Bone morphogenetic protein 2 exerts diverse effects on cell growth in vitro and is expressed in human pancreatic cancer in vivo

The TGF-β superfamily as potential therapeutic targets in pancreatic cancer

The transforming growth factor (TGF)-β superfamily has important physiologic roles and is dysregulated in many pathologic processes, including pancreatic cancer. Pancreatic cancer is one of the most lethal cancer diagnoses, and current therapies are largely ineffective due to tumor resistance and late-stage diagnosis with poor prognosis. Recent efforts are focused on the potential of immunotherapies in improving therapeutic results for patients with pancreatic cancer, among which TGF-β has been identified as a promising target. This review focuses on the role of TGF-β in the diseased pancreas and pancreatic cancer. It also aims to summarize the current status of therapies targeting the TGF-β superfamily and postulate potential future directions in targeting the TGF-β signaling pathways.

Predictive Value of MUC5AC Signature in Pancreatic Ductal Adenocarcinoma: A Hypothesis Based on Preclinical Evidence

Mucin 5AC (MUC5AC) glycoprotein plays a crucial role in carcinogenesis and drug sensitivity in pancreatic ductal adenocarcinoma (PDAC), both individually and in combination with other mucins. Its function and localization are glycoform-specific. The immature isoform (detected by the CLH2 monoclonal antibody, or mab) is usually in the perinuclear (cytoplasmic) region, while the mature (45 M1, 2-11, Nd2) variants are in apical and extracellular regions. There is preclinical evidence suggesting that mature MUC5AC has prognostic and predictive (response to treatment) value. However, these findings were not validated in clinical studies. We propose a MUC5AC signature with three components of MUC5AC-localization, variant composition, and intensity-suggesting a reliable marker in combination of variants than with individual MUC5AC variants alone. We also postulate a theory to explain the occurrence of different MUC5AC variants in abnormal pancreatic lesions (benign, precancerous, and cancerous). We also analyzed the effect of mature MUC5AC on sensitivity to drugs often used in PDAC management, such as gemcitabine, 5-fluorouracil, oxaliplatin, irinotecan, cisplatin, and paclitaxel. We found preliminary evidence of its predictive value, but there is a need for large-scale studies to validate them.

Effects of CCN6 overexpression on the cell motility and activation of p38/bone morphogenetic protein signaling pathways in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancer types that is highly resistant to conventional treatments, such as chemotherapy and radiotherapy. As the demand for more effective therapeutics for PDAC treatment increases, various approaches have been studied to develop novel targets. The cellular communication network (CCN) family is a matricellular protein that modulates various cellular functions, including cell adhesion, proliferation, migration, and invasiveness. Despite this, little is known about the role of CCN6 in PDAC. The current study investigated the role of CCN6 in PDAC by generating CCN6-overexpressing PANC-1 cells (PANC-1-CCN6) by infecting lentivirus particles containing CCN6. PANC-1-CCN6 induces cell viability and tumorigenesis than PANC-1 cells with empty vector (control). The PANC-1-CCN6 formed more colonies, and the size of spheroids increased compared to the control. The upregulation of CCN6 enhances the expression of bone morphogenetic proteins (BMPs) genes and the upregulation of p38 mitogen-activated protein kinases (MAPKs). In PANC-1-CCN6 cells, the levels of N-cadherin, VEGF, and Snail expression were higher than the control, while E-cadherin expression was lower, which is associated with upregulation of epithelial-to-mesenchymal transition (EMT). Consistent with the changes in EMT-related proteins in PANC-1-CCN6, the migratory ability and invasiveness were enhanced in PANC-1-CCN6. Xenografted PANC-1-CCN6 in immunocompromised mice exhibited accelerated tumor growth than the control group. In immunohistochemistry (IHC), the PANC-1-CCN6 xenografted tumor showed an increased positive area of PCNA and Ki-67 than the control. These results suggest that CCN6 plays a tumorigenic role and induces the metastatic potential by the p38 MAPK and BMPs signaling pathways. Although the role of CCN6 has been introduced as an antitumor factor, there was evidence of CCN6 acting to cause tumorigenesis and invasion in PANC-1.

The Role of SMAD4 Inactivation in Epithelial-Mesenchymal Plasticity of Pancreatic Ductal Adenocarcinoma: The Missing Link?

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is currently one of the deadliest cancers. Despite the progress that has been made in the research of patient care and the understanding of pancreatic cancer, the survival rate remains mediocre. SMAD4, a tumor-suppressor gene, is specifically inactivated in 50–55% of pancreatic cancers. The role of SMAD4 protein loss in PDAC remains controversial, but seems to be associated with worse overall survival and metastasis. Here, we review the function of SMAD4 inactivation in the context of a specific biological process called epithelial–mesenchymal transition, as it has been increasingly associated with tumor formation, metastasis and resistance to therapy. By improving our understanding of these molecular mechanisms, we hope to find new targets for therapy and improve the care of patients with PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) presents a five-year survival rate of 10% and its incidence increases over the years. It is, therefore, essential to improve our understanding of the molecular mechanisms that promote metastasis and chemoresistance in PDAC, which are the main causes of death in these patients. SMAD4 is inactivated in 50% of PDACs and its loss has been associated with worse overall survival and metastasis, although some controversy still exists. SMAD4 is the central signal transducer of the transforming growth factor-beta (TGF-beta) pathway, which is notably known to play a role in epithelial–mesenchymal transition (EMT). EMT is a biological process where epithelial cells lose their characteristics to acquire a spindle-cell phenotype and increased motility. EMT has been increasingly studied due to its potential implication in metastasis and therapy resistance. Recently, it has been suggested that cells undergo EMT transition through intermediary states, which is referred to as epithelial–mesenchymal plasticity (EMP). The intermediary states are characterized by enhanced aggressiveness and more efficient metastasis. Therefore, this review aims to summarize and analyze the current knowledge on SMAD4 loss in patients with PDAC and to investigate its potential role in EMP in order to better understand its function in PDAC carcinogenesis.

DNA Methylation Mediates EMT Gene Expression in Human Pancreatic Ductal Adenocarcinoma Cell Lines

Due to abundant stroma and extracellular matrix, accompanied by lack of vascularization, pancreatic ductal adenocarcinoma (PDAC) is characterized by severe hypoxia. Epigenetic regulation is likely one of the mechanisms driving hypoxia-induced epithelial-to-mesenchymal transition (EMT), responsible for PDAC aggressiveness and dismal prognosis. To verify the role of DNA methylation in this process, we assessed gene expression and DNA methylation changes in four PDAC cell lines. BxPC-3, MIA PaCa-2, PANC-1, and SU.86.86 cells were exposed to conditioned media containing cytokines and inflammatory molecules in normoxic and hypoxic (1% O2) conditions for 2 and 6 days. Cancer Inflammation and Immunity Crosstalk and Human Epithelial to Mesenchymal Transition RT² Profiler PCR Arrays were used to identify top deregulated inflammatory and EMT-related genes. Their mRNA expression and DNA methylation were quantified by qRT-PCR and pyrosequencing. BxPC-3 and SU.86.86 cell lines were the most sensitive to hypoxia and inflammation. Although the methylation of gene promoters correlated with gene expression negatively, it was not significantly influenced by experimental conditions. However, DNA methyltransferase inhibitor decitabine efficiently decreased DNA methylation up to 53% and reactivated all silenced genes. These results confirm the role of DNA methylation in EMT-related gene regulation and uncover possible new targets involved in PDAC progression.

