GDF11 contributes to hepatic hepcidin (HAMP) inhibition through SMURF1-mediated BMP-SMAD signalling suppression.

Hepcidin (HAMP) synthesis is suppressed by erythropoiesis to increase iron availability for red blood cell production. This effect is thought to result from factors secreted by erythroid precursors. Growth differentiation factor 11 (GDF11) expression was recently shown to increase in erythroid cells of ß-thalassaemia, and decrease with improvement in anaemia. Whether GDF11 regulates hepatic HAMP production has never been experimentally studied. Here, we explore GDF11 function during erythropoiesis-triggered HAMP suppression. Our results confirm that exogenous erythropoietin significantly increases Gdf11 as well as Erfe (erythroferrone) expression, and Gdf11 is also increased, albeit at a lower degree than Erfe, in phlebotomized wild type and ß-thalassaemic mice. GDF11 is expressed predominantly in erythroid burst forming unit- and erythroid colony-forming unit- cells during erythropoiesis. Exogeneous GDF11 administration results in HAMP suppression in vivo and in vitro. Furthermore, exogenous GDF11 decreases BMP-SMAD signalling, enhances SMAD ubiquitin regulatory factor 1 (SMURF1) expression and induces ERK1/2 (MAPK3/1) signalling. ERK1/2 signalling activation is required for GDF11 or SMURF1-mediated suppression in BMP-SMAD signalling and HAMP expression. This research newly characterizes GDF11 in erythropoiesis-mediated HAMP suppression, in addition to ERFE.

BMP9 (Bone Morphogenetic Protein-9)/Alk1 (Activin-Like Kinase Receptor Type I) Signaling Prevents Hyperglycemia-Induced Vascular Permeability.

Objective- Diabetic macular edema is a major cause of visual impairment. It is caused by blood-retinal barrier breakdown that leads to vascular hyperpermeability. Current therapeutic approaches consist of retinal photocoagulation or targeting VEGF (vascular endothelial growth factor) to limit vascular leakage. However, long-term intravitreal use of anti-VEGFs is associated with potential safety issues, and the identification of alternative regulators of vascular permeability may provide safer therapeutic options. The vascular specific BMP (bone morphogenetic protein) receptor ALK1 (activin-like kinase receptor type I) and its circulating ligand BMP9 have been shown to be potent vascular quiescence factors, but their role in the context of microvascular permeability associated with hyperglycemia has not been evaluated. Approach and Results- We investigated Alk1 signaling in hyperglycemic endothelial cells and assessed whether BMP9/Alk1 signaling could modulate vascular permeability. We show that high glucose concentrations impair Alk1 signaling, both in cultured endothelial cells and in a streptozotocin model of mouse diabetes mellitus. We observed that Alk1 signaling participates in the maintenance of vascular barrier function, as Alk1 haploinsufficiency worsens the vascular leakage observed in diabetic mice. Conversely, sustained delivery of BMP9 by adenoviral vectors significantly decreased the loss of retinal barrier function in diabetic mice. Mechanistically, we demonstrate that Alk1 signaling prevents VEGF-induced phosphorylation of VE-cadherin and induces the expression of occludin, thus strengthening vascular barrier functions. Conclusions- From these data, we suggest that by preventing retinal vascular permeability, BMP9 could serve as a novel therapeutic agent for diabetic macular edema.

miR-149 promotes human osteocarcinoma progression via targeting bone morphogenetic protein 9 (BMP9).

OBJECTIVES: To investigate the roles of miR-149 in the progression of human osteosarcoma (OS). RESULTS: miR-149 level was upregulated in tissues from OS patients more than in normal subjects. Cell proliferation and apoptosis assays revealed that miR-149 increased cell proliferation and inhibited cell apoptosis in OS cell line (MG63). An increase of Bcl-2 gene expression and a decrease of cleaved-caspase-3, and cleaved-PARP expression were observed in MG63 cells with transfection of miR-149. Additionally, bone morphogenetic protein 9 (BMP9) was identified as a target of miR-149 in MG63 cells, and BMP9 expression was negatively correlated with miR149 level in OS clinical samples. Co-overexpression of BMP9 with miR-149 in MG63 cells prohibited miR-149-mediated promotive effects on OS progression. Importantly, overexpression of miR-149 conferred chemoresistance in MG63 cells. CONCLUSIONS: miR-149 promotes OS progression via targeting BMP9.

A Prodomain Fragment from the Proteolytic Activation of Growth Differentiation Factor 11 Remains Associated with the Mature Growth Factor and Keeps It Soluble.

