Osteoprotegerin (OPG) activates integrin, focal adhesion kinase (FAK), and Akt signaling in ovarian cancer cells to attenuate TRAIL-induced apoptosis

Correlating Material Properties to Osteoprotegerin Expression on Nanoparticulate Mineralized Collagen Glycosaminoglycan Scaffolds

Precision material design directed by cell biological processes represents a frontier in developing clinically translatable regenerative technologies. While understanding cell-material interactions on multipotent progenitor cells yields insights on target tissue differentiation, equally if not more important is the quantification of indirect multicellular interactions. In this work, the relationship of two material properties, phosphate content and stiffness, of a nanoparticulate mineralized collagen glycosaminoglycan scaffold (MC-GAG) in the expression of an endogenous anti-osteoclastogenic secreted protein, osteoprotegerin (OPG) by primary human mesenchymal stem cells (hMSCs) is evaluated. The phosphate content of MC-GAG requires the type III sodium phosphate symporter PiT-1/SLC20A1 for OPG expression, correlating with β-catenin downregulation, but is independent of the effects of phosphate ion on osteogenic differentiation. Using three stiffness MC-GAG variants that do not differ significantly by osteogenic differentiation, it is observed that the softest material elicited ≈1.6-2 times higher OPG expression than the stiffer materials. Knockdown of the mechanosensitive signaling axis of YAP, TAZ, β-catenin and combinations thereof in hMSCs on MC-GAG demonstrates that β-catenin downregulation increases OPG expression by 1.5-fold. Taken together, these data constitute a roadmap for material properties that can used to suppress osteoclast activation via osteoprotegerin expression separately from the anabolic processes of osteogenesis.

Mechanisms underlying reversed TRAIL sensitivity in acquired bortezomib-resistant non-small cell lung cancer cells

Aim: The therapeutic targeting of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) death receptors in cancer, including non-small cell lung cancer (NSCLC), is a widely studied approach for tumor selective apoptotic cell death therapy. However, apoptosis resistance is often encountered. The main aim of this study was to investigate the apoptotic mechanism underlying TRAIL sensitivity in three bortezomib (BTZ)-resistant NSCLC variants, combining induction of both the intrinsic and extrinsic pathways. Methods: Sensitivity to TRAIL in BTZ-resistant variants was determined using a tetrazolium (MTT) and a clonogenic assay. A RT-qPCR profiling mRNA array was used to determine apoptosis pathway-specific gene expression. The expression of these proteins was determined through ELISA assays and western Blotting, while apoptosis (sub-G1) and cytokine expression were determined using flow cytometry. Apoptotic genes were silenced by specific siRNAs. Lipid rafts were isolated with fractional ultracentrifugation. Results: A549BTZR (BTZ-resistant) cells were sensitive to TRAIL in contrast to parental A549 cells, which are resistant to TRAIL. TRAIL-sensitive H460 cells remained equally sensitive for TRAIL as H460BTZR. In A549BTZR cells, we identified an increased mRNA expression of TNFRSF11B [osteoprotegerin (OPG)] and caspase-1, -4 and -5 mRNAs involved in cytokine activation and immunogenic cell death. Although the OPG, interleukin-6 (IL-6), and interleukin-8 (IL-8) protein levels were markedly enhanced (122-, 103-, and 11-fold, respectively) in the A549BTZR cells, this was not sufficient to trigger TRAIL-induced apoptosis in the parental A549 cells. Regarding the extrinsic apoptotic pathway, the A549BTZR cells showed TRAIL-R1-dependent TRAIL sensitivity. The shift of TRAIL-R1 from non-lipid into lipid rafts enhanced TRAIL-induced apoptosis. In the intrinsic apoptotic pathway, a strong increase in the mRNA and protein levels of the anti-apoptotic myeloid leukemia cell differentiation protein (Mcl-1) and B-cell leukemia/lymphoma 2 (Bcl-2) was found, whereas the B-cell lymphoma-extra large (Bcl-xL) expression was reduced. However, the stable overexpression of Bcl-xL in the A549BTZR cells did not reverse the TRAIL sensitivity in the A549BTZR cells, but silencing of the BH3 Interacting Domain Death Agonist (BID) protein demonstrated the importance of the intrinsic apoptotic pathway, regardless of Bcl-xL. Conclusion: In summary, increased sensitivity to TRAIL-R1 seems predominantly related to the relocalization into lipid rafts and increased extrinsic and intrinsic apoptotic pathways.

Single-Cell Sequencing of Malignant Ascites Reveals Transcriptomic Remodeling of the Tumor Microenvironment during the Progression of Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the main cause of mortality among gynecological malignancies worldwide. Although patients with EOC undergo aggregate treatment, the prognosis is often poor. Peritoneal malignant ascites is a distinguishable clinical feature in EOC patients and plays a pivotal role in tumor progression and recurrence. The mechanisms of the tumor microenvironment (TME) in ascites in the regulation of tumor progression need to be explored. We comprehensively analyzed the transcriptomes of 4680 single cells from five EOC patients (three diagnostic samples and two recurrent samples) derived from Gene Expression Omnibus (GEO) databases. Batch effects between different samples were removed using an unsupervised deep embedding single-cell cluster algorithm. Subcluster analysis identified the different phenotypes of cells. The transition of a malignant cell state was confirmed using pseudotime analysis. The landscape of TME in malignant ascites was profiled during EOC progression. The transformation of epithelial cancer cells into mesenchymal cells was observed to lead to the emergence of related anti-chemotherapy and immune escape phenotypes. We found the activation of multiple biological pathways with the transition of tumor-associated macrophages and fibroblasts, and we identified the infiltration of CD4⁺CD25⁺ T regulatory cells in recurrent samples. The cell adhesion molecules mediated by integrin might be associated with the formation of the tumorsphere. Our study provides novel insights into the remodeling of the TME heterogeneity in malignant ascites during EOC progression, which provides evidence for identifying novel therapeutic targets and promotes the development of ovarian cancer treatment.

