Dickkopf-related Protein Research Articles

The antifibrotic drug pirfenidone inhibits spondyloarthritis fibroblast-like synoviocytes and osteoblasts in vitro

BackgroundThe pathogenesis of spondyloarthritis (SpA) involves both inflammation and new bone formation in the spine. In line with this, the disease has been characterized as both inflammatory and fibrotic. The current treatment dampens inflammation while new bone formation can progress. Therefore, there is an unmet therapeutic need for the treatment of new bone formation in SpA. Fibrosis is mediated by myofibroblasts and new bone formation is the result of increased osteoblast mineralization and decreased osteoclast resorption. Here, we evaluate the potential effect of the newly approved anti-fibrotic agent pirfenidone (PFD) on fibrosis and new bone formation in cell culture models of SpA.MethodsFibroblast-like synoviocytes (FLSs) were isolated from SpA patients (n = 6) while the osteoblast cell line Saos-2 was purchased. The cells were cultured with PFD at 0.25 0.5, or 1.0 mg/ml. The proliferation of FLSs was analyzed with light microscopy and flow cytometry. The differentiation and activation of FLSs was assessed with flow cytometry, a membrane-based antibody array and enzyme-linked immunosorbant assays. The mineralization capacity of osteoblasts was studied with an assay measuring deposition of hydroxyapatite.ResultsPFD reduced the Ki67 expression 7.1-fold in untreated FLSs (p = 0.001) and 11.0-fold in FLSs stimulated with transforming growth factor beta (TGFβ), tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) (p = 0.022). There were no statistically significant changes in membrane expression of alpha smooth muscle actin (αSMA), intercellular adhesion molecule 1 (ICAM-1), or human leukocyte antigen DR (HLA-DR). In supernatants from FLSs stimulated with TGFβ, TNFα, and IFNγ, PFD decreased the secretion of 3 of 12 proteins more than 2-fold in the membrane-based antibody array. The changes in secretion of monocyte chemoattractant protein 1 (MCP-1) and chitinase-3-like protein 1 (CHI3L1, YKL-40) were validated with ELISA. PFD decreased the secretion of both Dickkopf-related protein 1 (DKK1) (p = 0.006) and osteoprotegerin (OPG) (p = 0.02) by SpA FLSs stimulated with TGFβ, TNFα, and IFNγ. Finally, PFD inhibited the deposition of hydroxyapatite by osteoblasts in a dose-dependent manner (p = 0.0001).ConclusionsPFD inhibited SpA FLS proliferation and function and osteoblast mineralization in vitro. This encourages studies of the in vivo effect of PFD in SpA.

MiR-410 acts as an oncogene in colorectal cancer cells by targeting dickkopf-related protein 1 via the Wnt/β-catenin signaling pathway.

Colorectal cancer (CRC) is a common malignancy with high morbidity. MicroRNAs (miRNAs or miRs) have been demonstrated to be critical post-transcriptional regulators in tumorigenesis. The current study aimed to investigate the effect of miR-410 on the proliferation and metastasis of CRC. The expression of miR-410 was examined in CRC cell lines. SW-480 and HCT-116 CRC cell lines were employed and transfected with miR-410 inhibitor or miR-410 mimics. The association between miR-410 and dickkopf-related protein 1 (DKK-1) was verified by luciferase reporter assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and flow cytometry assay. Cell migration and invasion capacity were determined by Transwell assay. The protein level of DKK1, β-catenin and phosphorylated glycogen synthase kinase-3β (pGSK-3β) were analyzed by western blotting. miR-410 was revealed to be upregulated in CRC cell lines. Further studies identified DKK-1 as a direct target of miR-410. In addition, knockdown of miR-410 promoted the expression of DKK, inhibited CRC cell proliferation, migration and invasion capacity, and induced cell apoptosis, while overexpression of miR-410 reversed these results. miR-410 silencing also decreased β-catenin and pGSK-3β levels. The current study indicated that miR-410 negatively regulates the expression of DKK-1 in vitro. miR-410 promotes malignancy phenotypes in CRC cell lines. This regulatory effect of miR-410 may be associated with the Wnt/β-catenin signaling pathway. Therefore, miR-410 could be used as a biomarker for predicting the progression of CRC.

Abstract 16870: Dickkopf-Related Protein 1, a Wingless-Regulatory Molecule, Identifies Maladaptive Left Ventricular Remodeling in Aortic Stenosis