Bone morphogenetic protein induces bone invasion of melanoma by epithelial-mesenchymal transition via the Smad1/5 signaling pathway

Oral malignant melanoma, which frequently invades the hard palate or maxillary bone, is extremely rare and has a poor prognosis. Bone morphogenetic protein (BMP) is abundantly expressed in bone matrix and is highly expressed in malignant melanoma, inducing an aggressive phenotype. We examined the role of BMP signaling in the acquisition of an aggressive phenotype in melanoma cells in vitro and in vivo. In five cases, immunohistochemistry indicated the phosphorylation of Smad1/5 (p-Smad1/5) in the nuclei of melanoma cells. In the B16 mouse and A2058 human melanoma cell lines, BMP2, BMP4, or BMP7 induces morphological changes accompanied by the downregulation of E-cadherin, and the upregulation of N-cadherin and Snail, markers of epithelial-mesenchymal transition (EMT). BMP2 also stimulates cell invasion by increasing matrix metalloproteinase activity in B16 cells. These effects were canceled by the addition of LDN193189, a specific inhibitor of Smad1/5 signaling. In vivo, the injection of B16 cells expressing constitutively activated ALK3 enhanced zygoma destruction in comparison to empty B16 cells by increasing osteoclast numbers. These results suggest that the activation of BMP signaling induces EMT, thus driving the acquisition of an aggressive phenotype in malignant melanoma.

The Epstein-Barr Virus-Encoded EBNA1 Protein Activates the Bone Morphogenic Protein (BMP) Signalling Pathway to Promote Carcinoma Cell Migration

The Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) protein is expressed in all virus-associated malignancies, where it performs an essential role in the maintenance, replication and transcription of the EBV genome. In recent years, it has become apparent that EBNA1 can also influence cellular gene transcription. Here, we demonstrate that EBNA1 is able to stimulate the expression of the Transforming growth factor-beta (TGFβ) superfamily member, bone morphogenic protein 2 (BMP2), with consequential activation of the BMP signalling pathway in carcinoma cell lines. We show that BMP pathway activation is associated with an increase in the migratory capacity of carcinoma cells, an effect that can be ablated by the BMP antagonist, Noggin. Gene expression profiling of authentic EBV-positive nasopharyngeal carcinoma (NPC) tumours revealed the consistent presence of BMP ligands, established BMP pathway effectors and putative target genes, constituting a prominent BMP “signature” in this virus-associated cancer. Our findings show that EBNA1 is the major viral-encoded protein responsible for activating the BMP signalling pathway in carcinoma cells and supports a role for this pathway in promoting cell migration and possibly, metastatic spread.

Extracellular BMP Antagonists, Multifaceted Orchestrators in the Tumor and Its Microenvironment

The bone morphogenetic proteins (BMPs), a subgroup of the transforming growth factor-β (TGF-β) superfamily, are involved in multiple biological processes such as embryonic development and maintenance of adult tissue homeostasis. The importance of a functional BMP pathway is underlined by various diseases, including cancer, which can arise as a consequence of dysregulated BMP signaling. Mutations in crucial elements of this signaling pathway, such as receptors, have been reported to disrupt BMP signaling. Next to that, aberrant expression of BMP antagonists could also contribute to abrogated signaling. In this review we set out to highlight how BMP antagonists affect not only the cancer cells, but also the other cells present in the microenvironment to influence cancer progression.

Function of BMP4 in the Formation of Vasculogenic Mimicry in Hepatocellular Carcinoma

Vasculogenic mimicry (VM) is linked to vascular invasion of human hepatocellular carcinoma (HCC). BMP4, one BMP family member, is upregulated in several cancers. The purpose of this report is to identify the function of BMP4 in the formation of VM in HCC and the mechanism underling this regulation. In our report, BMP4 up-regulation resulted in an increase in migration, invasion and channel-like structure formation as well as induced epithelial-mesenchymal transition (EMT) process and stem cell-associated proteins OCT4 and SOX2 expression in HCC cells. In addition, The VM-associated proteins, including EphA2, VE-cadherin and MMP2, also could be effectively enhanced by the overexpression of BMP4. Furthermore, according to the TCGA database, higher expression of BMP4 is seen in HCC in contrast to normal liver samples. Immunohistochemistry revealed that BMP4 was positively associated with VM formation, age, histological differentiation, HCC stage, and shorter survival duration. These data demonstrated that BMP4 could promote VM network formation in HCC through induction of stemness in EMT and modulating the EphA2/VE-cadherin/MMP2 signaling pathway.

Bidirectional tumor/stroma crosstalk promotes metastasis in mesenchymal colorectal cancer

Patients with the mesenchymal subtype colorectal cancer (CRC) have a poor prognosis, in particular patients with stroma-rich tumors and aberrant SMAD4 expression. We hypothesized that interactions between SMAD4-deficient CRC cells and cancer-associated fibroblasts provide a biological explanation. In transwell invasion assays, fibroblasts increased the invasive capacity of SMAD4-deficient HT29 CRC cells, but not isogenic SMAD4-proficient HT29 cells. A TGF-β/BMP-specific array showed BMP2 upregulation by fibroblasts upon stimulation with conditioned medium from SMAD4-deficient CRC cells, while also stimulating their invasion. In a mouse model for experimental liver metastasis, the co-injection of fibroblasts increased metastasis formation of SMAD4-deficient CRC cells (p = 0.02) but not that of SMAD4-proficient CRC cells. Significantly less metastases were seen in mice co-injected with BMP2 knocked-down fibroblasts. Fibroblast BMP2 expression seemed to be regulated by TRAIL, a factor overexpressed in SMAD4-deficient CRC cells. In a cohort of 146 stage III CRC patients, we showed that patients with a combination of high stromal BMP2 expression and the loss of tumor SMAD4 expression had a significantly poorer overall survival (HR 2.88, p = 0.04). Our results suggest the existence of a reciprocal loop in which TRAIL from SMAD4-deficient CRC cells induces BMP2 in fibroblasts, which enhances CRC invasiveness and metastasis.

Osteogenic Enhancement Between Icariin and Bone Morphogenetic Protein 2: A Potential Osteogenic Compound for Bone Tissue Engineering

Icariin, a typical flavonol glycoside, is the main active component of Herba Epimedii, which was used to cure bone-related diseases in China for centuries. It has been reported that Icariin can be delivered locally by biomaterials and it has an osteogenic potential for bone tissue engineering. Biomimetic calcium phosphate (BioCaP) bone substitute is a novel drug delivery carrier system. Our study aimed to evaluate the osteogenic potential when Icariin was internally incorporated into the BioCaP granules. The BioCaP combined with Icariin and bone morphogenetic protein 2 (BMP-2) was investigated in vitro using an MC3T3-E1 cell line. We also investigated its efficacy to repair 8 mm diameter critical size bone defects in the skull of SD male rats. BioCaP was fabricated according to a well-established biomimetic mineralization process. In vitro, the effects of BioCaP alone or BioCaP with Icariin and/or BMP-2 on cell proliferation and osteogenic differentiation of MC3T3-E1 cells were systematically evaluated. In vivo, BioCaP alone or BioCaP with Icariin and/or BMP-2 were used to study the bone formation in a critical-sized bone defect created in a rat skull. Samples were retrieved for Micro-CT and histological analysis 12 weeks after surgery. The results indicated that BioCaP with or without the incorporation of Icariin had a positive effect on the osteogenic differentiation of MC3T3-E1. BioCaP with Icariin had better osteogenic efficiency, but had no influence on cell proliferation. BioCap + Icariin + BMP-2 showed better osteogenic potential compared with BioCaP with BMP-2 alone. The protein and mRNA expression of alkaline phosphatase and osteocalcin and mineralization were higher as well. In vivo, BioCaP incorporate internally with both Icariin and BMP-2 induced significantly more newly formed bone than the control group and BioCaP with either Icariin or BMP-2 did. Micro-CT analysis revealed that no significant differences were found between the bone mineral density induced by BioCaP with icariin and that induced by BioCaP with BMP-2. Therefore, co-administration of Icariin and BMP-2 was helpful for bone tissue engineering.

