and secreted frizzled-related protein 1 (Sfrp1), a soluble modulator of Wnts, are co-expressed in mouse embryonic cortical neural progenitors (NPs). Knockout of Wnt7a in mice causes microcephaly due to reduced NP population and neurogenesis, and Sfrp1 has an opposing effect compared to Wnt7a. Similar to Dkk1, Sfrp1 decreases the Wnt1 and Wnt7a activity in vitro. Our results suggest that Wnt7a and Sfrp1 play opposite roles to ensure proper NP progeny in the developing cortex.

Wnt2 contributes to the progression of gastric cancer by promoting cell migration and invasion

Wnt2 plays a pivotal role in human cancer. However, it is not yet known whether Wnt2 contributes to promoting migration and invasion of gastric cancer. The present study aimed to investigate the expression of Wnt2 in gastric cancer tissues and cell lines, and to analyze the effect of Wnt2 on gastric cancer cells. Wnt2 expression level was evaluated in gastric cancer samples and adjacent normal gastric tissues by immunohistochemical and western blot analysis. To investigate the effect of Wnt2 on gastric cancer cells, an in vitro Wnt2 secreting system was established using CHO cells. The results indicated that Wnt2 is overexpressed in gastric cancer and is implicated in metastasis and TNM stage. Additionally, the results of in vitro experiments demonstrated that Wnt2 contributes to enhancing the migration and invasion abilities of gastric cancer cells. These results suggested that Wnt2 may be an effective target of treatment for patients with advanced gastric cancer.

Circulating Wnt inhibitory factor 1 levels are associated with development of cardiovascular disease

BACKGROUND AND AIMS

Wnt signaling is involved in atherosclerotic plaque formation directly and indirectly by modulating cardiovascular risk factors. We investigated whether circulating concentrations of Wnt inhibitors are associated with cardiovascular events in subjects with intermediate cardiovascular risk.

METHODS

904 non-diabetic subjects participating in the SAPHIR study were assessed. In the SAPHIR study, middle-aged women without overt atherosclerotic disease at study entry were followed up for 10 years. 88 patients of our study cohort developed cardiovascular disease at follow-up (CVD group). Subjects of the CVD group were 1:2 case-control matched for age, sex, BMI and smoking behavior with subjects without overt cardiovascular disease after a 10 year-follow-up (control group). 18 patients of the CVD group and 19 subjects of the control group were retrospectively excluded due to fulfilling exclusion criteria. Baseline circulating sclerostin, dickkopf (DKK)-1, secreted frizzled-related protein (SFRP)-1 and Wnt inhibitory factor (WIF)-1 levels were assessed by ELISA.

RESULTS

Baseline systemic SFRP-1 and WIF-1 levels were significantly higher in patients with cardiovascular events (n = 70) when compared to healthy controls (n = 157) while DKK-1 and sclerostin levels were similar in both groups. Logistic regression analysis revealed WIF-1 as a significant predictor of future cardiovascular events.

CONCLUSIONS

Our data suggest that increased SFRP-1 and WIF-1 levels precede the development of symptomatic atherosclerotic disease. Assessment of systemic WIF-1 levels, which turned out to be independently associated with CVD, might help to early identify patients at intermediate cardiovascular risk.

TIPE2 Inhibits the Expression of Asthma-Related Inflammatory Factors in Hyperstretched Bronchial Epithelial Cells Through the Wnt/β-Catenin Pathway

Childhood asthma, an airway inflammatory disease, is a serious threat to the child's quality of life. Recently, TIPE2 expression was reported to be decreased in children with asthma. Therefore, additional studies focusing on TIPE2 might provide an approach for treating childhood asthma. In this study, we found that TIPE2 was poorly expressed in hyperstretched human bronchial epithelial cells (BEAS-2B). TIPE2 overexpression also significantly suppressed the stretch-induced secretion of asthma-related inflammatory factors (TNF-α, TSLP, MMP-9, and VEGF). In contrast, TIPE2 inhibition significantly promoted the secretion of TNF-α, TSLP, MMP-9, and VEGF. Furthermore, overexpression of TIPE2 remarkably inhibited the activation of Wnt/β-catenin in hyperstretched BEAS-2B cells, while siTIPE2 activated Wnt/β-catenin in hyperstretched BEAS-2B cells. Further analysis showed that the Wnt/β-catenin signal inhibitor Dkk-1 could further enhance the TIPE2-induced suppression of Wnt/β-catenin signaling, which also suppressed the siTIPE2-induced secretion of TNF-α, TSLP, MMP-9, and VEGF in hyperstretched BEAS-2B cells. Dkk-1 reversed the effects of siRNA-TIPE2 on Wnt/β-catenin signaling and inflammatory cytokines. In summary, we have exhibited that TIPE2 inhibited the expression of asthma-related inflammatory factors in hyperstretched BEAS-2B cells by suppressing the Wnt/β-catenin signaling pathway. TIPE2 may be involved in airway inflammation during asthma attack, and it may be used as a potential therapeutic target for bronchial epithelial inflammation in childhood asthma.

WNT receptor signalling in lung physiology and pathology

The WNT signalling cascades have emerged as critical regulators of a wide variety of biological aspects involved in lung development as well as in physiological and pathophysiological processes in the adult lung. WNTs (secreted glycoproteins) interact with various transmembrane receptors and co-receptors to activate signalling pathways that regulate transcriptional as well as non-transcriptional responses within cells. In physiological conditions, the majority of WNT receptors and co-receptors can be detected in the adult lung. However, dysregulation of WNT signalling pathways contributes to the development and progression of chronic lung pathologies, including idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), asthma and lung cancer. The interaction between a WNT and the (co-)receptor(s) present at the cell surface is the initial step in transducing an extracellular signal into an intracellular response. This proximal event in WNT signal transduction with (cell-specific) ligand-receptor interactions is of great interest as a potential target for pharmacological intervention. In this review we highlight the diverse expression of various WNT receptors and co-receptors in the aforementioned chronic lung diseases and discuss the currently available biologicals and pharmacological tools to modify proximal WNT signalling.

The curious case of vacuolar ATPase: regulation of signaling pathways

The Vacuolar ATPase (V-ATPase) is a proton pump responsible for controlling the intracellular and extracellular pH of cells. The structure of V-ATPase has been highly conserved among all eukaryotic cells and is involved in diverse functions across species. V-ATPase is best known for its acidification of endosomes and lysosomes and is also important for luminal acidification of specialized cells. Several reports have suggested the involvement of V-ATPase in maintaining an alkaline intracellular and acidic extracellular pH thereby aiding in proliferation and metastasis of cancer cells respectively. Increased expression of V-ATPase and relocation to the plasma membrane aids in cancer modulates key tumorigenic cell processes like autophagy, Warburg effect, immunomoduation, drug resistance and most importantly cancer cell signaling. In this review, we discuss the direct role of V-ATPase in acidification and indirect regulation of signaling pathways, particularly Notch Signaling.

