Functional significance of secreted Frizzled-related protein 1 in metastatic renal cell carcinomas

Platelet PI3Kβ regulates breast cancer metastasis

Platelets promote tumor metastasis by several mechanisms. Platelet-tumor cell interactions induce the release of platelet cytokines, chemokines, and other factors that promote tumor cell epithelial-mesenchymal transition and invasion, granulocyte recruitment to circulating tumor cells (CTCs), and adhesion of CTCs to the endothelium, assisting in their extravasation at metastatic sites. Previous studies have shown that platelet activation in the context of thrombus formation requires the Class IA PI 3-kinase PI3Kβ. We now define a role for platelet PI3Kβ in breast cancer metastasis. Platelet PI3Kβ is essential for platelet-stimulated tumor cell invasion through Matrigel. Consistent with this finding, in vitro platelet-tumor cell binding and tumor cell-stimulated platelet activation are reduced in platelets isolated from PI3Kβ mutant mice. RNAseq and proteomic analysis of human breast epithelial cells co-cultured with platelets revealed that platelet PI3Kβ regulates the expression of EMT and metastasis-associated genes in these cells. The EMT and metastasis-associated proteins PAI-1 and IL-8 were specifically downregulated in co-cultures with PI3Kβ mutant platelets. PI3Kβ mutant platelets are impaired in their ability to stimulate YAP and Smad2 signaling in tumor cells, two pathways regulating PAI-1 expression. Finally, we show that mice expressing mutant PI3Kβ show reduced spontaneous metastasis, and platelets isolated from these mice are less able to stimulate experimental metastasis in WT mice. Taken together, these data support a role for platelet PI3Kβ in promoting breast cancer metastasis and highlight platelet PI3Kβ as a potential therapeutic target.

Significance

We demonstrate that platelet PI3Kβ regulates metastasis, broadening the potential use of PI3Kβ-selective inhibitors as novel agents to treat metastasis.

Lineage commitment pathways epigenetically oppose oncogenic Gαq/11-YAP signaling in dormant disseminated uveal melanoma

The mechanisms driving late relapse in uveal melanoma (UM) patients remains a medical mystery and major challenge. Clinically it is inferred that UM disseminated cancer cells (DCCs) persist asymptomatic for years-to-decades mainly in the liver before they manifest as symptomatic metastasis. Here we reveal using Gαq/11 mut /BAP wt human uveal melanoma models and human UM metastatic samples, that the neural crest lineage commitment nuclear receptor NR2F1 is a key regulator of spontaneous UM DCC dormancy in the liver. Using a quiescence reporter, RNA-seq and multiplex imaging we revealed that rare dormant UM DCCs upregulate NR2F1 expression and genes related to neural crest programs while repressing gene related to cell cycle progression. Gain and loss of function assays showed that NR2F1 silences YAP1/TEAD1 transcription downstream of Gαq/11 signaling and that NR2F1 expression can also be repressed by YAP1. YAP1 expression is repressed by NR2F1 binding to its promoter and changing the histone H3 tail activation marks to repress YAP1 transcription. In vivo CRISPR KO of NR2F1 led dormant UM DCCs to awaken and initiate relentless liver metastatic growth. Cut&Run and bulk RNA sequencing further confirmed that NR2F1 epigenetically stimulates neuron axon guidance and neural lineage programs, and it globally represses gene expression linked to G-protein signaling to drive dormancy. Pharmacological inhibition of Gαq/11 mut signaling resulted in NR2F1 upregulation and robust UM growth arrest, which was also achieved using a novel NR2F1 agonist. Our work sheds light on the molecular underpinnings of UM dormancy revealing that transcriptional programs driven by NR2F1 epigenetically short-circuit Gαq/11 signaling to its downstream target YAP1.

Highlights

Quiescent solitary uveal melanoma (UM) DCCs in the liver up- and down-regulate neural crest and cell cycle progression programs, respectively.NR2F1 drives solitary UM DCC dormancy by antagonizing the Gαq/11-YAP1 pathway; small molecule Gαq/11 inhibition restores NR2F1 expression and quiescence. NR2F1 short-circuits oncogenic YAP1 and G-protein signaling via a chromatin remodeling program. Loss of function of NR2F1 in dormant UM DCCs leads to aggressive liver metastasis.

Graphical abstract

Cancer metastasis under the magnifying glass of epigenetics and epitranscriptomics

Most of the cancer-associated mortality and morbidity can be attributed to metastasis. The role of epigenetic and epitranscriptomic alterations in cancer origin and progression has been extensively demonstrated during the last years. Both regulations share similar mechanisms driven by DNA or RNA modifiers, namely writers, readers, and erasers; enzymes responsible of respectively introducing, recognizing, or removing the epigenetic or epitranscriptomic modifications. Epigenetic regulation is achieved by DNA methylation, histone modifications, non-coding RNAs, chromatin accessibility, and enhancer reprogramming. In parallel, regulation at RNA level, named epitranscriptomic, is driven by a wide diversity of chemical modifications in mostly all RNA molecules. These two-layer regulatory mechanisms are finely controlled in normal tissue, and dysregulations are associated with every hallmark of human cancer. In this review, we provide an overview of the current state of knowledge regarding epigenetic and epitranscriptomic alterations governing tumor metastasis, and compare pathways regulated at DNA or RNA levels to shed light on a possible epi-crosstalk in cancer metastasis. A deeper understanding on these mechanisms could have important clinical implications for the prevention of advanced malignancies and the management of the disseminated diseases. Additionally, as these epi-alterations can potentially be reversed by small molecules or inhibitors against epi-modifiers, novel therapeutic alternatives could be envisioned.

Secreted frizzled-related proteins: A promising therapeutic target for cancer therapy through Wnt signaling inhibition

The Wnt signaling system is a critical pathway that regulates embryonic development and adult homeostasis. Secreted frizzled-related proteins (SFRPs) are extracellular inhibitors of Wnt signaling that act by binding directly to Wnt ligands or Frizzled receptors. SFRPs can act as anti-Wnt agents and suppress cancer growth by blocking the action of Wnt ligands. However, SFRPs are often silenced by promoter methylation in cancer cells, resulting in hyperactivation of the Wnt pathway. Epigenetic modifiers can reverse this silencing and restore SFRPs expression. Despite the potential of SFRPs as a therapeutic target, the effects of SFRPs on tumor development remain unclear. Therefore, a review of the expression of various members of the SFRPs family in different cancers and their potential as therapeutic targets is warranted. This review aims to summarize the current knowledge of SFRPs in cancer, focusing on their expression patterns and their potential as novel therapeutic targets.

