Secreted Frizzled-related Protein 2 Expression Research Articles

SFRP2 suppresses trophoblast cell migration by inhibiting the Wnt/β‑catenin pathway.

The present study investigates the role of Secreted Frizzled‑Related Protein 2 (SFRP2) in trophoblast cells, a key factor in preeclampsia (PE) progression. Elevated levels of Secreted Frizzled‑Related Protein 1/3/4/5 (SFRP1/3/4/5) are associated with PE, but the role of SFRP2 is unclear. We analyzed SFRP2 expression in PE placental tissue using the GSE10588 dataset and overexpressed SFRP2 in JEG‑3 cells via lentiviral transfection. The viability, migration, apoptosis, and proliferation of SFRP2‑overexpressing JEG‑3 cells were assessed using Cell Counting Kit‑8, Transwell assays, flow cytometry, and EdU staining. Additionally, we evaluated the impact of SFRP2 overexpression on key proteins in the Wnt/β‑catenin pathway and apoptosis markers (Bax, cleaved‑caspase 3, BCL‑2, MMP9, E‑cadherin, Wnt3a, Axin2, CyclinD1, c‑Myc, p‑β‑catenin, β‑catenin, phosphorylated Glycogen Synthase Kinase 3 beta (p‑GSK3β), and GSK3β) through western blotting. Results showed high SFRP2 mRNA and protein expression in PE placenta and JEG‑3 cells post‑transfection. SFRP2 overexpression significantly reduced JEG‑3 cell viability, proliferation, and migration, while increasing apoptosis. It also altered expression levels of Wnt pathway proteins, suggesting SFRP2's potential as a therapeutic target for PE by inhibiting trophoblast cell migration through the Wnt/β‑catenin signaling cascade.

Abstract A102: Secreted frizzled related-protein 2 is prognostic for survival in pancreatic cancer

Abstract INTRODUCTION: Secreted frizzled-related protein 2 (SFRP2) is overexpressed in several tumor types and blocks tumor apoptosis, increases angiogenesis, and promotes T-cell exhaustion. It has also been shown to be associated with fibrosis in non-neoplastic pathologies. We hypothesize SFRP2 is prognostic for survival and associated with PDAC fibrosis and mesenchymal transformation. METHODS: SFRP2 gene expression and protein levels in patients with PDAC were analyzed using NCI’s The Cancer Genome Atlas (TCGA) data and data from resected tumors analyzed for protein levels by western blot. Disease free survival (DFS) and overall survival (OS) were analyzed using Kaplan Meier test. The association of stroma content and SFPR2 RNA expression in human PDAC was studied using Spearman correlation between the ESTIMATE algorithm stromal score and TCGA data. The GEPIA tool was used to compare SFRP2 mRNA levels between PDAC and normal pancreas tissue. Immunohistochemistry (IHC) for SFRP2 in KPC PDAC tumors were correlated with fibrosis stains Picrosirus red and Massone trichome. The role of SFRP2 in mesenchymal transformation was assessed by western blot in fibroblasts. RESULTS: TCGA RNAseq analysis of SFRP2 expression showed highest SFRP2 mRNA levels in pancreatic cancer out of 32 cancer types. GEPIA analysis of PDAC (n=179) and normal pancreas (n=177) mRNA data showed higher levels of SFRP2 mRNA in PDAC compared to normal pancreas (p<.01). High SFRP2 mRNA levels were associated with decreased disease-free survival hazard ratio = 2.6; p=0.0097). PDAC tissue showed higher SFRP2 protein compared to matched normal-adjacent tissue (n=24, p=0.0003). High SFRP2 expression was associated with decreased OS (p=0.0158. The ESTIMATE stromal score correlated with SFRP2 expression in human PDAC (Spearman correlation coefficient 0.81). Fibrosis levels in KPC PDAC tumors correlated with SFRP2 IHC (Spearman correlation coefficient 0.75). Fibroblasts treated with SFRP2 and TGFβ showed higher mesenchymal markers compared to untreated control. CONCLUSIONS: SFRP2 is increased in PDAC, associated with tumor fibrosis, and prognostic for survival. SFRP2 is a novel therapeutic target in PDAC. Citation Format: Lillian Hsu, Julie Siegel, Patrick Nasarre, Rupak Mukherjee, Meghan Gormley, Bailey Richardson, Jordan Morningstar, Imran Khan, Eleanor Hilliard, John O’Bryan, Krist Helke, Laura Spruill, Nathan Dolloff, Nancy Klauber-Demore. Secreted frizzled related-protein 2 is prognostic for survival in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A102.

Secreted frizzled related-protein 2 is prognostic for human pancreatic cancer patient survival and is associated with fibrosis.