Introduction: Aortic stenosis (AS) may lead to left ventricular (LV) dysfunction with inadequate LV remodeling or may result in excessive LV hypertrophy. We hypothesized that circulatory Dickkopf-related protein 1 (DKK-1) as experimental regulator of myocardial repair could identify patients with a maladaptive LV response to AS. Maladaptive response may be defined by inadequate remodeling resulting in LV dysfunction or excessive hypertrophy. Methods: There were 53 adult patients demonstrated to have AS by echocardiogram or cardiac MRI completed between Jan 1st, 2016 and Dec 31st, 2017. Study patients were compared with 239 patients without AS. Patient and imaging data were collected. DKK-1 level was measured using Human DKK-1 quantikine ELISA kit. Values of DKK-1 were skewed, so non-parametric tests were used to determine the associations between DKK-1 and LV and AS parameters in echocardiography and cardiac MRI. Spearman’s Rank Order Correlation, Wilcoxon Rank Sum Test, and analysis of variance (ANOVA) were used to assess associations. Results: Among the 53 patients with AS, 29 (54.7%) were mild, 6 (11.3%) were moderate, and 18 (34%) were severe as per standard imaging criteria. In the study group, 32 (60.4%) were male, 21 (39.6%) were female, with a mean age of 72.2 years (range 47-90). In patients with AS, the median DKK-1 was 427.57 pg/mL, mean LV ejection fraction was 48.07%, mean LV mass was 147.5 g, and mean LV mass index was 69.1 g/m 2 . There was a statistically significant inverse correlation between DKK-1 and LV ejection fraction (correlation coefficient -0.28, p<0.05) only in patients with AS. There was an inverse trend of a correlation between DKK-1 and LV mass and mass index (correlation coefficient -0.3 and -0.23, respectively). There was no association between the severity of AS (aortic valve area, maximum velocity, or mean pressure gradient) and the level of DKK-1. Conclusions: In conclusion, DKK-1 might be a predictor of a maladaptive response in AS patients. In patients with elevated DKK-1 level, there is an associated diminished myocardial repair and LV dysfunction. In patients with low DKK-1 level there is a trend towards the development of accentuated LV hypertrophy. Our findings support further prospective clinical investigations of DKK-1 and other Wnt-regulatory molecules in patients with AS in the future.

Abstract 17353: Comparing the Association of DKK-1, a Wingless (Wnt)-Regulatory Molecule, and CRP-1 With Cardiovascular Risk Factor Profile and Coronary Plaque Burden in Patients With Coronary Artery Disease

Introduction: Our group has shown the Wnt-pathway to be a key regulator of SMC function and to be expressed in human coronary atheroma. Dickkopf-related protein 1 (DKK-1) is a member of the Wingless (Wnt) signaling pathway molecules and has recently been shown to improve GRACIE-risk factor score prediction of coronary events in chest pain patients and to predict restenosis post coronary stenting. We tested its association with coronary plaque burden and cardiovascular risk factors in comparison with CRP-1; Hypothesis: DKK-1 may be associated with coronary artery plaque burden and cardiovascular risk factors and play a role in coronary artery disease through modulation of SMC. Methods: 218 patients with angiographic evidence of CAD (mildly obstructive CAD, n=35; obstructive stable CAD, n=154; unstable CAD, n=29) were enrolled in this study at the time of cardiac catherization. DKK-1 and CRP-1 were measured by ELISA. Data are shown as Mean p SEM. Values of DKK-1 and CRP1 were skewed, so non-parametric tests were used to determine the associations between DKK-1 and CRP-1 with Syntax Score, age, BMI, LDL, HDL, and HgbA1c. . Spearman’s Rank Order Correlation, Wilcoxon Rank Sum Test, and analysis of variance (ANOVA) were used to assess associations. Results: Data are shown as Mean p SEM.Variables were as follows: DKK-1 736 pg/ml p 129, CRP-1 0.108 mg/ml p 0.01, age 66 years p 1, BMI 32 p 0.5, LDL 97 p 3, HDL 46 p 2, HgbA1C 6.5 p 0.2, Syntax score 11 p 0.7. With DKK-1 the only statistically significant correlation observed was between DKK-1 and HgbA1c (r=0.18, P<0.05). There was no association between DKK-1 and CRP-1, Syntax Score, Age, BMI, LDL, and HDL. With CRP-1, however, we observed significant positive correlations with Syntax Score (r=0.2, P<0.05), BMI (r=0.18, P<0.05), LDL (r=0.18, P<0.05) and significant negative correlation with age (r= -0.19, P<0.05) and with HDL (r=-0.18, P<0.05). There was no association between CRP-1 and HDL as well as HgbA1c. Conclusions: In patients with angiographically established CAD DKK-1 in contrast to CRP-1 is not a predictor of coronary plaque burden and has as only significant association a positive correlation with HgbA1c. Our data suggest that the reported role of DKK-1 in coronary event risk and in restenosis might be related to Diabetes mediated effects.

Alteration of cellular and immune-related properties of bone marrow mesenchymal stem cells and macrophages by K562 chronic myeloid leukemia cell derived exosomes.

