Secreted Frizzled-related Protein 5 Expression Research Articles

Role of SFRP5 in Non-Small Cell Lung Cancer and Its Correlation with SUV of 18F-FDG PET-CT

Aim: This study aimed to evaluate the relationship between secreted frizzled-related protein 5 (SFRP5) expression and fluorine 18-fluoro-deoxyglucose (18 F-FDG) uptake imaged with positron emission tomography/tomography (PET/CT) in patients with non-small cell lung cancer (NSCLC). In addition, we sought to elucidate the potential role and mechanism of action of SFRP5 in NSCLC.Materials and methods: The maximum standardized uptake value (SUVmax) of the lesions was calculated. SFRP5 expression was analyzed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). The correlation between SFRP5 expression and SUVmax was evaluated using Pearson’s correlation analysis. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, wound healing, and transwell assays were used to analyze cell viability, apoptosis, migration, and invasion, respectively.Results and conclusion: The results indicated that the SUVmax was higher in patients with NSCLC than that in healthy volunteers. Moreover, SFRP5 expression was lower in tissues from the four types of NSCLC than that in the adjacent normal tissues. SUVmax negatively correlated with SFRP5 expression in the four types of NSCLC. In addition, up-regulation of SFRP5 decreased the viability, migration, and invasion abilities, and increased apoptosis of NSCLC cells. Furthermore, SFRP5 inhibited the Wnt/β-catenin pathway in NSCLC cells. In conclusion, SFRP5 modulates the biological behaviors of NSCLC through Wnt/β-catenin pathway.

Role of secreted frizzled-related protein 5 in granulosa cells of hu sheep ovaries

The objective of this study was to examine the expression patterns of secreted frizzled-related protein 5 (SFRP5) in the ovaries of Hu sheep and to explore the key downstream factors of SFRP5 in sheep granulosa cells (GCs) using RNA-seq. In the present study, SFRP5 was widely expressed in the ovary and localized to GCs and oocytes during various stages of follicular development. In addition, the expression of SFRP5 increased with follicular diameter. In contrast to the negative control, SFRP5 knockdown promoted the EdU-positive cell rate with an increase in PCNA mRNA and protein levels, whereas SFRP5 overexpression had the opposite effect. In addition, the cell cycle was propelled from the G0/G1 phase to the S phase with the upregulation of CCNB1, CCND1, CDK1, and CDK4 after SFRP5 knockdown. Moreover, SFRP5 overexpression enhanced the apoptosis of GCs with increased Caspase3 protein levels. Following SFRP5 knockdown, differentially expressed genes were mainly enriched in the PI3K/AKT, MAPK, Wnt, and Hippo signaling pathways, and several related candidate genes such as MMP1, MMP3, SFRP4, INHA, TGFA, and CASP3 were screened. In general, this study enhances our understanding of the expression of SFRP5 in the GCs of Hu sheep, along with its functions in follicular development.

Secreted frizzled-related protein 5 protects against renal fibrosis by inhibiting Wnt/β-catenin pathway.

Renal fibrosis (RF) is an important pathogenesis for renal function deterioration in chronic kidney disease. Secreted frizzled-related protein 5 (SFRP5) is an anti-fibrotic adipokine but its direct role on RF remains unknown. It was aimed to study the protective effect of SFRP5 against RF and interference with Wnt/β-catenin signaling pathway for the first time. First, the therapeutic efficacy of SFRP5 was evaluated by adenovirus overexpression in rats with unilateral ureteral obstruction (UUO) in vivo. Thirty-six rats were randomly divided into the sham, UUO, and SFRP5 (UUO + Ad-SFRP5) groups. Half rats in each group were selected at random for euthanasia at 7 days and the others until 14 days. Then, the transforming growth factor (TGF)-β1-induced epithelial-mesenchymal transition (EMT) was established in HK-2 cells in vitro. The cells were divided into four groups: the control group, the TGF-β1 group, the TGF-β1 + SFRP5 group, and the TGF-β1 + SFRP5 + anti-SFRP5 group. The makers of EMT and Wnt/β-catenin pathway proteins were investigated. In the UUO model, expression of SFRP5 showed compensatory upregulation, and adenoviral-mediated SFRP5 over-expression remarkably attenuated RF, as demonstrated by maintenance of E-cadherin and suppression of α-smooth muscle actin (SMA). In vitro, SFRP5 was shown to inhibit TGF-β1-mediated positive regulation of α-SMA, fibronectin, collagen I but negative regulation of E-cadherin. Furthermore, SFRP5 abrogated activation of Wnt/β-catenin, which was the essential pathway in EMT and RF pathogenesis. The changes after a neutralizing antibody to SFRP5 confirmed the specificity of SFRP5 for inhibition. These findings suggest that SFRP5 can directly ameliorate EMT and protect against RF by inhibiting Wnt/β-catenin pathway.