Growth differentiation factor 11 (GDF11), a member of the transforming growth factor ß (TGF-ß) family, plays diverse roles in mammalian development. It is synthesized as a large, inactive precursor protein containing a prodomain, pro-GDF11, and exists as a homodimer. Activation requires two proteolytic processing steps that release the prodomains and transform latent pro-GDF11 into active mature GDF11. In studying proteolytic activation in vitro, we discovered that a 6-kDa prodomain peptide containing residues 60-114, PDP60-114, remained associated with the mature growth factor. Whereas the full-length prodomain of GDF11 is a functional antagonist, PDP60-114 had no impact on activity. The specific activity of the GDF11/PDP60-114 complex (EC50 = 1 nM) in a SMAD2/3 reporter assay was identical to that of mature GDF11 alone. PDP60-114 improved the solubility of mature GDF11 at neutral pH. As the growth factor normally aggregates/precipitates at neutral pH, PDP60-114 can be used as a solubility-enhancing formulation. Expression of two engineered constructs with PDP60-114 genetically fused to the mature domain of GDF11 through a 2x or 3x G4S linker produced soluble monomeric products that could be dimerized through redox reactions. The construct with a 3x G4S linker retained 10% activity (EC50 = 10 nM), whereas the construct connected with a 2x G4S linker could only be activated (EC50 = 2 nM) by protease treatment. Complex formation with PDP60-114 represents a new strategy for stabilizing GDF11 in an active state that may translate to other members of the TGF-ß family that form latent pro/mature domain complexes.

Bone morphogenetic protein 9 facilitates osteocarcinoma cell apoptosis and inhibits in vivo tumor growth.

Osteosarcoma (OS) causes millions of death worldwide and, since there is no effective therapy, it is necessary to identify the molecular mechanism of OS, which can direct the development of new therapies. This study investigated the role of bone morphogenetic protein 9 (BMP9), a member of the transforming growth factor (TGF)-ß family, in OS development. This study first examined BMP9 expression in tissue from OS patients and normal subjects. The OS cell line (MG63) and tumor cells from OS patients were then transfected with BMP9 and cell proliferation and apoptosis were assessed. Western blot and reverse transcription-polymerase chain reaction were used to study the expression of cancer-related genes [B cell lymphoma (Bcl)-2, cleaved Caspase-3, Caspase-9, and poly ADP-ribose polymerase]. To confirm the in vivo impact of BMP9, mice were transplanted with OS tumor cells and then treated with BMP9 carried in attenuated Salmonella enterica serovar Typhimurium. Our study found that the OS tumor tissue had a lower expression of BMP9 compared to normal tissue. Transfection of BMP9 in OS and MG63 cells inhibited cell growth and promoted apoptosis. In vitro studies showed a decrease in Bcl-2 gene expression and an increase in Cyto-c, Caspase-3, and Caspase-9 expression. In vivo studies indicated that consistent treatment with BMP9 in OS mice results in inhibition of tumor growth. This study shows that BMP9 inhibition is associated with OS development and that enhanced expression of BMP9 may be a potential treatment method for OS.

Induction of transient tenogenic phenotype of high-density cultured human dermal fibroblasts.

Previous study showed that high-density culture supported phenotype maintenance of in vitro expanded tenocytes. This study explored the possibility of inducing the tenogenic phenotype of dermal fibroblasts by high-density monolayer culture. Human fibroblasts were seeded either in high-density (2.5 × 10(6) per 10 cm dish) or at low-density (0.36 × 10(6) per 10 cm dish). A preliminary tenogenic phenotype was observed in high-density cultured cells after one passage with significantly enhanced tenogenic gene expression. With continued cultivation to passage 3, scleraxis (SCX), tenomodulin (TNMD), collagen I, III, VI, decorin and tenascin-c were all significantly upregulated in high-density cultured dermal fibroblasts as opposed to low-density cells. High-density culture also led to relatively elongated cell shape, whereas cells appeared in spread shape in low-density culture. In addition, cytochalasin D treatment disrupted the cellular cytoskeleton and resulted in inhibition of density-induced tenogenic gene expression. However, high-density cultured fibroblasts failed to induce other lineage differentiations (osteogenic, chondrogenic and adipogenic). It also failed to induce tenogenic phenotype in high-density cultured chondrocytes. Mechanism studies revealed enhanced gene expression of growth and differentiation factors (GDF) 5, 6, 7 and 8 and transforming growth factor-ß (TGF-ß)1 in the high-density group and enhanced protein production of both GDF8 and TGF-ß1. Moreover, BMP/GDF signaling inhibitor (LDN193189) and TGF-ß signaling inhibitor (LY2109761) could both abrogate the density induced phenotype. In conclusion, high-density culture was able to induce transient tenogenic phenotype of dermal fibroblasts likely via cell morphology change and production of pro-tenogenic factors.