WNT Signaling in Lung Aging and Disease

Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), represent a significant and increasing health burden. Current therapies are largely symptomatic, and novel therapeutic approaches are needed. Aging has emerged as a contributing factor for the development of both IPF and COPD because their prevalence increases with age, and several pathological features of these diseases resemble classical hallmarks of aging. Aging is thought to be driven in part by aberrant activity of developmental signaling pathways that thus might drive pathological changes, a process termed antagonistic pleiotropy or developmental drift. The developmental WNT pathway is fundamental for lung development, and altered WNT activity has been reported to contribute to the pathogenesis of CLD, in particular to COPD and IPF. Although to date only limited data on WNT signaling during lung aging exist, WNT signal regulation during aging and its effects on age-related pathologies in other organs have recently been investigated. In this review, we discuss evidence of dysregulated WNT signaling in CLD in the context of WNT signal alteration in organ aging and its potential impact on age-related cellular mechanisms, such as senescence or stem cell exhaustion.

Cell-specific expression of runt-related transcription factor 2 contributes to pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with limited therapeutic options and unknown etiology. IPF is characterized by epithelial cell injury, impaired cellular crosstalk between epithelial cells and fibroblasts, and the formation of fibroblast foci with increased extracellular matrix deposition (ECM). We investigated the role of runt-related transcription factor 2 (RUNX2), a master regulator of bone development that has been linked to profibrotic signaling. RUNX2 expression was up-regulated in lung homogenates from patients with IPF and in experimental bleomycin-induced lung fibrosis. The RUNX2 level correlated with disease severity as measured by decreased diffusing capacity and increased levels of the IPF biomarker, matrix metalloproteinase 7. Nuclear RUNX2 was observed in prosurfactant protein C-positive hyperplastic epithelial cells and was rarely found in myofibroblasts. We discovered an up-regulation of RUNX2 in fibrotic alveolar epithelial type II (ATII) cells as well as an increase of RUNX2-negative fibroblasts in experimental and human pulmonary fibrosis. Functionally, small interfering RNA-mediated RUNX2 knockdown decreased profibrotic ATII cell function, such as proliferation and migration, whereas fibroblasts displayed activation markers and increased ECM expression after RUNX2 knockdown. This study reveals that RUNX2 is differentially expressed in ATII cells vs. fibroblasts in lung fibrosis, which contributes to profibrotic cell function. Cell-specific targeting of RUNX2 pathways may represent a therapeutic approach for IPF.-Mümmler, C., Burgy, O., Hermann, S., Mutze, K., Günther, A., Königshoff, M. Cell-specific expression of runt-related transcription factor 2 contributes to pulmonary fibrosis.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

Impact of Altered WNT2B Expression on Bladder Wall Fibroblasts: Implications for Apoptosis Regulation in the Stroma of the Lower Urinary Tract

BACKGROUND

Little is known about the role of WNT signalling in pathological processes involving the urinary tract stroma. Here the impact of WNT signalling on bladder wall fibroblasts (BWFs) was studied using integrated expression profiling.

MATERIAL AND METHODS

WNT ligand and downstream WNT pathway component expression was profiled in human BWFs using qRT-PCR. Highly expressed WNT2B was knocked down using siRNA in BWFs. The expression of 730 mRNAs and 800 miRNAs was analyzed on the nCounter MAX platform in #WNT2B and control transfected BWFs. qRT-PCR was used for validation in vitro and in matched scar and healthy bladder wall tissue samples of 12 patients with vesico-urethral anastomotic stricture (VUAS).

RESULTS

Thirteen genes and 9 miRNAs showed differential expression in #WNT2B cells. Among these were TNFSF10, a key apoptosis inductor, (0.22fold, p = 0.011) and miR-1246 (36.2fold, p = 0.031). miRNA target prediction indicated TNFSF10 to be regulated by miR-1246. qRT-PCR analysis confirmed differential expression of miR-1246 and TNFSF10 in #WNT2B BWFs. Furthermore, TNFSF10 was significantly underexpressed in VUAS tissue (p = 0.009).

CONCLUSION

Perturbation of WNT signalling results in an altered expression of the apoptosis inductor TNFSF10. Similar changes are observed in VUAS. Further studies investigating the crosslink between WNT signalling and apoptosis regulation in the urinary tract stroma are warranted.

Expression profile and clinical significance of Wnt signaling in human gliomas

Wnt signaling has been identified as a critical regulator of human tumor development in vitro. However, there remains a lack of studies systematically examining the expression pattern and clinical relevance of the core molecules of Wnt signaling in glioma tissues. In the present study, it was identified that the mRNA expression levels of Wnt3a and 5a, and their receptors frizzled 2, 6 and 7 increased, whereas Wnt7b was markedly decreased in glioma relative to non-tumor tissue. The mRNA levels of β-catenin, adenomatous polyposis coli gene product, glycogen synthase kinase 3β (GSK3β) and AXIN1 and its target genes cyclin D1 and AXIN2 did not differ. Similarly, the protein levels of Wnt2b, 3a and 5a were increased in gliomas, while β-catenin, GSK3β and cyclin D1 were not. Furthermore, based on data from the R2: Genomics Analysis and Visualization Platform, the expression of Wnt2b and 5a, and frizzled 2, 6 and 7 were highly associated with the prognosis of patients with glioma. Taken together, the results of the present study demonstrate that β-catenin is not upregulated in gliomas and that the Wnt signaling pathway may promote glioma development via noncanonical or alternative pathways.

Therapeutic pro-fibrogenic signaling pathways in fibroblasts

Myofibroblasts (MFs) play a critical role in the progression of chronic inflammatory and fibroproliferative diseases in different tissues/organs, whatever the etiology. Fibrosis is preceded and sustained by persistent injury and inflammatory response in a profibrogenic scenario involving mutual interactions, operated by several mediators and pathways, of MFs and related precursor cells with innate immunity cells and virtually any cell type in a defined tissue. These interactions, mediators and related signaling pathways are critical in initiating and perpetuating the differentiation of precursor cells into MFs that in different tissues share peculiar traits and phenotypic responses, including the ability to proliferate, produce ECM components, migrate and contribute to the modulation of inflammatory response and tissue angiogenesis. Literature studies related to liver, lung and kidney fibrosis have outlined a number of MF-related core regulatory fibrogenic signaling pathways conserved across these different organs and potentially targetable in order to develop effective antifibrotic therapeutic strategies.

Involvement of WNT Signaling in the Regulation of Gestational Age-Dependent Umbilical Cord-Derived Mesenchymal Stem Cell Proliferation

Mesenchymal stem cells (MSCs) are a heterogeneous cell population that is isolated initially from the bone marrow (BM) and subsequently almost all tissues including umbilical cord (UC). UC-derived MSCs (UC-MSCs) have attracted an increasing attention as a source for cell therapy against various degenerative diseases due to their vigorous proliferation and differentiation. Although the cell proliferation and differentiation of BM-derived MSCs is known to decline with age, the functional difference between preterm and term UC-MSCs is poorly characterized. In the present study, we isolated UC-MSCs from 23 infants delivered at 22-40 weeks of gestation and analyzed their gene expression and cell proliferation. Microarray analysis revealed that global gene expression in preterm UC-MSCs was distinct from term UC-MSCs. WNT signaling impacts on a variety of tissue stem cell proliferation and differentiation, and its pathway genes were enriched in differentially expressed genes between preterm and term UC-MSCs. Cell proliferation of preterm UC-MSCs was significantly enhanced compared to term UC-MSCs and counteracted by WNT signaling inhibitor XAV939. Furthermore, WNT2B expression in UC-MSCs showed a significant negative correlation with gestational age (GA). These results suggest that WNT signaling is involved in the regulation of GA-dependent UC-MSC proliferation.