BMP-2 inhibits lung metastasis of osteosarcoma: an early investigation using an orthotopic model

Background

Bone morphogenetic proteins (BMPs), members of the TGF-β superfamily, are known to regulate cell proliferation, differentiation, apoptosis, chemotaxis, and angiogenesis. BMPs also participate in the development of most tissues and organs in vertebrates. Recombinant human (rh) BMPs, such as rhBMP-2, rhBMP-4, and rhBMP-7, have been recently approved to augment spinal fusion and recalcitrant long-bone non-unions because of their equivalent or superior efficacy to autogenous bone graft in enhancing bony fusion. Nonetheless, the use of BMPs is contraindicated in surgery for bone tumors because of concerns that this anabolic growth factor may cause tumor proliferation. However, we have repeatedly reported that BMP-2 is effective in inducing osteogenic differentiation of a subpopulation of osteosarcoma (OSA) cells that acquire stem cell attributes and are capable of reconstituting tumor masses, which in turn suppress the malignancy of the bone tumor.

Methods

3×10⁵/20 µL human OSA 143B cells were inoculated into 5–6 weeks old BABL/c nude mice to establish orthotopic OSA. X-ray device was used to monitor the developed tumors in animals. Necropsy was performed and the pathology of lung metastasis were tested by Haemotoxylin and Eosin. Moreover, bone formation induced by rhBMP-2 was investigated through micro-computed tomography. In addition, immunohistochemistry staining was used to evaluate the tumorigenicity and growth of OSA cells after rhBMP-2 treatment.

Results

In the present study, we established an orthotopic model of OSA by inoculating 143B cells into BABL/c mice, which resulted in a tumor occurrence rate of 100%. Following the treatment with rhBMP-2, lung metastasis, which contributes to poor prognosis, was significantly restricted, indicating an additional aspect of rhBMP-2 to suppress expansion of OSA. Concurrently, our micro-computed tomography and radiographic analyses showed that rhBMP-2 reduced the invasion of tumor cells into adjacent bone tissue, which in turn helped to preserve the integrity of the affected bone tissue. Finally, the growth of Ki-67-positive cells and those cells that express high levels of aldehyde dehydrogenase (ALDH^br) was found to be inhibited in the developed tumors.

Conclusion

On the basis of these results, we conclude that rhBMP-2 can impede the malignancy of OSA by reducing lung metastasis of the tumor. Induction of the tumor cells by rhBMP-2 also helps to preserve the impaired skeleton. These results imply that BMP-2 or BMP-2-mimetic drugs, if properly combined with traditional therapies, may provide a new therapeutic option for the treatment of OSA.

Risk of Cancer Following Lumbar Fusion Surgery With Recombinant Human Bone Morphogenic Protein-2 (rhBMP-2): An Analysis Using a Commercially Insured Patient Population

Background

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is frequently used to promote new bone growth after lumbar fusion surgery. However, because BMP receptors are found on cancer cells, there is concern about potential cancer following treatment with rhBMP-2. Data from clinical trials have reported divergent results and have been limited by small sample sizes and relatively short follow-up. We therefore examined the long-term risk of cancer following treatment with rhBMP-2 after lumbar fusion surgery.

Methods

Using the MarketScan Commercial Claims and Encounters database, we identified all patients <65 years without prior cancer who underwent lumbar fusion surgery between October 2003 and December 2009 and were followed at least 3 years after surgery. Development of any Surveillance Epidemiology and End Results malignancy in follow-up was identified through diagnosis and procedure codes.

Results

Among 39 448 eligible patients, 2345 (5.9%) received rhBMP at surgery; the median follow-up in this population was 4.87 years. Cancer in follow-up was observed in 49 BMP-treated patients (0.43/100 person years) and 1072 nontreated patients (0.58/100 person years). Use of rhBMP was associated with a cancer risk similar to that of untreated patients in both univariate (hazard ratio, 0.80; 95%, CI 0.54-1.19) and multivariate proportional hazards analyses (hazard ratio, 0.81; 95% CI, 0.54-1.20). Similar findings were observed in a secondary analysis after adjustment for likelihood of rhBMP administration.

Conclusions

In this retrospective cohort with at least 3 years of follow-up, administration of rhBMP during lumbar fusion surgery was not associated with an increased risk of subsequent cancer.

Level of Evidence

4.

Novel bone morphogenetic protein receptor inhibitor JL5 suppresses tumor cell survival signaling and induces regression of human lung cancer

BMP receptor inhibitors induce death of cancer cells through the downregulation of antiapoptotic proteins XIAP, pTAK1, and Id1-Id3. However, the current most potent BMP receptor inhibitor, DMH2, does not downregulate BMP signaling in vivo because of metabolic instability and poor pharmacokinetics. Here we identified the site of metabolic instability of DMH2 and designed a novel BMP receptor inhibitor, JL5. We show that JL5 has a greater volume of distribution and suppresses the expression of Id1 and pTak1 in tumor xenografts. Moreover, we demonstrate JL5-induced tumor cell death and tumor regression in xenograft mouse models without immune cells and humanized with adoptively transferred human immune cells. In humanized mice, JL5 additionally induces the infiltration of immune cells within the tumor microenvironment. Our studies show that the BMP signaling pathway is targetable in vivo and BMP receptor inhibitors can be developed as a therapeutic to treat cancer patients.

Systematic single-cell analysis provides new insights into heterogeneity and plasticity of the pancreas

BACKGROUND

Diabetes mellitus is characterized by loss or dysfunction of insulin-producing β-cells in the pancreas, resulting in failure of blood glucose regulation and devastating secondary complications. Thus, β-cells are currently the prime target for cell-replacement and regenerative therapy. Triggering endogenous repair is a promising strategy to restore β-cell mass and normoglycemia in diabetic patients. Potential strategies include targeting specific β-cell subpopulations to increase proliferation or maturation. Alternatively, transdifferentiation of pancreatic islet cells (e.g. α- or δ-cells), extra-islet cells (acinar and ductal cells), hepatocytes, or intestinal cells into insulin-producing cells might improve glycemic control. To this end, it is crucial to systematically characterize and unravel the transcriptional program of all pancreatic cell types at the molecular level in homeostasis and disease. Furthermore, it is necessary to better determine the underlying mechanisms of β-cell maturation, maintenance, and dysfunction in diabetes, to identify and molecularly profile endocrine subpopulations with regenerative potential, and to translate the findings from mice to man. Recent approaches in single-cell biology started to illuminate heterogeneity and plasticity in the pancreas that might be targeted for β-cell regeneration in diabetic patients.

SCOPE OF REVIEW

This review discusses recent literature on single-cell analysis including single-cell RNA sequencing, single-cell mass cytometry, and flow cytometry of pancreatic cell types in the context of mechanisms of endogenous β-cell regeneration. We discuss new findings on the regulation of postnatal β-cell proliferation and maturation. We highlight how single-cell analysis recapitulates described principles of functional β-cell heterogeneity in animal models and adds new knowledge on the extent of β-cell heterogeneity in humans as well as its role in homeostasis and disease. Furthermore, we summarize the findings on cell subpopulations with regenerative potential that might enable the formation of new β-cells in diseased state. Finally, we review new data on the transcriptional program and function of rare pancreatic cell types and their implication in diabetes.

MAJOR CONCLUSION

Novel, single-cell technologies offer high molecular resolution of cellular heterogeneity within the pancreas and provide information on processes and factors that govern β-cell homeostasis, proliferation, and maturation. Eventually, these technologies might lead to the characterization of cells with regenerative potential and unravel disease-associated changes in gene expression to identify cellular and molecular targets for therapy.