Pancreatic adenocarcinoma (PDAC) is one of the deadliest cancers, with five-year survival rates of 9%. We hypothesized that secreted frizzled-related protein 2 (SFRP2) may influence stromal growth in pancreatic cancer, since it increases fibrosis and collagen production in non-neoplastic pathologies. We assessed SFRP2 value as a biomarker and assessed its function in PDAC. SFRP2 gene expression in patients with PDAC was analyzed using TCGA data. Disease free survival (DFS) was analyzed using Kaplan Meier test. The effect of KRAS inhibition on SFRP2 expression in PDAC cells was assessed. The associations of stromal content with SFPR2 mRNA and protein with fibrosis were analyzed. The role of SFRP2 in mesenchymal transformation was assessed by western blot in fibroblasts. Of all cancers in TCGA, SFRP2 levels were highest in PDAC, and higher in PDAC than normal tissues (n= 234, p= 0.0003). High SFRP2 levels correlated with decreased DFS (p= 0.0097). KRAS inhibition reduced SFRP2 levels. Spearman correlation was 0.81 between stromal RNA and SFRP2 in human PDAC, and 0.75 between fibrosis and SFRP2 levels in PDAC tumors. SFRP2-treated fibroblasts displayed mesenchymal characteristics. SFRP2 is prognostic for PDAC survival, regulated by KRAS, and associated with PDAC fibrosis.

Abstract 4863: PMCA inhibition induces cytotoxic calcium stress and suppression of Wnt signaling in refractory molecular subtype of gastric cancer

Abstract Background: Gastric cancer (GC) is the fourth leading cause of cancer-related deaths worldwide, but its genetic heterogeneity retards the development of novel therapeutics. Recently, tumor molecular classification identified clinically refractory SEM (i.e., Stem-like, EMT and Mesenchymal) subtype GC which exhibited over-expression of the plasma membrane Ca2+ ATPase (PMCA) whose role is circumventing calcium overload causing ER stress and apoptosis. Here, we showed that PMCA4 is associated with Wnt signaling activity by regulating Secreted Frizzled-Related Protein 2 (SFRP2) expression and demonstrated that PMCA4 inhibition might achieve dual mechanism-specific anti-cancer effect by inducing calcium-mediated apoptosis and restraining oncogenic Wnt activity in SEM subtype GC. Materials and Methods: GC cell lines and patient-derived organoids (PDOs) were categorized either SEM-subtype (SNU484, SNU668, SK4, MKN1; GA077T, GA265T, GA333T, GA352T) or non-SEM subtype (MKN45, NCIN87, SNU16, SNU601; GA200T, GA247T, GA215T) based on transcriptome signatures or subtype-specific biomarker genes. PMCA4 expression was confirmed using western blot and its calcium clearance function was examined using Fluo-4 AM fluorescent Ca2+ dye. Biological and molecular characteristics of GC cell lines and PDOs upon PMCA4 inhibition were investigated using RT-qPCR, western blot, and TOPflash/FOPflash reporter assay. The target engagement of novel PMCA inhibitor PM058 (bis-indole maleimide derivative) was evaluated by cellular thermal shift assay (CETSA), and the efficacy was determined by CCK8 cell viability assay for cell lines and by Cell Titer-Glo for PDOs.Results: PMCA4 was highly expressed in SEM subtype GC cell lines and PDOs. The siRNA-mediated PMCA4 knockdown (KD) or pharmaceutical inhibition of PMCA4 suppressed the calcium clearance, the cell viability, and decreased cell invasion/migration. TCF/LEF-responsive reporter assay revealed that pharmaceutical inhibition of PMCA4 suppressed Wnt/beta-catenin signaling activity, proven by decrease in beta-catenin and Wnt target gene expression. PMCA inhibition was mechanistically associated with the increased expression of SFRP2, a Wnt antagonist. Importantly, PM058, a PMCA inhibitor, treatment resulted in highly efficacious anti-cancer effect in PDOs at nano molar range, which correlated with PMCA4 protein expression.Discussion and Conclusion: Our results provide the proof of concept that PMCA4 can be a promising therapeutic target for refractory subtype cancer. The proposed mechanism of PMCA4 inhibition is calcium overload - induced apoptosis and interfering with Wnt signaling activity via SFRP2 in GC. Importantly, we demonstrated a novel potent inhibitor PM058 that blocks PMCA function in clinically intractable SEM subtype GC cancer. Citation Format: Saeli Ban, Jungmin Kim, Jonghwan Bae, Ki Cheong Park, Suji Lee, Moon Hwan Kim, Jae-Ho Cheong. PMCA inhibition induces cytotoxic calcium stress and suppression of Wnt signaling in refractory molecular subtype of gastric cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4863.