Frizzled receptors and SFRP5 in lipid metabolism: Current findings and potential applications.

Lipid metabolism plays a very important role as the central metabolic process of the body. Lipid metabolism interruptions may cause many chronic diseases, for example, non-alcoholic fatty liver disease (NAFLD), diabetes, and obesity. Secreted Frizzled Related Protein 5 (SFRP5) and Frizzled receptors (FZD) are two newly discovered adipokines that are involved in lipid metabolism as well as lipogenesis. Both of these adipokines affect lipid metabolism and adipogenesis through three WNT signaling pathways (WNTSP): WNT/β-catenin, WNT/Ca2+, and WNT/JNK. FZD consists of 10 species, which have a cysteine-rich domain (CRD) to bind to the WNT protein for signal transduction. Depending on the type of ligand or co-receptor, they can stimulate or inhibit adipogenesis. In lipid metabolism, they play a role in recognizing fatty acids. In obesity, gene expression of the WNT/FZD receptors is significantly increased. In contrast, SFPR5 serves as an antagonist that can compete with FZD for inhibition of WNTSP. It is believed to have anti-inflammatory potential in obesity and diseases related to abnormal lipid metabolism. In these cases, the expression of SFRP5 is found to be very low leading to the promoted production of proinflammatory cytokines (PICS). Some methods that include using recombinant SFRP5 to improve non-alcoholic steatohepatitis (NASH), using secreted Ly-6/uPAR-related protein 1 (Slurp1) to regulate fat accumulation in the liver through SFRP5, and dietary and lifestyle interventions to improve overweight/obesity have been studied. However, understandings of the molecular mechanisms of these two adipokines and their interactions are very limited. Therefore, more in-depth studies are needed in the future.

Increased Secreted Frizzled-Related Protein 5 mRNA Expression in the Adipose Tissue of Women with Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5) is an anti-inflammatory adipocytokine secreted by adipocytes that seems to be linked with nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the role of the SFRP5-wingless-MMTV integration site family member 5a (WNT5A) pathway, closely related to adipogenesis, in subcutaneous (SAT) and visceral adipose tissues (VAT) and its relationship with obesity-related NAFLD. Our cohort was composed of 60 women with morbid obesity (MO), who underwent hypocaloric diet, subclassified according to their hepatic histopathology and 15 women with normal weight. We observed increased SFRP5 mRNA expression in VAT and lower WNT5A expression in SAT in MO compared to normal weight. We found elevated SFRP5 expression in nonalcoholic steatohepatitis (NASH) in SAT and in mild simple steatosis (SS) and NASH in VAT. We observed higher WNT5A expression in SS compared to normal liver in SAT, and a peak of WNT5A expression in mild SS. To conclude, we reported increased SFRP5 mRNA expression in SAT and VAT of NAFLD-related to obesity subjects, suggesting an implication of the SFRP5-WNT5A pathway in NAFLD pathogenesis, probably due to the adipose tissue-liver axis. Since the mechanisms by which this potential interaction takes place remain elusive, more research in this field is needed.

