Beyond Wnt inhibition: new functions of secreted Frizzled-related proteins in development and disease

Secreted frizzled-related protein 2 prevents pressure-overload-induced cardiac hypertrophy by targeting the Wnt/β-catenin pathway

BACKGROUND AND AIM

Secreted frizzled-related protein 2 (sFRP2) has been reported to be involved in cardiovascular diseases. However, its role in cardiac hypertrophy induced by pressure overload is still elusive. We aimed to examine the role of sFRP2 in the development of cardiac hypertrophy in vivo and in vitro.

METHODS AND RESULTS

Following cardiac hypertrophy stimulated by aortic banding (AB), the expression of sFRP2 was downregulated in the hypertrophic ventricle. Adeno-associated virus 9 (AAV9) was injected through the tail vein to overexpress sFRP2 in the mouse myocardium. Overexpression of sFRP2 alleviated cardiomyocyte hypertrophy and interstitial fibrosis, as identified by the reduced cardiomyocyte cross-sectional area, heart weight/body weight ratio, and left ventricular (LV) collagen ratio. Additionally, sFRP2 decreased cardiomyocyte apoptosis induced by pressure overload. Western blot showed that sFRP2 prevented the expression of active β-catenin. The Wnt/β-catenin agonist LiCl (1 mmol/kg) abolished the inhibitory effects of sFRP2 on cardiac hypertrophy and apoptosis, as evidenced by the increased cross-sectional area and LV collagen ratio and the deterioration of echocardiographic data.

CONCLUSION

Our study indicated that decreased sFRP2 levels were observed in failing mouse hearts. Overexpression of sFRP2 attenuated myocyte hypertrophy and interstitial fibrosis induced by hypertrophic stimuli by inhibiting the Wnt/β-catenin pathway. We revealed that sFRP2 may be a promising therapeutic target for the development of cardiac remodeling.

Wnt Signaling in Leukemia and Its Bone Marrow Microenvironment

Leukemia is an aggressive hematologic neoplastic disease. Therapy-resistant leukemic stem cells (LSCs) may contribute to the relapse of the disease. LSCs are thought to be protected in the leukemia microenvironment, mainly consisting of mesenchymal stem/stromal cells (MSC), endothelial cells, and osteoblasts. Canonical and noncanonical Wnt pathways play a critical role in the maintenance of normal hematopoietic stem cells (HSC) and LSCs. In this review, we summarize recent findings on the role of Wnt signaling in leukemia and its microenvironment and provide information on the currently available strategies for targeting Wnt signaling.

Heparan Sulfate Proteoglycan Clustering in Wnt Signaling and Dispersal

Wnt, a family of secreted signal proteins, serves diverse functions in animal development, stem cell systems, and carcinogenesis. Although Wnt is generally considered a morphogen, the mechanism by which Wnt ligands disperse is still debated. Heparan sulfate proteoglycans (HSPGs) are extracellular regulators involved in Wnt ligand dispersal. Drosophila genetics have revealed that HSPGs participate in accumulation and transport of Wnt ligands. Based on these findings, a "restricted diffusion" model, in which Wnt ligands are gradually transferred by repetitive binding and dissociation to HSPGs, has been proposed. Nonetheless, we recently found that HSPGs are not uniformly distributed, but are locally clustered on cell surfaces in Xenopus embryos. HSPGs with N-sulfo-rich HS chains and those with N-acetyl-rich unmodified HS chains form different clusters. Furthermore, endogenous Wnt8 ligands are discretely accumulated in a punctate fashion, colocalized with the N-sulfo-rich clusters. Based on these lines of evidence, here we reconsider the classical view of morphogen spreading controlled by HSPGs.

SFRP5 inhibits melanin synthesis of melanocytes in vitiligo by suppressing the Wnt/β-catenin signaling

Secreted frizzled-related protein 5 (SFRP5) plays a pivotal role in regulating the development of many tissues and organs, however, as an inhibitor of Wnt signaling, the role of SFRP5 in vitiligo remains unknown. Hence, we speculated that SFRP5 might be associated with melanogenesis in melanocytes by regulating Wnt signaling in vitiligo. In this study, we found that SFRP5 was overexpressed in the skin lesions of patients with vitiligo. Compared with that in normal epidermal melanocytes (PIG1), the expression of SFRP5 was increased in vitiligo melanocytes (PIG3V). To investigate the effect of SFRP5 on melanin synthesis, PIG1 cells were infected with recombinant SFRP5 adenovirus (AdSFRP5), and PIG3V cells were infected with recombinant siSFRP5 adenovirus (AdsiSFRP5). The results showed that SFRP5 overexpression inhibited melanin synthesis in PIG1 cells through downregulation of microphthalmia-associated transcription factor (MITF) and its target proteins via suppression of the Wnt/β-catenin signaling pathway. Accordingly, SFRP5 silencing increased melanin synthesis and activated the Wnt signaling pathway in PIG3V cells. Moreover, SFRP5 overexpression also downregulated the transcriptional activity of T cell factor/lymphoid enhancer factor (TCF/LEF) in PIG1 cells. Furthermore, this inhibitory effect of SFRP5 on melanin synthesis was reversed by treatment with the β-catenin agonist, SKL2001. The inhibitory action of SFRP5 in pigmentation was further confirmed in vivo using a nude mouse model. Hence, our results indicate that SFRP5 can inhibit melanogenesis in melanocytes. Additionally, our findings showed that SFRP5 plays a vital role in the development of vitiligo, and thus may serve as a potential therapeutic target for vitiligo.

Association between variation of circulating 25-OH vitamin D and methylation of secreted frizzled-related protein 2 in colorectal cancer

BACKGROUNDS

Colorectal cancer (CRC) results from the accumulation of epigenetic and genetic changes in colon cells during neoplasic transformation, which the activation of Wingless (Wnt) signaling pathway is a common mechanism for CRC initiation. The Wnt pathway is mainly regulated by Wnt antagonists, as secreted frizzled-related protein (SFRP) family. Indeed, SFRP2 is proposed as a noninvasive biomarker for CRC diagnosis. Vitamin D also antagonizes Wnt signaling in colon cancers cells. Several studies showed that vitamin D was able to alter DNA methylation, although this mechanism is not yet clear. Therefore, the aim of this study was to find an association between circulating 25-OH vitamin D (30th percentile of vitamin D) and the SFRP2 methylation.

METHODS

A total of 67 CRC patients were included in the study. These patients were subdivided into two groups based on their 30th percentile vitamin D (20 patients were below, and 47 participants were above the 30th percentile of vitamin D). We investigated the SFRP2 methylation in peripheral blood mononuclear cells (PBMCs), visceral adipose tissue (VAT), CRC tumor tissue, and adjacent tumor-free area. We also determined the relationship between SFRP2 methylation and methylation of carcinogenic and adipogenic genes. Finally, we tested the effect of vitamin D on the SFRP2 methylation in human colorectal carcinoma cell lines 116 (HCT116) and studied the association of neoadjuvant therapy under the 30th percentile vitamin D with SFRP2 promoter methylation.

RESULTS

SFRP2 methylation in tumor area was decreased in patients who had higher levels of vitamin D. SFRP2 promoter methylation was positively correlated in tumor area with insulin and homeostasis model assessment of insulin resistance (HOMA-IR) but negatively correlated with HDL-c. SFRP2 methylation was also correlated with T cell lymphoma invasion and metastasis 1 (TIAM1) methylation in tumor area and CCAAT/enhancer-binding protein alpha (C/EBPα) in VAT. Treatment with vitamin D did not affect SFRP2 methylation in HCT116 cell line. Finally, neoadjuvant treatment was correlated with higher circulating 25-OH vitamin D and SFRP2 methylation under linear regression model.

CONCLUSION

Our results showed that higher circulating vitamin D is associated with low SFRP2 promoter methylation. Therefore, our results could suggest that vitamin D may have an epigenetic effect on DNA methylation. Finally, higher vitamin D could contribute to an improvement response to neoadjuvant treatment.

RNA-seq reveals downregulated osteochondral genes potentially related to tibia bacterial chondronecrosis with osteomyelitis in broilers

Background

Bacterial chondronecrosis with osteomyelitis (BCO) develops in the growth plate (GP) of the proximal femur and tibia and is initiated by damage to the less mineralized chondrocytes followed by colonization of opportunistic bacteria. This condition affects approximately 1% of all birds housed, being considered one of the major causes of lameness in fast growing broilers. Although several studies have been previously performed aiming to understand its pathogenesis, the molecular mechanisms involved with BCO remains to be elucidated. Therefore, this study aimed to generate a profile of global differential gene expression involved with BCO in the tibia of commercial broilers, through RNA sequencing analysis to identity genes and molecular pathways involved with BCO in chickens.