Upregulation of circ_0059961 suppresses cholangiocarcinoma development by modulating miR-629-5p/SFRP2 axis

BackgroundCholangiocarcinoma (CCA) is a dangerous malignancy with a poor prognosis due to inefficient chemotherapy and surgery, and its pathophysiology could be linked to circular RNA (circRNAs) dysregulation. As a result, we wanted to see what role circ_0059961 plays in CCA. MethodsThe quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of circ_0059961, miR-629–5p, and secreted frizzled related protein 2 (SFRP2). Cell counting kit-8 (CCK-8) and 5-Ethynyl-2′-deoxyuridine (Edu) assay were used to determine the role of circ_0059961 in proliferation. The MMP (Δψm) assay was used to assess cell apoptosis. Transwell assay was used to detect cell migration and invasion. The SFRP2 protein and epithelia-mesenchymal transition (EMT) process related proteins expression were measured using Western blot. The putative relationship between miR-629–5p and circ_0059961 or SFRP2 was validated by dual-luciferase reporter assay. The circ_0059961 roles in cholangiocarcinoma were also investigated by tumor xenograft assay. ResultsCirc_0059961 expression was decreased in CCA tissues and carcinoma cells. Overexpressed circ_0059961 reduced tumor cell proliferation, migration, and invasion while inducing apoptosis. Circ_0059961 was proven to be a target of miR-629–5p, while miR-629–5p was confirmed to be a target of SFRP2. Circ_0059961 targeted miR-629–5p to modulate SFRP2 expression. Upregulation of miR-629–5p reversed the tumor-suppressive effects of circ_0059961 overexpression in rescue trials. Furthermore, SFRP2 overexpression restored miR-629–5p enrichment-promoted cell proliferation, migration, and invasion. Upregulated circ_0059961 reduced solid tumor growth in vivo. ConclusionUpregulation of circ_0059961 augmented SFRP2 expression by targeting miR-629–5p, which blocked cholangiocarcinoma tumor cell proliferation, migration, and invasion.

High Stromal SFRP2 Expression in Urothelial Carcinoma Confers an Unfavorable Prognosis.

BackgroundUrothelial carcinoma (UC) patients often bear clinical and genetic heterogeneity, which may differ in management and prognosis. Especially, patients with advanced/metastatic UC generally have a poor prognosis and survive for only few months. The Wnt/β-catenin signaling is found to be highly activated in several cancers, including UC. However, accumulated evidence has shown discordance between the Wnt/β-catenin signaling and UC carcinogenesis. Accordingly, we aim to get a better understanding of the molecular characterization of UC, focusing on the Wnt signaling, which may add value to guiding management more precisely.Patients and MethodsClinical data and pathological features were retrospectively surveyed. The correlations of secreted Frizzled-related protein 2 (SFRP2) immunoexpression with clinicopathological features were analyzed by Pearson’s chi-square test. The Kaplan–Meier method with a log-rank test was employed to plot survival curves. All significant features from the univariate analysis were incorporated into the Cox regression model for multivariate analysis.ResultsFollowing data mining on a transcriptome dataset (GSE31684), we identified that 8 transcripts in relation to the Wnt signaling pathway (GO: 0016055) were significantly upregulated in advanced/metastatic bladder tumors. Among these transcripts, the SFRP2 level showed the most significant upregulation. Additionally, as SFRP2 is a putative Wnt inhibitor and may be expressed by stroma, we were interested in examining the immunoexpression and clinical relevance of stromal and tumoral SFRP2 in our urothelial carcinoma cohorts containing 295 urinary bladder UC (UBUC) and 340 upper urinary tract UC (UTUC) patients. We observed that high SFRP2 expression in stroma but not in tumors is significantly linked to aggressive UC features, including high tumor stage and histological grade, positive nodal metastasis, the presence of vascular and perineural invasion, and high mitotic activity in UBUC and UTUC. Moreover, high stromal SFRP2 expression significantly and independently predicted worse clinical outcomes in UBUC and UTUC. Utilizing bioinformatic analysis, we further noticed that stromal SFRP2 may link epithelial–mesenchymal transition (EMT) to UC progression.ConclusionCollectively, these results imply that stromal SFRP2 may exert oncogenic function beyond its Wnt antagonistic ability, and stromal SFRP2 expression can provide prognostic and therapeutic implications for UC patients.

Downregulation of SFRP2 facilitates cancer stemness and radioresistance of glioma cells via activating Wnt/β-catenin signaling.