Leukemic cells can impact the bone marrow niche to create a tumor-favorable microenvironment using their secreted factors. Little knowledge is available about immunosuppressive and tumor-promoting properties of chronic myeloid leukemia derived exosomes in bone marrow stromal components. We report here that K562-derived exosomes can affect the gene expression, cytokine secretion, nitric oxide (NO) production, and redox potential of bone marrow mesenchymal stem cells (BM-MSCs) and macrophages. Human BM-MSCs and mouse macrophages were treated with K562-derived exosomes. Our results demonstrated that the expression of the genes involved in hematopoietic developmental pathways and immune responses, including C-X-C motif chemokine 12 (Cxcl12), Dickkopf-related protein 1 (DKK1), wnt5a, interleukin 6 (IL-6), transforming growth factor-beta, and tumor necrosis factor-alpha (TNF-alpha), changed with respect to time and exosome concentration in BM-MSCs. The TNF-alpha level was higher in exosome-treated BM-MSCs compared with the control. Exosome treatment of BM-MSCs led to an increased production ofNO and a decreased production of reactive oxygen species (ROS) in a time- and concentration-dependent manner. We have shown that K562-derived exosomes induce overexpression of IL-10 and TNF-alpha and downregulation of iNOS transcript levels in macrophages. The enzyme-linked immunosorbent assay results showed that TNF-alpha and IL-10 secretions increased in macrophages. Treatment of macrophages with purified exosomes led to reduced NO and ROS levels. These results suggest that K562-derived exosomes may alter the local bone marrow niche toward a leukemia-reinforcing microenvironment. They can modulate the inflammatory molecules (TNF-alpha and NO) and the redox potential of BM-MSCs and macrophages and direct the polarization of macrophages toward tumor-associated macrophages.

Association between non-alcoholic fatty liver disease and bone turnover biomarkers in post-menopausal women with type 2 diabetes

AimInformation is lacking on the association between non-alcoholic fatty liver disease (NAFLD) and bone mineral density (BMD) or circulating bone turnover biomarkers in post-menopausal women with type 2 diabetes (T2DM). MethodsWe recruited 77 white post-menopausal women with T2DM, who consecutively attended our diabetes outpatient service during a 3-month period. Liver ultrasonography and transient elastography (Fibroscan®) were used for diagnosing and staging NAFLD. A dual energy X-ray absorptiometry, and serum levels of 25-hydroxyvitamin D3 [25(OH)D], parathyroid hormone and multiple bone turnover biomarkers (periostin, sclerostin, dickkopf-related protein-1 [DKK-1], C-terminal telopeptide of type 1 collagen [sCTX], procollagen type 1 N-terminal propeptide [P1NP], receptor activator of nuclear factor-kB ligand [RANKL]) were also measured. ResultsOverall, 10 patients had NAFLD with clinically significant fibrosis (i.e., liver stiffness measurement > 7 kPa), 52 had NAFLD without fibrosis and 15 patients were free from steatosis. Although the three patient groups had comparable values of BMD, after adjustment for age, waist circumference, HOMA-insulin resistance and serum 25(OH)D levels, patients with NAFLD and significant fibrosis had significantly higher sclerostin levels (54.1 ± 16.4 vs. 36.1 ± 11.9 vs. 42.3 ± 14.7 pmol/L) and lower levels of serum DKK-1 (26.6 ± 17.8 vs. 49.0 ± 22.4 vs. 42.9 ± 19.4 pmol/L), RANKL (0.04 ± 0.03 vs. 0.08 ± 0.06 vs. 0.11 ± 0.06 pmol/L) and sCTX (0.16 ± 0.09 vs. 0.29 ± 0.17 vs. 0.40 ± 0.28 ng/mL) compared to other groups. Serum periostin and P1NP levels did not significantly differ between the groups. ConclusionIn post-menopausal women with T2DM, the presence of NAFLD and clinically significant fibrosis was strongly associated with a low bone turnover, which may reflect the presence of qualitative bone abnormalities.

The 24-hour serum profiles of bone markers in healthy older men and women.

The process of bone turnover displays variations over 24 h, with C-terminal cross-linked telopeptide of type 1 collagen (CTX) and osteocalcin exhibiting a nadir in the afternoon and a peak in the night. In contrast, N-terminal propeptide of type 1 procollagen (P1NP) did not display an apparent 24-hour rhythm. Other emerging novel biomarkers of bone, sclerostin and Dickkopf-related protein 1 (DKK1), are markers of osteocyte activity with limited data available regarding their 24-hour profiles. In this study, we aimed to extend available data on 24-hour profiles of CTX, osteocalcin, and P1NP and to assess the 24-hour profiles of sclerostin and DKK1 in healthy older men and women and to compare these between men and women. We measured these five bone markers in EDTA plasma collected every 4 h during 24 h in 37 healthy older men and women (range 52-76 years). Differences between time points were determined using repeated measures ANOVA and cosinor analyses were performed to determine circadian rhythmicity. The circadian rhythm of CTX was confirmed by the cosinor model, with women showing larger amplitude compared to men. Osteocalcin showed higher levels during nighttime compared to daytime in both men and women. For P1NP levels we observed a small but significant increase in the night in men. Sclerostin and DKK1 did not show a circadian rhythm, but sclerostin levels differed between time points. Because of the large intraindividual variation, DKK1 as measured in this study cannot be considered a reliable marker for diagnostic or research purposes. In conclusion, when measuring CTX, osteocalcin, P1NP, or sclerostin either in clinical practice or in a research setting, one should consider the 24-hour profiles of these bone markers.