Results

Our data showed 192 differentially expressed (DE) genes: 63 upregulated and 129 downregulated in the GP of the tibia proximal epiphysis of BCO-affected broilers. Using all DE genes, six Biological Processes (BP) were associated with bone development (connective tissue development, cartilage development, skeletal system development, organ morphogenesis, system development and skeletal system morphogenesis). The analyses of the upregulated genes did not indicate any significant BP (FDR < 0.05). However, with the downregulated genes, the same BP were identified when using all DE genes in the analysis, with a total of 26 coding genes explaining BCO in the tibia: ACAN, ALDH1A2, CDH7, CHAD, CHADL, COL11A1, COMP, CSGALNACT1, CYR61, FRZB, GAL3ST1, HAPLN1, IHH, KIF26B, LECT1, LPPR1, PDE6B, RBP4A, SERINC5, SFRP1, SOX8, SOX9, TENM2, THBS1, UCHL1 and WFIKKN2. In addition, seven transcription factors were also associated to BCO: NFATC2, MAFB, HIF1A-ARNT, EWSR1-FLI1, NFIC, TCF3 and NF-KAPPAB.

Conclusions

Our data show that osteochondral downregulated genes are potential molecular causes of BCO in broilers, and the bacterial process seems to be, in fact, a secondary condition. Sixteen genes responsible for bone and cartilage formation were downregulated in BCO-affected broilers being strong candidate genes to trigger this disorder.

Sfrp1 Modulates Cell-signaling Events Underlying Telencephalic Patterning, Growth and Differentiation

The mammalian dorsal telencephalic neuroepithelium develops-from medial to lateral-into the choroid plaque, cortical hem, hippocampal primordium and isocortex under the influence of Bmp, Wnt and Notch signaling. Correct telencephalic development requires a tight coordination of the extent/duration of these signals, but the identification of possible molecular coordinators is still limited. Here, we postulated that Secreted Frizzled Related Protein 1 (Sfrp1), a multifunctional regulator of Bmp, Wnt and Notch signaling strongly expressed during early telencephalic development, may represent 1 of such molecules. We report that in E10.5-E12.5 Sfrp1-/- embryos, the hem and hippocampal domains are reduced in size whereas the prospective neocortex is medially extended. These changes are associated with a significant reduction of the medio-lateral telencephalic expression of Axin2, a read-out of Wnt/βcatenin signaling activation. Furthermore, in the absence of Sfrp1, Notch signaling is increased, cortical progenitor cell cycle is shorter, with expanded progenitor pools and enhanced generation of early-born neurons. Hence, in postnatal Sfrp1-/- animals the anterior hippocampus is reduced and the neocortex is shorter in the antero-posterior and medio-lateral axis but is thicker. We propose that, by controlling Wnt and Notch signaling in opposite directions, Sfrp1 promotes hippocampal patterning and balances medio-lateral and antero-posterior cortex expansion.

Norepinephrine-stimulated HSCs secrete sFRP1 to promote HCC progression following chronic stress via augmentation of a Wnt16B/β-catenin positive feedback loop

Background

Sustained adrenergic signaling secondary to chronic stress promotes cancer progression; however, the underlying mechanisms for this phenomenon remain unclear. Hepatocellular carcinoma (HCC) frequently develops within fibrotic livers rich in activated hepatic stellate cells (HSCs). Here, we examined whether the stress hormone norepinephrine (NE) could accelerate HCC progression by modulating HSCs activities.

Methods

HCC cells were exposed to conditioned medium (CM) from NE-stimulated HSCs. The changes in cell migration and invasion, epithelial-mesenchymal transition, parameters of cell proliferation, and levels of cancer stem cell markers were analyzed. Moreover, the in vivo tumor progression of HCC cells inoculated with HSCs was studied in nude mice subjected to chronic restraint stress.

Results

CM from NE-treated HSCs significantly promoted cell migration and invasion, epithelial-mesenchymal transition (EMT), and expression of cell proliferation-related genes and cancer stem cell markers in HCC cells. These pro-tumoral effects were markedly reduced by depleting secreted frizzled related protein 1 (sFRP1) in CM. The pro-tumoral functions of sFRP1 were dependent on β-catenin activation, and sFRP1 augmented the binding of Wnt16B to its receptor FZD7, resulting in enhanced β-catenin activity. Additionally, sFRP1 enhanced Wnt16B expression, reinforcing an autocrine feedback loop of Wnt16B/β-catenin signaling. The expression of sFRP1 in HSCs promoted HCC progression in an in vivo model under chronic restraint stress, which was largely attenuated by sFRP1 knockdown.

Conclusions

We identify a new mechanism by which chronic stress promotes HCC progression. In this model, NE activates HSCs to secrete sFRP1, which cooperates with a Wnt16B/β-catenin positive feedback loop. Our findings have therapeutic implications for the treatment of chronic stress-promoted HCC progression.

Review Article: Is Wnt Signaling an Attractive Target for the Treatment of Osteoarthritis?

Osteoarthritis is the most common chronic joint disease affecting millions of people worldwide and a leading cause of pain and disability. Increasing incidence of obesity and aging of the population are two factors that suggest that the impact of osteoarthritis will further increase at the society level. Currently, there are no drugs available that can manage both structural damage to the joint or the associated pain. Increasing evidence supports the view that the Wnt signaling pathway plays an important role in this disease. The current concept, based on genetic and functional studies, indicates that tight regulation of Wnt signaling in cartilage is essential to keep the joint healthy. In this review, we discuss how this concept has evolved, provide insights into the regulation of Wnt signaling, in particular by Wnt modulators such as frizzled-related protein and DOT1-like histone lysine methyltransferase, and summarize preclinical evidence and molecular mechanisms of lorecivivint, the first Wnt antagonist in clinical development for osteoarthritis.

Wnt signalling pathway and tau phosphorylation: A comprehensive study on known connections

The Wnt pathway is the most important cascade in the nervous system; evidence has indicated that deregulation of the Wnt pathway induced pathogenic hallmarks of neurodegenerative diseases. Glycogen synthase kinase-3β (GSK-3β) as the main member of the Wnt pathway increases tau inclusions, the main marker in the neurodegenerative diseases. Phosphorylated tau is observed in the pre-tangle of the neurons in the early stage of neurodegenerative diseases. The researchers always try to improve pharmacological approaches of new therapeutic strategies to the treatment of neurodegenerative diseases that are required to represent a significant entry point by understanding the theoretical interactions of the molecular pathways. In this review, we have discussed the recent knowledge about the canonical and non-canonical Wnt signalling pathway, GSK-3β, Wnt/β-catenin antagonists, tau phosphorylation, and their important roles in the neurodegenerative diseases.

Sfrp1 deficiency makes retinal photoreceptors prone to degeneration

Millions of individuals worldwide suffer from impaired vision, a condition with multiple origins that often impinge upon the light sensing cells of the retina, the photoreceptors, affecting their integrity. The molecular components contributing to this integrity are however not yet fully understood. Here we have asked whether Secreted Frizzled Related Protein 1 (SFRP1) may be one of such factors. SFRP1 has a context-dependent function as modulator of Wnt signalling or of the proteolytic activity of A Disintegrin And Metalloproteases (ADAM) 10, a main regulator of neural cell-cell communication. We report that in Sfrp1^−/− mice, the outer limiting membrane (OLM) is discontinuous and the photoreceptors disorganized and more prone to light-induced damage. Sfrp1 loss significantly enhances the effect of the Rpe65^Leu450Leu genetic variant -present in the mouse genetic background- which confers sensitivity to light-induced stress. These alterations worsen with age, affect visual function and are associated to an increased proteolysis of Protocadherin 21 (PCDH21), localized at the photoreceptor outer segment, and N-cadherin, an OLM component. We thus propose that SFRP1 contributes to photoreceptor fitness with a mechanism that involves the maintenance of OLM integrity. These conclusions are discussed in view of the broader implication of SFRP1 in neurodegeneration and aging.

Crosstalk with lung epithelial cells regulates Sfrp2-mediated latency in breast cancer dissemination

The process of metastasis is complex1. In breast cancer, there are frequently long time intervals between cells leaving the primary tumour and growth of overt metastases2,3. Reasons for disease indolence and subsequent transition back to aggressive growth include interactions with myeloid and fibroblastic cells in the tumour microenvironment and ongoing immune surveillance4-6. However, the signals that cause actively growing cells to enter an indolent state, thereby enabling them to survive for extended periods of time, are not well understood. Here we reveal how the behaviour of indolent breast cancer cells in the lung is determined by their interactions with alveolar epithelial cells, in particular alveolar type 1 cells. This promotes the formation of fibronectin fibrils by indolent cells that drive integrin-dependent pro-survival signals. Combined in vivo RNA sequencing and drop-out screening identified secreted frizzled-related protein 2 (SFRP2) as a key mediator of this interaction. Sfrp2 is induced in breast cancer cells by signals from lung epithelial cells and promotes fibronectin fibril formation and survival, whereas blockade of Sfrp2 expression reduces the burden of indolent disease.