Secreted frizzled-related protein 2 (SFRP2) is a glycoprotein with frizzled-like cysteine-rich domain that binds with Wnt ligands or frizzled receptors to regulate Wnt signaling. SFRP2 is frequently hypermethylated in glioma patients, and analysis of TCGA data indicates that SFRP2 is one of the most downregulated genes in radiotherapy treated glioma patients. In the present study, we aimed to explore the potential function of SFRP2 in tumorigenesis and radioresistance of glioma. The RNA sequencing data of TCGA glioma samples were downloaded and analyzed. SFRP2 expression in 166 glioma patients was evaluated by qRT-PCR. The potential functions of SFRP2 in glioma were evaluated by loss-of-function assays and gain-of-function assays in glioma cell lines. We found that SFRP2 was downregulated in radiotherapy-treated glioma patients, and low SFRP2 expression was correlated with advanced tumor stage and poor prognosis. CRISP/Cas9-meidated SFRP2 knockdown promoted soft agar colony formation, cancer stemness and radioresistance of glioma cells, while enforced SFRP2 expression exhibited opposite effects. Moreover, Wnt/β-catenin signaling was activated in radiotherapy treated glioma patients. SFRP2 knockdown activated Wnt/β-catenin signaling in glioma cell lines, while overexpression of SFRP2 inhibited Wnt/β-catenin activation. Besides, pharmacological inhibition of Wnt/β-catenin signaling by XAV-939 abrogated the effects of SFRP2 knockdown on cancer stemness and radioresistance of glioma cells. Our data for the first time demonstrated a role of SFRP2 in radioresistance of glioma cells, and suggested that inhibition of Wnt/β-catenin signaling might be a potential strategy for increasing radiosensitivity of glioma patients.

Effects of YAP1 and SFRP2 overexpression on the biological behavior of colorectal cancer cells and their molecular mechanisms.

Colorectal cancer (CRC) is one of the most common malignancies worldwide and has a high mortality rate. With the development of tumor molecular biology, more and more attention is being paid to the mechanisms of cell pathways in colorectal carcinogenesis, such as the Hippo/Yes-associated protein 1 (YAP1) and Wnt/β-catenin signaling pathways. The abnormal expression of YAP1 and β-catenin have been reported in CRC, and can lead to excessive cell proliferation, and eventually, tumor formation. Secreted frizzled-related protein 2 (SFRP2) levels have been found to be decreased in a variety of cancers, and SFRP2 is an antagonist that binds directly to Wnt signal. At present, the molecular basis of colorectal tumors is still not fully understood. In the present study, we sought to identify the molecular mechanisms underlying YAP1 and SFRP2 in the development of CRC. We constructed CRC cell lines that stably overexpressed YAP1 and SFRP2 using lentivirus packaging and cell infection. The levels of expression of the proteins were evaluated by western blot and immunofluorescence assays. Protein complex immunoprecipitation (Co-IP) was used to detect the interaction between YAP1, SFRP2, and β-catenin. The functional roles of YAP1 and SFRP2 in CRC was determined by a Cell Counting Kit-8 (CCK8) proliferation assay and flow cytometric apoptosis assay. The data of the present study showed that the overexpression of SFRP2 promoted the expression of YAP1 and β-catenin protein, and the overexpression of YAP1 promoted the expression of β-catenin protein. YAP1 overexpression promoted cell proliferation, while SFRP2 overexpression inhibited cell proliferation and promoted cell apoptosis. Our findings showed that the expression of YAP1, SFRP2, and β-catenin is correlated in CRC cells. The Hippo pathway and Wnt pathway interact with each other in the pathogenesis of CRC, and YAP1 and SFRP2 are involved in the formation and development of CRC.

Concurrent Evaluation of the Expression and Methylation of secreted frizzled-related protein 2 along with beta-catenin Expression in Patients with non-M3 Acute Myeloid Leukemia.

Background: Wnt signaling is a critical pathway for the development of acute myeloid leukemia (AML). Some studies have evaluated the expression or methylation of secreted frizzled-related protein 2 (SFRP2) as an antagonist and beta-catenin (β-catenin) as a critical mediator of this pathway. Since we found no comprehensive study on these genes in Iran, we aimed to investigate the status of both SFRP2 expression and methylation, and also β-catenin expression, in conjunction with clinical characteristics, in Iranian patients with de novo non-M3 AML.Methods: The methylation and expression of SFRP2 were determined in 188 patients with primary non-M3 AML and 60 healthy controls, who were referred to Shariati Hospital, Tehran, Iran, between January 2017 and February 2019. The methylation-specific polymerase chain reaction (PCR) and real-time quantitative PCR were used, respectively. The expression of β-catenin was explored via real-time quantitative PCR. Statistical analysis was performed using the Mann–Whitney U test (SPSS software, version 23). A P value of less than 0.05 (2-tailed) was considered significant.Results: SFRP2 mRNA showed a significant decline in the AML group compared with the controls (P<0.001). The hypermethylation of the SFRP2 promoter occurred in 25.5% (48/188) of the cases. SFRP2 expression exhibited a negative correlation with the white blood cell count (P=0.003). The expression of β-catenin increased significantly in the patients in comparison with the controls (P<0001), and a significant difference was observed between the patients, who achieved complete remission and those, who did not (P=0.046).Conclusion: The findings of this study showed that alterations in SFRP2 and β-catenin expression can be used as a potential biomarker for differentiating patients with new non-M3 AML from the controls. Additionally, an evaluation of β-catenin expression may be valuable in predicting complete remission in patients with non-M3 AML.