Never let it go: Stopping key mechanisms underlying metastasis to fight pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive neoplasm, predicted to become the second leading cause of cancer-related deaths before 2030. This dismal trend is mainly due to lack of effective treatments against its metastatic behavior. Therefore, a better understanding of the key mechanisms underlying metastasis should provide new opportunities for therapeutic purposes. Genomic analyses revealed that aberrations that fuel PDAC tumorigenesis and progression, such as SMAD4 loss, are also implicated in metastasis. Recently, microRNAs have been shown to play a regulatory role in the metastatic behavior of many tumors, including PDAC. In particular, miR-10 and miR-21 have appeared as master regulators of the metastatic program, while members of the miR-200 family are involved in the epithelial-to-mesenchymal switch, favoring cell migration and invasiveness. Several studies have also found a close relationship between cancer stem cells (CSCs) and biological features of metastasis, and the CSC markers ALDH1, ABCG2 and c-Met are expressed at high levels in metastatic PDAC cells. Emerging evidence reveals that exosomes are involved in the modulation of the tumor microenvironment and can initiate PDAC pre-metastatic niche formation in the liver and lungs. In this review, we provide an overview of the role of all these pivotal factors in the metastatic behavior of PDAC, and discuss their potential exploitation in the clinic to improve current therapeutics and identify new drug targets.

Bone morphogenetic protein-2 and tumor growth: Diverse effects and possibilities for therapy

Concern regarding safety with respect to the clinical use of human bone morphogenetic protein-2 (BMP-2) has become an increasingly controversial topic. The role of BMP-2 in carcinogenesis is of particular concern. Although there have been many studies of this topic, the results have been contradictory and confusing. We conducted a systematic review of articles that are relevant to the relationship or effect of BMP-2 on all types of tumors and a total of 97 articles were included. Studies reported in these articles were classified into three major types: "expression studies", "in vitro studies", and "in vivo studies". An obvious pattern was that those works that hypothesize an inhibitory effect for BMP-2 most often examined only the proliferative properties of the tumor cells. This subset of studies also contained an extraordinary number of contradictory findings which made drawing a reliable general conclusion impossible. In general, we support a pro-tumorigenesis role for BMP-2 based on the data from these in vitro cell studies and in vivo animal studies, however, more clinical studies should be carried out to help make a firm conclusion.

Bone Morphogenetic Proteins and Their Receptors in the Eye

The human genome encodes at least 42 different members of the transforming growth factor-β superfamily of growth factors. Bone morphogenetic proteins (BMPs) are the largest subfamily of proteins within the transforming growth factor-β superfamily and are involved in numerous cellular functions including development, morphogenesis, cell proliferation, apoptosis, and extracellular matrix synthesis. This article first reviews BMPs and BMP receptors, BMP signaling pathways, and mechanisms controlling BMP signaling. Second, we review BMP and BMP receptor expression during embryonic ocular development/ differentiation and in adult ocular tissues. Lastly, future research directions with respect to BMP, BMP receptors, and ocular tissues are suggested.

RN1, a novel galectin-3 inhibitor, inhibits pancreatic cancer cell growth in vitro and in vivo via blocking galectin-3 associated signaling pathways

Galectin-3 (Gal-3) has been implicated in pancreatic ductal adenocarcinoma (PDAC), and its candidacy as a therapeutic target has been evaluated. Gal-3 is widely upregulated in tumors, and its expression is associated with the development and malignancy of PDAC. In the present study, we demonstrate that a polysaccharide, RN1, purified from the flower of Panax notoginseng binds to Gal-3 and suppresses its expression. In addition, RN1 markedly inhibits PDAC cells growth in vitro, in vivo and in patient-derived xenografts. Mechanistically, RN1 binds to epidermal growth factor receptor (EGFR) and Gal-3, thereby disrupting the interaction between Gal-3 and EGFR and downregulating extracellular-related kinase (ERK) phosphorylation and the transcription factor of Gal-3, Runx1 expression. Inhibiting the expression of Runx1 by RN1, suppresses Gal-3 expression and inactivates Gal-3-associated signaling pathways, including the EGFR/ERK/Runx1, BMP/smad/Id-3 and integrin/FAK/JNK signaling pathways. In addition, RN1 can also bind to bone morphogenetic protein receptors (BMPR1A and BMPR2) and block the interaction between Gal-3 and the BMPRs. Thus, our results suggest that a novel Gal-3 inhibitor RN1 may be a potential candidate for human PDAC treatment via multiple targets and multiple signaling pathways.

Bone morphogenetic protein-2 expression in an intraductal papillary mucinous neoplasm with marked ossification: A case report

Intratumoral ossification has been reported in a number of epithelial tumors, but its presence in intraductal papillary mucinous neoplasms (IPMNs) is very rare. Herein, we present a rare case of IPMN with marked ossification. A 56-year-old Japanese man was under follow-up for a previously diagnosed IPMN. Seven years later, he was found to have dilatation of the main pancreatic duct and an enlarged solid mass, for which pancreaticoduodenectomy was performed. Macroscopically, multiple and cystically dilated pancreatic branch ducts, as well as a dilated main pancreatic duct, were identified. There was a solid, polypoid hard mass measuring 15 × 12 mm in the cystically dilated branch of the duct in the pancreatic head. Histological examination revealed papillary proliferation of atypical cuboidal or columnar epithelial cells in the dilated main and branch pancreatic ducts. The solid mass included an invasive adenocarcinoma component with a tubular or trabecular structure that showed pronounced ossification. We diagnosed the patient with invasive IPMN accompanied by marked ossification. Immunohistochemically, tumor cells in both the non-invasive and invasive lesions expressed bone morphogenetic protein-2 (BMP-2). While the mechanism of intratumoral ossification is unclear, it may have involved BMP-2 in the present case.

A Review of the Clinical Side Effects of Bone Morphogenetic Protein-2

Bone morphogenetic protein-2 (BMP-2) is currently the only Food and Drug Administration (FDA)-approved osteoinductive growth factor used as a bone graft substitute. However, with increasing clinical use of BMP-2, a growing and well-documented side effect profile has emerged. This includes postoperative inflammation and associated adverse effects, ectopic bone formation, osteoclast-mediated bone resorption, and inappropriate adipogenesis. Several large-scale studies have confirmed the relative frequency of adverse events associated with the clinical use of BMP-2, including life-threatening cervical spine swelling. In fact, the FDA has issued a warning of the potential life-threatening complications of BMP-2. This review summarizes the known adverse effects of BMP-2, including controversial areas such as tumorigenesis. Next, select animal models that replicate BMP-2's adverse clinical effects are discussed. Finally, potential molecules to mitigate the adverse effects of BMP-2 are reviewed. In summary, BMP-2 is a potent osteoinductive cytokine that has indeed revolutionized the bone graft substitute market; however, it simultaneously has accrued a worrisome side effect profile. Better understanding of these adverse effects among both translational scientists and clinicians will help determine the most appropriate and safe use of BMP-2 in the clinical setting.

Bone morphogenetic protein signaling in musculoskeletal cancer

PURPOSE

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-β (TGF-β) superfamily of proteins; they were initially named after their ability to induce ectopic bone formation. Published studies have proved BMPs' role in a variety of biological processes such as embryogenesis and patterning of body axes, and maintaining adult tissue homeostasis. Other studies have focused on BMPs properties, functions and possible involvement in skeletal diseases, including cancer.

METHODS

A literature search mainly paying attention to the role of BMPs in musculoskeletal tumors was performed in electronic databases.

RESULTS

This article discusses BMPs synthesis and signaling, and summarizes their prominent roles in the skeletal system for the differentiation of osteoblasts, osteocytes and chondrocytes.

CONCLUSIONS

The review emphasizes on the role of BMP signaling in the initiation and progression of musculoskeletal cancer.

Association Between BMP-2 and Carcinogenicity

STUDY DESIGN

Literature review.

OBJECTIVE

To evaluate the association between recombinant human bone morphogenetic protein-2 (rhBMP-2) and malignancy.

SUMMARY OF BACKGROUND DATA

The use of rhBMP-2 in spine surgery has been the topic of much debate as studies assessing the association between rhBMP-2 and malignancy have come to conflicting conclusions.