Phagocytosis of Wnt inhibitor SFRP4 by late wound macrophages drives chronic Wnt activity for fibrotic skin healing

Human and murine skin wounding commonly results in fibrotic scarring, but the murine wounding model wound-induced hair neogenesis (WIHN) can frequently result in a regenerative repair response. Here, we show in single-cell RNA sequencing comparisons of semi-regenerative and fibrotic WIHN wounds, increased expression of phagocytic/lysosomal genes in macrophages associated with predominance of fibrotic myofibroblasts in fibrotic wounds. Investigation revealed that macrophages in the late wound drive fibrosis by phagocytizing dermal Wnt inhibitor SFRP4 to establish persistent Wnt activity. In accordance, phagocytosis abrogation resulted in transient Wnt activity and a more regenerative healing. Phagocytosis of SFRP4 was integrin-mediated and dependent on the interaction of SFRP4 with the EDA splice variant of fibronectin. In the human skin condition hidradenitis suppurativa, phagocytosis of SFRP4 by macrophages correlated with fibrotic wound repair. These results reveal that macrophages can modulate a key signaling pathway via phagocytosis to alter the skin wound healing fate.

Epigenetics of SFRP1: The Dual Roles in Human Cancers

Secreted frizzled-related protein 1 (SFRP1) is a gene that belongs to the secreted glycoprotein SFRP family. SFRP1 has been classified as a tumor suppressor gene due to the loss of expression in various human cancers, which is mainly attributed by epigenetic inactivation via DNA methylation or transcriptional silencing by microRNAs. Epigenetic silencing of SFRP1 may cause dysregulation of cell proliferation, migration, and invasion, which lead to cancer cells formation, disease progression, poor prognosis, and treatment resistance. Hence, restoration of SFRP1 expression via demethylating drugs or over-expression experiments opens the possibility for new cancer therapy approach. While the role of SFRP1 as a tumor suppressor gene is well-established, some studies also reported the possible oncogenic properties of SFRP1 in cancers. In this review, we discussed in great detail the dual roles of SFRP1 in cancers-as tumor suppressor and tumor promoter. The epigenetic regulation of SFRP1 expression will also be underscored with additional emphasis on the potentials of SFRP1 in modulating responses toward chemotherapeutic and epigenetic-modifying drugs, which may encourage the development of novel drugs for cancer treatment. We also present findings from clinical trials and patents involving SFRP1 to illustrate its clinical utility, extensiveness of each research area, and progression toward commercialization. Lastly, this review provides directions for future research to advance SFRP1 as a promising cancer biomarker.

Multiple Roles of sFRP2 in Cardiac Development and Cardiovascular Disease

The Wnt signaling pathway plays important roles in organ development and disease processes. Secreted frizzled-related protein 2 (sFRP2), a vital molecule of Wnt signaling, can regulate cardiac development and cardiovascular disease. Recent studies have suggested that sFRP2 is not only an antagonist of the canonical Wnt signaling pathway, but also has a more complex relationship in myocardial fibrosis, angiogenesis, cardiac hypertrophy and cardiac regeneration. Here, we review the role of sFRP2 and Wnt signaling in cardiac development and cardiovascular disease.

IGF-1 enhances BMSC viability, migration, and anti-apoptosis in myocardial infarction via secreted frizzled-related protein 2 pathway

BACKGROUND

Bone marrow mesenchymal stem cell (BMSC) transplantation represents a promising therapeutic strategy for ischemic heart disease. However, its effects are hampered by the poor viability of transplanted cells and the hostile microenvironment of the ischemic region. Insulin-like growth factor-1 (IGF-1) is an important paracrine growth factor of BMSC and plays an important role in the properties of BMSC. Here, we investigated whether overexpressing IGF-1 could enhance the BMSC viability, migration, anti-apoptosis, and protective effects of cardiomyocytes, and explore the underlying mechanisms' focus on the role of the AKT/secreted frizzled-related protein 2 (SFRP2)/β-catenin pathway.

METHODS

We constructed BMSCs overexpressing insulin-like growth factor-1 (BMSCs-IGF-1) or empty vector (BMSCs-NC) using lentivirus, and evaluated cell survival, proliferation, and migration under normoxic and hypoxic conditions. Co-culture of rat cardiomyoblasts with BMSCs was performed to explore the paracrine effect of BMSCs-IGF-1 for rescuing cardiomyoblasts under hypoxia. Transplantation of BMSCs in acute myocardial infarction rats was used to explore the effect of BMSCs-IGF-1 therapy.

RESULTS

BMSCs-IGF-1 exhibited a higher cell proliferation rate, migration capacity, and stemness, and were more resistant to apoptosis under hypoxia. Overexpression of IGF-1 upregulated the expression of total and nuclear β-catenin via the AKT-secreted frizzled-related protein 2 (SFRP2) pathway, which enhanced cell survival. Inhibition of AKT or SFRP2 knockdown by siRNA significantly antagonized the effect of IGF-1 and decreased the expression of β-catenin. The expression of β-catenin target genes, including cyclin D1 and c-Myc, were accordingly decreased. Moreover, BMSCs-IGF-1 could rescue cardiomyoblasts from hypoxia-induced apoptosis and preserve cell viability under hypoxia. Transplantation of BMSCs-IGF-1 into myocardial infarction rats greatly reduced infarct volume than BMSCs-NC, with significantly greater expression of SFRP2 and β-catenin.

CONCLUSIONS

These results suggest that in BMSCs overexpressing IGF-1, SFRP2 is an important mediator for the enhancement of stem cell viability via activating, rather than antagonizing, the Wnt/β-catenin pathway.

PRC1 promotes GLI1-dependent osteopontin expression in association with the Wnt/β-catenin signaling pathway and aggravates liver fibrosis

Background

PRC1 (Protein regulator of cytokinesis 1) regulates microtubules organization and functions as a novel regulator in Wnt/β-catenin signaling pathway. Wnt/β-catenin is involved in development of liver fibrosis (LF). We aim to investigate effect and mechanism of PRC1 on liver fibrosis.

Methods

Carbon tetrachloride (CCl₄)-induced mice LF model was established and in vitro cell model for LF was induced by mice primary hepatic stellate cell (HSC) under glucose treatment. The expression of PRC1 in mice and cell LF models was examined by qRT-PCR (quantitative real-time polymerase chain reaction), western blot and immunohistochemistry. MTT assay was used to detect cell viability, and western blot to determine the underlying mechanism. The effect of PRC1 on liver pathology was examined via measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and hydroxyproline, as well as histopathological analysis.

Results

PRC1 was up-regulated in CCl₄-induced mice LF model and activated HSC. Knockdown of PRC1 inhibited cell viability and promoted cell apoptosis of activated HSC. PRC1 expression was regulated by Wnt3a signaling, and PRC1 could regulate downstream β-catenin activation. Moreover, PRC1 could activate glioma-associated oncogene homolog 1 (GLI1)-dependent osteopontin expression to participate in LF. Adenovirus-mediated knockdown of PRC1 in liver attenuated LF and reduced collagen deposition.

Conclusions

PRC1 aggravated LF through regulating Wnt/β-catenin mediated GLI1-dependent osteopontin expression, providing a new potential therapeutic target for LF treatment.