β-Catenin Directs Nuclear Factor-κB p65 Output via CREB-Binding Protein/p300 in Human Airway Smooth Muscle

β-Catenin is a multifunctional protein that apart from its role in proliferative and differentiation events, also acts upon inflammatory processes, mainly via interaction with nuclear factor-κB (NF-κB). However, there is still controversy as to whether β-catenin facilitates or represses NF-κB output. Insights into the molecular mechanisms underlying the interaction between β-catenin and NF-κB have highlighted the cofactors CREB-binding protein (CBP) and p300 as important candidates. Here, we hypothesized that the interaction of β-catenin with CBP/p300 directs NF-κB output. Using human airway smooth muscle (ASM) cells, we found that β-catenin is essential in interleukin -1β (IL-1β)-mediated expression of interleukin-6 (IL-6) by promoting nuclear translocation of the p65 subunit of NF-κB. These effects were independent from WNT pathway activation or other factors that promote β-catenin signaling. In the nucleus, inhibition of either the CBP- or p300-β-catenin interaction could regulate NF-κB output, by enhancing (CBP inhibition) or inhibiting (p300 inhibition) IL-1β-induced expression of IL-6, respectively. Acetylation of p65 by p300 likely underlies these events, as inhibition of the p300-β-catenin interaction diminished levels of acetylated p65 at lysine 310, thereby reducing p65 transcriptional activity. In conclusion, β-catenin is a critical component of NF-κB-mediated inflammation in human ASM, affecting transcriptional output by interacting with the nuclear cofactors CBP and p300. Targeting β-catenin may be an alternative strategy to treat airway inflammation in patients with airway disease, such as asthma.

Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling

Embryonic lung development requires reciprocal endodermal-mesodermal interactions; mediated by various signaling proteins. Wnt/β-catenin is a signaling protein that exhibits the pivotal role in lung development, injury and repair while aberrant expression of Wnt/β-catenin signaling leads to asthmatic airway remodeling: characterized by hyperplasia and hypertrophy of airway smooth muscle cells, alveolar and vascular damage goblet cells metaplasia, and deposition of extracellular matrix; resulting in decreased lung compliance and increased airway resistance. The substantial evidence suggests that Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling. Here, we summarized the recent advances related to the mechanistic role of Wnt/β-catenin signaling in lung development, consequences of aberrant expression or deletion of Wnt/β-catenin signaling in expansion and progression of asthmatic airway remodeling, and linking early-impaired pulmonary development and airway remodeling later in life. Finally, we emphasized all possible recent potential therapeutic significance and future prospectives, that are adaptable for therapeutic intervention to treat asthmatic airway remodeling.

The Wnt Signalling Pathways: A Short Review and Specific Roles in Bone Biochemistry

As musculoskeletal diseases become an emerging healthcare problem worldwide, profound and comprehensive research has been focused on the biochemistry of bone metabolism in the past decades. Wnt signalling, one of the novel described pathways influencing bone metabolism from the early stages of tissue development, has been recently in the centre of attention. Several Wnt ligands are implied in bone forming pathways via canonical (β-catenin dependent) and non-canonical (β-catenin independent) signalling. Osteoporosis, a catabolic bone disease, has its pathologic background related, inter alia, to alterations in the Wnt signalling, thus key modulators of these pathways became one of the most promising targets in the treatment of osteoporosis. Antibodies inhibiting the activity of endogenous Wnt pathway inhibitors (sclerostin, dickkopf) are recently under clinical trials. The current article offers a brief review of the Wnt signalling pathways, its implication in bone metabolism and fate, and the therapeutic possibilities of osteoporosis through Wnt signalling.

The role of Dickkopf-1 as a potential prognostic marker in pancreatic ductal adenocarcinoma

Dickkopf-1(DKK-1), the downstream target of β-catenin/T-cell factor, participates in a negative feedback loop in the Wnt signaling and reported as an important biomarker in many tumors. In this study, we analyzed the expression of DKK-1 in pancreatic ductal adenocarcinoma (PDAC) patients at both mRNA and protein levels. We used real-time PCR to detect the expression of DKK-1 in 32 PDAC and paired adjacent non-tumor tissues, results suggested that the expression of DKK-1 was increased in PDAC tissues. We found the similar results in the analysis of 3 independent microarray data sets. Immunohistochemical staining of 311 pairs of PDAC tissues suggested that DKK-1 expression was significantly associated with T classification (P = 0.039) and lymph node metastasis (P = 0.035). Furthermore, Kaplan-Meier analysis for DKK-1 expression demonstrated that patients with higher DKK-1 level had shorter overall survival (OS) and relapse-free survival (RFS) time in Ren Ji cohort and online PDAC database at both mRNA and protein levels. Univariable and multivariable Cox regression analysis confirmed that DKK-1 as well as lymph node metastasis and histology were independent predictors of OS in patients with PDAC. This study demonstrated that DKK-1 may be a predictor for prognosis in PDAC patients.

Exposure to febrile-range hyperthermia potentiates Wnt signalling and epithelial-mesenchymal transition gene expression in lung epithelium

BACKGROUND

As environmental and body temperatures vary, lung epithelial cells experience temperatures significantly different from normal core temperature. Our previous studies in human lung epithelium showed that: (i) heat shock accelerates wound healing and activates profibrotic gene expression through heat shock factor-1 (HSF1); (ii) HSF1 is activated at febrile temperatures (38-41 °C) and (iii) hypothermia (32 °C) activates and hyperthermia (39.5 °C) reduces expression of a subset of miRNAs that target protein kinase-Cα (PKCα) and enhance proliferation.

METHODS

We analysed the effect of hypo- and hyperthermia exposure on Wnt signalling by exposing human small airway epithelial cells (SAECs) and HEK293T cells to 32, 37 or 39.5 °C for 24 h, then analysing Wnt-3a-induced epithelial-mesenchymal transition (EMT) gene expression by qRT-PCR and TOPFlash reporter plasmid activity. Effects of miRNA mimics and inhibitors and the HSF1 inhibitor, KNK437, were evaluated.

RESULTS

Exposure to 39.5 °C for 24 h increased subsequent Wnt-3a-induced EMT gene expression in SAECs and Wnt-3a-induced TOPFlash activity in HEK293T cells. Increased Wnt responsiveness was associated with HSF1 activation and blocked by KNK437. Overexpressing temperature-responsive miRNA mimics reduced Wnt responsiveness in 39.5 °C-exposed HEK293T cells, but inhibitors of the same miRNAs failed to restore Wnt responsiveness in 32 °C-exposed HEK293T cells.

CONCLUSIONS

Wnt responsiveness, including expression of genes associated with EMT, increases after exposure to febrile-range temperature through an HSF1-dependent mechanism that is independent of previously identified temperature-dependent miRNAs. This process may be relevant to febrile fibrosing lung diseases, including the fibroproliferative phase of acute respiratory distress syndrome (ARDS) and exacerbations of idiopathic pulmonary fibrosis (IPF).