Norepinephrine alleviates cyclosporin A-induced nephrotoxicity by enhancing the expression of SFRP1

Norepinephrine (NE) has a certain effect on the improvement of renal function. However, whether NE can alleviate cyclosporin A (CsA)-induced nephrotoxicity needs further study. The effect of CsA (1.25, 2.5, 5, and 10 μM) on the human renal epithelial cell vitality, lactate dehydrogenase (LDH) activity, apoptosis, and secreted frizzled-related protein 1 (SFRP1) level was examined by cell counting kit-8, enzyme-linked immunosorbent assay, flow cytometer, and western blot. The effect of NE on the LDH activity, apoptosis, and SFRP1 level of human renal epithelial cells induced by CsA was examined again. After silencing of SFRP1 in human renal epithelial cells, the SFRP1 level, cell vitality, and apoptosis were examined again. CsA (1.25, 2.5, 5, and 10 μM) attenuated the cell vitality and SFRP1 level but enhanced the LDH activity and apoptosis in human renal epithelial cells, while the above effects were reversed by NE. Moreover, SFRP1 silencing reversed the regulation of NE on the SFRP1 level, cell vitality, and apoptosis in human renal epithelial cells induced by CsA. In conclusion, NE relieved CsA-induced nephrotoxicity via enhancing the expression of SFRP1.

The logistics of Wnt production and delivery

Wnts are secreted proteins that control stem cell maintenance, cell fate decisions, and growth during development and adult homeostasis. Wnts carry a post-translational modification not seen in any other secreted protein: during biosynthesis, they are appended with a palmitoleoyl moiety that is required for signaling but also impairs solubility and hence diffusion in the extracellular space. In some contexts, Wnts act only in a juxtacrine manner but there are also instances of long range action. Several proteins and processes ensure that active Wnts reach the appropriate target cells. Some, like Porcupine, Wntless, and Notum are dedicated to Wnt function; we describe their activities in molecular detail. We also outline how the cell infrastructure (secretory, endocytic, and retromer pathways) contribute to the progression of Wnts from production to delivery. We then address how Wnts spread in the extracellular space and form a signaling gradient despite carrying a hydrophobic moiety. We highlight particularly the role of lipid-binding Wnt interactors and heparan sulfate proteoglycans. Finally, we briefly discuss how evolution might have led to the emergence of this unusual signaling pathway.

Matrix Metalloproteinase-10 in Kidney Injury Repair and Disease

Matrix metalloproteinase-10 (MMP-10) is a zinc-dependent endopeptidase with the ability to degrade a broad spectrum of extracellular matrices and other protein substrates. The expression of MMP-10 is induced in acute kidney injury (AKI) and chronic kidney disease (CKD), as well as in renal cell carcinoma (RCC). During the different stages of kidney injury, MMP-10 may exert distinct functions by cleaving various bioactive substrates including heparin-binding epidermal growth factor (HB-EGF), zonula occludens-1 (ZO-1), and pro-MMP-1, -7, -8, -9, -10, -13. Functionally, MMP-10 is reno-protective in AKI by promoting HB-EGF-mediated tubular repair and regeneration, whereas it aggravates podocyte dysfunction and proteinuria by disrupting glomerular filtration integrity via degrading ZO-1. MMP-10 is also involved in cancerous invasion and emerges as a promising therapeutic target in patients with RCC. As a secreted protein, MMP-10 could be detected in the circulation and presents an inverse correlation with renal function. Due to the structural similarities between MMP-10 and the other MMPs, development of specific inhibitors targeting MMP-10 is challenging. In this review, we summarize our current understanding of the role of MMP-10 in kidney diseases and discuss the potential mechanisms of its actions.

Comprehensive Analysis of SFRP Family Members Prognostic Value and Immune Infiltration in Gastric Cancer

Gastric cancer (GC) is the fifth most common cancer globally. Secreted frizzled-related proteins (SFRP) are important elements associated with the Wnt signaling pathway, and its dysregulated expression is found in multiple cancers. However, the function of distinct SFRPs in GC remains poorly understood. We investigated the differential expression, prognostic value, and immune cell infiltration of SFRPs in gastric cancer patients from the Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), UALCAN, Kaplan-Meier plotter, cBioPortal, STRING, Gene-MANIA, DAVID, MethSurv, and TIMER databases. We found that the expression levels of SFRP2 and SFRP4 were significantly increased in GC tissues, whereas the SFRP1 and SFRP5 expressions were reduced. SFRP1, SFRP2, and SFRP5 were significantly correlated with the clinical cancer stage in GC patients. Higher expression of SFRPs was associated with short overall survival (OS) in GC patients. Besides, high SFRPs methylation showed favorable OS in GC patients. The functions of SFRPs were primarily related to the Wnt signaling pathway, immune system development, and basal cell carcinoma. The expression of SFRPs was strongly correlated with immune infiltrating cells, including CD4+ T cells and macrophages in GC. Our study indicated that SFRPs could be potential targets of precision therapy and prognostic biomarkers for the survival of GC patients.

Identification of DNA methylation patterns and biomarkers for clear-cell renal cell carcinoma by multi-omics data analysis

Background

Tumorigenesis is highly heterogeneous, and using clinicopathological signatures only is not enough to effectively distinguish clear cell renal cell carcinoma (ccRCC) and improve risk stratification of patients. DNA methylation (DNAm) with the stability and reversibility often occurs in the early stage of tumorigenesis. Disorders of transcription and metabolism are also an important molecular mechanisms of tumorigenesis. Therefore, it is necessary to identify effective biomarkers involved in tumorigenesis through multi-omics analysis, and these biomarkers also provide new potential therapeutic targets.