MON-532 Characterization of the Angiogenic Factor SFRP2 in Papillary Thyroid Carcinoma

Over the last decade, there has been an average annual increase of 3.1% in thyroid cancer diagnosis in the U.S. Papillary thyroid carcinoma (PTC) accounts for 80% of all thyroid cancer diagnoses. However, few molecular markers exist to identify clinically aggressive phenotypes. The angiogenic factor, secreted frizzled-related protein 2 (SFRP2), is associated with a poor prognosis in several malignancies including breast cancer and melanoma. The role of SFRP2 in PTC has yet to be investigated. The aims of this study were to determine the differential expression of SFRP2 in PTC, benign thyroid adenomas, normal thyroid tissue (from patients without cancer), and normal adjacent tissue (NAT) (non-cancerous tissue from patients with PTC) and investigate the role of SFRP2 in tumor development in two PTC cell lines, PTC classical variant (PTC-CV) and PTC follicular variant (PTC-FV), upon treatment with a humanized anti-SFRP2 monoclonal antibody (hSFRP2 mAb). Immunohistochemistry (IHC) was performed using human tissue protein microarrays including 226 PTC, 79 benign adenomas, 112 NAT, and 30 normal thyroid tissue samples. In-vitro proliferation and apoptosis experiments were performed on MDA-T41 (PTC-CV) and MDA-T68 (PTC-FV) cell lines by treating with hSFRP2 mAb, Xolair IgG control, and a vehicle control. SFRP2 expression was significantly higher in PTC compared with benign adenomas and normal thyroid (mean expression scores 9, 6, and 1, respectively; p<0.05). SFRP2 expression was significantly higher in NAT than normal thyroid (mean expression score 4 and 0, respectively, p<0.05). Apoptotic rates were increased by 40% and 62% in the PTC-CV hSFRP2 mAb treatment group compared with the Xolair and vehicle treatment groups, respectively (p<0.05). Apoptotic rates were increased by 126% and 59% in the PTC-FV hSFRP2 mAb treatment group compared with the Xolair and vehicle treatment groups, respectively (p<0.05). Treatment with hSFRP2 mAb had no significant effect on proliferation in either cell line. In conclusion, SFRP2 expression is significantly higher in PTC than in benign adenomas and normal thyroid tissue. SFRP2 expression in NAT is significantly higher than in normal thyroid tissue and not significantly different from benign adenomas. SFRP2 expression in nonmalignant tissue adjacent to PTC could be due to expression in the tumor microenvironment. Treatment with a novel hSFPR2 mAb increases apoptotic rates in two different PTC cell lines. These data suggest that SFPR2 is involved in tumorigenesis of PTC.

Oncogenic role of SFRP2 in p53-mutant osteosarcoma development via autocrine and paracrine mechanism

Osteosarcoma (OS), the most common primary bone tumor, is highly metastatic with high chemotherapeutic resistance and poor survival rates. Using induced pluripotent stem cells (iPSCs) generated from Li-Fraumeni syndrome (LFS) patients, we investigate an oncogenic role of secreted frizzled-related protein 2 (SFRP2) in p53 mutation-associated OS development. Interestingly, we find that high SFRP2 expression in OS patient samples correlates with poor survival. Systems-level analyses identified that expression of SFRP2 increases during LFS OS development and can induce angiogenesis. Ectopic SFRP2 overexpression in normal osteoblast precursors is sufficient to suppress normal osteoblast differentiation and to promote OS phenotypes through induction of oncogenic molecules such as FOXM1 and CYR61 in a β-catenin-independent manner. Conversely, inhibition of SFRP2, FOXM1, or CYR61 represses the tumorigenic potential. In summary, these findings demonstrate the oncogenic role of SFRP2 in the development of p53 mutation-associated OS and that inhibition of SFRP2 is a potential therapeutic strategy.

DNA hypermethylation of SFRP2 influences the pathology of rheumatoid arthritis through the canonical Wnt signaling in model rats

In this work, the expression of secreted frizzled related protein 2 (SFRP2) in rheumatoid arthritis (RA) model rats and the mechanisms of SFRP2 on the RA pathogenesis were investigated. Data suggested that SFRP2 was significantly down-regulated in RA model rats compared with normal control, and overexpression of SFRP2 suppressed the RA pathogenesis and the canonical Wnt signaling in fibroblast-like synovial cells (FLS) from RA model rats, whereas knockdown of SFRP2 got an opposite observation. Interestingly, 5-azadC treatment up-regulated the SFRP2 expression, inhibited the FLS proliferation, suppressed the expression of IL-6 and IL-8 and the fibronectin production, suggesting that the decreased SFRP2 in RA model rats was due to the DNA methylation. Furthermore, DNMT1 knockdown up-regulated the SFRP2 expression, DNMT1 overexpression inhibited the SFRP2, and the quantitative methylation-specific PCR (qMSP) confirmed that the DNMT1 has direct methylation roles for the SFRP2 promoter, leading to a regulation of FLS proliferation and fibronectin expression in RA model rats. In addition, up-regulated MeCP2 was involved in the SFRP2 regulation and the pathogenesis of RA model rats, and MeCP2 and DNMT1 have synergistic inhibition roles in the SFRP2 expression. Combination of DNMT1 and DNA methylation may be a promising treatment strategy for individuals with RA in which SFRP2 is down-regulated.