Fucosterol inhibits adipogenesis through the activation of AMPK and Wnt/β-catenin signaling pathways

Fucosterol is a sterol constituent primarily derived from brown algae. Recently, the antiadipogenic effect of fucosterol has been reported; however, its molecular mechanism remains to be studied. Fucosterol effectively upregulated the phosphorylations of both adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), and downregulated the expression levels of lipogenesis-related factors. Moreover, fucosterol activated the major components of the Wnt/β-catenin signaling pathway, including β-catenin, disheveled 2 (DVL2), and cyclin D1 (CCND1), whereas it inactivated glycogen synthase kinase 3β (p-GSK3β) by stimulating its phosphorylation. In the presence or absence of fucosterol, the adipogenic transcriptional factors [peroxisome proliferator activated-receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), and sterol regulatory element binding protein-1c (SREBP-1c)] were upregulated by the inhibition of AMPK by compound C or the knockdown of β-catenin by siRNA. Overall, these data demonstrate that fucosterol prevents adipogenesis by mediating both AMPK- and Wnt/β-catenin-signaling pathways.

'WNT-er is coming': WNT signalling in chronic lung diseases

Chronic lung diseases represent a major public health problem with only limited therapeutic options. An important unmet need is to identify compounds and drugs that target key molecular pathways involved in the pathogenesis of chronic lung diseases. Over the last decade, there has been extensive interest in investigating Wingless/integrase-1 (WNT) signalling pathways; and WNT signal alterations have been linked to pulmonary disease pathogenesis and progression. Here, we comprehensively review the cumulative evidence for WNT pathway alterations in chronic lung pathologies, including idiopathic pulmonary fibrosis, pulmonary arterial hypertension, asthma and COPD. While many studies have focused on the canonical WNT/β-catenin signalling pathway, recent reports highlight that non-canonical WNT signalling may also significantly contribute to chronic lung pathologies; these studies will be particularly featured in this review. We further discuss recent advances uncovering the role of WNT signalling early in life, the potential of pharmaceutically modulating WNT signalling pathways and highlight (pre)clinical studies describing promising new therapies for chronic lung diseases.

Wnt5a Signaling in Normal and Cancer Stem Cells

Wnt5a is involved in activating several noncanonical Wnt signaling pathways, which can inhibit or activate canonical Wnt/β-catenin signaling pathway in a receptor context-dependent manner. Wnt5a signaling is critical for regulating normal developmental processes, including stem cell self-renewal, proliferation, differentiation, migration, adhesion, and polarity. Moreover, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a signaling in regulating normal and cancer stem cell self-renewal, cancer cell proliferation, migration, and invasion. In this article, we review recent findings regarding the molecular mechanisms and roles of Wnt5a signaling in stem cells in embryogenesis and in the normal or neoplastic breast or ovary, highlighting that Wnt5a may have different effects on target cells depending on the surface receptors expressed by the target cell.

Clinical relevance of breast and gastric cancer-associated polymorphisms as potential susceptibility markers for oral clefts in the Brazilian population

BACKGROUND

Epidemiological studies have indicated a higher incidence of breast and gastric cancer in patients with nonsyndromic cleft lip with or without cleft palate (NSCL ± P) and their relatives, which can be based on similar genetic triggers segregated within family with NSCL ± P.

METHODS

This multicenter study evaluated the association of 9 single nucleotide polymorphisms (SNP) in AXIN2 and CDH1, representing genes consistently altered in breast and gastric tumors, with NSCL ± P in 223 trios (father, mother and patient with NSCL ± P) by transmission disequilibrium test (TDT).

RESULTS

Our results showed that the minor A allele of rs7210356 (p = 0.01) and the T-G-G-A-G haplotype formed by rs7591, rs7210356, rs4791171, rs11079571 and rs3923087 SNPs (p = 0.03) in AXIN2 were significantly under-transmitted to patients with NSCL ± P. In CDH1 gene, the C-G-A-A and A-G-A-G haplotypes composed by rs16260, rs9929218, rs7186053 and rs4783573 polymorphisms were respectively over-transmitted (p = 0.01) and under-transmitted (p = 0.008) from parents to the children with NSCL ± P.

CONCLUSIONS

The results suggest that polymorphic variants in AXIN2 and CDH1 may be associated with NSCL ± P susceptibility, and reinforce the putative link between cancer and oral clefts.

A novel TCF7L2 type 2 diabetes SNP identified from fine mapping in African American women

SNP rs7903146 in the Wnt pathway’s TCF7L2 gene is the variant most significantly associated with type 2 diabetes to date, with associations observed across diverse populations. We sought to determine whether variants in other Wnt pathway genes are also associated with this disease. We evaluated 69 genes involved in the Wnt pathway, including TCF7L2, for associations with type 2 diabetes in 2632 African American cases and 2596 controls from the Black Women’s Health Study. Tag SNPs for each gene region were genotyped on a custom Affymetrix Axiom Array, and imputation was performed to 1000 Genomes Phase 3 data. Gene-based analyses were conducted using the adaptive rank truncated product (ARTP) statistic. The PSMD2 gene was significantly associated with type 2 diabetes after correction for multiple testing (corrected p = 0.016), based on the nine most significant single variants in the +/- 20 kb region surrounding the gene, which includes nearby genes EIF4G1, ECE2, and EIF2B5. Association data on four of the nine variants were available from an independent sample of 8284 African American cases and 15,543 controls; associations were in the same direction, but weak and not statistically significant. TCF7L2 was the only other gene associated with type 2 diabetes at nominal p <0.01 in our data. One of the three variants in the best gene-based model for TCF7L2, rs114770437, was not correlated with the GWAS index SNP rs7903146 and may represent an independent association signal seen only in African ancestry populations. Data on this SNP were not available in the replication sample.

Role of VR1 in the differentiation of bone marrow-derived mesenchymal stem cells into cardiomyocytes associated with Wnt/β-catenin signaling

AIM

Accumulating evidence showed that transient receptor potential channels play an important role in the regulation of cardiomyocyte differentiation. The vanilloid receptor 1 (VR1) is a member of the transient receptor channel super family and is expressed in cardiomyocytes. However, its function in cardiomyocytes remains unclear.

METHODS

Herein, the aim of this study was to investigate the functional role of VR1 in the cardiomyocyte differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and to elucidate the potential molecular mechanisms.

RESULTS

Immunofluorescence assay showed that cardiomyocyte marker cardiac troponin T (cTnT) was found significantly elevated in differentiated BMSCs induced by 5-azacytidine compared with control. Similarly, VR1 expression was also found significantly increased in induced BMSCs differentiation. Additionally, we examined the role of VR1 in BMSC differentiation processes through VR1 siRNAs. We found that the expression of cardiomyocyte marker genes, such as alpha-myosin heavy chain (α-MHC), α-cardiac actin, and Nkx2.5 (cardiac-specific transcription factor), was significantly decreased when VR1 was silenced. Furthermore, we found that inhibition of VR1 expression is associated with downregulation of Wnt/β-catenin signaling.