The Role of CCN1 in Esophageal Adenocarcinoma: What We Have Learned From the Lab

Background: Esophageal cancer is one of the most common and deadliest cancers in the world, particularly esophageal adenocarcinoma. There has never been a special drug to treat it.Purpose: This article summarizes the work that we have done in our laboratory about the role of CCN1 in esophageal cancer and gives a new perspective of CCN1 biology.Research Design: This is a review article. Study Sample: The work was done using validated cell lines and fixed human tissue slides.Data Collection and Analysis: This is a review article, therefore, no data collection or analysis was involved.Results: CCN1 is a matricellular protein supporting adhesion, migration, and survival in normal cells, but in the esophageal cancer cells, it induces TRAIL-mediated apoptosis. CCN1 promotes TRAIL and its death receptor expression but downregulates the decoy receptors and survivin in a p53-dependant manner. It was thought that CCN1 relies on TNF to induce apoptosis, but our study found that these two molecules antagonize each other. CCN1 promotes TNFR1 cleavage and uses the soluble product to block TNF signaling, while TNF upregulates PGLYRP1 to overcome this obstacle because PGLYRP1 is a secreted protein that competes with TNF for TNFR1 binding. As a result, when CCN1 and TNF are present together in the vicinity of esophageal tumors, they cancel each other out.Conclusions: Based on our laboratory study, CCN1 has much potential to be a candidate for the treatment of esophageal cancer.

The role of osteoprotegerin (OPG) in fibrosis: its potential as a biomarker and/or biological target for the treatment of fibrotic diseases

Fibrosis is defined by excessive formation and accumulation of extracellular matrix proteins, produced by myofibroblasts, that supersedes normal wound healing responses to injury and results in progressive architectural remodelling. Fibrosis is often detected in advanced disease stages when an organ is already severely damaged and can no longer function properly. Therefore, there is an urgent need for reliable and easily detectable markers to identify and monitor fibrosis onset and progression as early as possible; this will greatly facilitate the development of novel therapeutic strategies. Osteoprotegerin (OPG), a well-known regulator of bone extracellular matrix and most studied for its role in regulating bone mass, is expressed in various organs and functions as a decoy for receptor activator of nuclear factor kappa-B ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Recently, OPG has been linked to fibrosis and fibrogenesis, and has been included in a panel of markers to diagnose liver fibrosis. Multiple studies now suggest that OPG may be a general biomarker suitable for detection of fibrosis and/or monitoring the impact of fibrosis treatment. This review summarizes our current understanding of the role of OPG in fibrosis and will discuss its potential as a biomarker and/or novel therapeutic target for fibrosis.

Testing the efficacy of a human full-length OPG-Fc analog in a severe model of cardiotoxin-induced skeletal muscle injury and repair

Although receptor-activator of nuclear factor κB (RANK), its ligand RANKL, and osteoprotegerin (OPG), which are members of the tumor necrosis factor (TNF) superfamily, were first discovered in bone cells, they are also expressed in other cells, including skeletal muscle. We previously showed that the RANK/RANKL/OPG pathway is involved in the physiopathology of Duchenne muscular dystrophy and that a mouse full-length OPG-Fc (mFL-OPG-Fc) treatment is superior to muscle-specific RANK deletion in protecting dystrophic muscles. Although mFL-OPG-Fc has a beneficial effect in the context of muscular dystrophy, the function of human FL-OPG-Fc (hFL-OPG-Fc) during muscle repair is not yet known. In the present study, we investigated the impacts of an hFL-OPG-Fc treatment following the intramuscular injection of cardiotoxin (CTX). We show that a 7-day hFL-OPG-Fc treatment improved force production of soleus muscle. hFL-OPG-Fc also improved soleus muscle integrity and regeneration by increasing satellite cell density and fiber cross-sectional area, attenuating neutrophil inflammatory cell infiltration at 3 and 7 days post-CTX injury, increasing the anti-inflammatory M2 macrophages 7 days post-CTX injury. hFL-OPG-Fc treatment also favored M2 over M1 macrophage phenotypic polarization in vitro. We show for the first time that hFL-OPG-Fc improved myotube maturation and fusion in vitro and reduced cytotoxicity and cell apoptosis. These findings demonstrate that hFL-OPG-Fc has therapeutic potential for muscle diseases in which repair and regeneration are impaired.

Overexpression of c-Fos reverses osteoprotegerin-mediated suppression of osteoclastogenesis by increasing the Beclin1-induced autophagy

Osteoclastogenesis requires the involvement of transcription factors and degrading enzymes, and is regulated by upstream and downstream signalling. However, c-Fos how regulates osteoclastogenesis through autophagy remain unclear. This study aimed to explore the role of c-Fos during osteoprotegerin (OPG)-mediated suppression of osteoclastogenesis. We found that the number of osteoclasts and the expression of c-Fos, MMP-9, CAⅡ, Src and p62 were decreased after treated with OPG, including attenuation the PI3K/Akt and the TAK1/S6 signalling pathways, but the expression of Beclin1 and LC3Ⅱ were increased. Knockdown of Beclin1 could reverse the expression of c-Fos and MMP-9 by activating the PI3K/Akt signalling pathway, but inhibiting the autophagy and the TAK1/S6 signalling pathway. In addition, inhibition of autophagy using the PI3K inhibitor LY294002 did not rescues OPG-mediated suppression of osteoclastogenesis, but caused reduction of the expression of c-Fos and CAⅡ by attenuating the autophagy, as well as the PI3K/Akt and the TAK1/S6 signalling pathways. Furthermore, continuous activation of c-Fos could reverse OPG-mediated suppression of osteoclastogenesis by activating the autophagy and the PI3K/Akt and the TAK1/S6 signalling pathways. Thus, overexpression of c-Fos could reverse OPG-mediated suppression of osteoclastogenesis via activation of Beclin1-induced autophagy, indicating c-Fos might serve as a new candidate for bone-related basic studies.