Decreased expression of SFRP2 promotes development of the pituitary corticotroph adenoma by upregulating Wnt signaling.

Cushing's disease is primarily caused by pituitary adrenocorticotropin-secreting adenoma. However, its pathogenesis has remained obscure. In the present study, whole transcriptome analysis was performed by RNA sequencing (RNA-Seq) and expression of secreted frizzled-related protein 2 (SFRP2) was decreased in corticotroph tumors compared with normal pituitary glands. Furthermore, the RNA-Seq results were validated and the expression of SFRP2 in tumor tissues was analyzed by comparing another cohort of 23 patients with Cushing's disease and 3 normal human pituitary samples using reverse transcription-quantitative polymerase chain reaction, western blot and immunohistochemistry staining. Clinically, there was an association between lower SFRP2 expression and aggressive adenoma characteristics, including larger size and invasiveness. Conversely, SFRP2 overexpression reduced the ability of AtT20 cells to proliferate and migrate, and reduced production of the adrenocorticotrophic hormone in vitro. Mechanistically, overexpressed SFRP2 reduced the level of β-catenin in the cytoplasm and nucleus, and decreased Wnt signaling activity in AtT20 cells. Therefore, SFRP2 appears to act as a tumor suppressor in Cushing's disease by regulating the activity of the Wnt signaling pathway.

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

What is the role of SFRP2 in endometriosis? 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). 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. 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. 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. 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). 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. 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. 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.

Secreted Frizzled Related Protein 2 Modulates Epithelial–Mesenchymal Transition and Stemness via Wnt/β-Catenin Signaling in Choriocarcinoma

Background/Aims: Choriocarcinoma (CC) is a highly aggressive gestational trophoblastic neoplasia; however, the underlying molecular mechanisms of its invasiveness and metastasis remain poorly understood. Human secreted frizzled-related protein 2 (SFRP2) could function as a tumor promoter or suppressor in different tumors, yet the role it plays in CC’s invasion and metastasis is thoroughly unclear. The current study was aimed to explore the function and underlying mechanism of SFRP2 in CC. Methods: The expression of SFRP2 in CC tissues was examined via immunohistochemistry. The methylation level and expression of SFRP2 in CC cell lines, JEG-3 and JAR were examined via bisulfite sequencing PCR (BSP), western blotting and quantitative RT-PCR. The biological role of increasing expressed SFRP2 through its promoter demethylation with 5-Aza-2’-deoxycytidine (5-Aza) was examined by a series of in vitro functional studies. Furthermore, lentivirus transfection technology was adopted to investigate the biological roles of SFRP2 knockdown in JEG-3 and JAR cells in vitro and in vivo. Moreover, its downstream signaling pathway was investigated. Results: SFRP2 was downregulated in CC tissues, and its expression was inversely related to its promoter hypermethylation frequency in JEG-3 and JAR cells. Increased SFRP2 through its promoter demethylation inhibited cell migration, invasion and colony formation in JEG-3 and JAR cells, whereas decreased SFRP2 reversed the epithelial-mesenchymal transition (EMT) process and stemness in JEG-3 and JAR cells both in vitro and vivo. Mechanistically, SFRP2 regulated the EMT and stemness of CC cell lines via canonical Wnt/β-catenin signaling, validated by the usage of a Wnt activator and inhibitor. Conclusion: The current study indicates that downregulated SFRP2 has potent tumor-promotive effects in CC through the modulation of cancer stemness and the EMT phenotype via activation of Wnt/β-catenin signaling in vitro and in vivo.

Promoting roles of the secreted frizzled-related protein 2 as a Wnt agonist in lung cancer cells.

The secreted frizzled-related protein 2 (SFRP2) plays a pivotal role in the Wnt pathway, however, it functions as an agonist or an antagonist is still controversial. We profiled SFRP2 expression in several lung cancer cell lines, and found that A549 and 95-D exhibited the lowest and the highest level of SFRP2, respectively. Then we employed the SFRP2-overexpressing plasmid and siRNA to transfect A549 and 95-D cells, respectively. Through MTT assays, we found that SFRP2 knockdown inhibited cell proliferation, and halted the 95-D cells in G1 phase of the cell cycle by downregulation of CCND1 and CDK4, indicating that SFRP2 has the ability of promoting lung cancer cell proliferation. We further checked the cell properties of migration and invasion, using wound scratch assay and Transwell assays. The data showed decreased migrated and invasive 95-D cells after SFRP2 knockdown, and the observations were the opposite in the overexpressing model, implying that SFRP2 promoted lung cancer cell invasion. Moreover, the canonical Wnt pathway was also studied through detection of β-catenin by western blotting. In the SFRP2 overexpressing model, A549 cells presented stronger expression of β-catenin compared with controls, while it was the opposite in 95-D cells. These results suggested that SFRP2 serves as a Wnt agonist in lung cancer cells. Together, the findings of this study implied that SFRP2 is not only an agonist of Wnt pathway, but also a cancer promoting protein for lung cancer, indicating SFRP2 as a promising therapeutic target for lung cancer treatment.