METHODS

A systematic review of the literature was performed using the PubMed-National Library of Medicine/National Institute of Health databases. Only non-clinical studies directly addressing BMP-2 and cancer were included. Articles were categorized by study type (animal, in vitro cell line/human/animal), primary malignancy, cancer attributes, and whether BMP-2 was pro-malignancy or not.

RESULTS

A total of 4,131 articles were reviewed. Of those, 515 articles made reference to both BMP-2 and cancer, 99 of which were found to directly examine the role of BMP-2 in cancer. Seventy-five studies were in vitro and 24 were animal studies. Forty-three studies concluded that BMP-2 enhanced cancer function, whereas 18 studies found that BMP-2 suppressed malignancy. Thirty-six studies did not examine whether BMP-2 enhanced or suppressed cancer function. Fifteen studies demonstrated BMP-2 dose dependence (9 enhancement, 6 suppression) and one study demonstrated no dose dependence. Nine studies demonstrated BMP-2 time dependence (6 enhancement, 3 suppression). However, no study demonstrated that BMP-2 caused cancer de novo.

CONCLUSION

Currently, conflicting data exist with regard to the effect of exogenous BMP-2 on cancer. The majority of studies addressed the role of BMP-2 in prostate (17%), breast (17%), and lung (15%) cancers. Most were in vitro studies (75%) and examined cancer invasiveness and metastatic potential (37%). Of 99 studies, there was no demonstration of BMP-2 causing cancer de novo. However, 43% of studies suggested that BMP-2 enhances tumor function, motivating more definitive research on the topic that also includes clinically meaningful dose- and time-dependence.

LEVEL OF EVIDENCE

2.

Inhibitory effect of bone morphogenetic protein-2 on the proliferation of giant cell tumor of bone stromal cells in vitro

The inhibitory effect of bone morphogenetic protein-2 (BMP-2) on the proliferation of giant cell tumor of bone stromal cells (GCTSCs) has not been fully elucidated. Therefore, the aim of this study was to evaluate the role of recombinant human BMP-2 (rhBMP-2) in the growth of GCTSCs. The effects of exposure to different concentrations of rhBMP-2 (0, 10, 100 and 300 ng/ml) for 1, 3, 5 and 7 days on GCTSC proliferation were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, the effect of treatment with rhBMP-2 (0 or 10 ng/ml) for 48 h on the cell cycle pattern of GCTSCs was examined by flow cytometry. The apoptosis-inducing effect of rhBMP-2 (0 or 10 ng/ml) in GCTSCs was also determined by flow cytometry after 48 and 72 h. In addition, western blot assays were conducted to determine whether rhBMP-2 acts on non-Smad mitogen-activated protein kinase (MAPK) signaling pathways, namely extracellular signal-regulated kinase (ERK1/2), p38 and c-jun-N-terminal kinase (JNK) pathways. The proliferation of GCTSCs treated with rhBMP-2 (10, 100 or 300 ng/ml) for 5 or 7 days was significantly inhibited in a non dose-dependent and non-time-dependent manner (P<0.05). The treatment of GCTSCs with rhBMP-2 (10 ng/ml) for 48 h had no effect on cell cycle distribution. The apoptosis of GCTSCs induced by exposure to rhBMP-2 (10 ng/ml) for 48 or 72 h was significant (P<0.05). Expression levels of phospho-ERK1/2, phospho-p38 and phospho-JNK increased significantly when GCTSCs were treated with rhBMP-2 (10 ng/ml) for 72 h (P<0.05). The results indicate that rhBMP-2 has no stimulatory effect on GCTSC growth. However, it may lead to the apoptosis of GCTSCs by non-Smad MAPK signaling pathways.

Secreted phosphoprotein 24 kD (Spp24) inhibits growth of human pancreatic cancer cells caused by BMP-2

The emerging role of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers has drawn great attention in cancer research. In this study, we report that BMP-2 can promote the proliferation of the pancreatic tumor cell line, PANC-1. Secreted phosphoprotein 24 kD (Spp24), a BMP binding protein, did not affect the proliferation of the cells but promoted the apoptosis of the cells in vitro. In a xeneograft tumor model using PANC-1 cells, BMP-2 dramatically promoted tumor growth, while Spp24 not only abolished the effect of BMP-2, but also dramatically induced tumor shrinking when used alone. Activation of Smad1/5/8 participated in this process as demonstrated by immunohistochemical staining of phosphorylated Smad 1/5/8. We conclude that Spp24 can be developed into a therapeutic agent that could be employed in clinical situations where the inhibition of BMPs and related proteins is advantageous.

Differential expression of bone morphogenetic protein 5 in human lung squamous cell carcinoma and adenocarcinoma

Bone morphogenetic proteins (BMPs) play important roles in tumor cell proliferation, metastasis, and invasion. However, the expression patterns of BMPs in patients with non-small-cell lung cancer (NSCLC) and their correlations with NSCLC pathogenesis have not been examined yet. In this study, the mRNA levels of BMP family members in NSCLC tissues were analyzed and results showed that the mRNA levels of BMP5 and BMP7 were significantly down-regulated and up-regulated, respectively, in tumor tissues compared with those in the corresponding noncancerous tissues. Interestingly, the mRNA level of BMP5 was significantly higher in lung adenocarcinoma tissues than that in lung squamous cell carcinoma tissues. Furthermore, results from immunohistochemistry analysis confirmed stronger expression of BMP5 protein in lung adenocarcinoma than in lung squamous cell carcinoma. Our findings suggested that BMP5 might be a potential prognostic biomarker or therapeutic target for patients with NSCLC.

A comprehensive assessment of the risk of bone morphogenetic protein use in spinal fusion surgery and postoperative cancer diagnosis

The risk of postoperative cancer following the use of recombinant human bone morphogenetic protein (BMP)-2 in spinal fusion is one potential complication that has received significant interest. Until recently, there has been little clinical evidence to support the assertion of potential cancer induction after BMP use in spinal surgery. This report aims to summarize the findings from clinical data available to date from the Yale University Open Data Access (YODA) project as well as more recently published large database studies regarding the association of BMP use in spinal fusion and the risk of postoperative cancer. A detailed review was based on online databases, primary studies, FDA reports, and bibliographies of key articles for studies that assessed the efficacy and safety of BMP in spinal fusion. In an analysis of the YODA project, one meta-analysis detected a statistically significant increase in cancer occurrence at 24 months but not at 48 months, and the other meta-analysis did not detect a significant increase in postoperative cancer occurrence. Analysis of 3 large health care data sets (Medicare, MarketScan, and PearlDiver) revealed that none were able to detect a significant increase in risk of malignant cancers when BMP was used compared with controls. The potential risk of postoperative cancer formation following the use of BMP in spinal fusion must be interpreted on an individual basis for each patient by the surgeon. There is no conclusive evidence that application of the common formulations of BMP during spinal surgery results in the formation of cancer locally or at a distant site.

A glass polyalkenoate cement carrier for bone morphogenetic proteins

This work considers a glass polyalkenoate cement (GPC)-based carrier for the effective delivery of bone morphogenetic proteins (BMPs) at an implantation site. A 0.12 CaO-0.04 SrO-0.36 ZnO-0.48 SiO2 based glass and poly(acrylic acid) (PAA, Mw 213,000) were employed for the fabrication of the GPC. The media used for the water source in the GPC reaction was altered to produce a series of GPCs. The GPC liquid media was either 100 % distilled water with additions of albumin at 0, 2, 5 and 8 wt% of the glass content, 100 % formulation buffer (IFB), and 100 % BMP (150 µg rhBMP-2/ml IFB). Rheological properties, compressive strength, ion release profiles and BMP release were evaluated. Working times (Tw) of the formulated GPCs significantly increased with the addition of 2 % albumin and remained constant with further increases in albumin content or IFB solutions. Setting time (Ts) experienced an increase with 2 and 5 % albumin content, but a decrease with 8 % albumin. Changing the liquid source to IFB containing 5 % albumin had no significant effect on Ts compared to the 8 % albumin-containing BT101. Replacing the albumin with IFB/BMP-2 did not significantly affect Tw. However, Ts increased for the BT101_BMP-2 containing GPCs, compared to all other samples. The compressive strength evaluated 1 day post cement mixing was not affected significantly by the incorporation of BMPs, but the ion release did increase from the cements, particularly for Zn and Sr. The GPCs released BMP after the first day, which decreased in content during the following 6 days. This study has proven that BMPs can be immobilized into GPCs and may result in novel materials for clinical applications.