Targeting the Versatile Wnt/β-Catenin Pathway in Cancer Biology and Therapeutics: From Concept to Actionable Strategy

This expert review offers a critical synthesis of the latest insights and approaches at targeting the Wnt/β-catenin pathway in various cancers such as colorectal cancer, melanoma, leukemia, and breast and lung cancers. Notably, from organogenesis to cancer, the Wnt/β-catenin signaling displays varied and highly versatile biological functions in animals, with virtually all tissues requiring the Wnt/β-catenin signaling in one way or the other. Aberrant expression of the members of the Wnt/β-catenin has been implicated in many pathological conditions, particularly in human cancers. Mutations in the Wnt/β-catenin pathway genes have been noted in diverse cancers. Biochemical and genetic data support the idea that inhibition of Wnt/β-catenin signaling is beneficial in cancer therapeutics. The interaction of this important pathway with other signaling systems is also noteworthy, but remains as an area for further research and discovery. In addition, formation of different complexes by components of the Wnt/β-catenin pathway and the precise roles of these complexes in the cytoplasmic milieu are yet to be fully elucidated. This article highlights the latest medical technologies in imaging, single-cell omics, use of artificial intelligence (e.g., machine learning techniques), genome sequencing, quantum computing, molecular docking, and computational softwares in modeling interactions between molecules and predicting protein-protein and compound-protein interactions pertinent to the biology and therapeutic value of the Wnt/β-catenin signaling pathway. We discuss these emerging technologies in relationship to what is currently needed to move from concept to actionable strategies in translating the Wnt/β-catenin laboratory discoveries to Wnt-targeted cancer therapies and diagnostics in the clinic.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

High Serum Secreted Frizzled-Related Protein 5 Levels Associates with Early Improvement of Cardiac Function Following ST-Segment Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention

AIM

Several members of secreted frizzled-related protein (SFRP) are involved in the process of myocardial ischemia-reperfusion injury. However, little is known about the role of SFRP5 in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

In this cross-sectional study, 85 patients with first-time anterior STEMI who underwent timely primary percutaneous coronary intervention (PCI) and 35 patients without coronary artery disease (CAD) were enrolled. Serum SFRP5 levels were measured using an enzyme-linked immunosorbent assay kit. Patients with STEMI were divided into low-SFRP5 and high-SFRP5 groups according to their median baseline serum SFRP5 levels. To evaluate cardiac function and structure after infarction, the left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) were measured using echocardiography. The associations between changes in LVEF and reduced LVEF (≤ 50%) and clinical variables were determined by univariate and multivariate analyses.

RESULTS

Baseline serum SFRP5 levels were significantly higher in patients with STEMI than in those without CAD (23.3 ng/mL vs 19.8 ng/mL, P=0.008), although they decreased over time. Also, baseline serum SFRP5 levels were inversely correlated with peak hypersensitive cardiac troponin I (hs-cTnI) levels (r=-0.234, P=0.025) and peak hypersensitive C-reactive protein (hs-CRP) levels (r=-0.262, P=0.015). A multivariate linear regression model showed that changes in LVEF were positively correlated with serum SFRP5 levels at baseline (β= 0.249, 95% confidence interval (CI) 0.018-0.245, P=0.024) and 24 h after admission (β=0.220, 95% CI 0.003-0.264, P=0.045). At 3 months, LVEF in patients with high SFRP5 levels was significantly improved over baseline [(60.8±7.1) % vs (56.1±7.5) %, P=0.001]. LVEF was also significantly higher in patients with high SFRP5 levels than in those with low at the 3-month follow-up [(60.8±7.1) % vs (56.8±8.9) %, P=0.028]. Consequently, high serum SFRP5 levels at baseline were associated with a decreased risk of reduced LVEF at 3 months, independent of peak hs-cTnI and baseline cardiac function (hazard ratio 0.190, 95% CI 0.036-0.996; P=0.049).

CONCLUSIONS

High serum SFRP5 levels measured during the acute phase of STEMI were significantly associated with promoting myocardial recovery at an early phase following primary PCI, suggesting that SFRP5 is a potential therapeutic target in acute STEMI.

Molecular Profiles of Cell-to-Cell Variation in the Regenerative Potential of Mesenchymal Stromal Cells

Cell-to-cell variation in the regenerative potential of mesenchymal stromal cells (MSCs) impedes the translation of MSC therapies into clinical practice. Cellular heterogeneity is ubiquitous across MSC cultures from different species and tissues. This review highlights advances to elucidate molecular profiles that identify cell subsets with specific regenerative properties in heterogeneous MSC cultures. Cell surface markers and global signatures are presented for proliferation and differentiation potential, as well as immunomodulation and trophic properties. Key knowledge gaps are discussed as potential areas of future research. Molecular profiles of MSC heterogeneity have the potential to enable unprecedented control over the regenerative potential of MSC therapies through the discovery of new molecular targets and as quality attributes to develop robust and reproducible biomanufacturing processes. These advances would have a positive impact on the nascent field of MSC therapeutics by accelerating the development of therapies with more consistent and effective treatment outcomes.

Biomarkers of Ossification of the Spinal Ligament

STUDY DESIGN

Literature review.

OBJECTIVES

To review biomarkers in patients with ossification of the spinal ligament (OSL), including ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum and to raise the present issues.

METHODS

A literature search was performed using PubMed and MEDLINE databases. The biomarkers were classified according to category. The number of the subjects and reproducibility were assessed.

RESULTS

Eleven articles were included in this review. There were 9 articles from Japan, 1 article from Taiwan, and 1 article from China. The biomarkers were classified into calcium-phosphate metabolism markers, bone turnover markers, sclerostin, dickkopf-1, secreted frizzled-related protein-1, fibroblast growth factor-23, fibronectin, menatetrenone, leptin, pentosidine, and hypersensitive C-reactive protein. However, there were several limitations in the research studies, such as small research field, small number of subjects, and a lack of reproducibility.

CONCLUSIONS

Although there have been several studies that have analyzed biomarkers for OSL, there are no definitive conclusions to date. Numerous issues will need to be resolved in the future. It is imperative to continue this research because the results might prove beneficial to elucidate the pathology of OSL and the measures to prevent the initiation and progression of the disease.

A tale of two tracts: history, current advances, and future directions of research on sexual differentiation of reproductive tracts†

Alfred Jost's work in the 1940s laid the foundation of the current paradigm of sexual differentiation of reproductive tracts, which contends that testicular hormones drive the male patterning of reproductive tract system whereas the female phenotype arises by default. Once established, the sex-specific reproductive tracts undergo morphogenesis, giving rise to anatomically and functionally distinct tubular organs along the rostral-caudal axis. Impairment of sexual differentiation of reproductive tracts by genetic alteration and environmental exposure are the main causes of disorders of sex development, and infertility at adulthood. This review covers past and present work on sexual differentiation and morphogenesis of reproductive tracts, associated human disorders, and emerging technologies that have made impacts or could radically expand our knowledge in this field.

Expression of transcription factors and signaling molecules in the cerebellar granule cell development

Cerebellar granule cell precursors (GCPs) and granule cells (GCs) constitute a good model system to investigate proliferation of neural precursors and differentiation of neurons. During development, GCPs proliferate in the outer external granule cell layer (outer EGL) and then exit the cell cycle in the inner EGL to become GCs, which inwardly migrate to the inner granule cell layer (IGL). Misregulation of GCP proliferation or GC differentiation leads to maldevelopment of the cerebellum and the formation of a cerebellar tumor, medulloblastoma. Despite many efforts in this field, the mechanisms underlying GC development remain elusive. In this study, we performed detailed immunostaining in the developing cerebellum, with particular focus on GCPs and GCs, looking at several transcription factors, signaling molecules, cell cycle regulators, some of which are known to regulate neural development. Interestingly, we found distinct distribution patterns of certain proteins within the outer and inner EGL, suggesting the existence of subpopulations of GCPs and GCs in those layers. This study provides a basis for future studies on the cerebellar GC development and medulloblastoma.

Sfrp5/Wnt Pathway: A Protective Regulatory System in Atherosclerotic Cardiovascular Disease

Adipose tissue stores energy and is the largest endocrine organ in the body, producing several adipokines. However, among these adipokines, few play a role in the positive metabolism that promotes good health. Secreted frizzled-related protein (Sfrp)-5, an antagonist that directly binds to Wnt, has attracted interest due to its favorable effects on atherosclerotic cardiovascular disease (ASCVD). This review focuses on Sfrp5 biology and the roles of the Sfrp5/Wnt system in ASCVD.

Novel SFRP2 DNA Methylation Profile Following Neoadjuvant Therapy in Colorectal Cancer Patients with Different Grades of BMI

The relationship between body weight and different cancers is now well-recognized and among such cancers, colorectal cancer (CRC) is reported most frequently. Our group recently published findings, through an epigenome-wide association study, suggesting that body mass index (BMI) could act as a relevant risk factor in the CRC. In addition, aberrant SFRP2 methylation is one of the major mechanisms for Wnt signaling activation in CRC. Conversely, neoadjuvant chemo-radiotherapy appears to alter the rectal cancer epigenome. This study was aimed to evaluate the effect of obesity, measured by BMI, on the methylation of SFRP2 in tumor samples of patients with CRC. Non-treated CRC patients and CRC patients treated with pre-operative neoadjuvant therapy from 2011 to 2013 were included and classified by BMI < 25.0 kg/m² and BMI > 25.0 kg/m². SFRP2 DNA methylation in tumor samples was measured by pyrosequencing. Our findings suggest a possible interaction between SFRP2 methylation levels and BMI in CRC tumor samples. The correlation of SFRP2 hypomethylation with an elevated BMI was stronger within the non-treated CRC patient group than within the treated CRC patient group. We have successfully demonstrated that the beneficial association of tumor SFRP2 hypomethylation is dependent on patient BMI in non-treated CRC, suggesting a possible tumor suppressor role for SFRP2 in overweight and obese patients. Additional studies of clinical pathologies would be necessary to strengthen these preliminary results.