R-spondin 2 promotes osteoblastic differentiation of immature human periodontal ligament cells through the Wnt/β-catenin signaling pathway.

In this study, we measured the expression of R-spondin 2 (RSPO2) in periodontal ligament (PDL) tissue and cells. Further, we examined the effects of RSPO2 on osteoblastic differentiation of immature human PDL cells (HPDLCs). R-spondin (RSPO) family proteins are secreted glycoproteins that play important roles in embryonic development and tissue homeostasis through activation of the Wnt/β-catenin signaling pathway. RSPO2, a member of the RSPO family, has been reported to enhance osteogenesis in mice. However, little is known regarding the roles of RSPO2 in PDL tissues. Expression of RSPO2 in rat PDL tissue and primary HPDLCs was examined by immunohistochemical and immunofluorescence staining, as well as by semiquantitative RT-PCR. The effects of stretch loading on the expression of RSPO2 and Dickkopf-related protein 1 (DKK1) were assessed by quantitative RT-PCR. Expression of receptors for RSPOs, such as Leucine-rich repeat-containing G-protein-coupled receptors (LGRs) 4, 5, and 6 in immature human PDL cells (cell line 2-14, or 2-14 cells), was investigated by semiquantitative RT-PCR. Mineralized nodule formation in 2-14 cells treated with RSPO2 under osteoblastic inductive condition was examined by Alizarin Red S and von Kossa stainings. Nuclear translocation of β-catenin and expression of active β-catenin in 2-14 cells treated with RSPO2 were assessed by immunofluorescence staining and Western blotting analysis, respectively. In addition, the effect of Dickkopf-related protein 1 (DKK1), an inhibitor of Wnt/β-catenin signaling, was also examined. Rat PDL tissue and HPDLCs expressed RSPO2, and HPDLCs also expressed RSPO2, while little was found in 2-14 cells. Expression of RSPO2 as well as DKK1 in HPDLCs was significantly upregulated by exposure to stretch loading. LGR4 was predominantly expressed in 2-14 cells, which expressed low levels of LGR5 and LGR6. RSPO2 enhanced the Alizarin Red S and von Kossa-positive reactions in 2-14 cells. In addition, DKK1 suppressed nuclear translocation of β-catenin, activation of β-catenin, and increases of Alizarin Red S and von Kossa-positive reactions in 2-14 cells, all of which were induced by RSPO2 treatment. RSPO2, which is expressed in PDL tissue and cells, might play an important role in regulating the osteoblastic differentiation of immature human PDL cells through the Wnt/β-catenin signaling pathway.

Study of the incidence of osteoporosis in patients with Sjögren's syndrome (pSS) and investigation of activation of the RANKL /RANK and osteoprotegerin (OPG) system.

Primary Sjogren’s syndrome (pSS) is a common chronic autoimmune disease affecting 0.5–4.8% of the population. It is characterized by lymphocytic infiltration of exocrine glands - mainly salivary and lacrimal - resulting in oral and ocular dryness, although any organ system can virtually be affected. Among all autoimmune diseases, pSS has the highest risk for development of non-Hodgkin’s lymphoma (NHL) and approximately 10% of patients with SS associated with increased risk for B-cell lymphoma development and high mortality rates. In pSS there are various systemic manifestations; such as arthritis, rashes, Raynaud’s phenomenon, peripheral neuropathy and glomerulonephritis.1,2 While over the past few years, the importance of coexistence in the context of systemic autoimmune diseases such as subclinical atherosclerosis and osteoporosis has been extensively studied in pSS, data on the incidence and underlying pathophysiological mechanisms of osteopenia/osteoporosis are limited. In particular, osteopenia and osteoporosis levels appear to be elevated in patients with systemic autoimmune disorders, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and systemic sclerosis.3–5 Patients with pSS display a set of clinical and serological features that could possibly lead to reduced bone remodelling and reduced bone mineral density (BMD); such as low vitamin D levels, hypercalciuria associated with underlying interstitial nephritis, steroid use, as well as coexistence with other autoimmune disorders associated with an increased risk of osteoporosis such as primary biliary cirrhosis, celiac disease and distal renal tubular acidosis (dRTA). A strong relationship between the Wingless-type signalling pathway (Wnt) and pathophysiology of osteoporosis has been recognized, as mutations in that pathway lead to reduced bone density.(6) 77 with rheumatoid arthritis (RA A recent study found reduced bone density in pSS patients compared to reduced levels of DKK1 (Dickkopf-related protein 1) in the Wnt pathway, where it may be due to inhibition of bone formation.7 Another equally important signalling pathway crucial for bone homeostasis is the molecular pathway of RANKL and osteoprotegerin (OPG).7,8 Nf-κB receptor activating factor (RANK), its ligand (RANKL) and osteoprotegerin (OPG) - all members of the cytokine tumour necrosis factor (TNF) superfamily - play an important role in bone homeostasis as principal osteoclastogenic factors.8 RANKL is expressed by syno-vial cells, bone marrow stromal cells and osteocytes, and is secreted by osteoblasts and immune cells; such as activated T cells, including Tregs and activated B cells and lymphoid tissue cells.(9–13) The expression of RANKL is modulated by various cytokines upon stimulation by memory B cells, including interleukin-1 (IL-1), IL-6, IL-11, IL-12, IL-15 and TNF-α, glucocorticoids and parathyroid hormone.12–16 Osteoprotegerin acts as a competitive antagonist receptor, which binds membrane protein RANK and soluble RANKL molecule, plays an osteoprotective role.17 RANKL prevents bone reconstruction while OPG inhibits this action, effectively promoting bone reconstruction. The RANKL / OPG ratio appears to be the key to maintaining bone homeostasis. The RANKL / RANK / OPG signalling pathway has been shown to be activated in many autoimmune disorders, such as RA and systemic lupus erythematosus (SLE), with a role in the development of bone erosions and osteoporosis.14,18,19