Molecular Dynamics in Esophageal Adenocarcinoma: Who's in Control?

Esophageal adenocarcinoma (EAC) is one of the fastest-growing cancers in the world. It occurs primarily due to the chronic gastroesophageal reflux disease (GERD), during which the esophageal epithelium is frequently exposed to the acidic fluid coming up from the stomach. This triggers gene mutations in the esophageal cells, which may lead to EAC development. While p53 is activated to get rid of the mutated cells, NFκB orchestrates the remaining cells to heal the wound. However, if the mutations happen to TP53 (a common occasion), the mutant product turns to support tumorigenesis. In this case, NFκB goes along with the mutant p53 to facilitate cancer progression. TRAIL is one of the cytokines produced in response to GERD episodes and it can kill cancer cells selectively, but its clinical use has not been as successful as expected, because some highly sophisticated defense mechanisms against TRAIL have developed during the malignancy. To clear the obstacles for TRAIL action, using a second agent to disarm the cancer cells is required. CCN1 appears to be such a molecule. While supporting normal esophageal cell growth, CCN1 suppresses malignant transformation by inhibiting NFκB and kills the EAC cell through TRAIL-mediated apoptosis.

Changes in the Concentration of Markers Participating in the Regulation of the Apoptosis Receptor Pathway Involving Soluble Tumour Necrosis Factor Ligand inducing Apoptosis (sTRAIL) and Osteoprotegerin (OPG) in the Serum of Women with Ovarian Cancer-Participation in Pathogenesis or a Possible Clinical Use?

Due to the ability to selectively induce apoptosis in cancer cells, the most interesting target for clinical research is the tumour necrosis factor ligand inducing apoptosis (TRAIL), which binds specific receptors, including osteoprotegerin (OPG). The aim of the study was to analyse the concentration of soluble TRAIL (sTRAIL) and OPG in the serum of women with serous or mucinous ovarian cancer, taking into account different levels of cancer histological differentiation. The group included 97 women with the diagnosed Cystadenocarcinoma papillare serosum IIIc and Cystadenocarcinoma mucinosum IIIc. Concentrations of parameters were measured by ELISA. Analysis of the obtained results showed a statistically significantly higher concentration of sTRAIL and OPG in the serum of women with ovarian serous and mucinous cancer compared to the control group (p < 0.0001). Statistical significance was found between sTRAIL and OPG concentration in G1 and G3 serous cancer (p < 0.01) and in OPG mucinous cancer between G1 and G3 (p < 0.01) and G2 and G3 (p < 0.01). An important role in the pathogenesis of ovarian cancer is played by disorders of the apoptosis process involving the sTRAIL/OPG system, which are associated with the histological type and the degree of histological differentiation of the tumour. Determining the concentration of tested parameters in combination with other markers may be useful in the future in the diagnosis of ovarian cancer, but that requires further research.

Integrins in Osteocyte Biology and Mechanotransduction

PURPOSE OF REVIEW

Osteocytes are the main mechanosensitive cells in bone. Integrin-based adhesions have been shown to facilitate mechanotransduction, and therefore play an important role in load-induced bone formation. This review outlines the role of integrins in osteocyte function (cell adhesion, signalling, and mechanotransduction) and possible role in disease.

RECENT FINDINGS

Both β₁ and β₃ integrins subunits have been shown to be required for osteocyte mechanotransduction. Antagonism of these integrin subunits in osteocytes resulted in impaired responses to fluid shear stress. Various disease states (osteoporosis, osteoarthritis, bone metastases) have been shown to result in altered integrin expression and function. Osteocyte integrins are required for normal cell function, with dysregulation of integrins seen in disease. Understanding the mechanism of faulty integrins in disease may aid in the creation of novel therapeutic approaches.

Osteoprotegerin promotes islet β cell proliferation in intrauterine growth retardation rats through the PI3K/AKT/FoxO1 pathway

Osteoprotegerin (OPG) is a critical factor involved in bone metabolism. The level of OPG is increased in the serum of diabetic patients; however, there is no consensus in prior studies on the role of OPG in regulating the function of islet β cells. A rat model of intrauterine growth retardation (IUGR) was established in the present study to investigate whether OPG could enhance the proliferation of β cells; and an in vitro culture model of rat islet β cell line INS-1 was used, to confirm the effect of OPG supplementation and reveal the possible mechanism. The results showed that endogenous OPG expression was reduced and normal proliferation of β cells was impaired in the IUGR islets. Exogenous supplement of OPG restored β cell proliferation to an extent in the IUGR rats, possibly associated with regulation of the PI3K/AKT/FoxO1 signalling, as evidenced by the changes of protein expression in the pathway. Furthermore, treating rat islet INS-1 cells with a PI3K inhibitor, LY294002, blunted the effects of OPG supplement in promoting cell cycle and suppressing cell apoptosis. Taken together, the present work demonstrated that OPG supplementation could improve the proliferation of islet β cells in IUGR, and the PI3K/AKT/FoxO1 pathway is involved in the underlying mechanism.

