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Biomedical subjects

D Heymann

Publications and source records attributed to D Heymann.

At least 19 recordsLinked to original sources
PubMed2006

DU145 human prostate cancer cells express functional receptor activator of NFkappaB: new insights in the prostate cancer bone metastasis process.

Prostate cancer metastases to bone are observed in around 80% of prostate cancer patients and represent the most critical complication of advanced prostate cancer, frequently resulting in significant morbidity and mortality. As the underlying mechanisms are not fully characterized, understanding the biological mechanisms that govern prostate cancer metastases to bone at the molecular level should lead to the determination of new potential therapeutic targets. Receptor activator of NFkappaB ligand (RANKL)/RANK/Osteoprotegerin (OPG) are the key regulators of bone metabolism both in normal and pathological condition, including prostate cancer bone metastases. In the present study, we demonstrated that human prostate cancer cell lines, DU145 and PC3 express biologically functional RANK. Indeed, soluble human RANKL (shRANKL, 100 ng/ml) treatment induced ERK 1/2, p38 and IkappaB phosphorylations in these cells. shRANKL administration also promoted DU145 and PC3 prostate cancer cell invasion in vitro. Whereas human OPG (hOPG) administration alone (100 ng/ml) had no marked effect, combined association of both agents abolished the RANKL-induced DU145 cell invasion. As RANKL had no direct effect on DU145 cell proliferation, the observed effects were indeed related to RANKL-induced cell migration. DU145 human prostate cancer cells promoted osteoclastogenesis of osteoclast precursors generated from mouse bone marrow. Moreover, DU145 cells produced soluble factor(s) that up-regulate the proliferation of MC3T3-E1 pre-osteoblasts through the activation of the ERK 1/2 and STAT3 signal transduction pathways. This stimulation of pre-osteoblast proliferation resulted in an increased local RANKL expression that can activate both osteoclasts/osteoclast precursors and prostate cancer cells, thus facilitating prostate cancer metastasis development in bone. We confirm that RANKL is a factor that facilitates metastasis to bone by acting as an activator of both osteoclasts and RANK-positive prostate cancer cells in our model. Furthermore, the present study provides the evidence that blocking RANKL-RANK interaction offer new therapeutic approach not only at the level of bone resorbing cells, but also by interfering with RANK-positive prostate cancer cells in the prostate cancer bone metastasis development.

3T3 Cells↗
PubMed2006

Zoledronic acid activates the DNA S-phase checkpoint and induces osteosarcoma cell death characterized by apoptosis-inducing factor and endonuclease-G translocation independently of p53 and retinoblastoma status.

The molecular mechanisms responsible for the cellular effects of the nitrogen-containing bisphosphonate zoledronic acid (Zol) were assessed on several osteosarcoma cell lines differing in their p53 and retinoblastoma (Rb) status. Zol inhibited cell proliferation and increased atypical apoptosis. The Zol effects on proliferation were due to cell cycle arrest in S and G2/M phases subsequent to the activation of the intra-S DNA damage checkpoint with an increase in P-ATR, P-chk1, Wee1, and P-cdc2 levels and a decrease in cdc25c, regardless of the p53 and Rb status. In addition, the atypic apoptosis induced by Zol was independent of caspase activation, and it was characterized by nuclear alterations, increased Bax expression, and reduced Bcl-2 level. Furthermore, mitochondrial permeability was up-regulated by Zol independently of p53 in association with the translocation of apoptosis-inducing factor (AIF) and endonuclease-G (EndoG). Zol also disturbed cytoskeletal organization and cell junctions and inhibited cell migration and phosphorylation of focal adhesion kinases. The main difficulty encountered in treating cancer relates to mutations in key genes such as p53, Rb, or proteins affecting caspase signaling carried by many tumor cells. We have demonstrated for the first time that zoledronic acid activated the DNA damage S-phase checkpoint and the mitochondrial pathway via AIF and EndoG translocation, and it inhibited cell proliferation and induced cell death, bypassing these potentials mutations. Therefore, zoledronic acid may be considered as an effective therapeutic agent in clinical trials of osteosarcoma in which mutation for p53 and Rb very often occur, and where current treatment with traditional chemotherapeutic agents is ineffective.