Method

The discovery stage involved 160 pairs of ccRCC and matched normal tissues for investigation of DNAm and biomarkers as well as 318 cases of ccRCC including clinical signatures. Correlation analysis of epigenetic, transcriptomic and metabolomic data revealed the connection and discordance among multi-omics and the deregulated functional modules. Diagnostic or prognostic biomarkers were obtained by the correlation analysis, the Least Absolute Shrinkage and Selection Operator (LASSO) and the LASSO-Cox methods. Two classifiers were established based on random forest (RF) and LASSO-Cox algorithms in training datasets. Seven independent datasets were used to evaluate robustness and universality. The molecular biological function of biomarkers were investigated using DAVID and GeneMANIA.

Results

Based on multi-omics analysis, the epigenetic measurements uniquely identified DNAm dysregulation of cellular mechanisms resulting in transcriptomic alterations, including cell proliferation, immune response and inflammation. Combination of the gene co-expression network and metabolic network identified 134 CpG sites (CpGs) as potential biomarkers. Based on the LASSO and RF algorithms, five CpGs were obtained to build a diagnostic classifierwith better classification performance (AUC > 99%). A eight-CpG-based prognostic classifier was obtained to improve risk stratification (hazard ratio (HR) > 4; log-rank test, p-value < 0.01). Based on independent datasets and seven additional cancers, the diagnostic and prognostic classifiers also had better robustness and stability. The molecular biological function of genes with abnormal methylation were significantly associated with glycolysis/gluconeogenesis and signal transduction.

Conclusion

The present study provides a comprehensive analysis of ccRCC using multi-omics data. These findings indicated that multi-omics analysis could identify some novel epigenetic factors, which were the most important causes of advanced cancer and poor clinical prognosis. Diagnostic and prognostic biomarkers were identified, which provided a promising avenue to develop effective therapies for ccRCC.

Increased expression of secreted frizzled related protein 1 (SFRP1) predicts ampullary adenocarcinoma recurrence

Ampullary adenocarcinoma is a rare gastrointestinal cancer in which WNT signalling dysregulation has been previously reported. Secreted frizzled related protein 1 (SFRP1) is one of the extracellular ligands of WNT signalling. We performed bioinformatics analyses of SFRP1 expression in human cancer. Microarray analysis of SFRP1 in periampullary adenocarcinoma was obtained from the Gene Expression Omnibus GSE39409 dataset. SFRP1 expression in ampullary adenocarcinoma was detected by immunohistochemistry staining and correlated with patients’ clinical outcomes. Our results showed that SFRP1 expression had different clinical applications in all types of human cancer. No detected alteration of SFPR1 gene and SFRP1 expression in ampullary adenocarcinoma was lower than that in other periampullary adenocarcinomas. However, high expression levels of SFRP1 protein were correlated with cancer recurrence, peritoneal carcinomatosis and poor patient prognosis. Gene set enrichment analysis showed downregulation of multiple WNT-related genes in primary culture cells from ampullary adenocarcinoma, but SFRP1 expression was increased. We found an interaction between WNT, bone morphogenetic protein and hedgehog signalling with SFRP1. Furthermore, a high expression of SFRP1 predicted poor prognosis for ampullary adenocarcinoma patients. Because it is a multifunctional protein, SFRP1 targeting serves as a potential therapy for ampullary adenocarcinoma patients.

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.

SFRP4 expression correlates with epithelial mesenchymal transition-linked genes and poor overall survival in colon cancer patients

BACKGROUND

Colon cancer is among the most commonly diagnosed cancers in the United States with an estimated 97220 new cases expected by the end of 2018. It affects 1.2 million people around the world and is responsible for about 0.6 million deaths every year. Despite decline in overall incidence and mortality over the past 30 years, there continues to be an alarming rise in early-onset colon cancer cases (< 50 years). Patients are often diagnosed at late stages of the disease and tend to have poor survival. We previously showed that the WNT “gatekeeper” gene, secreted frizzled-related protein 4 (SFRP4), is over-expressed in early-onset colon cancer. SFRP4 is speculated to play an essential role in cancer by inhibiting the epithelial mesenchymal transition (EMT).

AIM

To investigate the correlation between SFRP4 expression and EMT-linked genes in colon cancer and how it affects patient survival.

METHODS

SFRP4 expression relative to that of EMT-linked genes and survival analysis were performed using the University of California Santa Cruz Cancer Browser interface.

RESULTS

SFRP4 was found to be co-expressed with the EMT-linked markers CDH2, FN1, VIM, TWIST1, TWIST2, SNAI1, SNAI2, ZEB1, ZEB2, POSTN, MMP2, MMP7, MMP9, and COL1A1. SFRP4 expression negatively correlated with the EMT-linked suppressors CLDN4, CLDN7, TJP3, MUC1, and CDH1. The expression of SFRP4 and the EMT-linked markers was higher in mesenchymal-like samples compared to epithelial-like samples which potentially implicates SFRP4-EMT mechanism in colon cancer. Additionally, patients overexpressing SFRP4 presented with poor overall survival (P = 0.0293).

CONCLUSION

Considering the implication of SFRP4 in early-onset colon cancer, particularly in the context of EMT, tumor metastasis, and invasion, and the effect of increased expression on colon cancer patient survival, SFRP4 might be a potential biomarker for early-onset colon cancer that could be targeted for diagnosis and/or disease therapy.

The molecular connection of histopathological heterogeneity in hepatocellular carcinoma: A role of Wnt and Hedgehog signaling pathways

Background

Hepatocellular carcinoma (HCC) is leading cause of cancer-related mortality and is categorized among the most common malignancies around the world. It is a heterogeneous tumor, which shows significant degree of histopathological heterogeneity. Despite the apparent histopathological diversity there has been very little distinct correlation between histopathological features and molecular aberrations particularly when it comes to the expression level of Wnt and Hh pathway molecules. The role of Wnt and Hh pathways in relation to HCC behavior viz. histopathological heterogeneity and aggressiveness is not known. Determining the sequential molecular changes and associated histopathological characteristic during HCC initiation, promotion, and progression would probably lead to a better treatment and prognosis.