Secreted frizzled‑related protein 2 is epigenetically silenced and functions as a tumor suppressor in oral squamous cell carcinoma.

The role of epigenetic inactivation of secreted frizzled-related protein 2 (SFRP2) and its functions in the development of oral squamous cell carcinoma (OSCC) remain to be elucidated. The present study demonstrated that SFRP2 mRNA was detected in 97.96% of tumor-adjacent normal tissues, while its expression was only detected in 16.33% of the tumor samples. In addition, the loss of SFRP2 expression was associated with hypermethylation of its promoter. As expected, the overexpression of SFRP2 in OSCC cell lines (Tca8113) suppressed cell proliferation and arrested the cell cycle in the G1 phase. Overexpression of SFRP2 also effectively repressed tumor growth in xenograft animals. Mechanistic investigations revealed that SFRP2 inhibited the development of OSCC in vitro and in vivo through an increase in the expression levels of glycogen synthase kinase-3β and a decrease in the expression level of cyclin D1, a direct read-out gene of active Wnt signaling. In addition, an increase in the expression of β-catenin was observed in the Tca8113/SFRP2 cells and in the animal models overexpressing SFRP2. Therefore, the results of the present study provide insight into the role of SFRP2 as a functional tumor suppressor in the development of OSCC through inhibition of the Wnt signaling pathway. Further studies on the precise mechanisms underlying the inhibition of Wnt signaling by SFRP2 and its association with β-catenin are required.

Ultrasound Molecular Imaging of Secreted Frizzled Related Protein-2 Expression in Murine Angiosarcoma

Angiosarcoma is a biologically aggressive vascular malignancy with a high metastatic potential. In the era of targeted medicine, knowledge of specific molecular tumor characteristics has become more important. Molecular imaging using targeted ultrasound contrast agents can monitor tumor progression non-invasively. Secreted frizzled related protein 2 (SFRP2) is a tumor endothelial marker expressed in angiosarcoma. We hypothesize that SFRP2-directed imaging could be a novel approach to imaging the tumor vasculature. To develop an SFRP2 contrast agent, SFRP2 polyclonal antibody was biotinylated and incubated with streptavidin-coated microbubbles. SVR angiosarcoma cells were injected into nude mice, and when tumors were established the mice were injected intravenously with the SFRP2 -targeted contrast agent, or a control streptavidin-coated contrast agent. SFRP2 -targeted contrast agent detected tumor vasculature with significantly more signal intensity than control contrast agent: the normalized fold-change was 1.6±0.27 (n = 13, p = 0.0032). The kidney was largely devoid of echogenicity with no significant difference between the control contrast agent and the SFRP2-targeted contrast agent demonstrating that the SFRP2-targeted contrast agent was specific to tumor vessels. Plotting average pixel intensity obtained from SFRP2-targeted contrast agent against tumor volume showed that the average pixel intensity increased as tumor volume increased. In conclusion, molecularly-targeted imaging of SFRP2 visualizes angiosarcoma vessels, but not normal vessels, and intensity increases with tumor size. Molecular imaging of SFRP2 expression may provide a rapid, non-invasive method to monitor tumor regression during therapy for angiosarcoma and other SFRP2 expressing cancers, and contribute to our understanding of the biology of SFRP2 during tumor development and progression.

SFRP2 and Slug Contribute to Cellular Resistance to Apoptosis in Hypertrophic Scars

Hypertrophic scars (HS) are skin disorders which occur after wounding and thermal injury. Our previous studies have suggested that secreted frizzled-related protein 2 (SFRP2) is involved in HS formation and that the suppression of SFRP2 promotes apoptosis of hypertrophic scar fibroblasts (HSFBs). However, the mechanisms have not been clarified. Previous studies revealed that Slug expression inhibits cell apoptosis, in vitro and in vivo, and SFRP2 regulates the expression of Slug in cervical cancer cells. In the present study, we quantified differential expression levels of expression of SFRP2 and Slug in HS and normal skin tissues by immunohistochemistry, both of which have important anti-apoptosis roles. Furthermore, a short hairpin RNA approach was adopted to investigate the potential function of SFRP2 and Slug in HSFB apoptosis. Cell apoptosis was detected using fluorescence-activated cell sorting and Caspase-3 activity was assayed by spectrophotometry. This study demonstrates that SFRP2 expression, as well as Slug, is dramatically up-regulated in HS relative to normal skin tissues, and the Slug expression is positively correlated with SFRP2. Slug expression was down-regulated in SFRP2-deficient cells, and the down-regulation of Slug expression increased sensitivity to apoptosis which was induced through a caspase-3-dependent pathway. The infected cells with reduced levels of Slug were tested for the expression of apoptosis-related genes (Bcl-2, Bax and PUMA) which were previously identified as Slug targets. Bcl-2 expression was down-regulated in Slug-deficient cells. In conclusion, SFRP2 appears to interact with Slug to affect the apoptosis of hypertrophic scar fibroblasts.