CONCLUSIONS

To summarize, our data demonstrate important role of VR1 in BMSCs differentiation into cardiomyocytes in conjunction of Wnt/β-catenin signaling.

FZD7 regulates BMSCs-mediated protection of CML cells

Inspite of effective treatment with imatinib (IM), chronic myeloid leukemia (CML) is still an incurable disease. Some patients became refractory because of IM resistance. Bone marrow mesenchymal stem cells (BMSCs) have been implicated a role in promoting CML cells' resistance against IM treatment. The detailed molecular mechanisms, however, remain largely unknown. In this study, we found that BMSCs increased the expression of FZD7 and activated Wnt/β-catenin signaling pathway in CML cells. BMSCs from CML patients showed increased efficiency to accelerate CML cell proliferation, enhance the drug resistance of K562 cells and up-regulate the expression of FZD7. Antagonism of FZD7 expression by shRNA significantly suppressed proliferation and increased IM sensitivity of CML cells co-cultured with BMSCs cells. Our findings suggest that FZD7, involved in canonical Wnt signaling pathway, plays a critical role in mediating BMSCs-dependent protection of CML cells, and potentially provide a novel therapeutic target for CML.

Anticancer activity and potential mechanisms of 1C, a ginseng saponin derivative, on prostate cancer cells

Background

AD-2 (20(R)-dammarane-3b, 12b, 20, 25-tetrol; 25-OH-PPD) is a ginsenoside and isolated from Panax ginseng, showing anticancer activity against extensive human cancer cell lines. In this study, effects and mechanisms of 1C ((20R)-3b-O-(L-alanyl)-dammarane-12b, 20, 25-triol), a modified version of AD-2, were evaluated for its development as a novel anticancer drug.

Methods

MTT assay was performed to evaluate cell cytotoxic activity. Cell cycle and levels of reactive oxygen species (ROS) were determined using flow cytometry analysis. Western blotting was employed to analyze signaling pathways.

Results

1C concentration-dependently reduces prostate cancer cell viability without affecting normal human gastric epithelial cell line-1 viability. In LNCaP prostate cancer cells, 1C triggered apoptosis via Bcl-2 family-mediated mitochondria pathway, downregulated expression of mouse double minute 2, upregulated expression of p53 and stimulated ROS production. ROS scavenger, N-acetylcysteine, can attenuate 1C-induced apoptosis. 1C also inhibited the proliferation of LNCaP cells through inhibition on Wnt/β-catenin signaling pathway.

Conclusion

1C shows obvious anticancer activity based on inducing cell apoptosis by Bcl-2 family-mediated mitochondria pathway and ROS production, inhibiting Wnt/β-catenin signaling pathway. These findings demonstrate that 1C may provide leads as a potential agent for cancer therapy.

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Ginseng saponin derivative 1C was obtained by structural modification.

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Anticancer activity of 1C is much better than that of the original compound AD-2 on cancer cells.

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1C induces cell apoptosis by Bcl-2 family-mediated mitochondria pathway and ROS production.

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1C inhibits Wnt/β-catenin signaling pathway

Noncanonical WNT-5A signaling impairs endogenous lung repair in COPD

Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. One main pathological feature of COPD is the loss of functional alveolar tissue without adequate repair (emphysema), yet the underlying mechanisms are poorly defined. Reduced WNT-β-catenin signaling is linked to impaired lung repair in COPD; however, the factors responsible for attenuating this pathway remain to be elucidated. Here, we identify a canonical to noncanonical WNT signaling shift contributing to COPD pathogenesis. We demonstrate enhanced expression of noncanonical WNT-5A in two experimental models of COPD and increased posttranslationally modified WNT-5A in human COPD tissue specimens. WNT-5A was increased in primary lung fibroblasts from COPD patients and induced by COPD-related stimuli, such as TGF-β, cigarette smoke (CS), and cellular senescence. Functionally, mature WNT-5A attenuated canonical WNT-driven alveolar epithelial cell wound healing and transdifferentiation in vitro. Lung-specific WNT-5A overexpression exacerbated airspace enlargement in elastase-induced emphysema in vivo. Accordingly, inhibition of WNT-5A in vivo attenuated lung tissue destruction, improved lung function, and restored expression of β-catenin-driven target genes and alveolar epithelial cell markers in the elastase, as well as in CS-induced models of COPD. We thus identify a novel essential mechanism involved in impaired mesenchymal-epithelial cross talk in COPD pathogenesis, which is amenable to therapy.

Genetic polymorphisms of Wnt/β-catenin pathway genes are associated with the efficacy and toxicities of radiotherapy in patients with nasopharyngeal carcinoma

Radiotherapy (RT) is the normative therapeutic treatment for primary nasopharyngeal carcinoma (NPC). Single nucleotide polymorphisms (SNPs) of genes in Wnt/β-catenin pathway are correlated to the development, prognosis, and treatment benefit of various cancers. However, it has not been established whether SNPs of Wnt/β-catenin pathway are associated with nasopharyngeal tumorigenesis and the efficacy of RT in NPC patients. Therefore, in this study, we aimed to investigate the nine potentially functional SNPs of four genes in the Wnt/β-catenin pathway and genotyped these in 188 NPC patients treated with RT. To achieve this goal, associations between these SNPs and the RT's curative efficacy, as well as acute radiation-induced toxic reaction were determined by multifactorial logistic regression. We observed that catenin beta 1 gene (CTNNB1) rs1880481 and rs3864004, and glycogen synthase kinase 3 beta gene (GSK3β) rs3755557 polymorphisms were significantly associated with poorer efficacy of RT in NPC patients. Moreover, GSK3β rs375557 and adenomatous polyposis coli gene (APC) rs454886 polymorphisms were correlated with acute grade 3-4 radiation-induced dermatitis and oral mucositis, respectively. In conclusion, this study suggests that gene polymorphisms of Wnt/β-catenin may be novel prognostic factors for NPC patients treated with RT.

Phospholipase Cγ1 (PLCγ1) Controls Osteoclast Numbers via Colony-stimulating Factor 1 (CSF-1)-dependent Diacylglycerol/β-Catenin/CyclinD1 Pathway

Phospholipases Cγ (PLCγ) 1 and 2 are a class of highly homologous enzymes modulating a variety of cellular pathways through production of inositol 1,4,5-trisphosphate and diacylglycerol (DAG). Our previous studies demonstrated the importance of PLCγ2 in osteoclast (OC) differentiation by modulating inositol 1,4,5-trisphosphate-mediated calcium oscillations and the up-regulation of the transcription factor NFATc1. Surprisingly, despite being expressed throughout osteoclastogenesis, PLCγ1 did not compensate for PLCγ2 deficiency. Because both isoforms are activated during osteoclastogenesis, it is plausible that PLCγ1 modulates OC development independently of PLCγ2. Here, we utilized PLCγ1-specific shRNAs to delete PLCγ1 in OC precursors derived from wild type (WT) mice. Differently from PLCγ2, we found that PLCγ1 shRNA significantly suppresses OC differentiation by limiting colony-stimulating factor 1 (CSF-1)-dependent proliferation and β-catenin/cyclinD1 levels. Confirming the specificity toward CSF-1 signaling, PLCγ1 is recruited to the CSF-1 receptor following exposure to the cytokine. To understand how PLCγ1 controls cell proliferation, we turned to its downstream effector, DAG. By utilizing cells lacking the DAG kinase ζ, which have increased DAG levels, we demonstrate that DAG modulates CSF-1-dependent proliferation and β-catenin/cyclinD1 levels in OC precursors. Most importantly, the proliferation and osteoclastogenesis defects observed in the absence of PLCγ1 are normalized in PLCγ1/DAG kinase ζ double null cells. Taken together, our study shows that PLCγ1 controls OC numbers via a CSF-1-dependent DAG/β-catenin/cyclinD1 pathway.