Individual or combination treatments with lapatinib and paclitaxel cause potential bone loss and bone marrow adiposity in rats.

Cancer treatments with cytotoxic drugs have been shown to cause bone loss. However, effects on bone are less clear for ErbB-targeting tyrosine kinase inhibitors or their combination use with cytotoxic drugs. This study examined the effects of individual or combination treatments with breast cancer drugs lapatinib (a dual ErbB1/ErbB2 inhibitor) and paclitaxel (a microtubule-stabilizing cytotoxic agent) on bone and bone marrow of rats. Wistar rats received lapatinib (240 mg/kg) daily, paclitaxel (12 mg/kg) weekly, or their combination for 4 weeks, and effects on bone/bone marrow were examined at the end of week 4. Microcomputed tomographical structural analyses showed a reduction in trabecular bone volume in tibia following the lapatinib, paclitaxel or their combination treatments ( P < 0.05). Histomorphometry analyses revealed marked increases in bone marrow adipocyte contents in all treatment groups. Reverse transcription polymerase chain reaction gene expression studies with bone samples and cell culture studies with isolated bone marrow stromal cells showed that the all treatment groups displayed significantly reduced levels of osterix expression and osteogenic differentiation potential but increased expression levels of adipogenesis transcription factor peroxisome proliferator-activated receptor γ. In addition, these treatments suppressed the expression of Wnt10b and/or increased expression of Wnt antagonists (secreted frizzled-related protein 1, Dickkopf-related protein 1 and/or sclerostin). Furthermore, all treatment groups showed increased numbers of bone-resorbing osteoclasts on trabecular bone surfaces, although only the lapatinib group displayed increased levels of osteoclastogenic signal (receptor activator of nuclear factor κΒ ligand/osteoclastogenesis inhibitor osteoprotegrin expression ratio) in the bones. Thus, inhibiting ErbB1 and ErbB2 by lapatinib or blocking cell division by paclitaxel or their combination causes significant trabecular bone loss and bone marrow adiposity involving a switch in osteogenesis/adipogenesis potential, altered expression of some major molecules of the Wnt/β-catenin signalling pathway, and increased recruitment of bone-resorbing osteoclasts.

Osteoprotegrin interacts with biomarkers and cytokines that have roles in osteoporosis, skin fibrosis, and vasculopathy in systemic sclerosis: A potential multifaceted relationship between OPG/RANKL/TRAIL and Wnt inhibitors

Objectives: We explored the interactions of osteoprotegerin (OPG) with biomarkers of bone turnover and cytokines, including soluble receptor activator for nuclear factor kappa beta ligand (sRANKL), tumor necrosis factor-related apoptosis-induced ligand (TRAIL), and Wnt inhibitors in osteoporosis, vasculopathy and fibrosis related to systemic sclerosis (SSc).Methods: The study included 46 SSc patients and 30 healthy controls. Skin thickness, pulmonary fibrosis and/or hypertension, digital ulcers, and calcinosis cutis of SSc patients were assessed. We determined bone mineral density (BMD), and OPG, sRANKL, TRAIL, secreted frizzled-related protein 1 (sFRP-1), Dickkopf-related protein 1 (DKK-1), sclerostin in the serum of both patients and controls.Results: OPG, sclerostin, and sFRP-1 levels were similar between patients and controls (P > 0.05). Femoral neck and lumbar spine BMD and vitamin D levels were lower, and the OC, NTX, sRANKL, DKK1 and TRAIL levels were significantly higher, in patients than in controls (p < 0.05). In subgroup analysis, patients with higher modified Rodnan skin score (mRodnan) had higher DKK-1, sclerostin, and TRAIL levels (p < 0.05); those with diffuse SSc subtype had lower BMD values than those with limited SSc (p < 0.05). Skin and pulmonary fibrosis linked negatively with BMD measures.Conclusion: we showed that sRANKL levels were higher and correlated with bone turnover markers. It may be related to osteoporosis in SSc. The OPG level was unaltered in SSc patients. Higher TRAIL levels associated with skin thickness may indicate vascular dysfunction or injury. Higher DKK-1 and sclerostin levels may be related to a reactive increase in cells and be prominently linked to fibrosis in SSc.