Methods

N-Nitrosodiethylamine (DEN) induced HCC model in male Wistar rats were established to study the expression level of Wnt and Hh pathway molecules during different stages of hepatocarcinogenesis. Their expression levels were checked at mRNA and protein levels at initiation, promotion, and progression stages of HCC. The expression levels of Wnt and Hh pathway molecules were correlated with biospecimens of HCC patients of different stages.

Results

In the present study we identified the comprehensive change in the expression pattern of Wnt and Hh pathway molecules in DEN induced rodent hepatocarcinogenesis model. Our results demonstrate that β-catenin /CTNNB1 plays important role in tumor initiation and promotion by stimulating tumor cell proliferation. The activated Wnt signaling in early stage of HCC is associated with well-differentiated histological pattern. The Hh activity although activated during the initiation stage but is significantly increased during the early promotion stage of hepatocarcinogenesis. The increased activity of both Wnt & Hh pathways during promotion stage is associated with moderately-differentiated histological pattern and was simultaneously linked with an increased expression of MMP9. Furthermore, our data demonstrated that during the progression stage Wnt pathway is modestly down-regulated but the Hh pathway activity sustained which in turn is associated with aggressive and invasive phenotype and poorly-differentiated histopathology.

Conclusion

Our data uncovers the grade related expression of Wnt and Hh pathway molecules and the potential utility of these molecular signatures in daily clinical practice is to decide best therapy according to patients characteristic. Additionally, our data offer insight into the interaction between Wnt and Hh pathways which triggers HCC development and progression.

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.

Matricellular proteins in cancer: a focus on secreted Frizzled-related proteins

Tumours are complex entities, wherein cancer cells interact with myriad soluble, insoluble and cell associated factors. These microenvironmental mediators regulate tumour growth, progression and metastasis, and are produced by cancer cells and by stromal components such as fibroblast, adipocytes and immune cells. Through their ability to bind to extracellular matrix proteins, cell surface receptors and growth factors, matricellular proteins enable a dynamic reciprocity between cancer cells and their microenvironment. Hence, matricellular proteins play a critical role in tumour progression by regulating where and when cancer cells are exposed to key growth factors and regulatory proteins. Recent studies suggest that, in addition to altering Wingless (Wnt) signalling, certain members of the Secreted Frizzled Related Protein (sFRP) family are matricellular in nature. In this review, we outline the importance of matricellular proteins in cancer, and discuss how sFRPs may function to both inhibit and promote cancer progression in a context-dependent manner. By considering the matricellular functionality of sFRPs, we may better understand their apparently paradoxical roles in cancers.

A pan-cancer analysis of secreted Frizzled-related proteins: re-examining their proposed tumour suppressive function

Secreted frizzled-related proteins (SFRPs), containing five family members (SFRPs 1-5) are putative extracellular Wnt inhibitors. Given their abilities to inhibit Wnt signalling, as well as the loss of SFRP1 in many cancers, this family is generally considered to be tumour suppressive. In this study we analyzed gene expression, promoter methylation and survival data from over 8000 tumour and normal samples from 29 cancers in order to map the context-specific associations of SFRPs 1-5 with patient survival, gene silencing and gene expression signatures. We show that only SFRP1 associates consistently with tumour suppressive functions, and that SFRP2 and SFRP4 typically associate with a poor prognosis concomitant with the expression of genes associated with epithelial-to-mesenchymal transition. Moreover, our results indicate that while SFRP1 is lost in cancer cells via the process of DNA methylation, SFRP2 and 4 are likely derived from the tumour stroma, and thus tend to increase in tumours as compared to normal tissues. This in-depth analysis highlights the need to study each SFRP as a separate entity and suggests that SFRP2 and SFRP4 should be approached as complex matricellular proteins with functions that extend far beyond their putative Wnt antagonistic ability.

DNA methylation level of OPCML and SFRP1: a potential diagnostic biomarker of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a malignancy of the bile duct epithelium which is caused by liver fluke infection. The clinical symptoms of CCA were revealed as the disease progresses to advanced stage. Thus, specific diagnostic biomarkers are important for this fatal disease. We applied methylation-sensitive high-resolution melting (MS-HRM) to quantify DNA methylation levels of opioid binding protein/cell adhesion molecule-like gene (OPCML) and Secreted frizzled-related protein 1 (SFRP1) in 73 primary CCA and 10 adjacent normal tissues and evaluated the sensitivity, specificity, and accuracy of the assay. The median methylation level of OPCML in CCA was 38.7 % (ranged from 0 to 82.2 %) and of SFRP1 was 31.5 % (ranged from 0 to 86.2 %). Methylation cutoff values of OPCML and SFRP1 derived from adjacent normal tissue were 6.90 and 10.44 %, respectively. With these cutoff values, the area under curve (AUC) of OPCML was 0.932 (95 % CI 0.878-0.986) and of SFRP1 was 0.951 (95 % CI 0.905-0.996). The sensitivity, specificity, and accuracy of OPCML were 89.04, 100, and 90.36 %, respectively, and of SFRP1 were 83.56, 100, and 85.54 %, respectively. In conclusion, the DNA methylation levels of OPCML and SFRP1 could be potential biomarkers for diagnosis of CCA with high specificity, sensitivity, and accuracy, in particular for biopsy specimens. Further validation in noninvasive samples such as serum or plasma is warranted for clinical applicability, especially as early diagnostic biomarkers.

Regional biases in mutation screening due to intratumoural heterogeneity of prostate cancer

Intratumoural heterogeneity (ITH) leads to regional biases of the mutational landscape in a single tumour and may influence the single biopsy-based clinical diagnosis and treatment decision. To evaluate the extent of ITH in unifocal prostate cancers (PCAs), we analysed multiple regional biopsies from three PCAs, using whole-exome sequencing, DNA copy number and gene expression profiling analyses. A substantial level of ITH was identified, in that 0-61% and 18-71% of somatic variants were common or private, respectively, within a given cancer. The enhanced mutation detection rate in the combined sequencing dataset across intratumoural biopsies was demonstrated with respect to the total number of mutations identified in a given tumour. Allele frequencies of the mutations were positively correlated with the levels of intratumoural recurrence (private < shared < common), but some common mutations showed low allele frequency, suggesting that not all were clonally fixed. Regional biases in the presentation of a well-known TMPRSS2-ERG fusion was noted in one PCA and the somatic mutation- and copy number-based phylogenetic relationships between intratumoural biopsies were largely concordant. Genes showing intratumoural expression variability were commonly enriched in the molecular function of eicosanoid metabolism and PCA-relevant clinical markers. Taken together, our analyses identified a substantial level of genetic ITH in unifocal PCAs at the mutation, copy number and expression levels, which should be taken into account for the identification of biomarkers in the clinical setting.