Identification and expression of a novel transcript of the growth and differentiation factor-11 gene.

The growth and differentiation factor-11 (GDF-11) gene is thought to code for a single protein that plays a crucial role in regulating the development of multiple tissues. In this study, we aimed to investigate if the GDF-11 gene has another transcript and, if so, to characterise this transcript and determine its tissue-specific and developmental expression. We have identified a novel transcript of GDF-11 in mouse muscle, which contains the 3' region of intron 1, exon 2, exon 3 and 3'UTR, and has two transcription initiation sites and a single termination site. We named the novel transcript GDF-11ΔEx1 because it does not contain exon 1 of canonical GDF-11. The GDF-11ΔEx1 transcript was expressed in the skeletal muscles, heart, brain and kidney, but was undetectable in the liver and gut. The concentration of the GDF-11ΔEx1 transcript was increased in gastrocnemius muscles from three to 6 weeks of age, a period of accelerated muscle growth, steadily declined thereafter and was higher in male than female mice (P < 0.001 for age and sex). GDF-11ΔEx1 cDNA was predicted to code for a putative N-terminal-truncated propeptide and the canonical ligand for GDF-11. However, propeptide-specific antibodies could not identify proteins of the expected size in skeletal muscle. Interestingly, in silico analysis of the GDF-11ΔEx1 RNA predicted a secondary structure with the potential to coordinate multiple protein interactions as a molecular scaffold. Therefore, we postulate that GDF-11ΔEx1 may act as a long non-coding RNA to regulate the transcription of canonical GDF-11 and/or other genes in skeletal muscle and other tissues.

BMP9 is produced by hepatocytes and circulates mainly in an active mature form complexed to its prodomain.

Bone Morphogenetic Protein 9 (BMP9) has been recently found to be the physiological ligand for the activin receptor-like kinase 1 (ALK1), and to be a major circulating vascular quiescence factor. Moreover, a soluble chimeric ALK1 protein (ALK1-Fc) has recently been developed and showed powerful anti-tumor growth and anti-angiogenic effects. However, not much is known concerning BMP9. This prompted us to investigate the human endogenous sources of this cytokine and to further characterize its circulating form(s) and its function. Analysis of BMP9 expression reveals that BMP9 is produced by hepatocytes and intrahepatic biliary epithelial cells. Gel filtration analysis combined with ELISA and biological assays demonstrate that BMP9 circulates in plasma (1) as an unprocessed inactive form that can be further activated by furin a serine endoprotease, and (2) as a mature and fully active form (composed of the mature form associated with its prodomain). Analysis of BMP9 circulating levels during mouse development demonstrates that BMP9 peaks during the first 3 weeks after birth and then decreases to 2 ng/mL in adulthood. We also show that circulating BMP9 physiologically induces a constitutive Smad1/5/8 phosphorylation in endothelial cells. Taken together, our results argue for the role of BMP9 as a hepatocyte-derived factor, circulating in inactive (40%) and active (60%) forms, the latter constantly activating endothelial cells to maintain them in a resting state.

Colorectal carcinoma cell production of transforming growth factor beta decreases expression of endothelial cell vascular endothelial growth factor receptor 2.

BACKGROUND: Vascular endothelial growth factor (VEGF) signaling is a target for antiangiogenic cancer therapy. The authors have previously observed that up to 40% of vessels in colorectal carcinoma (CRC) tumors are negative for VEGF receptor 2 (VEGFR2) expression. Differential activity of transforming growth factor beta (TGF-ß) is a potential contributor to this receptor heterogeneity because TGF-ß contributes to both angiogenesis and CRC tumor progression. METHODS: The authors analyzed VEGFR2 expression by Western blotting, and TGF-ß expression in endothelial and CRC cell lines, respectively. In addition, they immunostained endothelial cells in CRC xenografts to find an association between VEGFR2 and TGF-ß levels or activity. RESULTS: In bovine aortic endothelial cells (BAECs), TGF-ß1 significantly repressed VEGFR2 protein in a time-dependent and dose-dependent fashion (P < .05). Serum-free conditioned media from various malignant human CRC cell lines (HCT116, 379.2, Dks8, and DLD1) induced down-regulation of VEGFR2 in BAECs. This effect was proportional to the total levels of TGF-ß1 and TGF-ß2 and was blocked by SB-431542 and SD-208, TGF-ß receptor I inhibitors. Immunofluorescence staining of subcutaneous mouse xenografts of HCT116, 379.2, Dks8, and SW480 cells revealed vessels with an inverse relationship between TGF-ß activity and VEGFR2 expression. Oxygen and bone morphogenetic protein 9 levels were shown to modulate TGF-ß-induced VEGFR2 down-regulation. CONCLUSIONS: In combination with other factors, TGF-ß may contribute to the vascular heterogeneity in human colorectal tumors.