Genetic deletion of muscle RANK or selective inhibition of RANKL is not as effective as full-length OPG-fc in mitigating muscular dystrophy

Although there is a strong association between osteoporosis and skeletal muscle atrophy/dysfunction, the functional relevance of a particular biological pathway that regulates synchronously bone and skeletal muscle physiopathology is still elusive. Receptor-activator of nuclear factor κB (RANK), its ligand RANKL and the soluble decoy receptor osteoprotegerin (OPG) are the key regulators of osteoclast differentiation and bone remodelling. We thus hypothesized that RANK/RANKL/OPG, which is a key pathway for bone regulation, is involved in Duchenne muscular dystrophy (DMD) physiopathology. Our results show that muscle-specific RANK deletion (mdx-RANK^mko) in dystrophin deficient mdx mice improves significantly specific force [54% gain in force] of EDL muscles with no protective effect against eccentric contraction-induced muscle dysfunction. In contrast, full-length OPG-Fc injections restore the force of dystrophic EDL muscles [162% gain in force], protect against eccentric contraction-induced muscle dysfunction ex vivo and significantly improve functional performance on downhill treadmill and post-exercise physical activity. Since OPG serves a soluble receptor for RANKL and as a decoy receptor for TRAIL, mdx mice were injected with anti-RANKL and anti-TRAIL antibodies to decipher the dual function of OPG. Injections of anti-RANKL and/or anti-TRAIL increase significantly the force of dystrophic EDL muscle [45% and 17% gains in force, respectively]. In agreement, truncated OPG-Fc that contains only RANKL domains produces similar gains, in terms of force production, than anti-RANKL treatments. To corroborate that full-length OPG-Fc also acts independently of RANK/RANKL pathway, dystrophin/RANK double-deficient mice were treated with full-length OPG-Fc for 10 days. Dystrophic EDL muscles exhibited a significant gain in force relative to untreated dystrophin/RANK double-deficient mice, indicating that the effect of full-length OPG-Fc is in part independent of the RANKL/RANK interaction. The sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) activity is significantly depressed in dysfunctional and dystrophic muscles and full-length OPG-Fc treatment increased SERCA activity and SERCA-2a expression. These findings demonstrate the superiority of full-length OPG-Fc treatment relative to truncated OPG-Fc, anti-RANKL, anti-TRAIL or muscle RANK deletion in improving dystrophic muscle function, integrity and protection against eccentric contractions. In conclusion, full-length OPG-Fc represents an efficient alternative in the development of new treatments for muscular dystrophy in which a single therapeutic approach may be foreseeable to maintain both bone and skeletal muscle functions.

Caspase-8 function, and phosphorylation, in cell migration

Caspase-8 is involved in a number of cellular functions, with the most well established being the control of cell death. Yet caspase-8 is unique among the caspases in that it acts as an environmental sensor, transducing a range of signals to cells, modulating responses that extend far beyond simple survival. Ranging from the control of apoptosis and necroptosis and gene regulation to cell adhesion and migration, caspase-8 uses proteolytic and non-proteolytic functions to alter cell behavior. Novel interacting partners provide mechanisms for caspase-8 to position itself at signaling nodes that affect a variety of signaling pathways. Here, we examine the catalytic and noncatalytic modes of action by which caspase-8 influences cell adhesion and migration. The mechanisms vary from post-cleavage remodeling of the cytoskeleton to signaling elements that control focal adhesion turnover. This is facilitated by caspase-8 interaction with a host of cell proteins ranging from the proteases caspase-3 and calpain-2 to adaptor proteins such as p85 and Crk, to the Src family of tyrosine kinases.

Androgen deprivation therapy sensitizes triple negative breast cancer cells to immune-mediated lysis through androgen receptor independent modulation of osteoprotegerin

Among breast cancer types, triple-negative breast cancer (TNBC) has the fewest treatment options and the lowest 5-year survival rate. Androgen receptor (AR) inhibition has displayed efficacy against breast cancer preclinically and is currently being examined clinically in AR positive TNBC patients. Androgen deprivation has been shown to induce immunogenic modulation; the alteration of tumor cell phenotype resulting in increased sensitivity to immune-mediated killing. We evaluated the ability of AR inhibition to reduce the growth and improve the immune-mediated killing of breast cancer cells with differing expression of the estrogen receptor and AR. While AR expression was required for the growth inhibitory effects of enzalutamide on breast cancer cells, both enzalutamide and abiraterone improved the sensitivity of breast cancer cells to immune-mediated lysis independent of detectable AR expression. This increase in sensitivity was linked to an increase in cell surface tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor expression as well as a significant reduction in the expression of osteoprotegerin (OPG). The reduction in OPG was further examined and found to be critical for the increase in sensitivity of AR- TNBC cells to immune-mediated killing. The data presented herein further support the use of AR inhibition therapy in the AR+ TNBC setting. These data, however, also support the consideration of AR inhibition therapy for the treatment of AR- TNBC, especially in combination with cancer immunotherapy, providing a potential novel therapeutic option for select patients.