Elevated levels of Secreted-Frizzled-Related-Protein 1 contribute to Alzheimer's disease pathogenesis

The deposition of aggregated amyloid-β peptides derived from the pro-amyloidogenic processing of the amyloid precurson protein (APP) into characteristic amyloid plaques (APs) is distinctive to Alzheimer's disease (AD). Alternative APP processing via the metalloprotease ADAM10 prevents amyloid-β formation. We tested whether downregulation of ADAM10 activity by its secreted endogenous inhibitor secreted-frizzled-related protein 1 (SFRP1) is a common trait of sporadic AD. We demonstrate that SFRP1 is significantly increased in the brain and cerebrospinal fluid of patients with AD, accumulates in APs and binds to amyloid-β, hindering amyloid-β protofibril formation. Sfrp1 overexpression in an AD-like mouse model anticipates the appearance of APs and dystrophic neurites, whereas its genetic inactivation or the infusion of α-SFRP1-neutralizing antibodies favors non-amyloidogenic APP processing. Decreased Sfrp1 function lowers AP accumulation, improves AD-related histopathological traits and prevents long-term potentiation loss and cognitive deficits. Our study unveils SFRP1 as a crucial player in AD pathogenesis and a promising AD therapeutic target.

The interplay between intrinsic and extrinsic Wnt signaling in controlling intestinal transformation

The intestinal epithelial layer is the fastest renewing tissue in the human body. Due to its incredible turnover rate, the intestine is especially prone to develop cancer, in particular in the colon. Colorectal cancer (CRC) development is characterized by the stepwise accumulation of mutations over time, of which mutations in the tumor suppressor APC are often very early to occur. Generally, mutations in this gene lead to truncated APC proteins that cannot bind to β-catenin to promote its degradation, resulting in a constant overstimulation of the Wnt pathway. The level of intrinsic Wnt activation is dependent on the number of functional β-catenin binding sites remaining within the APC proteins, and the right amount of Wnt signaling is rate-limiting in the formation of polyps. In addition, the intestinal niche provides an extensive spectrum of Wnt ligands, amplifiers and antagonists that locally regulate basal Wnt levels and consequently influence polyp formation propensity. Here we will discuss the crosstalk between transforming epithelial cells and their regional niche in the development of intestinal cancer.

Evidence of Intrinsic Impairment of Osteoblast Phenotype at the Curve Apex in Girls With Adolescent Idiopathic Scoliosis

STUDY DESIGN

An observational descriptive study based on a single cohort of patients.

OBJECTIVE

To determine whether spinal facet osteoblasts at the curve apex display a different phenotype to osteoblasts from outside the curve in adolescent idiopathic scoliosis (AIS) patients.

SUMMARY OF BACKGROUND DATA

Intrinsic differences in the phenotype of spinal facet bone tissue and in spinal osteoblasts have been implicated in the pathology of AIS. However, no study has compared the phenotype of facet osteoblasts at the curve apex compared with outside the curve in AIS patients.

METHODS

Facet spinal tissue was collected perioperatively from three sites, the concave and convex side at the curve apex and from outside the curve (noncurve) from three AIS female patients aged 13-16 years. Spinal tissue was analyzed by micro-computed tomography to determine bone mineral density (BMD) and trabecular structure. Primary osteoblasts were cultured from concave, convex, and noncurve facet bone chips. The phenotype of osteoblasts was determined by assessment of cellular proliferation, cellular metabolism (alkaline phosphatase and Seahorse Analyzer), bone nodule mineralization (Alizarin red assay), and the mRNA expression of Wnt signaling genes (quantitative reverse transcriptase polymerase chain reaction).

RESULTS

Convex facet tissue exhibited greater BMD and trabecular thickness, compared with concave facet tissue. Osteoblasts at the convex side of the curve apex exhibited a significantly higher proliferative and metabolic phenotype and a greater capacity to form mineralized bone nodules, compared with concave osteoblasts. mRNA expression of SKP2 was significantly greater in both concave and convex osteoblasts, compared with noncurve osteoblasts. The expression of SFRP1 was significantly downregulated in convex osteoblasts, compared with either concave or noncurve.

CONCLUSIONS

Intrinsic differences that affect osteoblast function are exhibited by spinal facet osteoblasts at the curve apex in AIS patients.

LEVEL OF EVIDENCE

Level IV, Prognostic.

SFRP4 Is a Negative Regulator of Ovarian Follicle Development and Female Fertility

WNT signaling regulates a variety of ovarian processes, including follicle development, granulosa cell (GC) proliferation and differentiation, steroidogenesis, and ovulation. The secreted frizzled-related proteins (SFRPs) comprise a family of WNT signaling antagonists. Sfrp4 expression was previously reported to be induced in ovarian GCs and cumulus cells in vivo following human chorionic gonadotropin treatment, suggesting that it may play key roles in cumulus expansion, ovulation/luteinization, and corpus luteum (CL) function. In this study, we aimed to define the physiological roles of Sfrp4 in the ovary by gene targeting. Sfrp4-null female mice were found to produce larger litters than did their wild-type littermates. Although previous studies had suggested roles of Sfrp4 in luteal cell survival, no differences in CL formation, morphology, steroidogenesis, involution, or luteal cell apoptosis were found in Sfrp4-null mice. Likewise, cumulus expansion occurred normally in Sfrp4-null mice, with minimal changes in cumulus cell gene expression. Hyperfertility in the Sfrp4-null model was ultimately attributed to decreased antral follicle atresia, leading to an enhanced ovulatory rate. Increased expression of FSH- and LH-responsive genes was found in GCs from Sfrp4-null mice, and GCs isolated from Sfrp4-null mice were found to be hyperresponsive to FSH and LH in vitro. Although Sfrp2 was found to be overexpressed in the GCs of Sfrp4-null mice (suggesting a compensatory mechanism), Sfrp2-null mice had normal fertility and ovulatory rates, and Sfrp2/4 double knockout mice did not differ from Sfrp4-null mice. Taken together, our results suggest that SFRP4 acts to attenuate GC responsiveness to gonadotropins, thereby decreasing follicle survival, ovulatory rate, and fertility.

Sfrp4 repression of the Ror2/Jnk cascade in osteoclasts protects cortical bone from excessive endosteal resorption

Loss-of-function mutations in the Wnt inhibitor secreted frizzled receptor protein 4 (SFRP4) cause Pyle's disease (OMIM 265900), a rare skeletal disorder characterized by wide metaphyses, significant thinning of cortical bone, and fragility fractures. In mice, we have shown that the cortical thinning seen in the absence of Sfrp4 is associated with decreased periosteal and endosteal bone formation and increased endocortical resorption. While the increase in Rankl/Opg in cortical bone of mice lacking Sfrp4 suggests an osteoblast-dependent effect on endocortical osteoclast (OC) activity, whether Sfrp4 can cell-autonomously affect OCs is not known. We found that Sfrp4 is expressed during bone marrow macrophage OC differentiation and that Sfrp4 significantly suppresses the ability of early and late OC precursors to respond to Rankl-induced OC differentiation. Sfrp4 deletion in OCs resulted in activation of canonical Wnt/β-catenin and noncanonical Wnt/Ror2/Jnk signaling cascades. However, while inhibition of canonical Wnt/β-catenin signaling did not alter the effect of Sfrp4 on OCgenesis, blocking the noncanonical Wnt/Ror2/Jnk cascade markedly suppressed its regulation of OC differentiation in vitro. Importantly, we report that deletion of Ror2 exclusively in OCs (CtskCreRor2 ^fl/fl ) in Sfrp4 null mice significantly reversed the increased number of endosteal OCs seen in these mice and reduced their cortical thinning. Altogether, these data show autocrine and paracrine effects of Sfrp4 in regulating OCgenesis and demonstrate that the increase in endosteal OCs seen in Sfrp4 ^-/- mice is a consequence of noncanonical Wnt/Ror2/Jnk signaling activation in OCs overriding the negative effect that activation of canonical Wnt/β-catenin signaling has on OCgenesis.