GDF11 expressed in the adult brain negatively regulates hippocampal neurogenesis.

Growth differentiation factor 11 (GDF11) is a transforming factor-ß superfamily member that functions as a negative regulator of neurogenesis during embryonic development. However, when recombinant GDF11 (rGDF11) is administered systemically in aged mice, it promotes neurogenesis, the opposite of its role during development. The goal of the present study was to reconcile this apparent discrepancy by performing the first detailed investigation into the expression of endogenous GDF11 in the adult brain and its effects on neurogenesis. Using quantitative histological analysis, we observed that Gdf11 is most highly expressed in adult neurogenic niches and non-neurogenic regions within the hippocampus, choroid plexus, thalamus, habenula, and cerebellum. To investigate the role of endogenous GDF11 during adult hippocampal neurogenesis, we generated a tamoxifen inducible mouse that allowed us to reduce GDF11 levels. Depletion of Gdf11 during adulthood increased proliferation of neural progenitors and decreased the number of newborn neurons in the hippocampus, suggesting that endogenous GDF11 remains a negative regulator of hippocampal neurogenesis in adult mice. These findings further support the idea that circulating systemic GDF11 and endogenously expressed GDF11 in the adult brain have different target cells or mechanisms of action. Our data describe a role for GDF11-dependent signaling in adult neurogenesis that has implications for how GDF11 may be used to treat CNS disease.

GDF11 upregulation independently predicts shorter overall-survival of uveal melanoma.

Growth differentiation factor 11 (GDF11), is a member of the transforming growth factor-beta (TGF-ß) superfamily and bone morphogenetic protein (BMP) subfamily. In this study, we aimed to assess the expression profile of GDF11, its prognostic value in terms of OS, as well as the potential mechanisms leading to its dysregulation in uveal melanoma. A retrospective study was conducted using our primary data and genetic, clinicopathological and overall survival (OS) data from the Cancer Genome Atlas-Uveal Melanoma (TCGA-UVM). Results showed that GDF11 expression was significantly higher in tumor tissues compared with that in adjacent normal tissues. High GDF11 expression was associated with uveal melanoma in advanced stages (IV), epithelioid cell dominant subtype, as well as extrascleral extension. Univariate analysis showed that older age, epithelioid cell dominant, with extrascleral extension and increased GDF11 expression were associated with unfavorable OS. Multivariate analysis confirmed that GDF11 expression was an independent prognostic indicator of unfavorable OS (HR: 1.704, 95%CI: 1.143-2.540, p = 0.009), after adjustment of age, histological subtypes and extrascleral extension. Among the 80 cases of uveal melanoma, only 3 cases had low-level copy gain (+1) and 2 cases had heterozygous loss (-1). No somatic mutations, including SNPs and small INDELs were observed in GDF11 DNA. The methylation of these four CpG sites had weakly (cg22950598 and cg23689080), moderately (cg09890930), or strongly (cg05511733) negative correlation with GDF11 expression. In addition, the patients with high methylation of these four sites had significantly better OS compared to the group with low methylation. Based on these findings, we infer that methylation modulated GDF11 expression might be a valuable prognostic biomarker regarding OS in uveal melanoma.

GDF11 expression in the adult rat central nervous system.

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11 (BMP11), is a member of the transforming growth factor ß (TGF-ß) superfamily. Although GDF11 plays pivotal roles during development, including anterior/posterior patterning, formation of the kidney, stomach, spleen and endocrine pancreas, little information is available for GDF11 expression in the adult central nervous system (CNS). We, thus, investigated GDF11 expression in the adult rat CNS using immunohistochemistry. GDF11 was intensely expressed in most neurons and their axons. Furthermore, we found that astrocytes and ependymal cells also express GDF11 protein. These data indicate that GDF11 is widely expressed throughout the adult CNS, and its abundant expression in the adult brain strongly supports the idea that GDF11 plays important roles in the adult brain.