Expression of Wnt-Inhibitors and SDF-1 in Whole Bone Marrow Biopsies in Association to the Osteolytic Bone Disease of Multiple Myeloma.

AbstractAbstract 2922Osteolytic bone disease (OBD) in multiple myeloma (MM) is caused by a combination of osteoclast hyperactivation and osteoblast inhibition. Several studies have shown that the Wnt-inhibitor DKK1 is one of the factors involved in osteoblast inhibition (Tian, NEJM, 2003), while the role of other Wnt-pathway inhibitors, such as secreted frizzled related protein-2 (SFRP2), SFRP3, sclerostin and Wnt inhibitory factor 1 (WIF1) are less studied. In addition stromal derived factor 1 (SDF-1/CXCL12) that interacts with CXCR4 in bone-marrow (BM) is a potential factor in OBD, although conflicting data has been reported. SDF-1has in mesenchymal stromal cells (MSC) been found downregulated in MM patients compared to healthy volunteers (HV) and also downregulated in MM plasma cells vs. normal plasma cells, while SDF-1 serum levels has been correlated to the extent of OBD in MM.Until now, gene expression studies in MM have been performed on isolated MM plasma cells or bone marrow aspirates, which are not completely representative of the cell composition in the BM micro-environment. We used a novel strategy whereby BM biopsies are snap-frozen and subsequently gene expression is analyzed. Using this strategy we have examined the gene-expression of Wnt inhibitors and SDF1. In addition, we have evaluated the protein levels of DKK1 and SDF-1 in matched BM plasma samples.An additional BM core biopsy obtained during the diagnostic procedure of MM patients was snap-frozen. Biopsies were cut, homogenized and RNA was purified and analyzed by qRT-PCR using low density arrays (Applied Biosystems). The relative quantitative gene expression was calculated using 3 internal reference genes (ABL, GAPDH and GUS). OBD was evaluated using standard radiographs. All patients were untreated and did not receive medicine that could influence bone remodeling. We examined 10 healthy volunteers (HV), 35 monoclonal gammopathy of unknown significance (MGUS) and 65 untreated MM patients, which according to radiographic findings were divided into NO/LOW and advanced OBD, i.e. OBD in ≥2 regions.ELISA was performed on a total of 31 matched BM plasma samples of HV, MGUS and MM obtained at the same time point as the biopsies. In addition, extra samples without gene data (N=52) were analyzed. Commercial kits for DKK-1 (RnD, Quantikine) and SDF-1 (RnD, Quantikine) were run in duplicates according to manufacturer's instructions.Gene expression of DKK1 and SFRP3 were significantly (p<0.05) associated with OBD with increasing gene-expression with increasing OBD, while SDF-1 were significantly associated with decreasing gene-expression with increasing OBD. Gene expression of SFRP2, sclerostin and WIF1 did not associate with the extent of OBD. When comparing HV, MGUS and MM independent of OBD, sclerostin showed a tendency to be higher expressed in MM vs. MGUS and HV (p=0.08).A significant correlation between gene expression levels and protein expression levels was found for DKK-1 (Spearman's rho= 0.57, p=0.0006,) while the correlation of gene and protein expression levels of SDF-1 did not reach significance (Spearman's rho =0.31, p=0.074).The protein level of DKK1 in BM plasma was upregulated in MM and associated significantly with the OBD level (p<0.05). The protein level of SDF1 did not correlate to the extent of OBD.Our gene expression study of MM with minimal manipulation of the samples showed that the Wnt-inhibitors DKK1 and SFRP3 were significantly associated to the extent of OBD, while SDF1 gene expression inversely correlated with the extent of OBD. The report of simultaneous measurement of not only DKK1 but also SFRP3 and other Wnt-inhibitors is novel. The use of whole snap-frozen BM biopsies is a new method to evaluate gene expression in MM that makes it possible to include the tumor micro-environment and investigate patients independent of degree of MM plasma cell infiltration, and we were able to reproduce the DKK1 findings by others. The gene expression results were complemented by protein data for DKK1 and SDF-1. Our study shows for the first time the difference between SDF1 gene and protein levels in matched MM patient samples, and the difference measured incites us to further investigate the post-translational regulation of SDF-1, and the possibility of SDF1 protein being less bound to CXCR4 in MM. [Display omitted] Disclosures:No relevant conflicts of interest to declare.