Protein expression under sustained activation of signal transducer and activator of transcription-3 in diethylnitrosamine-induced rat liver carcinogenesis

The aim of the present study was to investigate the expression of proteins associated with the sustained activation of the signal transducer and activator of transcription (STAT)-3 pathway during diethylnitrosamine (DEN)-induced rat liver carcinogenesis. DEN was intermittently administered to rats to induce liver cancer, and light and electron microscopy were used to observe the morphological changes in the liver during carcinogenesis. Western blotting and quantitative polymerase chain reaction (qPCR) were used to detect the expression of STAT-3, phosphorylated (p)-STAT-3, matrix metalloproteinase (MMP)-10, vascular endothelial growth factor (VEGF), kinase insert domain receptor (KDR), hypoxia inducible factor (HIF)-1α, basic fibroblast growth factor (bFGF) and interleukin (IL)-10, in order to investigate the association between STAT-3 and p-STAT-3 expression and MMP-10, VEGF, KDR, HIF-1α, bFGF and IL-10. The western blotting and qPCR results revealed that the expression of STAT-3, p-STAT-3, MMP-10, VEGF, KDR, HIF-1α, bFGF and IL-10 proteins gradually increased during carcinogenesis. Furthermore, the STAT-3 and p-STAT-3 levels were found to positively correlate with MMP-10, VEGF, KDR, HIF-1α, bFGF and IL-10 protein expression. During DEN-induced rat liver carcinogenesis, STAT-3 protein continually activated MMP-10, VEGF, KDR, HIF-1α, bFGF and IL-10, and its expression was found to positively correlate with the expression of these proteins.

Myofibroblast-derived SFRP1 as potential inhibitor of colorectal carcinoma field effect

Epigenetic changes of stromal-epithelial interactions are of key importance in the regulation of colorectal carcinoma (CRC) cells and morphologically normal, but genetically and epigenetically altered epithelium in normal adjacent tumor (NAT) areas. Here we demonstrated retained protein expression of well-known Wnt inhibitor, secreted frizzled-related protein 1 (SFRP1) in stromal myofibroblasts and decreasing epithelial expression from NAT tissues towards the tumor. SFRP1 was unmethylated in laser microdissected myofibroblasts and partially hypermethylated in epithelial cells in these areas. In contrast, we found epigenetically silenced myofibroblast-derived SFRP1 in CRC stroma. Our results suggest that the myofibroblast-derived SFRP1 protein might be a paracrine inhibitor of epithelial proliferation in NAT areas and loss of this signal may support tumor proliferation in CRC.

Secreted frizzled related proteins: Implications in cancers

The Wnt (wingless-type) signaling pathway plays an important role in embryonic development, tissue homeostasis, and tumor progression becaluse of its effect on cell proliferation, migration, and differentiation. Secreted frizzled-related proteins (SFRPs) are extracellular inhibitors of Wnt signaling that act by binding directly to Wnt ligands or to Frizzled receptors. In recent years, aberrant expression of SFRPs has been reported to be associated with numerous cancers. As gene expression of SFRP members is often lost through promoter hypermethylation, inhibition of methylation through the use of epigenetic modifying agents could renew the expression of SFRP members and further antagonize deleterious Wnt signaling. Several reports have described epigenetic silencing of these Wnt signaling antagonists in various human cancers, suggesting their possible role as tumor suppressors. SFRP family members thus come across as potential tools in combating Wnt-driven tumorigenesis. However, little is known about SFRP family members and their role in different cancers. This review comprehensively covers all the available information on the role of SFRP molecules in various human cancers.

MiR-328 promotes glioma cell invasion via SFRP1-dependent Wnt-signaling activation

Background Diffusely infiltrative growth of human astrocytic gliomas is one of the major obstacles to successful tumor therapy. Thorough insights into the molecules and pathways signaling glioma cell invasion thus appear of major relevance for the development of targeted and individualized therapies. By miRNA expression profiling of microdissected human tumor biopsy specimens we identified miR-328 as one of the main miRNAs upregulated in invading glioma cells in vivo and further investigated its role in glioma pathogenesis. Methods We employed miRNA mimics and inhibitors to functionally characterize miR-328, 3' untranslated region luciferase assays, and T-cell factor/lymphoid enhancer factor reporter assays to pinpoint miR-328 targets and signaling pathways, and analyzed miR-328 expression in a large panel of gliomas. Results First, we corroborated the invasion-promoting role of miR-328 in A172 and TP365MG glioma cells. Secreted Frizzled-related protein 1 (SFRP1), an inhibitor of Wnt signaling, was then pinpointed as a direct miR-328 target. SFRP1 expression is of prognostic relevance in gliomas with reduced expression, being associated with significantly lower overall patient survival in both the Repository of Molecular Brain Neoplasia Data (REMBRANDT) and The Cancer Genome Atlas. Of note, miR-328 regulated both SFRP1 protein expression levels and Wnt signaling pathway activity. Finally, in human glioma tissues miR-328 appeared to account for the downregulation of SFRP1 preferentially in lower-grade astrocytic gliomas and was inversely related to SFRP1 promoter hypermethylation. Conclusion Taken together, we report on a novel molecular miR-328-dependent mechanism that via SFRP1 inhibition and Wnt activation contributes to the infiltrative glioma phenotype at already early stages of glioma progression, with unfavorable prognostic implications for the final outcome of the disease.