Reduced expression of growth differentiation factor 11 promoted the progression of chronic obstructive pulmonary disease by activating the AKT signaling pathway.

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease, which is associated with significant mortality and costs. The molecular mechanisms underlying the roles of cigarette smoke (an accepted risk factor for COPD) and growth differentiation factor 11 (GDF11), which is reduced in patients with COPD, in the occurrence of COPD are unclear. The aim of the present study was to explore the function of GDF11 in the progression of COPD. Western blotting analysis was used to determine the expression levels of GDF11 in serum and primary lung mesenchymal cells from patients with COPD and the healthy people, and the effect of cigarette smoke extract (CSE) on the expression of AKT, p-AKT (Ser473), p-AKT (Thr308) and GDF11 was examined. The correlations between the expression level of GDF11 and the ratio of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), as well as GDF11 and p-AKT (Ser473 and Thr308) in vivo and in vitro were examined. GDF11 expression was decreased in COPD patients' serum and cells when compared with that from the healthy people, and it was positively correlated with the FEV1/FVC ratio. Exposure to CSE reduced the expression of GDF11 but increased the expression of p-AKT (Ser473 and Thr308). Together, the results suggested that CSE promoted the progression of COPD by downregulating the expression of GDF11, which then activated the AKT signaling pathway. This study suggests that GDF11 may be a novel target for the diagnosis and treatment of COPD.

Supraphysiological levels of GDF11 induce striated muscle atrophy.

Growth and differentiation factor (GDF) 11 is a member of the transforming growth factor ß superfamily recently identified as a potential therapeutic for age-related cardiac and skeletal muscle decrements, despite high homology to myostatin (Mstn), a potent negative regulator of muscle mass. Though several reports have refuted these data, the in vivo effects of GDF11 on skeletal muscle mass have not been addressed. Using in vitro myoblast culture assays, we first demonstrate that GDF11 and Mstn have similar activities/potencies on activating p-SMAD2/3 and induce comparable levels of differentiated myotube atrophy. We further demonstrate that adeno-associated virus-mediated systemic overexpression of GDF11 in C57BL/6 mice results in substantial atrophy of skeletal and cardiac muscle, inducing a cachexic phenotype not seen in mice expressing similar levels of Mstn. Greater cardiac expression of Tgfbr1 may explain this GDF11-specific cardiac phenotype. These data indicate that bioactive GDF11 at supraphysiological levels cause wasting of both skeletal and cardiac muscle. Rather than a therapeutic agent, GDF11 should be viewed as a potential deleterious biomarker in muscle wasting diseases.

Repair of critical sized cranial defects with BMP9-transduced calvarial cells delivered in a thermoresponsive scaffold.

Large skeletal defects caused by trauma, congenital malformations, and post-oncologic resections of the calvarium present major challenges to the reconstructive surgeon. We previously identified BMP-9 as the most osteogenic BMP in vitro and in vivo. Here we sought to investigate the bone regenerative capacity of murine-derived calvarial mesenchymal progenitor cells (iCALs) transduced by BMP-9 in the context of healing critical-sized calvarial defects. To accomplish this, the transduced cells were delivered to the defect site within a thermoresponsive biodegradable scaffold consisting of poly(polyethylene glycol citrate-co-N-isopropylacrylamide mixed with gelatin (PPCN-g). A total of three treatment arms were evaluated: PPCN-g alone, PPCN-g seeded with iCALs expressing GFP, and PPCN-g seeded with iCALs expressing BMP-9. Defects treated only with PPCN-g scaffold did not statistically change in size when evaluated at eight weeks postoperatively (p = 0.72). Conversely, both animal groups treated with iCALs showed significant reductions in defect size after 12 weeks of follow-up (BMP9-treated: p = 0.0025; GFP-treated: p = 0.0042). However, H&E and trichrome staining revealed more complete osseointegration and mature bone formation only in the BMP9-treated group. These results suggest that BMP9-transduced iCALs seeded in a PPCN-g thermoresponsive scaffold is capable of inducing bone formation in vivo and is an effective means of creating tissue engineered bone for critical sized defects.

Bone morphogenetic protein 9 regulates tumor growth of osteosarcoma cells through the Wnt/ß-catenin pathway.