Selective targeting of CREB-binding protein/β-catenin inhibits growth of and extracellular matrix remodelling by airway smooth muscle

BACKGROUND AND PURPOSE

Asthma is a heterogeneous chronic inflammatory disease, characterized by the development of structural changes (airway remodelling). β-catenin, a transcriptional co-activator, is fundamentally involved in airway smooth muscle growth and may be a potential target in the treatment of airway smooth muscle remodelling.

EXPERIMENTAL APPROACH

We assessed the ability of small-molecule compounds that selectively target β-catenin breakdown or its interactions with transcriptional co-activators to inhibit airway smooth muscle remodelling in vitro and in vivo.

KEY RESULTS

ICG-001, a small-molecule compound that inhibits the β-catenin/CREB-binding protein (CBP) interaction, strongly and dose-dependently inhibited serum-induced smooth muscle growth and TGFβ1-induced production of extracellular matrix components in vitro. Inhibition of β-catenin/p300 interactions using IQ-1 or inhibition of tankyrase 1/2 using XAV-939 had considerably less effect. In a mouse model of allergic asthma, β-catenin expression in the smooth muscle layer was found to be unaltered in control versus ovalbumin-treated animals, a pattern that was found to be similar in smooth muscle within biopsies taken from asthmatic and non-asthmatic donors. However, β-catenin target gene expression was highly increased in response to ovalbumin; this effect was prevented by topical treatment with ICG-001. Interestingly, ICG-001 dose-dependently reduced airway smooth thickness after repeated ovalbumin challenge, but had no effect on the deposition of collagen around the airways, mucus secretion or eosinophil infiltration.

CONCLUSIONS AND IMPLICATIONS

Together, our findings highlight the importance of β-catenin/CBP signalling in the airways and suggest ICG-001 may be a new therapeutic approach to treat airway smooth muscle remodelling in asthma.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

Linking bronchopulmonary dysplasia to adult chronic lung diseases: role of WNT signaling

Bronchopulmonary dysplasia (BPD) is one of the most common chronic lung diseases in infants caused by pre- and/or postnatal lung injury. BPD is characterized by arrested alveolarization and vascularization due to extracellular matrix remodeling, inflammation, and impaired growth factor signaling. WNT signaling is a critical pathway for normal lung development, and its altered signaling has been shown to be involved in the onset and progression of incurable chronic lung diseases in adulthood, such as chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF). In this review, we summarize the impact of WNT signaling on different stages of lung development and its potential contribution to developmental lung diseases, especially BPD, and chronic lung diseases in adulthood.

Aberrant nonfibrotic parenchyma in idiopathic pulmonary fibrosis is correlated with decreased β-catenin inhibition and increased Wnt5a/b interaction

Idiopathic pulmonary fibrosis (IPF), an insidious disease with grave prognosis, is characterized by heterogeneous fibrosis with densely fibrotic areas surrounded by nonfibrotic normal‐looking tissue, believed to reflect a temporal development. The etiology is incompletely elucidated, but aberrant wound healing is believed to be involved. Embryonic signaling pathways, including Wnt signaling, are reactivated in wound healing, and we therefore aimed to investigate Wnt signaling, and hypothesized that Wnt signaling would correspond to degree of fibrosis. Material from 10 patients with IPF were included (four diagnostic biopsies and six donated lungs) and compared to healthy controls (n = 7). We investigated markers of Wnt signaling (β‐catenin, Wnt3a, ICAT, Wnt5a/b, DAAM1 and NLK) histologically in lung parenchyma with variable degree of fibrosis. Our results suggest that Wnt signaling is significantly altered (P < 0.05) already in normal‐looking parenchyma. The expression of Wnt3a and ICAT decreased (both P < 0.01) in IPF compared to healthy lungs, whereas β‐catenin, Wnt5a/b, DAAM1 and NLK increased (P < 0.05 for all). ICAT is further decreased in dense fibrosis compared to normal‐looking parenchyma in IPF (P < 0.001). On the basis of our results, we conclude that from a Wnt perspective, there is no normal parenchyma in IPF, and Wnt signaling corresponds to degree of fibrosis. In addition, β‐catenin and Wnt5a appears coupled, and decreased inhibition of β‐catenin may be involved. We suggest that the interaction between β‐catenin, ICAT, and Wnt5a/b may represent an important research area and potential target for therapeutic intervention.

Wnt5a Signaling in Cancer

Wnt5a is involved in activating several non-canonical WNT signaling pathways, through binding to different members of the Frizzled- and Ror-family receptors. Wnt5a signaling is critical for regulating normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a in regulating cancer cell invasion, metastasis, metabolism and inflammation. In this article, we review findings regarding the molecular mechanisms and roles of Wnt5a signaling in various cancer types, and highlight Wnt5a in ovarian cancer.

Analysis of the expression of the Wnt family of proteins and its modulatory role on cytokine expression in non activated and activated astroglial cells

Despite the essential functions of astrocytes and the emerging relevance of the Wnt family of proteins in the CNS under physiological and pathological conditions, the astroglial expression of this family of proteins and its potential modulatory role on astroglial activation is almost unknown. Thus, we have evaluated the expression of all Wnt ligands, receptors and regulators, and the activation state of Wnt-related signaling pathways in non-activated and differentially activated astroglial cultures. We found that numerous Wnt ligands, receptors and regulators were expressed in non-activated astrocytes, while the Wnt-dependent pathways were constitutively active. Moreover, the expression of most detectable Wnt-related molecules and the activity of the Wnt-dependent pathways suffered post-activation variations which frequently depended on the activation system. Finally, the analysis of the effects exerted by Wnt1 and 5a on the astroglial expression of prototypical genes related to astroglial activation showed that both Wnt ligands increased the astroglial expression of interleukin 1β depending on the experimental context, while did not modulate tumor necrosis factor α, interleukin 6, transforming growth factor β1 and glial fibrillary acidic protein expression. These results strongly suggest that the Wnt family of proteins is involved in how astrocytes modulate and respond to the physiological and pathological CNS.