Osteoprotegerin rich tumor microenvironment: implications in breast cancer

Osteoprotegerin (OPG) is a soluble decoy receptor for tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL). It belongs to the tumor necrosis factor receptor superfamily (TNFRSF). OPG was initially discovered to contribute to homeostasis of bone turnover due to its capability of binding to receptor activator of nuclear factor-kappaB (NF-kB). However, apart from bone turnover, OPG plays important and diverse role(s) in many biological functions. Besides having anti-osteoclastic activity, OPG is thought to exert a protective anti-apoptotic action in OPG-expressing tumors by overcoming the physiologic mechanism of tumor surveillance exerted by TRAIL. Along with inhibiting TRAIL induced apoptosis, it can induce proliferation by binding to various cell surface receptors and thus turning on the canonical cell survival and proliferative pathways. OPG also induces angiogenesis, one of the hallmarks of cancer, thus facilitating tumor growth. Recently, the understanding of OPG and its different roles has been augmented substantially. This review is aimed at providing a very informative overview as to how OPG affects cancer progression especially breast cancer.

Osteoprotegerin Disruption Attenuates HySu-Induced Pulmonary Hypertension Through Integrin αvβ3/FAK/AKT Pathway Suppression

BACKGROUND

Pulmonary arterial remodeling characterized by increased vascular smooth muscle proliferation is commonly seen in life-threatening disease, pulmonary arterial hypertension (PAH). Clinical studies have suggested a correlation between osteoprotegerin serum levels and PAH severity. Here, we aimed to invhestigate vascular osteoprotegerin expression and its effects on pulmonary arterial smooth muscle cell proliferation in vitro and in vivo, as well as examine the signal transduction pathways mediating its activity.

METHODS AND RESULTS

Serum osteoprotegerin levels were significantly elevated in patients with PAH and correlated with disease severity as determined by the World Health Organization (WHO) functional classifications and 6-minute walking distance tests. Similarly, increased osteoprotegerin expression was observed in the pulmonary arteries of hypoxia plus SU5416- and monocrotaline-induced PAH animal models. Moreover, osteoprotegerin disruption attenuated hypoxia plus SU5416-induced PAH progression by reducing pulmonary vascular remodeling, whereas lentiviral osteoprotegerin reconstitution exacerbated PAH by increasing pulmonary arterial smooth muscle cell proliferation. Furthermore, pathway analysis revealed that osteoprotegerin induced pulmonary arterial smooth muscle cell proliferation by interacting with integrin α_vβ₃ to elicit downstream focal adhesion kinase and AKT pathway activation.

CONCLUSIONS

Osteoprotegerin facilitates PAH pathogenesis by regulating pulmonary arterial smooth muscle cell proliferation, suggesting that it may be a potential biomarker and therapeutic target in this disease.

CCN1 sensitizes esophageal cancer cells to TRAIL-mediated apoptosis

TRAIL is one of the best anti-cancer molecules in our body. It kills a variety of cancer cells that are resistant to conventional chemotherapy, without causing much negative impact on normal cells, because its death receptors are almost exclusively found on cancer cells. However, some cancer cells are not sensitive to TRAIL treatment, even though they express its death receptors. A second molecule is needed to help TRAIL to complete its mission. Finding such molecules now becomes a top priority in cancer research. Our study shows that CCN1 is such a molecule. CCN1 was highly expressed in the esophageal epithelium of the patients suffering from gastroesophageal reflux disease, but faded away as the situation worsened towards adenocarcinoma. Treating the tumor cells with CCN1 resulted in apoptosis, while the same treatment to the normal cells only nourished cell growth. It was TRAIL that mediated this process. Apparently, CCN1 altered the expression profile of TRAIL and its receptors in tumor cells, namely, activating TRAIL and its death receptors and shutting down its decoy receptors. CCN1 and TRAIL worked as a team to put the cancer cells to death, as elimination of either one failed apoptosis.

From bones to blood pressure, developing novel biologic approaches targeting the osteoprotegein pathway for pulmonary vascular disease

Osteoprotegerin (tnfsf11b, OPG) is a soluble member of the TNF superfamily originally described as an important regulator of osteoclastogenesis almost 20 years ago. OPG is a heparin-binding secreted glycoprotein that exists as a 55–62 kDa monomer or a 110–120 kDa disulphide-linked homodimer. Acting as a soluble decoy receptor for RANKL, OPG actively regulates RANK signalling, and thereby osteoclastogenesis. OPG has subsequently been shown to also be a decoy receptor TNF related apoptosis inducing-ligand (tnfsf10, TRAIL, Apo2L). TRAIL is a type II transmembrane protein that is widely expressed in a variety of human tissues, including the spleen, lung, and prostate. Through binding to TRAIL, OPG can inhibit TRAIL-induced apoptosis of cancer cells. More recently, OPG has been demonstrated to be secreted by, and influence, vascular smooth muscle cells phenotype particularly related to vascular calcification and pulmonary vascular remodelling. In pulmonary artery smooth muscle cell (PASMC) suppression of BMP, induction of 5-HT and IL-1 signalling have been shown to stimulate the release of OPG in vitro, which causes cell migration and proliferation. Patients with idiopathic PAH (IPAH) demonstrate increased circulating and tissue levels of OPG, and circulating serum levels predict survival. In pre-clinical models, OPG levels correlate with disease severity. Since OPG is a naturally circulating protein, we are investigating the potential of novel biologic antibody therapies to rescue PAH phenotype in disease models. Further pre-clinical and mechanistic data are forthcoming, but we believe current published data identify OPG as an exciting and novel therapeutic target in PAH.

Osteoprotegerin secreted by inflammatory and invasive breast cancer cells induces aneuploidy, cell proliferation and angiogenesis

Background

Osteoprotegerin (OPG) is a glycoprotein that has multifaceted role and is associated with several cancer malignancies like that of bladder carcinoma, gastric carcinoma, prostate cancer, multiple myeloma and breast cancer. Also OPG has been associated with several organ pathologies. The widespread expression of OPG suggests that OPG may have multiple biological activities that are yet to be explored.