Increased expression of Nodal correlates with reduced patient survival in pancreatic cancer

BACKGROUND

Nodal (nodal growth differentiation factor) and its inhibitor Lefty (left right determination factor), which are ligands of the TGF (transforming growth factor) β superfamily, are responsible for the determination of left-right asymmetry in vertebrates. Nodal/Lefty signaling has been suggested to play a role in the development of metastatic melanoma and breast cancer. However, it remains unclear whether this pathway is also involved in human pancreatic ductal adenocarcinoma (PDAC).

METHODS

Pancreatic cancer patient specimens with clinical data (n = 54) were used to investigate the clinical significance of Nodal-Lefty signaling. A set of in vitro assays were carried out in a human pancreatic cancer cell line (Colo-357) to assess the functional relevance of Nodal-Lefty signaling.

RESULTS

Nodal was absent in the human normal pancreas, while Lefty was present in islet cells. Though Nodal and Lefty expression were found in cancer cells at various expression levels, the cancer-associated tubular complexes were particularly positive for Lefty. Survival analysis revealed that high expression of Nodal correlated with reduced patient survival (median survival 17.8 vs 33.0 months, p = 0.013). Cultured pancreatic cancer cell lines expressed Nodal and Lefty at different levels. In vitro functional assays revealed that treatment with human recombinant Nodal inhibited cell growth and increased invasion of Colo-357 pancreatic cancer cells whereas no effect was found upon treatment with recombinant Lefty.

CONCLUSION

Nodal-Lefty signaling might be involved in the pathogenesis of PDAC as Nodal expression marks a subtype of PDAC with unfavorable prognosis.

Severe mandibular atrophy treated with a subperiosteal implant and simultaneous graft with rhBMP-2 and mineralized allograft: a case report

A 71-year-old patient was successfully rehabilitated by means of a 3D model-derived, hydroxyapatite-coated titanium subperiosteal mandibular implant. The implant was specifically designed to allow bone augmentation. The deficient bone was simultaneously grafted with mineralized bone allograft and recombinant bone morphogenetic protein -2 (rhBMP-2). The 32-month postoperative cone beam computerized tomography follow-up showed vertical bone augmentation beneath the implant frame.

BMP-2 inhibits tumor-initiating ability in human renal cancer stem cells and induces bone formation

PURPOSE

We have previously shown that BMP-2 induces bone formation and inhibits tumorigenicity of cancer stem cells (CSCs) in a human osteosarcoma OS99-1 cell line. In this study, we sought to determine whether BMP-2 can similarly induce bone formation and inhibit the tumorigenicity of renal CSCs identified based on aldehyde dehydrogenase (ALDH) activity in renal cell carcinoma (RCC) cell lines and primary tumors.

METHODS

Using a xenograft model in which cells from human RCC cell lines ACHN, Caki-2, and primary tumors were grown in NOD/SCID mice, renal CSCs were identified as a subset of ALDH(br) cells. The ALDH(br) cells possessed a greater colony-forming efficiency, higher proliferative output, increased expression of stem cell marker genes Oct3/4A, Nanog, renal embryonic marker Pax-2, and greater tumorigenicity compared to cells with low ALDH activity (ALDH(lo) cells), generating new tumors with as few as 25 cells in mice.

RESULTS

In vitro, BMP-2 was found to inhibit the ALDH(br) cell growth, down-regulate the expression of embryonic stem cell markers, and up-regulate the transcription of osteogenic markers. In vivo, all animals receiving a low number of ALDH(br) cells (5 × 10(3)) from ACHN, Caki-2, and primary tumor xenografts treated with 30 µg BMP-2 per animal showed limited tumor growth with significant bone formation, while untreated cells developed large tumor masses without bone formation.

CONCLUSIONS

These results suggest that BMP-2 inhibits the tumor-initiating ability of renal CSCs and induces osseous bone formation. BMP-2 may therefore provide a beneficial strategy for human RCC treatment by targeting the CSC-enriched population.

Specific-detection of clinical samples, systematic functional investigations, and transcriptome analysis reveals that splice variant MUC4/Y contributes to the malignant progression of pancreatic cancer by triggering malignancy-related positive feedback loops signaling

Background

MUC4 plays important roles in the malignant progression of human pancreatic cancer. But the huge length of MUC4 gene fragment restricts its functional and mechanism research. As one of its splice variants, MUC4/Y with coding sequence is most similar to that of the full-length MUC4 (FL-MUC4), together with alternative splicing of the MUC4 transcript has been observed in pancreatic carcinomas but not in normal pancreas. So we speculated that MUC4/Y might be involved in malignant progression similarly to FL-MUC4, and as a research model of MUC4 in pancreatic cancer. The conjecture was confirmed in the present study.

Methods

MUC4/Y expression was detected by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) using gene-specific probe in the clinic samples. The effects of MUC4/Y were observed by serial in vitro and in vivo experiments based on stable over-expressed cell model. The underlying mechanisms were investigated by sequence-based transcriptome analysis and verified by qRT-PCR, Western blot and enzyme-linked immunosorbent assays.

Results

The detection of clinical samples indicates that MUC4/Y is significantly positive-correlated with tumor invasion and distant metastases. Based on stable forced-expressed pancreatic cancer PANC-1 cell model, functional studies show that MUC4/Y enhances malignant activity in vitro and in vivo, including proliferation under low-nutritional-pressure, resistance to apoptosis, motility, invasiveness, angiogenesis, and distant metastasis. Mechanism studies indicate the novel finding that MUC4/Y triggers malignancy-related positive feedback loops for concomitantly up-regulating the expression of survival factors to resist adverse microenvironment and increasing the expression of an array of cytokines and adhesion molecules to affect the tumor milieu.

Conclusions

In light of the enormity of the potential regulatory circuitry in cancer afforded by MUC4 and/or MUC4/Y, repressing MUC4 transcription, inhibiting post-transcriptional regulation, including alternative splicing, or blocking various pathways simultaneously may be helpful for controlling malignant progression. MUC4/Y- expression model is proven to a valuable tool for the further dissection of MUC4-mediated functions and mechanisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0309-8) contains supplementary material, which is available to authorized users.

Complications with the use of bone morphogenetic protein 2 (BMP-2) in spine surgery

BACKGROUND CONTEXT

Recombinant human bone morphogenetic protein 2 (rhBMP-2) is a very potent osteogenic growth factor that has been used successfully in various spine fusions, obviating the need for autologous iliac crest bone graft harvest and therefore avoiding the associated morbidities.

PURPOSE

In the past few years, a tremendous increase in rhBMP-2 usage was noted, and concerns regarding costs, benefits, and safety issues were raised by many. The goal of this work was to provide a comprehensive review of the adverse events and complications associated with use of rhBMP-2.

STUDY DESIGN

Literature review.

METHODS

This is a review of the current literature on the reported adverse events, complications, and concerns associated with rhBMP-2 use.