Animals↗
PubMed2006

Characterization of osteoprotegerin binding to glycosaminoglycans by surface plasmon resonance: role in the interactions with receptor activator of nuclear factor kappaB ligand (RANKL) and RANK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), a key inducer of osteoclastogenesis via its receptor RANK. We previously showed that RANK, RANKL, and OPG are able to form a tertiary complex and that OPG must be also considered as a direct effector of osteoclast functions. As OPG contains a heparin-binding domain, the present study investigated the interactions between OPG and glycosaminoglycans (GAGs) by surface plasmon resonance and their involvement in the OPG functions. Kinetic data demonstrated that OPG binds to heparin with a high-affinity (KD: 0.28 nM) and that the pre-incubation of OPG with heparin inhibits in a dose-dependent manner the OPG binding to the complex RANK-RANKL. GAGs from different structure/origin (heparan sulfate, dermatan sulfate, and chondroitin sulfate) exert similar activity on OPG binding. The contribution of the sulfation pattern and the size of the oligosaccharide were determined in this inhibitory mechanism. The results demonstrated that sulfation is essential in the OPG-blocking function of GAGs since a totally desulfated heparin loses its capacity to bind and to block OPG binding to RANKL. Moreover, a decasaccharide is the minimal structure that totally inhibits the OPG binding to the complex RANK-RANKL. Western blot analysis performed in 293 cells surexpressing RANKL revealed that the pre-incubation of OPG with these GAGs strongly inhibits the OPG-induced decrease of membrane RANKL half-life. These data support an essential function of the related glycosaminoglycans heparin and heparan sulfate in the activity of the triad RANK-RANKL-OPG.

Binding, Competitive↗
PubMed2005

Phenotypic and functional analysis of lymphocytes infiltrating osteolytic tumors: use as a possible therapeutic approach of osteosarcoma.

BACKGROUND: Osteosarcoma is the most common type of primary bone tumor. The use of aggressive chemotherapy has drastically improved the prognosis of the patients with non-metastatic osteosarcomas, however the prognosis of the patients with metastasis is still very poor. Then, new and more effective treatments for curing osteosarcoma, such as immunotherapy are needed. Tumor-infiltrating lymphocytes (TIL) have been involved in the control of tumor development and already assessed with success for the treatment of several cancers including melanoma. While TIL represent a fascinating therapeutic approach in numerous malignant pathologies, there is few report concerning adult bone-associated tumors including osteosarcoma. METHODS: Human TIL were isolated and characterized (phenotype, lytic activity) from twenty-seven patients with bone-associated tumors (osteosarcoma, Ewing's sarcoma, giant cell tumor, chondrosarcoma, plasmocytoma and bone metastases). Similar experiments were performed using rat osteosarcoma model. RESULTS: While TIL with a main CD4+ profile were easily isolated from most of the tumor samples, only TIL extracted from osteosarcoma were cytotoxic against allogeneic tumor cells. In all cases, TIL lytic activity was significantly higher compared to autologous peripheral blood leukocytes. Similar data were observed in rat osteosarcoma model where TIL were characterized by a main CD4+ profile and high lytic activity against allogeneic and autologous tumor cells. Moreover, rat TIL expansion was not accompanied by refractoriness to further activation stimulus mainly by tumor antigens. CONCLUSION: These results demonstrated that TIL therapy could be a very efficient strategy for the treatment of adult osteosarcoma.

Adolescent↗
PubMed2005

A new experimental rat model of osteosarcoma established by intrafemoral tumor cell inoculation, useful for biology and therapy investigations.