Methods

The anchorage-independent sphere cultures of the adherent cells were instrumental in our study as it provided a deeper insight into the complexity of a 3D tumor. Cytokine profiling was performed for OPG’s detection in the microenvironment. ELISA and western blotting were performed to quantify the OPG secretion and measure the protein levels respectively. OPG expression was detected in human breast cancer tissue samples by IHC. To decipher OPG’s role in tumor aggressiveness both recombinant human OPG as well as OPG rich and depleted breast cancer cell conditioned media were tested. Western blotting and MTT assay were performed to detect changes in signaling pathways and proliferation that were induced in presence of OPG. Onset of aneuploidy, in presence of OPG, was measured by cell cycle analysis and western blotting. Finally, human Breast Cancer qBiomarker Copy Number PCR Array was used to detect how OPG remarkably induced gene copy numbers for oncogenic pathway regulators.

Results

SUM149PT and SUM1315M02 cells secrete high levels of the cytokine OPG compared to primary human mammary epithelial cells (HMEC). High expression of OPG was also detected in human breast cancer tissue samples compared to the uninvolved tissue from the same patient. OPG induced proliferation of control HMEC spheres and triggered the onset of aneuploidy in HMEC sphere cultures. OPG induced the expression of aneuploidy related kinases Aurora-A Kinase (IAK-1), Bub1 and BubR1 probably through the receptor activator of nuclear factor kappa-B ligand (RANKL) and syndecan-1 receptors via the Erk, AKT and GSK3(3 signaling pathway. Gene copy numbers for oncogenic pathway regulators such AKT1, Aurora-A Kinase (AURKA or IAK-1), epidermal growth factor receptor (EGFR) and MYC with a reduction in the copy numbers of cyclin dependent kinase inhibitor 2A (CDKN2A), PTEN and DNA topoisomerase 2 alpha (TOP2A) were induced in presence of OPG.

Conclusions

These results highlight the role of OPG in reprogramming normal mammary epithelial cells to a tumorigenic state and suggest promising avenues for treating inflammatory breast cancer as well as highly invasive breast cancer with new therapeutic targets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1837-1) contains supplementary material, which is available to authorized users.

Cytosolic calreticulin inhibits microwave radiation-induced microvascular endothelial cell injury through the integrin-focal adhesion kinase pathway

OBJECTIVE

To determine the effects of cytosolic CRT on MR-induced MMEC injury, and the underlying mechanism.

METHODS

MMECs were randomized into eight groups: control, AdCRT (infected with pAdCMV/V5-DEST-CRT adenovirus), stCRT (transfected with rCRT-siRNAs), Mock (transfected with scrambled siRNAs), MR (exposed to MR for six minutes), AdCRT + MR, stCRT + MR, and Mock + MR. The magnitude of cell injury were assessed by Annexin V-PI staining, LDH activity in culture medium, MMEC migration ability, ultrastructure and cytoskeletal stability. Subcellular colocalization of CRT and ConA or integrin were evaluated by immunocytochemistry. The mRNA and protein expression levels of target genes were examined by qRT-PCR and western blotting, respectively.

RESULTS

MR-induced cytotoxicity was dose-dependent. Overexpression of cytosolic CRT suppressed MR injury, shown as decreased cell apoptosis, reduced LDH activity, enhanced cell migration capability, and maintenance of ultrastructure and cytoskeleton integrity. Conversely, CRT deficiency aggravated MR-induced injury. Exposure of AdCRT MMECs to MR promoted membrane translocation of CRT and the interaction of CRT-integrin-α. Correlation analysis revealed that integrin-α expression or FAK phosphorylation was positively associated with cytosolic CRT expression.

CONCLUSIONS

Cytosolic CRT inhibits MR-induced MMEC injury through activation of the integrin-FAK pathway.

Inflammation-regulating factors in ascites as predictive biomarkers of drug resistance and progression-free survival in serous epithelial ovarian cancers

Background

Platinum-based combination therapy is the standard first-line treatment for women with advanced serous epithelial ovarian carcinoma (EOC). However, about 20 % will not respond and are considered clinically resistant. The availability of biomarkers to predict responses to the initial therapy would provide a practical approach to identify women who would benefit from a more appropriate first-line treatment. Ascites is an attractive inflammatory fluid for biomarker discovery as it is easy and minimally invasive to obtain. The aim of this study was to evaluate whether six selected inflammation-regulating factors in ascites could serve as diagnostic or drug resistance biomarkers in patients with advanced serous EOC.

Methods

A total of 53 women with stage III/IV serous EOC and 10 women with benign conditions were enrolled in this study. Eleven of the 53 women with serous EOC were considered clinically resistant to treatment with progression-free survival < 6 months. Ascites were collected at the time of the debulking surgery and the levels of cytokines were measured by ELISA. The six selected cytokines were evaluated for their ability to discriminate serous EOC from benign controls, and to discriminate platinum resistant from platinum sensitive patients.

Results

Median ascites levels of IL-6, IL-10 and osteoprotegerin (OPG) were significantly higher in women with advanced serous EOC than in controls (P ≤ 0.012). There were no significant difference in the median ascites levels of leptin, soluble urokinase plasminogen activator receptor (suPAR) and CCL18 among serous EOC women and controls. In Receiver Operator curve (ROC) analysis, IL-6, IL-10 and OPG had a high area under the curve value of 0.905, 0.832 and 0.825 respectively for distinguishing EOC from benign controls. ROC analysis of individual cytokines revealed low discriminating potential to stratify patients according to their sensitivity to first-line treatment. The combination of biomarkers with the highest discriminating potential was with CA125 and leptin (AUC = 0.936, 95 % CI: 0.894–0.978).