Secreted Frizzled-related protein potentiation versus inhibition of Wnt3a/β-catenin signaling

Wnt signaling regulates a variety of cellular processes during embryonic development and in the adult. Many of these activities are mediated by the Frizzled family of seven-pass transmembrane receptors, which bind Wnts via a conserved cysteine-rich domain (CRD). Secreted Frizzled-related proteins (sFRPs) contain an amino-terminal, Frizzled-like CRD and a carboxyl-terminal, heparin-binding netrin-like domain. Previous studies identified sFRPs as soluble Wnt antagonists that bind directly to Wnts and prevent their interaction with Frizzleds. However, subsequent observations suggested that sFRPs and Frizzleds form homodimers and heterodimers via their respective CRDs, and that sFRPs can stimulate signal transduction. Here, we present evidence that sFRP1 either inhibits or enhances signaling in the Wnt3a/β-catenin pathway, depending on its concentration and the cellular context. Nanomolar concentrations of sFRP1 increased Wnt3a signaling, while higher concentrations blocked it in HEK293 cells expressing a SuperTopFlash reporter. sFRP1 primarily augmented Wnt3a/β-catenin signaling in C57MG cells, but it behaved as an antagonist in L929 fibroblasts. sFRP1 enhanced reporter activity in L cells that were engineered to stably express Frizzled 5, though not Frizzled 2. This implied that the Frizzled expression pattern could determine the response to sFRP1. Similar results were obtained with sFRP2 in HEK293, C57MG and L cell reporter assays. CRDsFRP1 mimicked the potentiating effect of sFRP1 in multiple settings, contradicting initial expectations that this domain would inhibit Wnt signaling. Moreover, CRDsFRP1 showed little avidity for Wnt3a compared to sFRP1, implying that the mechanism for potentiation by CRDsFRP1 probably does not require an interaction with Wnt protein. Together, these findings demonstrate that sFRPs can either promote or suppress Wnt/β-catenin signaling, depending on cellular context, concentration and most likely the expression pattern of Fzd receptors.

High levels of secreted frizzled-related protein 1 correlate with poor prognosis and promote tumourigenesis in gastric cancer

BACKGROUND

Secreted frizzled-related protein 1 (sFRP1), Wnt signalling regulator, can positively or negatively regulate tumourigenesis and progression. We sought to determine the clinical relevance and the role of sFRP1 in gastric cancer development and progression.

METHODS

We investigated the sFRP1 protein expression levels and its clinicopathological correlations using 85 cases of human gastric samples with survival information (JWCI cohort). mRNA levels of sFRP1 and coexpressed genes were analysed using 131-sample cDNA microarray data (Ruijin cohort). The effects of sFRP1 alteration were investigated using cell proliferation, colony formation, migration, and invasion and xenograft models.

RESULTS

We show that sFRP1 is overexpressed in some human cancers and is significantly associated with lymph node metastasis and decreased overall survival in gastric cancer patients. Using gastric cancer cell models, we demonstrate that sFRP1 overexpression is correlated with the activation of TGFβ (transforming growth factor-beta) signalling pathway and thereby induces cell proliferation, epithelial-mesenchymal transition (EMT), and invasion. Conversely, sFRP1 knockdown shows the opposite effects. Furthermore, sFRP1 overexpression promotes tumourigenesis and metastasis in a xenograft model.

CONCLUSION

Our studies demonstrate that sFRP1 is a biomarker for aggressive subgroups of human gastric cancer and a prognostic biomarker for patients with poor survival. Our data provide insight into a crosstalk between Wnt and TGFβ pathways which underlies gastric cancer development and progression.

Expression of SFRP Family Proteins in Human Keratoconus Corneas

We investigated the expression of the secreted frizzled-related proteins (SFRPs) in keratoconus (KC) and control corneas. KC buttons (∼8 mm diameter) (n = 15) and whole control corneas (n = 7) were fixed in 10% formalin or 2% paraformaldehyde and subsequently paraffin embedded and sectioned. Sections for histopathology were stained with hematoxylin and eosin, or Periodic Acid Schiff's reagent. A series of sections was also immunolabelled with SFRP 1 to 5 antibodies, visualised using immunofluorescence, and examined with a Zeiss LSM700 scanning laser confocal microscope. Semi-quantitative grading was used to compare SFRP immunostaining in KC and control corneas. Overall, KC corneas showed increased immunostaining for SFRP1 to 5, compared to controls. Corneal epithelium in all KC corneas displayed heterogeneous moderate to strong immunoreactivity for SFRP1 to 4, particularly in the basal epithelium adjacent to cone area. SFRP3 and 5 were localised to epithelial cell membranes in KC and control corneas, with increased SFRP3 cytoplasmic expression observed in KC. Strong stromal expression of SFRP5, including extracellular matrix, was seen in both KC and control corneas. In control corneas we observed differential expression of SFRP family proteins in the limbus compared to more central cornea. Taken together, our results support a role for SFRPs in maintaining a healthy cornea and in the pathogenesis of epithelial and anterior stromal disruption observed in KC.

Unexpected close surgical margin in resected buccal cancer: very close margin and DAPK promoter hypermethylation predict poor clinical outcomes

OBJECTIVES

In resected buccal cancer patients, an unexpected close surgical margin has been observed to correlate with poor clinical outcomes. However, close surgical margin alone does not independently guide post-operative therapies, revealing a clinical debate. Hence, the present study intended to explore epigenetic-based bio-predictors for further stratifying this debating patient population.

MATERIALS AND METHODS

Between 2000 and 2008, we retrospectively recruited 44 resected buccal cancer patients with a close surgical margin of ≤5 mm. All patients had post-operative radiotherapy. Genomic DNA was extracted from tumor-enrich areas that contained cancer cells of >70%. Methylation-specific PCR was performed to detect promoter methylation of four tumor suppressor genes, including RASSF1A, DAPK, IRF8, and SFRP1. Post-irradiation locoregional control was defined as the primary end point.

RESULTS

There were 40 males and 4 females, with a median age of 53.5 years (range, 32-82 years). Multivariate analysis identified two independent predictors for locoregional recurrence: very close margin of ≤1 mm (HR: 4.96; 95% CI, 1.63-15.09; P=0.018) and promoter hypermethylation of DAPK (HR: 2.83; 95% CI, 1.05-7.63; P=0.042). The highest risk of locoregional recurrence was observed in patients with both of the two factors (HR, 8.05; 95% CI, 2.56-25.82; P=0.002) when compared with patients with none. Shorter disease-free survival, but not overall survival, was also observed.