Satisfactory experimental models for preclinical cancer studies must follow several criteria: (1) reproducibility of the method used to induce the tumor and (2) clinical, pathological and kinetic similarity with the corresponding human tumors. We developed a model of osteosarcoma locally induced by the intrafemoral injection of osteosarcoma (OSR) cells in Sprague-Dawley rats. This method yields nearly 80% of bone tumors at the injection site. These tumors double their volume fairly slowly (in approximately 20 days) and lung metastases occur in 96% of the animals. The OSR cell-induced tumor is characterized by a direct production of mineralized matrix by the tumor cells themselves, as revealed by histochemical analysis. The microarchitectural parameters which were quantified by a microscanner show an increased trabecular bone volume (+238%) when OSR cells were injected in the femur, as compared to controls injected with vehicle. Osteoblastic markers such as alkaline phosphatase, osteopontin, osteocalcin and bone sialoprotein were expressed by the tumor in vivo, whereas the initially injected OSR cells did not express some of these markers, suggesting that OSR cells reacquired an osteoblastic phenotype in a favorable environment. The clinical, radiological and histological data show that this model shares high similarities with the osteocondensing forms of osteosarcoma in humans.

Animals↗
PubMed2005

Enhanced tumor regression and tissue repair when zoledronic acid is combined with ifosfamide in rat osteosarcoma.

The efficacy of zoledronic acid (ZOL), with or without the anticancer drug ifosfamide (IFO), was tested on primary bone tumor growth using a rat-transplantable model of osteosarcoma. The effects on bone remodeling and tumor growth were analyzed by radiography, micro-computed tomography (micro-CT), and histological staining. The in vitro effects of ZOL were studied by proliferation, apoptosis, and cell cycle analyses on the osteosarcoma cells OSRGA compared to rat primary osteoblasts. Treatment with ZOL was effective in preventing the formation of osteolytic lesions that developed in bone sites and in reducing the local tumor growth, as compared to the untreated rats. The combination of ZOL and IFO was more effective than each agent alone in preventing tumor recurrence, improving tissue repair, and increasing bone formation as revealed by the analysis of trabecular architecture. In vitro studies demonstrated that ZOL was more potent against the OSRGA cell line than osteoblasts (with a half-maximal inhibitory effect on proliferation seen at 0.2 and 20 microM, respectively), the ZOL-induced inhibition of OSRGA proliferation being due to cell cycle arrest in S-phase. No effect on OSRGA apoptosis could be observed in vitro, as assessed by Hoechst staining and caspase-1 and -3 activation. In situ cell death was determined by TUNEL staining on tumor tissue sections. No significant difference in TUNEL-positive cells could be observed between ZOL-treated and -untreated rats. This is the first report of the anti-bone resorption and antitumoral activities of zoledronic acid in a rat model of osteosarcoma, and its beneficial association with an antitumoral chemotherapeutic drug in preventing tumor recurrence.

Animals↗
PubMed2004

RANKL/RANK/OPG: new therapeutic targets in bone tumours and associated osteolysis.

The emergence of the molecular triad osteoprotegerin (OPG)/Receptor Activator of NF-kB (RANK)/RANK Ligand (RANKL) has helped elucidate a key signalling pathway between stromal cells and osteoclasts. The interaction between RANK and RANKL plays a critical role in promoting osteoclast differentiation and activation leading to bone resorption. OPG is a soluble decoy receptor for RANKL that blocks osteoclast formation by inhibiting RANKL binding to RANK. The OPG/RANK/RANKL system has been shown to be abnormally regulated in several malignant osteolytic pathologies such as multiple myeloma [MM, where enhanced RANKL expression (directly by tumour cells or indirectly by stromal bone cells or T-lymphocytes)] plays an important role in associated bone destruction. By contrast, production of its endogenous counteracting decoy receptor OPG is either inhibited or too low to compensate for the increase in RANKL production. Therefore, targeting the OPG/RANK/RANKL axis may offer a novel therapeutic approach to malignant osteolytic pathologies. In animal models, OPG or soluble RANK was shown both to control hypercalcaemia of malignancy and the establishment and progression of osteolytic metastases caused by various malignant tumours. To this day, only one phase I study has been performed using a recombinant OPG construct that suppressed bone resorption in patients with multiple myeloma or breast carcinoma with radiologically confirmed bone lesions. RANK-Fc also exhibits promising therapeutic effects, as revealed in animal models of prostate cancer and multiple myeloma. If the animal results translate to similar clinical benefits in humans, using RANK-Fc or OPG may yield novel and potent strategies for treating patients with established or imminent malignant bone diseases and where standard therapeutic regimens have failed.