Conclusion

IL-6 was found to be strongly associated with advanced serous EOC and could be used in combination with serum CA125 to discriminate benign and EOC. Furthermore, the combination of serum CA125 and ascites leptin was a strong predictor of clinical resistance to first-line therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1511-7) contains supplementary material, which is available to authorized users.

Gene polymorphisms in RANKL/RANK/OPG pathway are associated with ages at menarche and natural menopause in Chinese women

Background

Age at menarche (AAM) and age at natural menopause (AANM) have been shown intimately associated with woman’s health later in life. Previous studies have indicated that AAM and AANM are highly heritable. RANKL/RANK/OPG signaling pathway is essential for mammary gland development, which is also found associated with post-menopausal and hormone-related diseases. The aim of this study was to evaluate associations between the polymorphisms in the TNFSF11, TNFRSF11A and TNFRSF11B genes in the RANKL/RANK/OPG pathway with AAM and AANM in Chinese women.

Methods

Post-menopausal Chinese women (n = 845) aged from 42 to 89 years were recruited in the study. Information about AAM and AANM were obtained through questionnaires and the genomic DNA was isolated from peripheral blood from the participants. Total 21 tagging single nucleotide polymorphisms (SNPs) of TNFSF11, TNFRSF11A and TNFRSF11B were genotyped.

Results

Three SNPs of TNFRSF11A (rs4500848, rs6567270 and rs1805034) showed significant association with AAM (P < 0.01, P = 0.02 and P = 0.01, respectively), and one SNP (rs9962159) was significantly associated with AANM (P = 0.03). Haplotypes TC and AT (rs6567270-rs1805034) of TNFRSF11A were found to be significantly associated with AAM (P = 0.01 and P = 0.02, respectively), and haplotypes GC and AC (rs9962159-rs4603673) of TNFRSF11A showed significant association with AANM (P = 0.03 and P < 0.01, respectively). No significant association between TNFSF11 or TNFRSF11B gene with AAM or AANM was found.

Conclusions

The present study suggests that TNFRSF11A but not TNFSF11 and TNFRSF11B genetic polymorphisms are associated with AAM and AANM in Chinese women. The findings provide evidence that genetic variations in RANKL/RANK/OPG pathway may be associated with the onset and cessation of the menstruation cycle.

Neutralization of osteopontin attenuates neutrophil migration in sepsis-induced acute lung injury

Introduction

Sepsis refers to severe systemic inflammation leading to acute lung injury (ALI) and death. Introducing novel therapies can reduce the mortality in ALI. Osteopontin (OPN), a secretory glycoprotein produced by immune reactive cells, plays a deleterious role in various inflammatory diseases. However, its role in ALI caused by sepsis remains unexplored. We hypothesize that treatment with an OPN-neutralizing antibody (anti-OPN Ab) protects mice against ALI during sepsis.

Methods

Sepsis was induced in 8-week-old male C57BL/6 mice by cecal ligation and puncture (CLP). Anti-OPN Ab or non-immunized IgG as control, at a dose of 50 μg/mouse, was intravenously injected at the time of CLP. After 20 hours, the expression of OPN and proinflammatory cytokines in tissues and plasma was examined by real-time PCR, Western blot, and ELISA. Plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) and the lung myeloperoxidase (MPO) levels were determined by colorimetric assays. Lung damage and neutrophil infiltrations were determined by histological H&E and Gr-1 staining, respectively. The effect of recombinant mouse OPN (rmOPN) on human neutrophil-like cell (HL-60) migration was performed by Boyden chamber assays and the involvement of intracellular signaling molecules in HL-60 cells was revealed by Western blot.

Results

After 20 hours of sepsis, mRNA and protein levels of OPN were significantly induced in lungs, spleen, and plasma. Treatment with an anti-OPN Ab in septic mice significantly reduced the plasma levels of ALT, AST, and LDH, and the proinflammatory cytokines IL-6, IL-1β and the chemokine MIP-2, compared with the vehicle group. Similarly, the lung mRNA and protein expressions of proinflammatory cytokines and chemokine were greatly reduced in anti-OPN Ab-treated animals. The lung histological architecture, MPO and neutrophil infiltration were significantly improved in anti-OPN Ab-treated mice compared with the vehicle animals. Treatment of rmOPN in HL-60 cells significantly increased their migration, in vitro. The neutrophils treated with rmOPN remarkably increased the levels of phospho focal adhesion kinase (pFAK), phospho extracellular signal-regulated kinase (pERK) and phospho p38.

Conclusions

Our findings clearly demonstrate the beneficial outcomes of anti-OPN Ab treatment in protecting against ALI, implicating a novel therapeutic strategy in sepsis.

Assessment of selected cytokines, proteins, and growth factors in the peritoneal fluid of patients with ovarian cancer and benign gynecological conditions

Objectives

The ovarian tumor microenvironment, ie, the peritoneal fluid, is an intriguing research subject. The goal of this study was to assess the behavior of selected cytokines and growth factors within the peritoneal fluid in pathologies associated with ascites and to assess the relationship between the levels of these substances and select prognostic factors of ovarian cancer.