Sfrp3 modulates stromal-epithelial crosstalk during mammary gland development by regulating Wnt levels

Mammary stroma is essential for epithelial morphogenesis and development. Indeed, postnatal mammary gland (MG) development is controlled locally by the repetitive and bi-directional cross-talk between the epithelial and the stromal compartment. However, the signalling pathways involved in stromal–epithelial communication are not entirely understood. Here, we identify Sfrp3 as a mediator of the stromal–epithelial communication that is required for normal mouse MG development. Using Drosophila wing imaginal disc, we demonstrate that Sfrp3 functions as an extracellular transporter of Wnts that facilitates their diffusion, and thus, their levels in the boundaries of different compartments. Indeed, loss of Sfrp3 in mice leads to an increase of ductal invasion and branching mirroring an early pregnancy state. Finally, we observe that loss of Sfrp3 predisposes for invasive breast cancer. Altogether, our study shows that Sfrp3 controls MG morphogenesis by modulating the stromal-epithelial cross-talk during pubertal development.

The signalling pathways regulating how the mammary gland stroma interacts with the epithelia to then regulate gland development are unclear. Here, the authors identify Sfrp3 as regulating stroma communication via Wnts, on deletion, this increases ductal invasion and initiates an early pregnancy state.

Correlation between SFRP1 expression and clinicopathological parameters in patients with triple-negative breast cancer

Aim: Breast cancer is a heterogeneous disease with distinct molecular and clinical behavior demanding reliable biomarkers, especially in triple-negative breast cancer (TNBC). This study seeks to improve the understanding of SFRP1 as a potential biomarker in breast cancer focusing on TNBC. Materials & methods: SFRP1 expression was investigated via immunohistochemistry with two anti-SFRP1-antibodies on tissue-microarrays of 376 invasive breast cancers. Results: Statistical analysis revealed a highly significant association between TNBC (n = 36) and SFRP1 expression (p < 0.001). SFRP1 expression was significantly associated with younger age, higher tumor stage, size and grade. Conclusion: SFRP1 expression is strongly correlated with TNBC on protein level. Associations with age and tumor grade support the role of SFRP1 as a biomarker for chemotherapy response in TNBC.

Nerve modulation therapy in gouty arthritis: targeting increased sFRP2 expression in dorsal root ganglion regulates macrophage polarization and alleviates endothelial damage

Gouty arthritis (GA) is a form of arthritis caused by uric acid deposition in the joints that result in intense inflammation and pain. Accumulating evidence showed the importance of the sensory neurons signal upon immune cells by releasing neuropeptides and chemokines to regulate associated immune-inflammatory response. In this study, we investigated the significance of sensory neuron neuropeptides and chemokine signals on inflammation-induced macrophages polarization during GA.

Methods: We screened the mRNA expression profile during GA in dorsal root ganglion (DRG) neurons to identify the most likely candidate that mediates the neuro-immune communication. Then, we silenced specific gene expression in the DRG by lentiviral vectors in the monosodium urate (MSU)-induced ankle GA mouse model and evaluated alterations in the inflammatory response. In vitro, primary macrophages were used to investigate the neural impact on M1/M2 subtype polarization, proinflammatory cytokine production and downstream endothelial damage. Mechanism by which macrophage inflammation is induced in the DRG was evaluated by Western blot, immunofluorescence, and immunoprecipitation.

Results: We found that secreted frizzled-related protein 2 (sFRP2) was the most upregulated gene in dorsal root ganglion (DRG) neurons in response to monosodium urate (MSU) deposition. Injection of LV-sFRP2-shRNA into the L4 and L5 DRG significantly suppressed inflammatory cell infiltration and M1 polarization in the synovial membrane, attenuating hyperalgesia and ankle swelling in the GA mouse model. In vitro, DRG neurons-derived sFRP2 promoted M1 polarization and macrophage migration, thereby upregulating the production of proinflammatory cytokines and preventing endothelial apoptosis. Furthermore, DRG-derived sFRP2 activated the nuclear factor (NF)-κB pathway by destabilizing the β-catenin and p65 complex.

Conclusion: We demonstrated the involvement of a sensory neuron-macrophage axis in GA pathology that was regulated by sFRP2 expression in a paracrine manner. Targeting increased sFRP2 expressions in DRG provide novel insights for future GA research in both pain alleviation and treatment of gout inflammation.

Human Intestinal Morphogenesis Controlled by Transepithelial Morphogen Gradient and Flow-Dependent Physical Cues in a Microengineered Gut-on-a-Chip

We leveraged a human gut-on-a-chip (Gut Chip) microdevice that enables independent control of fluid flow and mechanical deformations to explore how physical cues and morphogen gradients influence intestinal morphogenesis. Both human intestinal Caco-2 and intestinal organoid-derived primary epithelial cells formed three-dimensional (3D) villi-like microarchitecture when exposed to apical and basal fluid flow; however, 3D morphogenesis did not occur and preformed villi-like structure involuted when basal flow was ceased. When cells were cultured in static Transwells, similar morphogenesis could be induced by removing or diluting the basal medium. Computational simulations and experimental studies revealed that the establishment of a transepithelial gradient of the Wnt antagonist Dickkopf-1 and flow-induced regulation of the Frizzled-9 receptor mediate the histogenesis. Computational simulations also predicted spatial growth patterns of 3D epithelial morphology observed experimentally in the Gut Chip. A microengineered Gut Chip may be useful for studies analyzing stem cell biology and tissue development.

Sfrp5 increases glucose-stimulated insulin secretion in the rat pancreatic beta cell line INS-1E

Previous studies reported that secreted frizzled-related protein-5 (Sfrp5) decreases beta cell proliferation and increases fasting insulin levels, but studies on direct effects of Sfrp5 on insulin secretion and its underlying mechanisms are missing. This study examined effects of Sfrp5 on (i) beta cell viability and proliferation, (ii) basal and glucose-stimulated insulin secretion and (iii) canonical and non-canonical Wnt signalling pathways. We incubated rat INS-1E cells with 0.1, 1 or 5 μg/ml recombinant Sfrp5 for 24h. We measured basal and glucose-stimulated insulin secretion at glucose concentrations of 2.5 and 20 mmol/l. Phosphorylated and total protein content as well as mRNA levels of markers of cell proliferation, canonical and non-canonical Wnt signalling pathways were examined using Western blotting and real-time PCR. Differences between treatments were analysed by repeated measurement one-way ANOVA or Friedman’s test followed by correction for multiple testing using the Benjamini-Hochberg procedure. At 5 μg/ml, Sfrp5 reduced mRNA levels of cyclin-B1 by 25% (p<0.05). At 1 and 5 μg/ml, Sfrp5 increased glucose-stimulated insulin secretion by 24% and by 34% (both p<0.05), respectively, but had no impact on basal insulin secretion. Sfrp5 reduced the phosphorylation of the splicing forms p46 and p54 of JNK by 39% (p<0.01) and 49% (p<0.05), respectively. In conclusion, Sfrp5 reduced markers of cell proliferation, but increased in parallel dose-dependently glucose-stimulated insulin secretion in INS-1E cells. This effect is likely mediated by reduced JNK activity, an important component of the non-canonical Wnt signalling pathway.

Wnt Signaling Alterations in the Human Spinal Cord of Amyotrophic Lateral Sclerosis Cases: Spotlight on Fz2 and Wnt5a

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with no cure, and elucidation of the mechanisms mediating neuronal death in this neuropathology is crucial to develop effective treatments. It has recently been demonstrated in animal models that the Wnt family of proteins is involved in this neuropathology, although its potential involvement in case of humans is almost unknown. We analyzed the expression of Wnt signaling components in healthy and ALS human spinal cords by quantitative RT-PCR, and we found that most Wnt ligands, modulators, receptors, and co-receptors were expressed in healthy controls. Moreover, we observed clear alterations in the mRNA expression of different components of this family of proteins in human spinal cord tissue from ALS cases. Specifically, we detected a significant increase in the mRNA levels of Wnt3, Wnt4, Fz2, and Fz8, together with several non-significant increases in the mRNA expression of other genes such as Wnt2b, Wnt5a, Fz3, Lrp5, and sFRP3. Based on these observations and on previous reports of studies performed in animal models, we evaluated with immunohistochemistry the protein expression patterns of Fz2 and Fz5 receptors and their main ligand Wnt5a in control samples and ALS cases. No substantial changes were observed in Fz5 protein expression pattern in ALS samples. However, we detected an increase in the amount of Fz2+ astrocytes in the borderline between gray and white matter at the ventral horn in ALS samples. Finally, Wnt5a expression was observed in neurons and astrocytes in both control and ALS samples, although Wnt5a immunolabeling in astroglial cells was significantly increased in ALS spinal cords in the same region where changes in Fz2 were observed. Altogether, these observations strongly suggest that the Wnt family of proteins, and more specifically Fz2 and Wnt5a, might be involved in human ALS pathology.

Secreted Frizzled-Related Protein 2 Is Associated with Disease Progression and Poor Prognosis in Breast Cancer

Purpose

Secreted frizzled-related protein 2 (sFRP2) is a secreted protein associated with cancer drug resistance and metastasis. However, few studies have reported serum sFRP2 levels in breast cancer. We evaluated serum sFRP2 as a potential biomarker for breast cancer.