Meridianin C inhibits the growth of YD-10B human tongue cancer cells through macropinocytosis and the down-regulation of Dickkopf-related protein-3.

Meridianin C is a marine natural product known for its anti‐cancer activity. At present, the anti‐tumour effects of meridianin C on oral squamous cell carcinoma are unknown. Here, we investigated the effect of meridianin C on the proliferation of four different human tongue cancer cells, YD‐8, YD‐10B, YD‐38 and HSC‐3. Among the cells tested, meridianin C most strongly reduced the growth of YD‐10B cells; the most aggressive and tumorigenic of the cell lines tested. Strikingly, meridianin C induced a significant accumulation of macropinosomes in the YD‐10B cells; confirmed by the microscopic and TEM analysis as well as the entry of FITC‐dextran, which was sensitive to the macropinocytosis inhibitor amiloride. SEM data also revealed abundant long and thin membrane extensions that resemble lamellipodia on the surface of YD‐10B cells treated with meridianin C, pointing out that meridianin C‐induced macropinosomes was the result of macropinocytosis. In addition, meridianin C reduced cellular levels of Dickkopf‐related protein‐3 (DKK‐3), a known negative regulator of macropinocytosis. A role for DKK‐3 in regulating macropinocytosis in the YD‐10B cells was confirmed by siRNA knockdown of endogenous DKK‐3, which led to a partial accumulation of vacuoles and a reduction in cell proliferation, and by exogenous DKK‐3 overexpression, which resulted in a considerable inhibition of the meridianin C‐induced vacuole formation and decrease in cell survival. In summary, this is the first study reporting meridianin C has novel anti‐proliferative effects via macropinocytosis in the highly tumorigenic YD‐10B cell line and the effects are mediated in part through down‐regulation of DKK‐3.

Wnt signaling in human and mouse breast cancer: Focusing on Wnt ligands, receptors and antagonists.

Wnt proteins, a group of secreted glycoproteins, mainly combine with receptors Frizzled (FZD) and/or low‐density‐lipoprotein receptor‐related proteins 5/6 (LRP5/6), initiating β‐catenin‐dependent and ‐independent signaling pathways. These pathways, which can be regulated by some secreted antagonists such as secreted Frizzled‐related proteins (SFRP) and dickkopf‐related protein (DKK), play a critical role in embryo development and adult homeostasis. Overactivation of Wnt signaling has been implicated in some human diseases including cancer. Wnt transgenic mice provide convincing evidence that Wnt signaling is involved in breast cancer initiation and progression, which is further strengthened by observations on human clinical breast cancer patients and studies on in vitro cultured human breast cancer cells. This review focuses on the roles of Wnt ligands, receptors and antagonists in breast cancer development instead of molecules or signaling transactivating β‐catenin independent on Wnt upstream components.

An Optimized System for Effective Derivation of Three-Dimensional Retinal Tissue via Wnt Signaling Regulation.

Effective derivation of three-dimensional (3D) retinal tissue from human-induced pluripotent stem cells (hiPSCs) could provide models for drug screening and facilitate patient-specific retinal cell replacement therapy. However, some hiPSC lines cannot undergo 3D self-organization and show inadequate differentiation efficiency to meet clinical demand. In this study, we developed an optimized system for derivation of 3D retinal tissue. We found that the Wnt signaling pathway antagonist Dickkopf-related protein 1 (DKK-1) rescued the inability of differentiated retinal progenitors to self-organize. By evaluating DKK-1 expression and supplying DKK-1 if necessary, retinal organoids were differentiated from six hiPSC lines, which were reprogramed from three common initiating cell types. Retinal tissues derived from the optimized system were well organized and capable of surviving for further maturation. Thus, using this system, we generated retinal tissues from various hiPSC lines with high efficiency. This novel system has many potential applications in regenerative therapy and precision medicine. Stem Cells 2018;36:1709-1722.

MiR-214 ameliorates acute kidney injury via targeting DKK3 and activating of Wnt/\u03b2-catenin signaling pathway