CONCLUSION

More aggressive managements should be considered in resected buccal cancer patients with both very close margin and DAPK promoter hypermethylation rather than post-operative observation or radiotherapy alone.

Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review)

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in progress in the treatment of liver cancer.

SFRP1 CpG island methylation locus is associated with renal cell cancer susceptibility and disease recurrence

Loss of the secreted Fzd-related protein 1 (SFRP1) and concurrent alteration of the SFRP1/WNT pathway are frequently observed in human cancers such as in renal cell cancer (RCC). Whether methylation of a SFRP1 CpG island locus in normal human solid tissues is associated with increased tissue specific cancer risk has not been determined to date. Here we measure the cancer risk attributable to SFRP1 DNA methylation in renal tissue. Pyrosequencing of bisulfite treated DNA was used for a case-control study including 120 normal-appearing renal tissues of autopsy specimens and 72 normal-appearing tissues obtained from tumor adjacent areas, and a cross sectional study of 96 RCCs. Association of methylation with demographic risk factor age, clinicopathological parameters and course of patients was investigated. We show significant hypermethylation of a SFRP1 CpG island locus in normal-appearing renal tissues from RCC patients compared with normal-appearing autopsy kidney tissues. Inter quartile analysis revealed a 6-, 13- and 11-fold increased cancer risk for the second, third and fourth quartiles of methylation in the age matched subgroup of tissues (p = 0.001, p = 1.3E-6, p = 6.9E-6). Methylation in autopsy tissues increased with age and methylation in tumors was an independent predictor of recurrence free survival. SFRP1 DNA methylation, accumulates with age in normal-appearing kidney tissues and is associated with increased renal cancer risk, suggesting this CGI sub region as an epigenetic susceptibility locus for RCC. Our data underline the need to further analyze the tissue specific risks conferred by methylated loci for the development of human cancers.

TGF-β-activated kinase-1: New insights into the mechanism of TGF-β signaling and kidney disease

Transforming growth factor-β (TGF-β) is a multifunctional cytokine that regulates a wide variety of cellular functions, including cell growth, cellular differentiation, apoptosis, and wound healing. TGF-β1, the prototype member of the TGF-β superfamily, is well established as a central mediator of renal fibrosis. In chronic kidney disease, dysregulation of expression and activation of TGF-β1 results in the relentless synthesis and accumulation of extracellular matrix proteins that lead to the development of glomerulosclerosis and tubulointerstitial fibrosis, and ultimately to end-stage renal disease. Therefore, specific targeting of the TGF-β signaling pathway is seemingly an attractive molecular therapeutic strategy in chronic kidney disease. Accumulating evidence demonstrates that the multifunctionality of TGF-β1 is connected with the complexity of its cell signaling networks. TGF-β1 signals through the interaction of type I and type II receptors to activate distinct intracellular pathways. Although the Smad signaling pathway is known as a canonical pathway induced by TGF-β1, and has been the focus of many previous reviews, importantly TGF-β1 also induces various Smad-independent signaling pathways. In this review, we describe evidence that supports current insights into the mechanism and function of TGF-β-activated kinase 1 (TAK1), which has emerged as a critical signaling molecule in TGF-β-induced Smad-independent signaling pathways. We also discuss the functional role of TAK1 in mediating the profibrotic effects of TGF-β1.

Wnt signaling pathways in urological cancers: past decades and still growing

The Wnt signaling pathway is involved in a wide range of embryonic patterning events and maintenance of homeostasis in adult tissues. The pathological role of the Wnt pathway has emerged from studies showing a high frequency of specific human cancers associated with mutations that constitutively activate the transcriptional response of these pathways. Constitutive activation of the Wnt signaling pathway is a common feature of solid tumors and contributes to tumor development, progression and metastasis in various cancers. In this review, the Wnt pathway will be covered from the perspective of urological cancers with emphasis placed on the recent published literature. Regulation of the Wnt signaling pathway by microRNAs (miRNA), small RNA sequences that modify gene expression profiles will also be discussed. An improved understanding of the basic genetics and biology of Wnt signaling pathway will provide insights into the development of novel chemopreventive and therapeutic strategies for urological cancers.

The complex roles of Wnt antagonists in RCC

Renal cell carcinoma (RCC) is the most lethal of all the genitourinary cancers, as it is generally refractory to current treatment regimens, including chemotherapy and radiation therapy. Targeted therapies against critical signaling pathways associated with RCC pathogenesis, such as vascular endothelial growth factor, von Hippel-Lindau tumor suppressor and mammalian target of rapamycin, have shown limited efficacy so far. Thus, Wnt signaling, which is known to be intricately involved in the pathogenesis of RCC, has attracted much interest. Several Wnt signaling components have been examined in RCC, and, while studies suggest that Wnt signaling is constitutively active in RCC, the molecular mechanisms differ considerably from other human carcinomas. Increasing evidence indicates that secreted Wnt antagonists have important roles in RCC pathogenesis. Considering these vital roles, it has been postulated--and supported by experimental evidence--that the functional loss of Wnt antagonists, for example by promoter hypermethylation, can contribute to constitutive activation of the Wnt pathway, resulting in carcinogenesis through dysregulation of cell proliferation and differentiation. However, subsequent functional studies of these Wnt antagonists have demonstrated the inherent complexities underlying their role in RCC pathogenesis.

Physiological inhibitors of Wnt signaling

Wnt signaling is crucial for cell proliferation and differentiation. It represents a complex network with mechanisms of self-regulation through positive and negative feedback. Recent increasing interest in this signaling pathway has led to the discovery of many new proteins that down-regulate Wnt activity. Here, we provide a short description of the most important and best-studied inhibitors, group them according to the target molecule within the Wnt cascade, and discuss their clinical potential. Although most of the inhibitors discussed here may also interact with proteins from other signaling pathways, we focus only on their ability to modulate Wnt signaling.