Secreted frizzled-related protein 5 promotes angiogenesis of human umbilical vein endothelial cells and alleviates myocardial injury in diabetic mice with myocardial infarction by inhibiting Wnt5a/JNK signaling

ABSTRACT The purpose of this study is to investigate whether secreted frizzled-related protein 5 (SFRP5) affects the proliferation, migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) induced by high glucose (HG). HUVECs were treated with different concentrations of glucose. MTT, wound healing, angiogenesis, and ELISA assays were used to detect cell cytotoxicity, migration, tube formation, and VEGF165 and VEGF165b levels, respectively. The mice model of type 2 diabetes mellitus (T2DM) complicated with myocardial infarction (MI) was established. SFRP5 was injected intrabitoneally for 2 weeks. cardiac output (CO), left ventricular ejection fraction (LVEF) and left ventricular shortening fraction (LVSF) were detected by echocardiography. Western blot was used to detect the protein levels of SFRP5, Wnt5a, JNK1/2/3, p-JNK1/2/3, TGF-β1, Caspase3, Bax, and Bcl-2. The expression of SFRP5 was declined in HG-induced HUVECs and T2DM-MI. Intervention of SFRP5 promoted the migration of HUVECs and angiogenesis, as evidenced by a lower expression of Bax and caspase3, but a higher expression of Bcl-2. Meanwhile, SFRP5 inhibition repress Wnt5a and p-JNK expression. Howerver, The JNK inhibitor (SP600125) enhanced the down-regulation of Wnt5a/JNK pathway proteins by SFRP5. SFRP5 intervention increased the levels of CO, LVSF, and LVEF in T2DM-MI mice. SFRP5 inhibited myocardial pathological injury and fibrosis in T2DM-MI mice and SFRP5 could down-regulate Wnt5a and p-JNK1/2/3 activation. SFRP5 promotes the proliferation, migration and angiogenesis of HUVECs induced by HG, and inhibits cardiac dysfunction, pathological damage, fibrosis, and myocardial angiogenesis in diabetic myocardial ischemia mice, which is achieved by inhibiting Wnt5a/JNK signaling.

Deregulation of Secreted Frizzled-Related Protein 5 in Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5), an antagonist of the noncanonical WNT pathway, has a controversial role in liver disease. The aim of this study was to analyze the role of SFRP5 and the noncanonical WNT pathway in nonalcoholic fatty liver disease (NAFLD). Plasma SFRP5 levels were determined by ELISA in women with normal weight (NW; n = 20) and morbid obesity (MO; n = 69). Women with MO were subclassified according to hepatic histology into normal liver (NL; n = 28), NAFLD (n = 41) (simple steatosis (SS; n = 24), and nonalcoholic steatohepatitis (NASH; n = 17)). We used RT-qPCR to evaluate the hepatic mRNA expression of SFRP5, WNT5A, and JNK in women with MO. SFRP5 levels were lower in NW than in MO patients who underwent a very low-calorie diet before surgery. Hepatic SFRP5 mRNA expression was higher in SS than in NL or NASH; additionally, patients with hepatic inflammation or ballooning presented lower SFRP5 abundance. WNT5A and JNK expression was enhanced in NAFLD compared with NL. In conclusion, circulating SFRP5 levels depend on the diet, and hepatic SFRP5 seems to have a protective role in the first steps of NAFLD; however, SFRP5 could be deregulated in an advanced stage while WNT5A and JNK are activated, promoting liver damage.

The regulatory role of SFRP5/WNT5A axis in allergic rhinitis through inhibiting JNK pathway activation and lowering mucin generation in human nasal epithelial cells