Antineoplastic Agents↗
PubMed2004

Relevance of an in vitro osteoclastogenesis system to study receptor activator of NF-kB ligand and osteoprotegerin biological activities.

Receptor activator of NF-kB Ligand (RANKL) is an essential requirement for osteoclastogenesis and its activity is neutralized by binding to the soluble decoy receptor osteoprotegerin (OPG). The purpose of this work was to study the effects of RANKL and OPG during osteoclastogenesis using the murine monocytic cell line RAW 264.7 that can differentiate into osteoclasts in vitro. RAW 264.7 cells plated at 10(4) cells/cm(2) and cultured for 4 days in the presence of RANKL represent the optimal culture conditions for osteoclast differentiation, with an up-regulation of all parameters related to bone resorption: tartrate resistant acid phosphatase (TRAP), calcitonin receptor (CTR), RANK, cathepsin K, matrix metalloproteinase (MMP)-9 mRNA expressions. RANKL and OPG biological effects vary according to the differentiation state of the cells: in undifferentiated RAW 264.7 cells, TRAP expression was decreased by OPG and RANKL, RANK expression was inhibited by OPG, while MMP-9 and cathepsin K mRNA expressions were not modulated. In differentiated RAW 264.7 cells, RANKL and OPG both exert an overall inhibitory effect on the expression of all the parameters studied. In these experimental conditions, OPG-induced MMP-9 inhibition was abrogated in the presence of a blocking anti-RANKL antibody, suggesting that part of OPG effects are RANKL-dependent.

Acid Phosphatase↗
PubMed2004

Cellular activity and signaling induced by osteoprotegerin in osteoclasts: involvement of receptor activator of nuclear factor kappaB ligand and MAPK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), an inducer of osteoclastogenesis via its receptor RANK. We recently demonstrated that OPG also exerts a direct effect in osteoclasts by regulating protease expression. Herein, we showed that OPG-induced pro-matrix metalloproteinase-9 activity was abolished by ras/MAPK inhibitors in purified osteoclasts. OPG induced the phosphorylation of p38 and ERK1/2 in RAW264.7 cells. Only p38 activation was totally abolished by a blocking anti-RANKL antibody or an excess of RANKL. Surface plasmon resonance experiments revealed that RANK, RANKL and OPG are able to form a tertiary complex. These results suggested a potential formation of a tertiary complex RANK-RANKL-OPG on osteoclasts. Thus, OPG is not only a soluble decoy receptor for RANKL but must be also considered as a direct effector of osteoclast functions.

Animals↗
PubMed2004

Neointimal hyperplasia after stenting in a human mammary artery organ culture.

Although the use of stents has limited the incidence of restenosis, in-stent restenosis remains an important problem. In-stent restenosis is the result of a healing process that induced neointimal hyperplasia through mechanisms that are still not understood. The aim of this study was to analyze the histological consequences of the healing process following stent implantation. Internal mammary arteries from atheroslerotic patients undergoing coronary artery bypass surgery were stented and maintained in culture for 0-28 days. Stent implantation after predilatation induced an extensive loss of endothelial cells whereas direct stenting preserved endothelium between the struts. Morphometric analysis shows that stent placement induced neointimal thickening. Smooth muscle alpha-actin labeling indicates that neo-intimal formation was mainly due to proliferation and migration of smooth muscle cells. Smooth muscle cell proliferation, assessed by MIB-1 staining, was maximal at day 14 after stent insertion. Human mammary artery organ culture thus provides valuable information on histological consequences of stent implantation with or without predilatation regarding endothelial cell disappearance and neointimal hyperplasia. These data also demonstrate that neointimal thickening induced by stent implantation comprises an intrinsic component resulting from the vessel wall response to stent insertion and suggest that blood factors could play an amplifying but not necessary role.

Cell Division↗
PubMed2003

Regulation of osteoclast protease expression by RANKL.