RESULTS

This article discusses the wide spectrum of adverse outcomes related to rhBMP-2 use in the lumbar and the cervical spine; retrograde ejaculation, antibodies formation, postoperative radiculitis, postoperative nerve root injury, ectopic bone formation, vertebral osteolysis/edema, dysphagia and neck swelling, hematoma formation, interbody graft lucency, and wound healing complications are reviewed. Cost-related concerns, dosage considerations, carrier types, and theoretical carcinogenesis concerns were also presented.

CONCLUSIONS

Despite the excellent spinal fusion rates promoted by this powerful molecule, the increasingly reported adverse outcomes associated with bone morphogenetic protein usage have created real concerns. This article will provide the reader with a good understanding of the reported complications associated with rhBMP-2 use and ultimately help recognize its safety spectrum and limits for better clinical application.

Biomaterial scaffolds for treating osteoporotic bone

Healing fractures resulting from osteoporosis or cancer remains a significant clinical challenge. In these populations, healing is often impaired not only due to age and disease, but also by other therapeutic interventions such as radiation, steroids, and chemotherapy. Despite substantial improvements in the treatment of osteoporosis over the last few decades, osteoporotic fractures are still a major clinical challenge in the elderly population due to impaired healing. Similar fractures with impaired healing are also prevalent in cancer patients, especially those with tumor growing in bone. Treatment options for cancer patients are further complicated by the fact that bone anabolic therapies are contraindicated in patients with tumors. Therefore, many patients undergo surgery to repair the fracture, and bone grafts are often used to stabilize orthopedic implants and provide a scaffold for ingrowth of new bone. Both synthetic and naturally occurring biomaterials have been investigated as bone grafts for repair of osteoporotic fractures, including calcium phosphate bone cements, resorbable polymers, and allograft or autograft bone. In order to re-establish normal bone repair, bone grafts have been augmented with anabolic agents, such as mesenchymal stem cells or recombinant human bone morphogenetic protein-2. These developing approaches to bone grafting are anticipated to improve the clinical management of osteoporotic and cancer-induced fractures.

BMP-2 expression correlates with local failure in head and neck squamous cell carcinoma

OBJECTIVE

Preclinical data show that exogenous administration of recombinant human bone morphogenetic protein-2 (rhBMP-2) to human oral carcinoma cell lines increases pathogenicity using a nude mouse model. The objectives of this study are to (1) describe the characteristics of baseline protein expression of BMP-2 in head and neck squamous cell carcinomas (HNSCC) and (2) determine if BMP-2 expression level correlates with worse oncologic outcomes.

STUDY DESIGN

Retrospective analysis of previously harvested patient samples.

SETTING

Academic medical center.

SUBJECTS

In total, 149 patients with oral cavity, oropharynx, larynx, and hypopharynx HNSCC treated between January 1, 1997, and December 31, 2004.

METHODS

A tissue microarray of HNSCC was assembled and immunohistochemistry for BMP-2 performed. Staining was quantified using a standardized scoring system. Specimens were dichotomized into high or low expression level. Statistical analyses using log-rank, Wilcoxon, and Fisher exact test were performed for associations between BMP-2 protein level and clinicopathologic features and patient survival.

RESULTS

BMP-2 expression at any level was noted in 146 of 149 (98%) of samples. Tumors with high BMP-2 expression had higher rates of local failure compared with low-expressing tumors (17.3% vs 6.3%; P = .04). There was no significant association for BMP-2 expression level with tumor location, T stage, N stage, overall survival, regional failure, or distant failure.

CONCLUSION

Head and neck squamous cell carcinomas with high baseline BMP-2 protein level are associated with higher rates of local recurrence. These data have important implications for using rhBMP-2 in tissue engineering reconstructive approaches in the setting of cancer-related defects.

Risk of cancer after lumbar fusion surgery with recombinant human bone morphogenic protein-2 (rh-BMP-2)

STUDY DESIGN

Retrospective cohort study among Medicare beneficiaries with lumbar spinal fusion surgery.

OBJECTIVE

To determine the risk of subsequent cancer among patients who received recombinant human bone morphogenic protein (rhBMP) at surgery compared with those who did not.

SUMMARY OF BACKGROUND DATA

rhBMP is commonly used to promote bone union after spinal surgery. BMP receptors are present on multiple cancer types, but the risk of cancer after receiving rhBMP has not been well studied.

METHODS

We identified 146,278 subjects aged 67 years and older who underwent surgery in 2003 to 2008 and were followed through 2010 for a new diagnosis of 1 of 26 cancers. Proportional hazards models were used to determine cancer risk associated with rhBMP use.

RESULTS

rhBMP was administered in 15.1% of the cohort. After an overall average follow-up of 4.7 years, 15.4% of rhBMP-treated and 17.0% of untreated patients had a new cancer diagnosis, with most commonly recorded types as prostate, breast, lung, and colorectal. In a multivariate proportional hazards model, there was no association of rhBMP with cancer risk (hazard ratio: 0.99, 95% confidence interval: 0.95-1.02). There was also no association of rhBMP with the risk of any individual cancer types. The results were consistent in analyses using 2 secondary definitions of incident cancer.

CONCLUSION

In this large population-based analysis of Medicare beneficiaries, we found no evidence that administration of rhBMP at the time of lumbar fusion surgery was associated with cancer risk.

LEVEL OF EVIDENCE

4.

Reduced expression of bone morphogenetic protein receptor IA in pancreatic cancer is associated with a poor prognosis

Background:

The expression of SMAD4, the central component of the transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signalling pathways, is lost in 50% of pancreatic cancers and is associated with a poor survival. Although the TGF-β pathway has been extensively studied and characterised in pancreatic cancer, there is very limited data on BMP signalling, a well-known tumour-suppressor pathway. BMP signalling can be lost not only at the level of SMAD4 but also at the level of BMP receptors (BMPRs), as has been described in colorectal cancer.

Methods:

We performed immunohistochemical analysis of the expression levels of BMP signalling components in pancreatic cancer and correlated these with survival. We also manipulated the activity of BMP signalling in vitro.

Results:

Reduced expression of BMPRIA is associated with a significantly worse survival, primarily in a subset of SMAD4-positive cancers. In vitro inactivation of SMAD4-dependent BMP signalling increases proliferation and invasion of pancreatic cancer cells, whereas inactivation of BMP signalling in SMAD4-negative cells does not change the proliferation and invasion or leads to an opposite effect.

Conclusion:

Our data suggest that BMPRIA expression is a good prognostic marker and that the BMP pathway is a potential target for future therapeutic interventions in pancreatic cancer.

Bone formation induced by BMP-2 in human osteosarcoma cells

Our previous studies demonstrated that BMP-2 inhibits the tumorigenicity of cancer stem cells identified as cells with high aldehyde dehydrogenase activity (ALDH ^br cells) from the human osteosarcoma cell line OS99-1. We further investigated whether BMP-2 is capable of inducing bone formation in OS99-1 cells. Flow cytometry sorting was used to isolate tumorigenic ALDH ^br and non-tumorigenic ALDH ^lo cells. qRT-PCR was used to quantify the gene expression. A xenograft model was used to verify the bone formation in vivo . There was significantly higher mRNA expression of BMPR1B and BMPR2 in ALDH ^lo cells compared with that in ALDH ^br cells and the BMPR1B expression in ALDH ^lo cells was ∼8-fold higher compared to that in ALDH ^br cells. BMP-2 was also found to induce higher transcription of osteogenic markers Runx-2, Osterix (Osx), alkaline phosphatase (ALP) and collagen type I in ALDH ^lo cells compared to ALDH ^br cells, which were mediated by the canonical Smad signaling pathway. In vivo , BMP-2 was identified to induce bone formation in both ALDH ^br and ALDH ^lo cells. All animals receiving 1×10 ⁴ ALDH ^lo cells treated with 30 μ g of BMP-2 per animal showed bone formation within 1–2 weeks after injection in mice. Bone formation induced by BMP-2 in ALDH ^lo cells showed significantly more bone mineral content compared to that in ALDH ^br cells. BMP-2 induces bone formation in heterogeneous osteosarcoma cells and BMP-2 may have a promising therapeutic role for treating human osteosarcoma by inducing differentiation along an osteogenic pathway.