Methods

Serum sFRP2 concentrations were detected in 274 breast cancer patients along with 147 normal healthy controls by enzyme-linked immunosorbent assay (ELISA). Diagnostic significance was evaluated by area under the curve (AUC) analysis and the Youden index. Prognostic significance was determined by Kaplan-Meier survival method and univariate and multivariate Cox proportional hazard regression model analyses.

Results

Serum sFRP2 was elevated in breast cancer patients compared to normal healthy controls (P < 0.001). The sensitivity of sFRP2 in diagnosing breast cancer was 76.9% at a specificity of 76.6%. Elevated serum sFRP2 levels are associated with primary tumor size, TNM stage, and lymph node metastases. The Kaplan-Meier curves showed a significant association of serum sFRP2 with progression-free survival. The multivariate Cox analysis confirmed that high serum sFRP2 was an independent prognostic factor for poor prognosis (HR = 3.89, 95% CI = 1.95-7.68, P = 0.001).

Conclusions

In conclusion, serum sFRP2 may serve as a potential biomarker for breast cancer diagnosis and prognostic evaluation.

Wnt/β-catenin signalling plays diverse functions during the process of fibrotic remodelling in the exocrine pancreas

BACKGROUND/OBJECTIVES

Wnt/β-catenin signalling plays vital roles in tissue homeostasis. Dysregulation of the pathway has been implicated in the pathogenesis of cancer and fibroses in numerous tissues, including the pancreas. We studied the effect of microenvironmental changes pertaining to fibrotic tissue remodelling on the expression of selected Wnt/β-catenin pathway proteins in the human exocrine pancreas. The role of acinar/stellate cross-talk on the expression of the proteins was elucidated in a long-term mouse co-culture system.

METHODS

Expression of β-catenin, Wnt2, Wnt5a and SFRP4 was analysed immunohistochemically in normal and moderately or highly fibrotic human pancreata (n = 8). The effect of humoral interactions on the expression of the proteins was studied by immunocytochemical means in parallel mono- and co-cultures of mouse acinar and stellate cells (PSCs).

RESULTS

In human pancreatic tissue, fibrotic microenvironment was associated with redistribution of the proteins in and between epithelial and stromal compartments, compared to acinar-rich tissue. In non-fibrotic and moderately fibrotic tissue the proteins appeared only in acinar cells whereas in highly fibrotic tissue stromal fibroblastoid/stellate cells and macrophages were their predominant locations. Subcellular changes in the expression of β-catenin and Wnt5a were detected. Our in vitro data suggest potential involvement of acinar cell/PSC cross-talk in mediating the changes observed in tissue specimens.

CONCLUSIONS

Wnt/β-catenin pathway-associated proteins are abundantly expressed in the exocrine pancreas with prominent changes in their cellular and subcellular expression patterns along with increasing levels of fibrosis. Diverse functions for Wnt/β-catenin signalling during the course of fibrotic remodelling in the exocrine pancreas are suggested.

The potential contribution of stromal cell-derived factor 2 (SDF2) in endoplasmic reticulum stress response in severe preeclampsia and labor-onset

Endoplasmic reticulum (ER) stress occurs when the protein folding machinery in the cell is unable to cope with newly synthesized proteins, which results in an accumulation of misfolded proteins in the ER lumen. In response, the cell activates a cellular signaling pathway known as the Unfolded Protein Response (UPR), aiming to restore cellular homeostasis. Activation and exacerbation of the UPR have been described in several human pathologies, including cancer and neurological disorders, and in some gestational diseases such as preeclampsia and gestational diabetes. This review explores the participation of stromal cell-derived factor 2 (SDF2) in UPR pathways, shows new information and discusses its exacerbation regarding protein expression in severe preeclampsia and labor, both of which are associated with ER stress.

Dysregulation of ß-catenin, WISP1 and TCF21 predicts disease-specific survival and primary response against radio(chemo)therapy in patients with locally advanced squamous cell carcinomas of the head and neck

OBJECTIVE

The objective of this study was to determine the prognostic and predictive impact of β-catenin, TCF21 and WISP1 expression in patients with squamous cell carcinomas of the head and neck who underwent primary radiotherapy or concomitant chemoradiotherapy.

STUDY DESIGN

Prospective cohort study.

SETTING

University hospital.

PARTICIPANTS

Protein expression profiles of β-catenin, TCF21, WISP1 and p16 were determined by immunohistochemical analyses in tissue samples of 59 untreated patients. Expression was correlated with different outcome parameters.

MAIN OUTCOME MEASURES

Impact of TNM classification, grading, sex, age, gender, type of therapy, response to therapy and p16 status on disease-specific (DSS) and disease-free survival (DFS).

RESULTS

Patients with high expression of TCF21 were associated with significantly worse disease-specific survival (P = 0.005). In a multivariable analysis, TCF21 was a significant determinant of disease-specific survival. (HR 3.01; P = 0.036). Conversely, low expression of β-catenin (P = 0.025) and WISP1 (P = 0.037) revealed a better response to radiotherapy.

CONCLUSION

Since data show that TCF21 is a prognostic factor for disease-specific survival and WISP1 and ß-catenin are predictive factors for clinical outcome after definitive radiotherapy, further studies are warranted to prove these preliminary but very promising findings.

Secreted frizzled-related protein 2 (SFRP2) expression promotes lesion proliferation via canonical WNT signaling and indicates lesion borders in extraovarian endometriosis

STUDY QUESTION

What is the role of SFRP2 in endometriosis?

SUMMARY ANSWER

SFRP2 acts as a canonical WNT/CTNNB1 signaling agonist in endometriosis, regulating endometriosis lesion growth and indicating endometriosis lesion borders together with CTNNB1 (also known as beta catenin).

WHAT IS KNOWN ALREADY

Endometriosis is a common, chronic disease that affects women of reproductive age, causing pain and infertility, and has significant economic impact on national health systems. Despite extensive research, the pathogenesis of endometriosis is poorly understood, and targeted medical treatments are lacking. WNT signaling is dysregulated in various human diseases, but its role in extraovarian endometriosis has not been fully elucidated.

STUDY DESIGN, SIZE, DURATION

We evaluated the significance of WNT signaling, and especially secreted frizzled-related protein 2 (SFRP2), in extraovarian endometriosis, including peritoneal and deep lesions. The study design was based on a cohort of clinical samples collected by laparoscopy or curettage and questionnaire data from healthy controls and endometriosis patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Global gene expression analysis in human endometrium (n = 104) and endometriosis (n = 177) specimens from 47 healthy controls and 103 endometriosis patients was followed by bioinformatics and supportive qPCR analyses. Immunohistochemistry, Western blotting, primary cell culture and siRNA knockdown approaches were used to validate the findings.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the 220 WNT signaling and CTNNB1 target genes analysed, 184 genes showed differential expression in extraovarian endometriosis (P < 0.05) compared with endometrium tissue, including SFRP2 and CTNNB1. Menstrual cycle-dependent regulation of WNT genes observed in the endometrium was lost in endometriosis lesions, as shown by hierarchical clustering. Immunohistochemical analysis indicated that SFRP2 and CTNNB1 are novel endometriosis lesion border markers, complementing immunostaining for the known marker CD10 (also known as MME). SFRP2 and CTNNB1 localized similarly in both the epithelium and stroma of extraovarian endometriosis tissue, and interestingly, both also indicated an additional distant lesion border, suggesting that WNT signaling is altered in the endometriosis stroma beyond the primary border indicated by the known marker CD10. SFRP2 expression was positively associated with pain symptoms experienced by patients (P < 0.05), and functional loss of SFRP2 in extraovarian endometriosis primary cell cultures resulted in decreased cell proliferation (P < 0.05) associated with reduced CTNNB1 protein expression (P = 0.05).

LIMITATIONS REASONS FOR CAUTION

SFRP2 and CTNNB1 improved extraovarian endometriosis lesion border detection in a relatively small cohort (n = 20), although larger studies with different endometriosis subtypes in variable cycle phases and under hormonal medication are required.

WIDER IMPLICATIONS OF THE FINDINGS

The highly expressed SFRP2 and CTNNB1 improve endometriosis lesion border detection, which can have clinical implications for better visualization of endometriosis lesions over CD10. Furthermore, SFRP2 acts as a canonical WNT/CTNNB1 signaling agonist in endometriosis and positively regulates endometriosis lesion growth, suggesting that the WNT pathway may be an important therapeutic target for endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Academy of Finland and by Tekes: Finnish Funding Agency for Innovation. The authors have no conflict of interest to declare.