Allergic rhinitis (AR) is tightly associated with type 2 inflammation. SFRP5 combined with WNT5A mainly inhibits chronic inflammatory response, atherosclerosis, and other metabolic disorders. However, the effect of SFRP5/WNT5A axis on recombinant human interleukin-13 (rhIL-13)-induced inflammation has not been studied. In this study, we aimed to investigate whether secreted frizzled-related protein 5 (SFRP5) could modulate the production of cytokines relevant to eosinophil infiltration and mucin secretion through blocking the activation of Wnt family 5A (WNT5A) signaling pathway. A mouse model of AR demonstrated low expression of SFRP5 and high expression of WNT5A, and indicated that the number of eosinophil and goblet cells was increased, concomitant with elevated IL-13, colony stimulating factor 2 (CSF2), chemokine ligand 11 (CCL11), Mucin 4, and Mucin 5AC levels. Furthermore, lentivirus-SFRP5 overexpression up-regulated the expression of SFRP5 but down-regulated WNT5A level, and inhibited the activation of JNK pathway via decreasing p-JNK1/2 (Thr183/Tyr185) and p-c-Jun (Ser73) protein expressions in rhIL-13-treated human nasal epithelial cells (HNEpCs). Noticeably, SFRP5 overexpression markedly reduced rhIL-13-induced inflammatory protein and mucin generation through lowered CSF2, CCL11, Mucin 4, as well as Mucin 5AC levels. Taken together, these findings confirmed the regulatory role of SFRP5/WNT5A axis in rhIL-13-mediated inflammatory response in HNEpCs.

287 Secreted frizzled-related protein 5 (SFRP5 ) inhibits the melanin synthesis of melanocytes via Wnt/β-catenin signaling pathway in vitiligo

Vitiligo is an acquired chronic depigmentation disorder characterized by progressive depigmentation due to the destruction of epidermal melanocytes. The dysfunction of melanocytes plays an important role in the pathogenesis of vitiligo. In this study, we found that secreted frizzled-related protein 5 (SFRP5) is overexpressed in the skin lesions of vitiligo patients. Compared with normal epidermal melanocytes (PIG1), the expression of SFRP5 is increased in vitiligo melanocytes (PIG3V). To investigate the effect of SFRP5 on melanin synthesis, PIG1 cells were infected with recombinant SFRP5 adenovirus (AdSFRP5), and PIG3V cells were infected with recombinant siSFRP5 adenovirus (AdsiSFRP5).

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

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

Circ_LAS1L regulates cardiac fibroblast activation, growth, and migration through miR-125b/SFRP5 pathway.

Current studies have shown that circular RNAs (circRNAs) and microRNAs (miRNAs) are closely related in acute myocardial infarction (AMI). Previous studies have shown that miR-125b promotes fibrosis and up-regulates in cardiac fibroblasts (CFs), and further experiments showed that circ_LAS1L had multiple binding sites of miR-125b, and their expression was inversely related in AMI patients and CFs. RNA immunoprecipitation (RIP), pull down, and dual luciferase reporter gene assay all confirmed that miR-125b directly bound to circ_LAS1L. Circ_LAS1L overexpression promoted the expression of downstream target gene secreted frizzled-related protein 5 (SFRP5), inhibited the expression of alpha-SMA, collagen I, and collagen III, inhibited CF proliferation and migration, and promoted apoptosis. When cotransfected with circ_LAS1L overexpression vector and miR-125b mimics, the above gene expression and CF biological behaviours did not change significantly. But when cotransfected with circ_LAS1L overexpression vector and SFRP5 siRNA, SFRP5 expression was still down-regulated, the expression of alpha-SMA, collagen I, and collagen III was up-regulated, and the proliferation and migration of CFs were increased. Therefore, circ_LAS1L inhibits the activity of miR-125b by adsorbing it, thus promoting the expression of SFRP5 and then regulating the biological characteristics of CFs. These findings may provide an important experimental basis for the regulation of myocardial fibrosis after myocardial infarction. SIGNIFICANCE OF THE STUDY: Studies have shown that circular RNAs (circRNAs) play important roles in cardiovascular diseases, but there are few studies on their roles in the process of myocardial fibrosis. In this study, we found that circ_LAS1L was down-regulated in acute myocardial infarction (AMI) patients and cardiac fibroblasts (CFs), and could bind directly to miR-125b, thereby promoting the expression of downstream target gene secreted frizzled-related protein 5 (SFRP5), ultimately inhibiting the activation, proliferation and migration of CF, and promoting apoptosis. This suggests that circ_LAS1L/miR-125b/SFRP5 pathway can regulate the biological function of CF and may play an important role in the process of myocardial fibrosis, thus providing an important theoretical basis for the regulation of myocardial fibrosis after myocardial infarction.