Cancer After Spinal Fusion

BACKGROUND:

Bone morphogenetic protein (BMP) is used in tens of thousands of spinal fusions each year. A trial evaluating a high-dose BMP formulation demonstrated that its use may be associated with an increased risk of cancer.

OBJECTIVE:

To evaluate whether BMP, as commonly used today, is associated with an increased risk of cancer or benign tumors.

METHODS:

We performed a retrospective study using the Thomson Reuter MarketScan database. We retained all patients who had no previous diagnosis of cancer or benign tumor and had at least 2 years of uninterrupted enrollment in the database before and after their operations. A propensity score--matched cohort was created to ensure greater covariate balance between treatment groups.

RESULTS:

Within the propensity score--matched cohort (n = 4698), BMP-exposed patients had a nonsignificant increase in the rate of cancer diagnosis (9.37% vs 7.92%; P = .08). After adjustment for covariates, BMP exposure was associated with a 31% increased risk of benign tumor diagnosis (odds ratio, 1.31; 95% confidence interval, 1.02-1.68; P &lt; .05). When the benign tumor diagnoses were stratified by organ type, BMP patients had significantly more diagnoses of benign nervous system tumors (0.81% vs 0.34%; P = .03), and within this group, benign tumors of the spinal meninges were much more common in the BMP-treated group (0.13% vs 0.02%; P = .002).

CONCLUSION:

The results of this large, independent, propensity-matched study suggest that the use of BMP in lumbar fusions is associated with a significantly higher rate of benign neoplasms but not malignancies.

Fibroblast growth factor-2 and bone morphogenetic protein-2 have a synergistic stimulatory effect on bone formation in cell cultures from elderly mouse and human bone

Combined regimens of fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2) were investigated to stimulate osteogenic differentiation. In young mouse calvaria-derived cells, FGF-2 (0.16ng/mL) in combination with BMP-2 (50ng/mL) did not enhance mineralization, but in old mouse cells it resulted in more mineralization than BMP-2 alone. In young long bone mouse cultures, FGF-2 enhanced mineralization relative to BMP-2 alone, but in old cultures, lower dose of FGF-2 (0.016ng/mL) was necessary. In neonatal mouse calvarial cells, sequential delivery of low-dose FGF-2 and low-dose BMP-2 (5ng/mL) was more stimulatory than co-delivery. In young human cultures, 0.016ng/mL of FGF-2 did not enhance mineralization, in combination with 5ng/mL of BMP-2, but in older cultures, codelivery of FGF-2 and BMP-2 was superior to BMP-2 alone. In conclusion, BMP-2 treatment alone was sufficient for maximal mineralization in young osteoblast cultures. However, coadministration of FGF-2 and BMP-2 increases mineralization more than BMP-2 alone in cultures from old and young mouse long bones and old humans but not in young mouse calvarial cultures.

Tumor-stromal interactions in pancreatic cancer

Pancreatic adenocarcinoma has one of the worse prognoses of any cancer with a 5-year survival of only 3%. Pancreatic cancer displays one of the most prominent stromal reactions of all tumors and it is evident that this is a key contributing factor to disease outcome. The tumor microenvironment of pancreatic cancer harbors a wide spectrum of cell types and a complex network of mechanisms which all serve to promote tumor progression. It is clear that the symbiotic relationship between pancreatic cancer cells and stellate cells is the chief factor creating this unique tumor milieu. Pancreatic stellate cells play critical roles in evasion of cancer cell apoptosis, invasion and metastases, angiogenesis, and promotion of an immunosuppressive environment, all key hallmarks of malignancy. Existing treatments for pancreatic cancer focus on targeting the cancer cells rather than the whole tumor, of which cancer cells represent a small proportion. It is now increasingly evident that research targeted towards the interactions between these cell types, ideally at an early stage of tumor development, is imperative in order to propel the way forward to more effective treatments.

Regulators of epithelial mesenchymal transition in pancreatic cancer

Pancreatic cancer is a leading cause of cancer-related death due to its invasive nature. Despite the improvement of diagnostic strategy, early diagnosis of pancreatic cancer is still challenging. Surgical resection is the only curative therapy, while vast majority of patients are not eligible for this therapeutic option. Complex biological processes are involved in the establishment of invasion and metastasis of pancreatic cancer and epithelial-mesenchymal transition (EMT) has been reported to play crucial role. EMT is part of the normal developmental processes which mobilizes epithelial cells and yields mesenchymal phenotype. Deregulation of EMT inducing molecules in pancreatic cancer is reported, such as multiple cytokines, growth factors and downstream transcriptional factors. In addition to these molecules, non-coding RNA including miRNA also contributes to EMT. EMT of cancer cell also correlates with cancer stem cell (CSC) properties such as chemoresistance or tumorigenicity, therefore these upstream regulators of EMT could be attractive therapeutic targets and several candidates are examined for clinical application. This review summarizes recent advances in this field, focusing the regulatory molecules of EMT and their downstream targets. Further understanding and research advances will clarify the cryptic mechanism of cancer metastasis and delineate novel therapeutic targets.

Effect of grafting BMP2-derived peptide to nanoparticles on osteogenic and vasculogenic expression of stromal cells

Bone morphogenetic protein-2 (BMP2) plays a major role in initiating the cascade of osteogenesis. However, high doses of exogenous BMP2 coupled with diffusion away from the intended site cause adverse side-effects. An alternative is to use biodegradable polymeric nanoparticles (NPs) grafted with peptides of the active domains of BMP2. NPs present a multivalent form of the peptide for stronger interaction with cell surface receptors, leading to a stronger activation of osteogenic signalling pathways. The objective of this work was to compare osteogenic activity of the BMP2 peptide (BMP2Pe), corresponding to residues 73-92 of BMP2 protein (BMP2Pr), grafted to biodegradable NPs with that of BMP2 protein (BMP2Pr). BMP2Pe was functionalized with a cysteine residue and grafted to poly(lactide fumarate) and poly(lactide-co-ethylene oxide fumarate) (PLAF/PLEOF) NPs via a thioether link. The calcium content of bone marrow stromal (BMS) cells cultured in osteogenic medium supplemented with BMP2 peptide/protein-grafted NPs (BMP2Pe-gNP and BMP2Pr-gNP) was slightly higher than other BMP2-treated groups, but all osteogenic groups showed similar levels of mineralization after 21 days. The expression pattern of master transcription factors Dlx5 and Runx2 indicated that BMP2 protein induced faster osteogenic signalling than the BMP peptide. The expression level of Osteopontin (OP), Osteocalcin (OC) and PECAM-1 in the NP-grafted BMP2 groups was significantly higher than those of ungrafted BMP2Pr and BMP2Pe groups, which may be due to a more effective presentation of the peptide/protein to cell surface receptors, thus leading to a stronger interaction of the peptide/protein with clustered cell surface receptors.

BMPs and their clinical potentials

Bone morphogenetic protein (BMP) signaling in diseases is the subject of an overwhelming array of studies. BMPs are excellent targets for treatment of various clinical disorders. Several BMPs have already been shown to be clinically beneficial in the treatment of a variety of conditions, including BMP-2 and BMP-7 that have been approved for clinical application in nonunion bone fractures and spinal fusions. With the use of BMPs increasingly accepted in spinal fusion surgeries, other therapeutic approaches targeting BMP signaling are emerging beyond applications to skeletal disorders. These approaches can further utilize next-generation therapeutic tools such as engineered BMPs and ex vivo- conditioned cell therapies. In this review, we focused to provide insights into such clinical potentials of BMPs in metabolic and vascular diseases, and in cancer. [BMB reports 2011; 44(10): 619-634].