Omentin-regulated proteins combine a pro-inflammatory phenotype with an anti-inflammatory counterregulation in human adipocytes: A proteomics analysis

AIMS

Experimental and epidemiological studies reported controversial data on the role of omentin in type 2 diabetes and cardiovascular diseases. This study aimed to characterise the impact of omentin on the secretome of human adipocytes to analyse the enrichment of these proteins in metabolic and cellular signalling pathways underlying its physiological function.

MATERIAL/METHODS

Differentiated primary human adipocytes were treated without or with 500 or 2000 ng/mL omentin for 24 hours. The secretome was analysed by liquid chromatography coupled tandem-mass spectrometry. Differences in protein secretion between untreated and omentin-treated adipocytes were compared using a paired t-test. Other potential upstream regulators and the overrepresentation in canonical pathways of omentin-stimulated proteins were analysed using Ingenuity Pathway Analysis.

RESULTS

The supernatant of adipocytes contained 3493 proteins, of which 140 were differentially secreted by both concentrations of omentin compared with untreated adipocytes. Among the most strongly increased proteins, tumour necrosis factor-inducible gene 6 protein (TNFAIP6) was increased by 140-fold in the supernatant. Omentin-regulated proteins were overrepresented in seven canonical pathways including eukaryotic initiation factor 2 signalling, complement system, and inhibition of matrix metalloproteases. We further identified 25 other potential upstream activators of omentin-regulated proteins, mainly pro-inflammatory cytokines and transcription regulators including NFκB.

CONCLUSIONS

In differentiated human adipocytes, the release of the anti-inflammatory TNFAIP6 might be part of a counterregulatory response to the pro-inflammatory action of omentin. Omentin-regulated proteins were overrepresented in pathways indicating cellular stress, a pro-inflammatory environment and a crosstalk with other organs. Other potential activators of omentin-regulated proteins point towards a central role of NFκB activation in the omentin-induced secretory process.

Vitamin D, Inflammation and Osteoporosis in Rheumatoid Arthritis

Patients with Rheumatoid Arthritis (RA) commonly develop osteoporosis and fragility fractures. This fact cannot be explained only with the use of glucocorticoids, known to be detrimental for bone health. RA is characterized by a chronic inflammation caused by the continuous activation of innate and adaptive immunity with proinflammatory cytokines overproduction. This process is detrimental for several organs and physiological processes, including the impairment of bone remodeling. We will briefly review the pathogenesis of inflammation-related bone loss in RA, describing well-known and new molecular pathways and focusing on vitamin D and Parathyroid Hormone role.

Wnt/β-Catenin Signaling Pathway Governs a Full Program for Dopaminergic Neuron Survival, Neurorescue and Regeneration in the MPTP Mouse Model of Parkinson's Disease

Wingless-type mouse mammary tumor virus (MMTV) integration site (Wnt) signaling is one of the most critical pathways in developing and adult tissues. In the brain, Wnt signaling contributes to different neurodevelopmental aspects ranging from differentiation to axonal extension, synapse formation, neurogenesis, and neuroprotection. Canonical Wnt signaling is mediated mainly by the multifunctional β-catenin protein which is a potent co-activator of transcription factors such as lymphoid enhancer factor (LEF) and T-cell factor (TCF). Accumulating evidence points to dysregulation of Wnt/β-catenin signaling in major neurodegenerative disorders. This review highlights a Wnt/β-catenin/glial connection in Parkinson's disease (PD), the most common movement disorder characterized by the selective death of midbrain dopaminergic (mDAergic) neuronal cell bodies in the subtantia nigra pars compacta (SNpc) and gliosis. Major findings of the last decade document that Wnt/β-catenin signaling in partnership with glial cells is critically involved in each step and at every level in the regulation of nigrostriatal DAergic neuronal health, protection, and regeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD, focusing on Wnt/β-catenin signaling to boost a full neurorestorative program in PD.

The N-terminal domain of unknown function (DUF959) in collagen XVIII is intrinsically disordered and highly O-glycosylated

Collagen XVIII (ColXVIII) is a non-fibrillar collagen and proteoglycan that exists in three isoforms: short, medium and long. The medium and long isoforms contain a unique N-terminal domain of unknown function, DUF959, and our sequence-based secondary structure predictions indicated that DUF959 could be an intrinsically disordered domain. Recombinant DUF959 produced in mammalian cells consisted of ∼50% glycans and had a molecular mass of 63 kDa. Circular dichroism spectroscopy confirmed the disordered character of DUF959, and static light scattering indicated a monomeric state for glycosylated DUF959 in solution. Small-angle X-ray scattering showed DUF959 to be a highly extended, flexible molecule with a maximum dimension of ∼23 nm. Glycosidase treatment demonstrated considerable amounts of O-glycosylation, and expression of DUF959 in HEK293 SimpleCells capable of synthesizing only truncated O-glycans confirmed the presence of N-acetylgalactosamine-type O-glycans. The DUF959 sequence is characterized by numerous Ser and Thr residues, and this accounts for the finding that half of the recombinant protein consists of glycans. Thus, the medium and long ColXVIII isoforms contain at their extreme N-terminus a disordered, elongated and highly O-glycosylated mucin-like domain that is not found in other collagens, and we suggest naming it the Mucin-like domain in ColXVIII (MUCL-C18). As intrinsically disordered regions and their post-translational modifications are often involved in protein interactions, our findings may point towards a role of the flexible mucin-like domain of ColXVIII as an interaction hub affecting cell signaling. Moreover, the MUCL-C18 may also serve as a lubricant at cell-extracellular matrix interfaces.

Role of wnt5a in Metabolic Inflammation in Humans

CONTEXT

Common nutrition-associated diseases like obesity and type 2 diabetes are linked to chronic low-grade inflammation. The secreted glycopeptide wingless-type mouse mammary tumor virus integration site family member 5a (wnt5a) has been implicated in metabolic inflammation in rodent models, suggesting a potential treatment target. Data on the role of wnt5a in human physiology have yielded conflicting results.

OBJECTIVE

Serum concentrations of wnt5a were measured in a cross-sectional cohort of 896 people to gain deeper insights into wnt5a physiology.

DESIGN

Serum concentrations of wnt5a were measured by ELISA and related to several phenotyping and genotyping data. In vitro experiments were performed in THP-1 macrophages to examine potential molecular mechanisms.

RESULTS

Wnt5a levels were significantly positively correlated to IL-6 and triglyceride levels. In subjects with diabetes, wnt5a levels were elevated and significantly correlated with fasting plasma glucose concentrations. Although wnt5a levels were not influenced by common single-nucleotide polymorphisms in the human wnt5a gene, environmental factors significantly altered wnt5a concentrations, as follows: (1) wnt5a levels were reduced in subjects with high nutritional load of the long-chain eicosatetraenoic acid independent of the total caloric intake and overall composition of the macronutrients, and (2) wnt5a levels were lower in humans with a high gut microbiome α diversity. In vitro experiments revealed that stimulation of the IL-6 receptor or the long-chain fatty acid receptor GPR40 directly affected wnt5a expression in human macrophages.

CONCLUSION

Our data suggest that wnt5a is important in linking inflammation to metabolism. The nutrition and the microbiome might be interesting targets to prevent and/or treat wnt5a-mediated metabolic inflammation.

sFRP1 exerts effects on gastric cancer cells through GSK3β/Rac1‑mediated restraint of TGFβ/Smad3 signaling

Secreted frizzled-related protein 1 (sFRP1) is an inhibitor of canonical Wnt signaling; however, previous studies have determined a tumor-promoting function of sFRP1 in a number of different cancer types. A previous study demonstrated that sFRP1 overexpression was associated with an aggressive phenotype and the activation of transforming growth factor β (TGFβ) signaling. sFRP1 overexpression and sFRP1 knockdown cell models were established. Immunoblotting was conducted to examine the protein levels of the associated molecules. Immunofluorescence staining followed by confocal microscopy was performed to visualize the cytoskeleton alterations and subcellular localization of key proteins. sFRP1 overexpression restored glycogen synthase kinase 3β (GSK3β) activity, which activated Rac family small GTPase 1 (Rac1). GSK3β and Rac1 mediated the effect of sFRP1 on the positive regulation of cell growth and migration/invasion. Inhibition of GSK3β or Rac1 abolished the regulation of sFRP1 on TGFβ/SMAD family member 3 (Smad3) signaling and the aggressive phenotype; however, GSK3β or Rac1 overexpression increased cell migration/invasion and restrained Smad3 activity by preventing its nuclear translocation and limiting its transcriptional activity. The present study demonstrated a tumor-promoting function of sFRP1-overexpression by selectively activating TGFβ signaling in gastric cancer cells. GSK3β and Rac1 serve an important function in mediating the sFRP1-induced malignant alterations and signaling changes.