Regulation and its mechanism of MeCP2 on biological behavior and epithelial-mesenchymal transition of LECs

Objective To investigate the role of methyl-CpG-binding protein 2 (MeCP2) in the regulation and epithelial-mesenchymal transition (EMT) of human lens epithelial cells (LECs) and its possible mechanism. Methods Human LEC lines (SRA01/04) were divided into MeCP2-mimic group, MeCP2-NC group and small interferening RNA-MeCP2 (si-MeCP2) group, and MeCP2 analog plasmid, blank plasmid and MeCP2 si-RNA plasmid was used respectively to transfect the cells.The expression of MeCP2 mRNA in the cells was detected by using real-time PCR 24 hours after transfection.At 48 hours after transfection, the migration rate of the cells was evaluated by scratching test, and the expression of Wnt3a protein in the cells was detected by immunofluorescence stainning.The relative expressions of β-catenin, E-cadherin, Vimentin, matrix metallo proteinase (MMP)-9, MMP-7 and secreted frizzled-related protein 5 (SFRP5) proteins in the cells were detected by Western blot. Results After 24 hours of transfection, the relative expression of MeCP2 mRNA in the cells was significantly different among the MeCP2-mimic group, MeCP2-NC group and si-MeCP2 group (F=4 773.00, P<0.00 1). The migrating rate of the cells in the MeCP2-mimic group, MeCP2-NC group and si-MeCP2 group was (57.45±5.20)%, (32.71±10.02)% and (17.77±9.22)%, respectively, showing a significant difference among the three groups (F=124.00, P<0.001), and the migrating rate of the cells in the si-MeCP2 group was significantly lower than that of the MeCP2-mimic group or MeCP2-NC group (both at P<0.001). The relative expressing intensity (absorbance) of Wnt3a in the cells of the MeCP2-mimic group, MeCP2-NC group and si-MeCP2 group was 75.92±6.10, 52.03±5.22 and 28.75±3.39, respectively, with a significant difference among three the groups (F=221.30, P<0.001), and the relative expressing intensity (absorbance) of Wnt3a in the cells was significantly lower in the si-MeCP2-mimic group than that of the MeCP2-NC group and MeCP2-mimic group (both at P<0.001). The relative expressing level of E-cadherin protein was significantly elevated and the expressions of β-catenin, Vimentin, MMP-9 and MMP-7 were significantly reduced in the si-MeCP2 group compared with the MeCP2-mimnic group and MeCP2-NC group (all at P<0.01). The relative expressing level of SFRP5 protein in the MeCP2-mimic group, MeCP2-NC group and si-MeCP2 group was 27.19±0.03, 47.54±0.05 and 74.93±0.05, respectively, showing a statistical difference among the three groups (F=183.49, P<0.001), and the relative expressing level of SFRP5 in the si-MeCP2 group was significantly higher than that in the MeCP2-mimic group and MeCP2-NC group (both at P<0.001). Conclusions MeCP2C can promote EMT of human LECs by down-regulating the expression of SFRP5 and therefore activating the Wnt3a/β-catenin signal pathway. Key words: Methyl-CpG-binding protein 2; Lens epithelial cells, human; Epithelial-mesenchymal transition; Signal pathway

Adipocyte-derived SFRP5 inhibits breast cancer cells migration and invasion through Wnt and epithelial-mesenchymal transition signaling pathways.