Receptor activator of NF-kappaB ligand (RANKL) is essential for osteoclast (OC) differentiation/activation and functions through its receptor RANK at the surface of the osteoclastic cells. This study investigated for the first time the direct effects of hRANKL on protease/protease inhibitor expressions and protease activities in purified rabbit osteoclast cultures, using semi-quantitative RT-PCR, gelatin zymography, and enzymatic assays. RANKL was shown to exert in vitro pro-resorptive effects by increasing osteoclast marker expressions (Tartrate resistant acid phosphatase (TRAP) and cathepsin K), MMP-9 expression, and pro-MMP-9 activity and by diminishing TIMP-1 expression, leading to an up-regulation of the MMP-9/TIMP-1 ratio.

Acid Phosphatase↗
PubMed2003

Metatarsal giant cell tumors and giant cell reparative granuloma are similar entities.

Light and electron microscopic investigations and studies of the resorption ability in vitro of giant cells were done in two patients with giant cell osteolytic lesions of metatarsal bone. Giant cells harvested from both patients were similar in morphologic features and ability to resorb dentin. After other diagnoses of osteolytic lesions of metatarsal bone were ruled out, one lesion was considered a giant cell reparative granuloma and the other a true giant cell tumor of bone. Clinical, radiologic, ultrastructural, functional studies, and data in the literature, indicated that giant cell reparative granuloma only can be differentiated from giant cell tumor by younger age at diagnosis and the occurrence of giant cell clusters. All other features (cortical erosion, high rate of recurrence, hemorrhage areas, predominant intercellular collagenous substance) are characteristic of both lesions. If these two giant cell lesions are different entities, more accurate means are needed to distinguish them.

Adolescent↗
PubMed2002

Leukaemia inhibitory factor (lif) is expressed in hypertrophic chondrocytes and vascular sprouts during osteogenesis.

Avascular cartilage is replaced by highly vascularized bone tissue during endochondral ossification, a process involving capillary invasion of calcified hypertrophic cartilage in association with apoptosis of hypertrophic chondrocytes, degradation of cartilage matrix and deposition of bone matrix. All of these events are closely controlled, especially by cytokines and growth factors. Leukaemia inhibitory factor (LIF), a member of the gp130 cytokine family, is involved in osteoarticular tissue metabolism and might participate in osteogenesis. Immunohistochemical staining showed that LIF is expressed in hypertrophic chondrocytes and vascular sprouts of cartilage and bone during rat and human osteogenesis. LIF is also present in osteoblasts but not in osteoclasts. Observations in a rat endochondral ossification model were confirmed by studies of human cartilage biopsies from foetuses with osteogenesis imperfecta. LIF was never detected in adult articular chondrocytes and bone-marrow mesenchymal cells. These results and other data in the literature suggest that LIF is involved in the delicate balance between the rate of formation of calcified cartilage and its vascularization for bone development.

Animals↗
PubMed2002

Osteoprotegerin differentially regulates protease expression in osteoclast cultures.

Cysteine proteases and matrix metalloproteinases (MMPs) are important factors in the degradation of organic matrix components of bone. Osteoprotegerin (OPG) is an osteoblast-secreted decoy receptor that inhibits osteoclast differentiation and activation. This study investigated the direct effects of human OPG on cathepsin K, MMP-9, MMP-2, and tissue inhibitors of metalloproteinases (TIMP1 and TIMP2) expressed by purified rabbit osteoclasts. The expression of two osteoclast markers, namely tartrate-resistant acid phosphatase (TRAP) and cathepsin K, was inhibited by 100 ng/mL hOPG, whereas MMP-9 expression was enhanced. Gelatinase activities were measured using a zymographic assay, and hOPG was shown to enhance both pro-MMP-9 and MMP-2 activities. Concomitantly, TIMP1 expression was greatly stimulated by hOPG, whereas TIMP2 mRNA levels were not modulated. Overall, these results show that hOPG regulates the proteases produced by purified osteoclasts differentially, producing a marked inhibitory effect on the expression of cathepsin K, the main enzyme involved in bone resorption.

Acid Phosphatase↗
PubMed2002

Osteoclastic acidification pathways during bone resorption.