Cooperative signaling by TGF-β1 and WNT-11 drives sm-α-actin expression in smooth muscle via Rho kinase-actin-MRTF-A signaling

Airway smooth muscle (ASM) remodeling is a key feature in asthma and includes changes in smooth muscle-specific gene and protein expression. Despite this being a major contributor to asthma pathobiology, our understanding of the mechanisms governing ASM remodeling remains poor. Here, we studied the functional interaction between WNT-11 and TGF-β1 in ASM cells. We demonstrate that WNT-11 is preferentially expressed in contractile myocytes and is strongly upregulated following TGF-β1-induced myocyte maturation. Knock-down of WNT-11 attenuated TGF-β1-induced smooth muscle (sm)-α-actin expression in ASM cells. We demonstrate that TGF-β1-induced sm-α-actin expression is mediated by WNT-11 via RhoA activation and subsequent actin cytoskeletal remodeling, as pharmacological inhibition of either Rho kinase by Y27632 or actin remodeling by latrunculin A attenuated sm-α-actin induction. Moreover, we show that TGF-β1 regulates the nuclear expression of myocardin-related transcription factor-A (MRTF-A) in a Rho kinase-dependent fashion, which in turn mediates sm-α-actin expression. Finally, we demonstrate that TGF-β1-induced MRTF-A nuclear translocation is dependent on endogenous WNT-11. The present study thus demonstrates a WNT-11-dependent Rho kinase-actin-MRTF-A signaling axis that regulates the expression of sm-α-actin in ASM cells.

Hyaluronic acid enhances proliferation of human amniotic mesenchymal stem cells through activation of Wnt/β-catenin signaling pathway

This study investigated the pro-proliferative effect of hyaluronic acid (HA) on human amniotic mesenchymal stem cells (hAMSCs) and the underlying mechanisms. Treatment with HA increased cell population growth in a dose- and time-dependent manner. Analyses by flow cytometry and immunocytochemistry revealed that HA did not change the cytophenotypes of hAMSCs. Additionally, the osteogenic, chondrogenic, and adipogenic differentiation capabilities of these hAMSCs were retained after HA treatment. Moreover, HA increased the mRNA expressions of wnt1, wnt3a, wnt8a, cyclin D1, Ki-67, and β-catenin as well as the protein level of β-catenin and cyclin D1 in hAMSCs; and the nuclear localization of β-catenin was also enhanced. Furthermore, the pro-proliferative effect of HA and up-regulated expression of Wnt/β-catenin pathway-associated proteins - wnt3a, β-catenin and cyclin D1 in hAMSCs were significantly inhibited upon pre-treatment with Wnt-C59, an inhibitor of the Wnt/β-catenin pathway. These results suggest that HA may positively regulate hAMSCs proliferation through regulation of the Wnt/β-catenin signaling pathway.

Eosinophils enhance WNT-5a and TGF-β1 genes expression in airway smooth muscle cells and promote their proliferation by increased extracellular matrix proteins production in asthma

Background

Recent studies have suggested that eosinophils may have a direct effect on airway smooth muscle cells (ASMC), causing their proliferation in patients with asthma, but the precise mechanism of the interaction between these cells remains unknown. We propose that changes in Wnt signaling activity and extracellular matrix (ECM) production may help explain these findings. Therefore, the aim of this study was to investigate the effect of eosinophils from asthmatic and non-asthmatic subjects on Wnt-5a, transforming growth factor β₁ (TGF-β₁), and ECM protein (fibronectin and collagen) gene expression and ASMC proliferation.

Methods

A total of 18 subjects were involved in the study: 8 steroid-free asthma patients and 10 healthy subjects. Peripheral blood eosinophils were isolated using centrifugation and magnetic separation. An individual co-culture of eosinophils with human ASMC was prepared for each study subject. Adhesion of eosinophils to ASMC (evaluated by assaying eosinophil peroxidase activity) was determined following various incubation periods (30, 45, 60, 120, and 240 min). The expression of Wnt-5a, TGF-β₁, and ECM protein genes in ASMC was measured using quantitative real-time polymerase chain reaction (PCR) after 24 h of co-culture. Proliferation of ASMC was measured using the Alamar blue method after 48 h and 72 h of co-culture with eosinophils.

Results

Eosinophils from asthmatic subjects demonstrated increased adhesion to ASMC compared with eosinophils from healthy subjects (p < 0.05) in vitro. The expression of Wnt-5a, TGF-β₁, collagen, and fibronectin genes in ASMC was significantly higher after 24 h of co-culture with eosinophils from asthmatic subjects, while co-culture of ASMC with eosinophils from healthy subjects increased only TGF-β₁ and fibronectin gene expression. ASMC proliferation was augmented after co-culture with eosinophils from asthma patients compared with co-culture with eosinophils from healthy subjects (p < 0.05).

Conclusions

Eosinophils enhance Wnt-5a, TGF-β₁, fibronectin, and collagen gene expression in ASMC and promote proliferation of these cells in asthma.

Trial registration

ClinicalTrials.gov Identifier: NCT02648074.

MiR-3162-3p Is a Novel MicroRNA That Exacerbates Asthma by Regulating β-Catenin

Asthma is a common chronic respiratory disease. In a previous study, we found several circulating microRNA signatures associated with childhood asthma and selected miR-3162-3p for subsequent studies. Since the target proteins and underlying molecular mechanisms of miR-3162-3p in asthma etiopathogenesis are not well characterized, we designed this study to clarify its role. We employed bioinformatics and quantitative PCR methods as a first step to determine the target of miR-3162-3p, and we elucidated β-catenin. Luciferase assays and western blot analysis confirmed β-catenin as a direct target of miR-3162-3p as the 3'-untranslated region of β-catenin mRNA possesses a specific miR-3162-3p pairing site. The correlation between the expression levels of miR-3162-3p and β-catenin is confirmed by quantitative PCR and western blot studies in A549, Beas-2B and H1299 cell lines and OVA-induced asthma mouse model. Of note, upregulation of the endogenous miR-3162-3p level is concomitant with the reduction of β-catenin mRNA and protein expression levels. MiR-3162-3p antagomir treatment antagonizes the endogenous miR-3162-3p and effectively rescues the attenuation of endogenous β-catenin in OVA-induced asthmatic mice, which alleviates airway hyperresponsiveness and ameliorates airway inflammation. Collectively, our findings suggest a novel relationship between miR-3162-3p and β-catenin and clarify their mechanistic role in asthma etiopathogenesis.

TGF-β-induced profibrotic signaling is regulated in part by the WNT receptor Frizzled-8

TGF-β is important in lung injury and remodeling processes. TGF-β and Wingless/integrase-1 (WNT) signaling are interconnected; however, the WNT ligand-receptor complexes involved are unknown. Thus, we aimed to identify Frizzled (FZD) receptors that mediate TGF-β-induced profibrotic signaling. MRC-5 and primary human lung fibroblasts were stimulated with TGF-β1, WNT-5A, or WNT-5B in the presence and absence of specific pathway inhibitors. Specific small interfering RNA was used to knock down FZD8. In vivo studies using bleomycin-induced lung fibrosis were performed in wild-type and FZD8-deficient mice. TGF-β1 induced FZD8 specifically via Smad3-dependent signaling in MRC-5 and primary human lung fibroblasts. It is noteworthy that FZD8 knockdown reduced TGF-β1-induced collagen Iα1, fibronectin, versican, α-smooth muscle (sm)-actin, and connective tissue growth factor. Moreover, bleomycin-induced lung fibrosis was attenuated in FZD8-deficient mice in vivo Although inhibition of canonical WNT signaling did not affect TGF-β1-induced gene expression in vitro, noncanonical WNT-5B mimicked TGF-β1-induced fibroblast activation. FZD8 knockdown reduced both WNT-5B-induced gene expression of fibronectin and α-sm-actin, as well as WNT-5B-induced changes in cellular impedance. Collectively, our findings demonstrate a role for FZD8 in TGF-β-induced profibrotic signaling and imply that WNT-5B may be the ligand for FZD8 in these responses.-Spanjer, A. I. R., Baarsma, H. A., Oostenbrink, L. M., Jansen, S. R., Kuipers, C. C., Lindner, M., Postma, D. S., Meurs, H., Heijink, I. H., Gosens, R., Königshoff, M. TGF-β-induced profibrotic signaling is regulated in part by the WNT receptor Frizzled-8.