BackgroundmiR-214 was demonstrated to be upregulated in models of renal disease and promoted fibrosis in renal injury independent of TGF-β signaling in vivo. However, the detailed role of miR-214 in acute kidney injury (AKI) and its underlying mechanism are still largely unknown.MethodsIn this study, an I/R-induced rat AKI model and a hypoxia-induced NRK-52E cell model were used to study AKI. The concentrations of kidney injury markers serum creatinine, blood urea nitrogen, and kidney injury molecule-1 were measured. The expressions of miR-214, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, were detected by RT-qPCR. The protein levels of Bcl-2, Bax, Dickkopf-related protein 3, β-catenin, c-myc, and cyclinD1 were determined by western blot. Cell apoptosis and caspase 3 activity were evaluated by flow cytometry analysis and caspase 3 activity assay, respectively. Luciferase reporter assay was used to confirm the interaction between miR-214 and Dkk3.ResultsmiR-214 expression was induced in ischemia–reperfusion (I/R)-induced AKI rat and hypoxic incubation of NRK-52E cells. Overexpression of miR-214 alleviated hypoxia-induced NRK-52E cell apoptosis while inhibition of miR-214 expression exerted the opposite effect. Dkk3 was identified as a target of miR-214. Anti-miR-214 abolished the inhibitory effects of DKK3 knockdown on hypoxia-induced NRK-52E cell apoptosis by inactivation of Wnt/β-catenin signaling. Moreover, miR-214 ameliorated AKI in vivo by inhibiting apoptosis and fibrosis through targeting Dkk3 and activating Wnt/β-catenin pathway.ConclusionmiR-214 ameliorates AKI by inhibiting apoptosis through targeting Dkk3 and activating Wnt/β-catenin signaling pathway, offering the possibility of miR-214 in the therapy of ischemic AKI.

Rehmanniae Radix Preparata suppresses bone loss and increases bone strength through interfering with canonical Wnt/β-catenin signaling pathway in OVX rats.

Determine the anti-osteoporotic effect of RRP in ovariectomized (OVX) rats and identify the signaling pathway involved in this process. OVX rats were treated with RRP aqueous extract for 14weeks. The serum levels of tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear factor kappa-Β ligand(RANKL), alkaline phosphatase (ALP), and osteoprotegerin (OPG) were determined by ELISA. Bone histopathological alterations were evaluated by H&E, Alizarin red S, and Safranin O staining. Bone mineral density (BMD) and bone microstructure in rat femurs and lumbar bones were determined by dual-energy X-ray absorptiometry and micro-computed tomography. Femoral bone strength was detected by a three-point bending assay. The expression of Phospho-glycogen synthase kinase 3 beta (p-GSK-3β), GSK-3β, Dickkopf-related protein 1 (DKK1), cathepsin K, OPG, RANKL, IGF-1, Runx2, β-catenin, and p-β-catenin was determined by western blot and/or immunohistochemical staining. Treatment of OVX rats with RRP aqueous extract rebuilt bone homeostasis demonstrated by increasing the levels of OPG as well as decreasing the levels of TRAP, RANKL, and ALP in serum. Furthermore, RRP treatment preserved BMD and mechanical strength by increasing cortical bone thickness and epiphyseal thickness as well as improving trabecular distribution in the femurs of OVX rats. In addition, RRP downregulated the expression of DKK1, sclerostin, RANKL, cathepsin K, and the ratio of p-β-catenin to β-catenin, along with upregulating the expression of IGF-1, β-catenin, and Runx2 and the ratio of p-GSK-3β to GSK-3β in the tibias and femurs of OVX rats. Echinacoside, jionoside A1/A2, acetoside, isoacetoside, jionoside B1, and jionoside B2 were identified in the RRP aqueous extract. RRP attenuates bone loss and improves bone quality in OVX rats partly through its regulation of the canonical Wnt/β-catenin signaling pathway, suggesting that RRP has the potential to provide a new source of anti-osteoporotic drugs.

Pigment epithelium derived factor regulates human Sost/Sclerostin and other osteocyte gene expression via the receptor and induction of Erk/GSK-3beta/beta-catenin signaling

Mutations in Serpinf1 gene which encodes pigment epithelium derived factor (PEDF) lead to osteogenesis imperfecta type VI whose hallmark is defective mineralization. We reported that PEDF suppressed expression of Sost/Sclerostin and other osteocyte related genes in mineralizing osteoblast cultures and suggested that this could be part of the mechanisms by which PEDF regulates matrix mineralization (Li et al. J Cellular Phys. 2014). We have used a long-term differentiated mineralizing osteoblast culture (LTD) to define mechanisms by which PEDF regulates osteocyte gene expression. LTD cultures were established by culturing human osteoblasts in an osteogenic medium for 4 months followed by analysis of osteocytes related genes and encoded proteins. LTD cells synthesized Sclerostin, matrix extracellular phosphoglycoprotein (MEPE) and dentin matrix protein (DMP-1) and their synthesis was reduced by treatment with PEDF. Treatment of the cultures with PEDF induced phosphorylation of Erk and glycogen synthase kinase 3-beta (GSK-3β), and accumulation of nonphosphorylated β-catenin. Inhibition of Erk activation and neutralizing antibodies to the pigment epithelium derived receptor (PEDF-R) suppressed GSK-3β phosphorylation and accumulation of nonphosphorylated β-catenin in presence of PEDF. Topflash assays demonstrated that PEDF activated luciferase reporter activity and this activity was inhibited by treatment with Erk inhibitor or neutralizing antibodies to PEDF-R. Dickkopf-related protein 1 treatment of the cells in presence of PEDF had minimal effect suggesting that GSK-3β phosphorylation and accumulation of nonphosphorylayted β-catenin may not involve LRP5/6 in osteocytes. Taken together, the data demonstrate that PEDF regulates osteocyte gene expression through its receptor and possible involvement of Erk/GSK-3β/β-catenin signaling pathway.