ObjectiveObesity is closely associated with metastasis in breast cancer patients. Secreted frizzled-related protein 5 (SFRP5), one of the novel adipokines with anti-inflammatory properties, is associated with obesity. This study aims to study the role of SFRP5 in the crosstalk between obesity and breast cancer metastasis and identify the underlying mechanism.Methods3T3-L1 pre-adipocytes were differentiated to mature adipocytes and a hypertrophic adipocyte model was induced with palmitic acid (PA). Cell motility was measured in MDA-MB-231 and MCF-7 breast cancer cells co-cultured with adipocytes conditioned medium (CM) with or without SFRP5 protein. Wnt and epithelial-mesenchymal transition (EMT) signal pathways were investigated by western blot. Circulating SFRP5 level in 218 breast cancer patients and the association with clinicopathologic characteristics of breast cancer were further determined. Online databases ENCORI and PREDICT Plus were used to exam the link between SFRP5 and prognosis.ResultsReduced SFRP5 level was detected in the hypertrophic adipocyte model. Recombinant SFRP5 protein inhibited MDA-MB-231 and MCF-7 cells invasion and migration induced by PA-treated adipocyte CM, and SFRP5 inhibition by specific antibody reversed the effect of SFRP5. Furthermore, SFRP5 significantly inhibited Wnt and downstream EMT in breast cancer cells. Low circulating SFRP5 level correlated with body mass index (BMI), lymph node (LN) metastasis, TNM stage and high Ki67 expression in breast cancer patients. Increased SFRP5 level was associated with favorable predicted survival. Kaplan-Meier curves showed high SFRP5 level in tumor tissue was associated with better outcome of breast cancer patients.ConclusionsOur findings demonstrated SFRP5 is a vital adipokine that mediates the crosslink between obesity and the metastatic potential of breast cancer. Promotion of SFRP5 expression in the adipose microenvironment may represent a novel approach for preventing breast cancer metastasis.

SFRP5 inhibits the migration and invasion of melanoma cells through Wnt signaling pathway.

BackgroundSecreted frizzled-related protein 5 (SFRP5) plays a key role in the development and progression of multiple tumors. However, the role and underlying mechanisms of SFRP5 in melanoma cells remain unknown.Materials and methodsWe used immunohistochemistry and Western blot analysis to detect the expression of SFRP5 in melanoma tissues and melanoma cells, respectively. Furthermore, both in vitro and in vivo assays were used to determine the effect of SFRP5 on malignant behavior in melanoma cells.ResultsWe found that SFRP5 was markedly downregulated in melanoma tissues and cell lines. The SFRP5 overexpression exhibited no effect on the proliferation and apoptosis of melanoma cells but markedly suppressed the migration and invasion of melanoma cells in vitro. Regarding mechanisms, the SFRP5 overexpression inhibited the migration and invasion of melanoma cells by suppressing the epithelial–mesenchymal transition process and decreasing the matrix metalloproteinase-2/9 expression through the Wnt signaling pathway. Finally, in a xenograft animal model, we illustrated that the SFRP5 overexpression suppressed the tumor growth by decreasing angiogenesis and declined lung metastasis.ConclusionThis study suggests that SFRP5 expression could be potentially useful in the invasion and metastasis of melanoma and serve as a putative promising target for human melanoma therapy.

SFRP5 serves a beneficial role in arterial aging by inhibiting the proliferation, migration and inflammation of smooth muscle cells

Secreted frizzled-related protein5(SFRP5) is one of the anti-inflammatory adipokines secreted from white adipose tissue. However, little is known about the effect of SFRP5 on the cardiovascular system. The aim of the present study was to determine the effect of SFRP5 on smooth muscle cell (SMC) proliferation, migration and inflammation. The plasma levels of SFRP5 were evaluated in a cohort‑based elderly population using ELISA, and the expression of SFRP5 in Sprague‑Dawley rat aortas was detected using immunohistochemistry. SMC proliferation and migration were evaluated invitro using 5‑ethynyl‑2'‑deoxyuridine cell proliferation and wound‑healing assays, respectively, while reactive oxygen species (ROS) production and cell signaling were assessed using a 2',7'‑dichlorodihydrofluorescein diacetate assay and immunoblotting, respectively. The results revealed that plasma levels of SFRP5 were positively correlated with age in the elderly Chinese cohort. Similarly, aorta SFRP5 expression was significantly higher in 15‑month‑old rats compared with 6‑month‑old rats. Invitro, SFRP5 significantly inhibited rat aortic SMC proliferation and migration that were induced by platelet‑derived growth factor (PDGF)‑BB, as well as inhibiting ROS generation. Compared with the effect of PDGF‑BB on SMCs, SFRP5 at 100 and 200ng/ml significantly decreased SMC proliferation by 31.5 and 34.8%, respectively (P<0.05). SFRP5 at 100 and 200ng/ml also inhibited the migration of SMCs by 24.9 and 28.4%, respectively, when compared with the effects of PDGF‑BB. SFRP5 attenuated the PDGF‑BB‑induced expression of β‑catenin and proliferating cell nuclear antigen, while p38 phosphorylation was significantly attenuated. Together, the present results suggested that SFRP5 may inhibit SMC proliferation, migration and inflammation by suppressing the Wnt/β‑catenin and p38/mitogen‑activated protein kinase signaling pathways.