Methods

A total of 74 patients were enrolled in the study, including 36 patients with ovarian cancer and 38 patients with benign gynecological conditions. Peritoneal fluid collected during surgical procedures was used to assess the levels of interleukin (IL)-6, IL-8, stem cell factor (SCF), dickkopf-1, growth differentiation factor-15 (GDF-15), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), osteoprotegerin (OPG), osteopontin, osteonectin, and human epididymis protein 4. The median levels of these factors were compared between the two groups, and the levels of selected factors were assessed in the ovarian cancer group with regard to the clinical stage of cancer, tumor differentiation, presence of peritoneal spread and positive peritoneal fluid cytology results. The diagnostic value of the analyzed proteins within the peritoneal fluid was also assessed.

Results

Differences were observed between the patients with ovarian cancer and the patients with benign gynecological conditions associated with ascites with regard to the levels of IL-6, IL-8, GDF-15, SCF, osteopontin, osteonectin, and OPG. There were no differences in dickkopf-1, TRAIL, and human epididymis protein 4 levels between the two study groups. Cancer stage affected only the mean SCF and OPG levels, with lower SCF values and higher OPG values in advanced cancers compared to less-advanced cancers. Tumor differentiation was associated with significantly lower SCF values in the group of poorly differentiated tumors. A significant reduction in SCF values and a significant increase in OPG and IL-6 values were also observed within cancer cell-positive peritoneal fluid. Peritoneal spread was associated with higher levels of TRAIL, osteonectin, and IL-6 in ovarian cancer patients.

Conclusion

On the basis of the conducted studies, it appears that of the studied factors, GDF-15, SCF, and OPG deserve special attention in the context of future research on the tumor microenvironment. With regard to diagnostics, attention should be given primarily to GDF-15, IL-6, and osteonectin.

NADPH oxidases in bone homeostasis and osteoporosis

Bone formation and degradation are perfectly coordinated. In case of an imbalance of these processes diseases occur associated with exaggerated formation of new bone or bone loss as in osteoporosis. Most studies investigating osteoporosis either focus on osteoblast or osteoclast function and differentiation. Both processes have been suggested to be affected by reactive oxygen species (ROS). Besides a potentially harmful role of ROS, these small molecules are important second messengers. The family of NADPH oxidases produces ROS in a controlled and targeted manner, to specifically regulate signal transduction. This review will highlight the role of reactive oxygen species in bone cell differentiation and bone-loss associated disease with a special focus on osteoporosis and NADPH oxidases as specialized sources of ROS.

Upregulation of osteoprotegerin expression correlates with bone invasion and predicts poor clinical outcome in oral cancer

OBJECTIVES

We aimed to determine the prognostic significance of receptor activator of nuclear factor kappa-B ligand (RANKL), RANK and osteoprotegerin (OPG) in patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

The protein expression of RANKL, RANK and OPG was assessed by immunohistochemistry on pretreatment biopsies of 93 patients with locally advanced OSCC who received preoperative chemoradiotherapy (CRT). The primary endpoint was cancer-specific survival. Secondary endpoints were correlation of biomarkers with bone invasion and pathological tumor response. Kaplan-Meier curves and Cox regression models were used for survival analyses.

RESULTS

A significantly higher OPG expression was demonstrated in patients with malignant bone invasion and non-responders to CRT as compared to patients without bone invasion and responders (p=0.032 and p=0.033, respectively). Multivariate analysis revealed that higher OPG expression was independently associated with shorter cancer-specific survival (p=0.04). The expression status of RANKL and RANK was not significantly related to clinicopathological characteristics and had no impact on survival of OSCC patients.

CONCLUSION

Upregulation of OPG expression is associated with bone invasion, poor pathological tumor regression to neoadjuvant CRT, and worse long-term cancer-specific survival in patients with locally advanced OSCC. Our results indicate that OPG may be a novel prognostic biomarker in oral cancer.

Osteoprotegerin expressed by osteoclasts: an autoregulator of osteoclastogenesis

Osteoprotegerin (OPG) is secreted by stromal and osteoblastic lineage cells and inhibits osteoclastogenesis by preventing the interaction of receptor activator of nuclear factor-κB ligand (RANKL) with receptor activator of nuclear factor-κB (RANK). In this study, the expression of OPG in osteoclasts themselves and its biological functions during osteoclastogenesis were investigated for the first time. OPG expression in vivo in the developing rat maxilla was examined by immunofluorescence analysis. OPG expression in osteoclasts during in vitro osteoclastogenesis was determined by reverse-transcription polymerase chain-reaction (RT-PCR), Western blot, and immunofluorescence staining. We determined the function of OPG produced by osteoclasts during osteoclastogenesis by silencing the OPG gene. The effects of OPG on bone-resorbing activity and apoptosis of mature osteoclasts were examined by the assay of resorptive pit formation on calcium-phosphate-coated plate and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining, respectively. In the immunofluorescence findings, strong immunoreactivities were unexpectedly seen in multinucleated tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts around the growing and erupting tooth germs in the rat alveolar bone. In vitro, OPG expression was significantly increased during the differentiation of osteoclasts from mouse bone-marrow-derived cells treated with a combination of macrophage colony-stimulating factor (M-CSF) and RANKL. Interestingly, it was found that OPG small interfering (si)RNA treatment during osteoclastogenesis enhanced the sizes of osteoclasts, but attenuated their bone-resorbing activity. Also, the increased chromosomal DNA fragmentation and caspase-3 activity in the late phase of osteoclastogenesis were found to be decreased by treatment with OPG siRNA. Furthermore, effects of OPG siRNA treatment on osteoclastogenesis and bone-resorbing activity were recovered by the treatment of exogenous OPG. These results suggest that OPG, expressed by the osteoclasts themselves, may play an auto-regulatory role in the late phase of osteoclastogenesis through the induction of apoptosis.