Wnt signaling pathway in cardiac fibrosis: New insights and directions

OBJECTIVE

Wnt signaling pathway significantly participates in cardiac fibrosis and CFs activation. Therefore, we reviewed current evidence on the new perspectives and biological association between Wnt signaling pathway and cardiac fibrosis.

DESIGN AND METHODS

A PubMed database search was performed for studies of Wnt signaling pathway in cardiac fibrosis and CFs activation.

RESULTS

Numerous studies have shown that the Wnt signaling pathway significantly participates in cardiac fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the Wnt signaling pathway significantly participating in cardiac fibrosis and CFs activation, and look ahead on new perspectives of Wnt signaling pathway research. Moreover, we will discuss the different insights that interact with the Wnt signaling pathway-regulated cardiac fibrosis. The Wnt proteins are glycoproteins that bind to the Fz receptors on the cell surface, which lead to several important biological functions, such as cell differentiation and proliferation. There are several signals among the characterized pathways of cardiac fibrosis, including Wnt/β-catenin signaling. In this review, new insight into the Wnt signaling pathway in cardiac fibrosis pathogenesis is discussed, with special emphasis on Wnt/β-catenin.

CONCLUSION

It seems reasonable to suggest the potential targets of Wnt signaling pathway and it can be developed as a therapeutic target for cardiac fibrosis.

ROS-induced endothelial stress contributes to pulmonary fibrosis through pericytes and Wnt signaling

Pulmonary fibrosis is a grave diagnosis with insidious progression, generally considered as a consequence of aberrant epithelial wound healing and excessive scarring. This process is commonly modeled in animals by local bleomycin administration, resulting in peribronchial inflammation and subsequent fibrosis. We have previously described initiation and early development of distal pulmonary fibrosis following repeated subcutaneous bleomycin injections (systemic administration). The aim of this study was to identify mechanisms for the development of pulmonary fibrosis, which we hypothesize is related to endothelial stress and activation. Bleomycin was administered subcutaneously 3 times/week during 0.33-4w, and parenchymal alterations were studied. In addition, we used microvascular endothelial cells to investigate effects of bleomycin in vitro. Our results confirmed that systemic administration of bleomycin exerts oxidative stress indicated by an increase in Sod1 at 0.33, 1, and 4w (P<0.05). Endothelial cells were activated (increased CD106 expression) from 1w and onwards (P<0.05), and p21 expression was increased 2-3 times throughout the study (P<0.05) as were the number of β-catenin-positive nuclei (P<0.001). Wnt3a was increased at 0.33, 1, and 4w (P<0.01) and Wnt5a from 1w and onwards (P<0.001). The present study suggests that bleomycin-induced reactive oxygen species (ROS) causes DNA stress affecting the endothelial niche, initiating repair processes including Wnt signaling. The repeated systemic administrations disrupt a normally fine-tuned balance in the Wnt signaling. In addition, pericyte differentiation was affected, which may have significant effects on fibrosis due to their ability to differentiate into myofibroblasts. We conclude that the endothelial niche may have an important role in the development of pulmonary fibrosis and warrants further investigations.

WNT-5A: signaling and functions in health and disease

WNT-5A plays critical roles in a myriad of processes from embryonic morphogenesis to the maintenance of post-natal homeostasis. WNT-5A knock-out mice fail to survive and present extensive structural malformations. WNT-5A predominantly activates β-catenin-independent WNT signaling cascade but can also activate β-catenin signaling to relay its diverse cellular effects such as cell polarity, migration, proliferation, cell survival, and immunomodulation. Moreover, aberrant WNT-5A signaling is associated with several human pathologies such as cancer, fibrosis, and inflammation. Thus, owing to its diverse functions, WNT-5A is a crucial signaling molecule currently under intense investigation with efforts to not only delineate its signaling mechanisms and functions in physiological and pathological conditions, but also to develop strategies for its therapeutic targeting.

A pro-inflammatory role for the Frizzled-8 receptor in chronic bronchitis

RATIONALE

We have previously shown increased expression of the Frizzled-8 receptor of the Wingless/integrase-1 (WNT) signalling pathway in COPD. Here, we investigated if the Frizzled-8 receptor has a functional role in airway inflammation associated with chronic bronchitis.

METHODS

Acute cigarette-smoke-induced airway inflammation was studied in wild-type and Frizzled-8-deficient mice. Genetic association studies and lung expression quantitative trait loci (eQTL) analyses for Frizzled-8 were performed to evaluate polymorphisms in FZD8 and their relationship to tissue expression in chronic bronchitis. Primary human lung fibroblasts and primary human airway epithelial cells were used for in vitro studies.

RESULTS

Cigarette-smoke-exposure induced airway inflammation in wild-type mice, which was prevented in Frizzled-8-deficient mice, suggesting a crucial role for Frizzled-8 in airway inflammation. Furthermore, we found a significant genetic association (p=0.009) between single nucleotide polymorphism (SNP) rs663700 in the FZD8 region and chronic mucus hypersecretion, a characteristic of chronic bronchitis, in a large cohort of smoking individuals. We found SNP rs663700 to be a cis-eQTL regulating Frizzled-8 expression in lung tissue. Functional data link mesenchymal Frizzled-8 expression to inflammation as its expression in COPD-derived lung fibroblasts was regulated by pro-inflammatory cytokines in a genotype-dependent manner. Moreover, Frizzled-8 regulates inflammatory cytokine secretion from human lung fibroblasts, which in turn promoted MUC5AC expression by differentiated human airway epithelium.

CONCLUSIONS

These findings indicate an important pro-inflammatory role for Frizzled-8 and suggest that its expression is related to chronic bronchitis. Furthermore, our findings indicate an unexpected role for fibroblasts in regulating airway inflammation in COPD.

Molecular targets for the treatment of pancreatic cancer: Clinical and experimental studies

Pancreatic cancer is the fourth most common cause of cancer deaths worldwide. Although recent therapeutic developments for patients with pancreatic cancer have provided survival benefits, the outcomes for patients with pancreatic cancer remain unsatisfactory. Molecularly targeted cancer therapy has advanced in the past decade with the use of a number of pathways as candidates of therapeutic targets. This review summarizes the molecular features of this refractory disease while focusing on the recent clinical and experimental findings on pancreatic cancer. It also discusses the data supporting current standard clinical outcomes, and offers conclusions that may improve the management of pancreatic cancer in the future.