SFRP5 is a target gene transcriptionally regulated by PPARγ in 3T3-L1 adipocytes

Secreted frizzled-related protein 5 (SFRP5) is a newly identified adipokine. SFRP5 expression increases during the differentiation and maturation of adipocytes, but the factors regulating SFRP5 expression during this process remain unclear. This study showed that peroxisome proliferator-activated receptor γ (PPARγ) adenovirus transfection could enhance the SFRP5 expression of 3T3-L1 adipocytes. Three potential binding sites of PPARγ in the SFRP5 promoter domain were found by bioinformatics analysis. Luciferase reporter gene assay demonstrated that PPARγ regulated the activity of the SFRP5 promoter through cis-acting elements at −2,284–−1,500bp. Further experiments verified that PPARγ could specifically bind to the SFRP5 promoter at −2,284–−2,263bp using chromatin immunoprecipitation and electrophoretic mobility shift assay. These results suggest that SFRP5 be a target gene of PPARγ, and its expression may be under the transcriptional regulation of PPARγ.

Secreted frizzled-related protein 5 protects against oxidative stress-induced apoptosis in human aortic endothelial cells via downregulation of Bax.

This study was undertaken to determine the role of secreted frizzled-related protein 5 (SFRP5) in endothelial oxidative injury. Human aortic endothelial cells (HAECs) were exposed to different oxidative stimuli and examined for SFRP5 expression. The effects of SFRP5 overexpression and knockdown on cell viability, apoptosis, and reactive oxygen species production were measured. HAECs treated with angiotensin (Ang) II (1μM) or oxidized low-density lipoprotein (oxLDL) (150μg/mL) showed a significant increase in SFRP5 expression. Overexpression of SFRP5 significantly attenuated the viability suppression and apoptosis induction by Ang II and oxLDL, whereas the knockdown of SFRP5 exerted opposite effects. Overexpression of SFRP5 prevented ROS formation and β-catenin activation and reduced Bax expression. Co-expression of Bax significantly reversed the anti-apoptotic effect of SFRP5 overexpression, whereas knockdown of Bax restrained Ang II- and oxLDL-induced apoptosis in HAECs. Taken together, SFRP5 confers protection against oxidative stress-induced apoptosis through inhibition of β-catenin activation and downregulation of Bax.

MiR-125b regulates SFRP5 expression to promote growth and activation of cardiac fibroblasts.

Myocardial fibrosis (MF), which typically occurs after a myocardial infarction (MI), is a major factor involved in the process of ventricular remodeling and subsequent progression to heart failure. Current studies have found that various microRNAs (miRNAs), such as miR-125b, play an important role in this process. However, few studies have investigated the specific mechanism of miR-125b. Transfection of miR-125b mimics into cardiac fibroblasts (CFs) resulted in significantly increased expression of the myofibroblast marker alpha-smooth muscle actin (α-SMA) and vinculin by Western blot analysis, while transfection of miR-125b inhibitors resulted in the opposite effect. Analysis of putative CF target genes for miR-125b revealed that miR-125b specifically inhibits expression of secreted frizzled-related protein 5 (SFRP5). SFRP5 inhibited expression of α-SMA and collagen I and III in CFs, while miR-125b promoted the expression of these proteins. Cotransfection of the SFRP5 overexpression vector and miR-125b mimics did not result in significant upregulation of SFRP5 expression or downregulation of α-SMA and collagen I and III. Further analysis revealed that miR-125b promotes the proliferation and migration of CFs and inhibits their apoptosis, while SFRP5 exhibits the opposite effects. These results indicate that miR-125b can regulate SFRP5 expression and thus influence the growth and activation of CFs. Hence, this study provides important insight into possible approaches for the prevention and treatment of MF after an MI.