The role of the basal stem cell of the human breast in normal development and cancer

MCF-10F, an ERα negative human breast epithelial cell line derived from normal breast tissue, is able to form ductal structures in a tridimensional collagen matrix system. MCF-10F cells that are estrogen transformed (trMCF cells) progressively express phenotypes of in vitro cell transformation, including colony formation in agar methocel and loss of the ductulogenic capacity. Selection of these trMCF cells for invasiveness identified cells (bcMCF) that formed tumors in severe combined immunodeficient mice. The cell lines derived from those tumors (caMCF) were poorly differentiated ER, PR, and ERBB2 negative adenocarcinomas. These characteristics are similar to the human basal cell-like carcinomas. This in vitro-in vivo model demonstrates the importance of the basal cell type as a stem cell that reconstitutes the branching pattern of the breast and that is also target of a carcinogenic insult leading to transformation and cancer.

High-resolution analysis of genomic alteration on chromosome arm 8p in urothelial carcinoma

Loss of chromosome arm 8p, sometimes in combination with amplification of proximal 8p, is found in urothelial carcinoma (UC) and other epithelial cancers and is associated with more advanced tumor stage. We carried out array comparative genomic hybridization on 174 UC and 33 UC cell lines to examine breakpoints and copy number. This was followed by a detailed analysis of the cell lines using fluorescence in situ hybridization (FISH) and, in some cases, M-FISH, to refine breakpoints and determine translocation partners, heterozygosity analysis, and analysis of expression of selected genes. We showed an overall pattern of 8p loss with reduced heterozygosity and reduced gene expression. Amplification was seen in some samples and shown in the cell line JMSU1 to correlate with overexpression of ZNF703, ERLIN2, PROSC, GPR124, and BRF2. Apart from the centromere, no single breakpoint was overrepresented, and we postulate that frequent complex changes without consistent breakpoints reflect the need for alterations of combinations of genes. The region around 2 Mb, which was homozygously deleted in one cell line and includes the gene ARHGEF10 and the micro-RNA hsa-mir-596, is one candidate tumor suppressor gene region.

Epigenetics of renal cell carcinoma: the path towards new diagnostics and therapeutics

Aberrant DNA methylation, in particular promoter hypermethylation and transcriptional silencing of tumor suppressor genes, has an important role in the development of many human cancers, including renal cell carcinoma (RCC). Indeed, apart from mutations in the well studied von Hippel-Lindau gene (VHL), the mutation frequency rates of known tumor suppressor genes in RCC are generally low, but the number of genes found to show frequent inactivation by promoter methylation in RCC continues to grow. Here, we review the genes identified as epigenetically silenced in RCC and their relationship to pathways of tumor development. Increased understanding of RCC epigenetics provides new insights into the molecular pathogenesis of RCC and opportunities for developing novel strategies for the diagnosis, prognosis and management of RCC.

The advantages and disadvantages of sfrp1 and sfrp2 expression in pathological events

Secreted Frizzled Related Proteins (Sfrps) are a family of secreted proteins that can bind both to Wnt ligands and Frizzled receptors, thereby modulating the Wnt signalling cascades. Recent studies have shown that Sfrps can also interact with Wnt unrelated molecules such as RANKL, a member of the tumor necrosis factor family, Tolloid metalloproteinases or integrin-fibronectin complexes. Alterations in the levels of Sfrp expression have been recently associated with different pathological conditions, including tumor formation and bone and myocardial disorders. Here, we summarise the evidence that relates Sfrps with these diseases and discuss how the proposed multiple Sfrp interactions with Wnt related and unrelated pathways may explain their implication in such diverse pathologies.

Wnt/beta-catenin signaling: a novel target for therapeutic intervention of fibrotic kidney disease

Fibrosis of epithelial parenchymal organs and end-stage organ failure, the final common pathway of many progressive chronic diseases including chronic kidney disease, continue to increase worldwide and are a major determinant of morbidity and mortality. Fibrosis is an active biosynthetic healing response initiated to protect the tissue from injury through the timed release of proteins but leads to serious tissue damage when it becomes independent from the initiating stimulus. Massive deposition of extracellular matrix by accumulation of myofibroblasts and disruption of the normal tissue architecture are characteristic of tissue fibrosis. The highly conserved Wnt/beta-catenin signaling pathway is essential to embryonic development in general and kidney morphogenesis in particular by regulating the expression of target genes, most often through the transcription factor T cell factor (TCF) and/or lymphoid enhancer factor (LEF). Emerging evidence from studies of renal fibrosis suggests that altered Wnt/beta-catenin signaling is linked to the pathogenesis of renal fibrosis. The renoprotective properties of some currently available drugs might be attributable in part to inhibition of Wnt signaling. The development of orally active Wnt modulators will provide a potentially important pharmacological tool for further investigating the role of Wnt/beta-catenin signaling and might offer a novel therapeutic strategy in renal fibrosis.

Role of secreted frizzled-related protein 3 in human renal cell carcinoma

The secreted frizzled-related protein (sFRP) family plays an important role in the inhibition of the Wnt signaling pathway in various cancers. The functional significance of Wnt antagonist sFRP3 has not been investigated in renal cancer. We performed tissue microarray and found that the level of sFRP3 protein was high in normal kidney, low in primary renal cancer tissues, and high in metastatic renal cancer tissues. Therefore, we hypothesized that sFRP3 may play an important role in metastatic renal cancer. To test this hypothesis, we performed a series of experiments to determine the role of sFRP3 using primary and metastatic renal cancer cell lines. Functional analysis showed increased numbers of viable and invaded cells and tube formation and decreased numbers of apoptotic cells in the sFRP3-transfected renal cancer cell line A498. Promotion of tumor growth was also observed in nude mice injected with sFRP3-transfected A498 cells. In contrast, the number of viable cells and invasive cells was decreased in sFRP3 mRNA knockdown metastatic cells (ACHN and Hs891.T). To investigate the mechanism of sFRP3 function, we performed microarray analysis to see which genes were upregulated or downregulated by sFRP3 expression. Among these genes, MMP-3 and ANGPT1 were significantly upregulated in sFRP3-transfected cells. In conclusion, this is the first report to show that sFRP3 expression promotes cell growth, invasion, and inhibition of apoptosis in renal cancer cells.