Elevated hydrostatic pressure promotes ameloblastoma cell invasion through upregulation of MMP-2 and MMP-9 expression via Wnt/β-catenin signalling.

The process of marsupialization involves the release of intracystic pressure and the fluid contained within. Marsupialization of cystic ameloblastoma is controversial; therefore, we investigated how hydrostatic pressure influences biological behaviours of ameloblastoma cells and its underlying mechanisms. An ameloblastoma epithelial cell line, hTERT+ -AM, was exposed to different hydrostatic pressures with or without Dickkopf-related protein 1 (also known as DKK), a canonical Wnt signalling pathway inhibitor. A CCK-8 assay, a monolayer wound assay, and a Transwell assay were used to determine cell proliferation, migration and invasion, respectively. qRT-PCR and Western blot were used to detect expression of MMP-2, MMP-9, RANKL and other downstream targets of Wnt signalling. Elevated hydrostatic pressure promoted migration and invasion of ameloblastoma cells, but inhibited proliferation. Expression of MMP-2, MMP-9, LEF-1, cyclin D1, c-Jun and c-Myc was significantly upregulated under elevated hydrostatic pressure, and these effects could be abolished by DKK1. Expression of RANKL, which is thought to be a downstream target of Wnt signalling, did not significantly change under elevated hydrostatic pressure. This study indicates that elevated hydrostatic pressure promotes the migration and invasion of ameloblastoma cells by activating the Wnt/β-catenin pathway, thereby increasing expression of MMP-2, MMP-9 and other Wnt signalling downstream targets. This suggests that marsupialization may reduce invasiveness and reverse the bone resorption process by lowering intracystic hydrostatic pressure in cystic ameloblastoma.

Metformin protects bone mass in ultra-high-molecular-weight polyethylene particle-induced osteolysis by regulating osteocyte secretion.

Metformin, an anti-hyperglycemic agent used for type 2 diabetes, has recently been found to have more effects apart from glucose regulation. We found that, in ultra-high-molecular-weight polyethylene particle-induced osteolysis mouse models, metformin had bone protect property and reduced the negative regulator of bone formation sclerostin (SOST) and Dickkopf-related protein 1 (DKK1), and increased osteoprotegerin (OPG) secretion and the ratio of OPG/Receptor Activator for Nuclear Factor-κB Ligand (RANKL). In vitro, we established a 3D co-culture system in which metformin affects osteoblasts and osteoclasts through mature osteocytes secretion. Metformin (50μM) significantly decreased SOST and DKK1 mRNA expression, stimulating alkaline phosphatase activity and proliferation of osteoblast, and increased OPG secretion and the ratio of OPG/RANKL, inhibiting osteoclastogenesis. Moreover, the effect on OPG was reversed by adenosine 5'-monophosphate-activated protein kinase inhibitor, Compound C. Our finding suggests that metformin induces differentiation and mineralization of osteoblasts, while inhibits osteoclastogenesis via mature osteocytes secretion. Therefore, the drug might be beneficial for not only diabetes but also in other bone disorders by acting on mature osteocytes.

FGF23-klotho axis, bone fractures, and arterial stiffness in dialysis: a case-control study.

New bone markers such as sclerostin, Dickkopf-related protein 1 (DKK1), fibroblast growth factor-23 (FGF23), and α-klotho have been identified as potential key players in bone and vascular abnormalities of chronic kidney disease. Therefore, we aimed to assess whether these markers are associated with fractures, bone metabolism, and vascular stiffness in dialysis patients. In a prospective hemodialysis cohort, where plasma samples and vascular assessment were performed at baseline, we matched patients who experienced a fracture during follow-up with sex- and age-matched non-fractured patients on a 1:4 ratio. Sclerostin, DKK1, α-klotho, FGF23, and markers of bone formation (alkaline phosphatase and procollagen type 1-N terminal propeptide [P1NP]) and bone resorption (tartrate-resistant acid phosphatase 5b [TRAP5b]) were measured in baseline plasma samples. Aortic-brachial pulse wave velocity ratio, a blood pressure independent measure of arterial stiffness, was used to assess vascular stiffness at baseline. We included 130 hemodialysis patients (26 fractured, 104 non-fractured) with a median follow-up of 42months and a median age of 72years. In multivariate Cox regression models, high FGF23 levels were associated with increased fracture incidence (adjusted HR = 2.97; 95% CI 1.18, 7.43). α-Klotho levels were associated with bone formation but not resorption markers. In both univariate and multivariable adjusted models, α-klotho levels were inversely associated with the aortic-brachial pulse wave velocity ratio (β = - 0.070; 95% CI - 0.133, - 0.006). These results suggest a role for FGF23/klotho axis on bone and vascular metabolism in dialysis populations.