SFRP5 hepatic expression is associated with non-alcoholic liver disease in morbidly obese women

Background and aims. Secreted frizzled-related protein 5 (SFRP5) was recently described as a new adipokine protective for hepatic steatosis and other obesity-related complications in the mouse model. To date, SFRP5 expression in non-alcoholic fatty liver disease (NAFLD) has not been fully assessed in humans. We measured circulating SFRP5 levels and its expression in liver and adipose tissue, and evaluated its association with NAFLD in morbidly obese women.Material and methods. Fifty-four morbidly obese women undergoing bariatric surgery were included in the study. Liver biopsies were used for histology and hepatic triglyceride content quantification. Circulating SFRP5 levels were measured through enzyme-linked immunoabsorbent assay, and SFRP5 expression was performed in hepatic and adipose tissue (subcutaneous and visceral).Results. Although circulating SFRP5 levels showed a tendency to decrease with NAFLD progression, no significant differences were observed among non-alcoholic steatosis, steatohepatitis, and control subjects. Hepatic SFRP5 expression showed a negative correlation with hepatic triglyceride content (r = -0.349, P = 0.016 for mRNA and r = -0.291, P = 0.040 for SRFP5 protein) and ALT serum levels (r = -0.437, P = 0.001 for SRFP5 protein). In addition, hepatic SFRP5 protein levels were significantly lower in NASH than in control subjects (P = 0.006). Conclusion. This is the first study reporting an association of hepatic SFRP5 expression with NAFLD in humans.

Epigenetic inactivation of the secreted frizzled-related protein-5 ( SFRP5 ) gene in human breast cancer is associated with unfavorable prognosis

Disruption of the Wnt pathway is thought to be crucial in the development of human cancer. Pathway inhibitory members of the secreted frizzled-related protein (SFRP) family were found to be downregulated due to epigenetic inactivation in various malignancies. To date, only SFRP1 has been studied in human breast cancer and we questioned whether other SFRP genes may be implicated in the pathogenesis of this disease as well. An initial real-time polymerase chain reaction analysis of SFRP5 expression in normal human tissues (n = 9) revealed weak expression in most tissues, including breast. Malignant mammary cell lines showed further SFRP5 expression loss in five of six cases. Consistently, in matched pairs of primary breast tumor/normal breast tissue, this downregulation (>5-fold) could be confirmed (n = 8/13; 62%). We identified promoter methylation as the predominant mechanism of SFRP5 gene silencing since SFRP5 promoter methylation correlated significantly with loss of SFRP5 expression in cell lines (P = 0.040) and primary tumors (P = 0.003). Moreover, cancerous cell lines re-expressed SFRP5 messenger RNA following treatment with DNA-demethylating drugs. Of 168 primary breast carcinomas, 73% harbored a methylated SFRP5 promoter, whereas 27% were unaffected by epigenetic alteration. Most interestingly, SFRP5 methylation was associated with reduced overall survival (OS) (P = 0.045) and was an independent risk factor affecting OS in a multivariate Cox proportional hazard model (hazard ratio): 4.55; 95% confidence interval: 1.01-20.56; P = 0.049). In conclusion, SFRP5 is a target of epigenetic inactivation in human breast cancer, supporting the hypothesis of its role as tumor suppressor gene. SFRP5 methylation may be a novel DNA-based biomarker potentially useful in clinical breast cancer management.