Osteoclasts resorb bone by attaching to the surface and then secreting protons into an extracellular compartment formed between osteoclast and bone surface. This secretion is necessary for bone mineral solubilization and the digestion of organic bone matrix by acid proteases. This study summarizes the characterization and role of each type of ion transport and defines the main biochemical mechanisms involved in the dissolution of bone mineral during bone resorption. The primary mechanism responsible for acidification of the osteoclast-bone interface is vacuolar H+-adenosine triphosphatase (ATPase) coupled with Cl- conductance localized to the ruffled membrane. Carbonic anhydrase II (CAII) provides the proton source for extracellular acidification by H+-ATPase and the HCO3- source for the HCO3-/Cl- exchanger. Whereas some transporters are responsible for the bone resorption process, others are essential for pH regulation in the osteoclast. The HCO3-/Cl- exchanger, in association with CAII, is the major transporter for maintenance of normal intracellular pH. An Na+/H+ antiporter may also contribute to the recovery of intracellular pH during early osteoclast activation. Once this mechanism has been rendered inoperative, another conductive pathway translocates the protons and modulates cytoplasmic pH. Inward-rectifying K+ channels may also be involved by compensating for the external acidification due to H+ transport. These different effects of transport processes, either on bone resorption or pH homeostasis, increase the number of possible sites for pharmacological intervention in the treatment of metabolic bone diseases.

Acids↗
PubMed2002

Influence of metal ion solutions on rabbit osteoclast activities in vitro.

The purpose of the present study was to compare the effects of various metal ions (aluminium, chromium, cobalt, gold, iron, strontium, titanium and vanadium) on rabbit osteoclast activities, with respect to their number, size, resorptive capacity and their capacity to release proteinases. Marked heterogeneous osteoclastic behaviour was observed early in culture with metal ions (24 h) in term of resorption parameters. In contrast, protease activities (cysteine-proteinase and metalloproteinase activities) were not modulated in our culture conditions. Aluminium, iron, gold and titanium reduced the number of osteoclasts significantly. Aluminium and gold had no effect on osteoclast-mediated resorption on dentin-slices, although aluminium induced a greater number of very small lacunae. Titanium reduced only the mean surface area per lacunae, cobalt reduced the mean surface area of lacunae and increased their number, and iron reduced both parameters. Strontium had no effect on osteoclast formation and on total dentin slice surface resorbed. However, strontium increased the number of small lacunae formed on dentin-slices by osteoclasts. Chromium had no effect on osteoclast activities. These findings indicate that metal ions induce very early effects on osteoclasts, which can contribute to periprosthetic pathologies via different cellular mechanisms.

Animals↗
PubMed2002

Bone remodelling and tumour grade modifications induced by interactions between bone and swarm rat chondrosarcoma.

Chondrosarcoma is currently defined as a malignant cartilage tumour arising de novo or within a pre-existing benign cartilage tumour. Chondrosarcoma can be surgically resected, but all grades have significant rates of local recurrence. The purpose of the present study was to develop an animal intraosseous chondrosarcoma model simulating the progression of human chondrosarcoma and elucidating its behaviour and biology. An intraosseous Swarm rat model was designed to assess interactions between bone and chondrosarcoma. A comparison of tumour grading was carried out according to transplantation site. The effects of chondrosarcoma cells (SRC cells) on the mineralisation capacities of osteoblasts and on osteoclast differentiation were studied in relation to modifications observed in vivo at the cellular level. Transplantation of Swarm rat chondrosarcoma within bone marrow or contiguous to induced periosteal lesions led to extensive bone remodelling with trabecular bone rarefaction and periosteal apposition. Transplantation in close contact to bone but without any periosteal lesion had no effect on bone, suggesting that bone healing factors interact with tumour development. With the intramedullary model, the development of tumours of different grade confirms that bone environment is an important factor in malignancy. A decrease of bone nodule formation was noted after cocultures of SRC cells with rat bone marrow, but there was no modification of osteoclast differentiation after cultures of total rabbit bone cells with SRC cells. These data reveal the importance of interactions between bone environment and tumour in inducing bone remodelling and variations in tumour malignancy.

Animals↗