Bone morphogenetic protein 9 (BMP9) is a member of the transforming growth factor-ß (TGF-ß) family, which has been shown to regulate the progression of several tumors. Recent studies indicated that BMP9 affects osteosarcoma (OS) processes, but its specific roles and molecular mechanisms have yet to be fully elucidated. The human OS cell lines 143B and MG63 were used for the present study. We found that BMP9 overexpression suppressed the growth of OS cells, whereas inhibition of BMP9 reversed this effect. Our results also showed that BMP9 overexpression induced G0/G1 phase arrest and apoptosis in OS cells. We further investigated the possible molecular mechanisms mediating the biological role of BMP9. We observed that BMP9 overexpression reduced ß-catenin mRNA and protein levels, and also downregulated its downstream proteins c-Myc and osteoprotegerin (OPG) and inhibited the phosphorylation levels of GSK-3ß (Ser 9) in OS cells, whereas inhibition of BMP9 reversed these effects. Moreover, the suppressive effects of BMP9 overexpression on OS cells was reversed by exogenous ß-catenin expression, but augmented by ß-catenin silencing. In conclusion, our results revealed that BMP9 can regulate tumor growth of OS cells through the Wnt/ß-catenin pathway. Therefore, BMP9 may be a new therapeutic target in OS.

Adaptive immune response in osteoclastic bone resorption induced by orally administered Aggregatibacter actinomycetemcomitans in a rat model of periodontal disease.

There is mounting evidence that innate and adaptive immunity are critical for periodontal disease-mediated bone resorption. These studies examined the role of B and CD4 T cells in adaptive immunity of rats infected with Aggregatibacter actinomycetemcomitans (Aa). Sprague-Dawley male rats were fed Aa-containing mash or control-mash for 2 weeks. B and CD4 T cells were obtained from draining lymph nodes at 2, 4 and 12 weeks, postinoculation. Quantitative polymerase chain reaction-based messenger RNA expression was conducted for 89 cytokine family genes. Disease-relevance of the differentially expressed genes was assessed using a biological interaction pathway analysis software. B and CD4 T cells of Aa-infected rats increased and were activated, resulting in enhanced isotype-switched serum immunoglobulin G by 2 weeks postinoculation. Bone resorption was evident 12 weeks after Aa-feeding. In B cells, interleukin-2 (IL-2), macrophage-inhibiting factor, IL-19, IL-21, tumor necrosis factor (TNF), CD40 ligand (CD40L), CD70, bone morphogenetic protein 2 (BMP2), BMP3, and BMP10 were upregulated early; while IL-7, Fas ligand (FasL), small inducible cytokine subfamily E1, and growth differentiation factor 11 (GDF11; BMP11) were upregulated late (12 weeks). BMP10 was sustained throughout. In CD4 T cells, IL-10, IL-16, TNF, lymphotoxin-beta (LTbeta), APRIL, CD40L, FasL, RANKL and osteoprotegerin were upregulated early, whereas IL-1beta, IL-1RN, IL-1F8, IL-24, interferon-alpha1, GDF11 (BMP11), and GDF15 were upregulated late (12 weeks). Adaptive immunity appears crucial for bone resorption. Several of the deregulated genes are, for the first time, shown to be associated with bone resorption, and the results indicate that activated B cells produce BMP10. The study provides a rationale for a link between periodontal disease and other systemic diseases.

Autocrine bone morphogenetic protein-9 signals through activin receptor-like kinase-2/Smad1/Smad4 to promote ovarian cancer cell proliferation.

Bone morphogenetic proteins (BMPs) act as central regulators of ovarian physiology and may be involved in ovarian cancer development. In an effort to understand these processes, we characterized transforming growth factor beta/BMP receptor and Smad expression in immortalized ovarian surface epithelial cells and a panel of ovarian cancer cell lines. These studies prompted us to evaluate the potential role of BMP9 signaling in ovarian cancer. Using small interfering RNA, ligand trap, inhibitor, and ligand stimulation approaches, we show that BMP9 acts as a proliferative factor for immortalized ovarian surface epithelial cells and ovarian cancer cell lines, signaling predominantly through an ALK2/Smad1/Smad4 pathway rather than through ALK1, the major BMP9 receptor in endothelial cells. Importantly, we find that some ovarian cancer cell lines have gained autocrine BMP9 signaling that is required for proliferation. Furthermore, immunohistochemistry analysis of an ovarian cancer tissue microarray reveals that approximately 25% of epithelial ovarian cancers express BMP9, whereas normal human ovarian surface epithelial specimens do not. Our data indicate that BMP9 signaling through ALK2 may be a novel therapeutic target in ovarian cancer.