Biology of the osteoclast in Paget's disease.
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Cell Division↗
Biomedical subjects
G D Roodman
Publications and source records attributed to G D Roodman.
Phase I trial of dacarbazine with cyclophosphamide, carmustine, etoposide, and autologous stem-cell transplantation in patients with lymphoma and multiple myeloma.
PURPOSE: We investigated the feasibility of escalating doses of dacarbazine (DTIC) in combination with high-dose cyclophosphamide, carmustine, and etoposide (CBV) given with autologous stem-cell transplantation in 33 patients with relapsed or refractory lymphoma or multiple myeloma. PATIENTS AND METHODS: Eligible patients were treated in this phase I study with cyclophosphamide (7.2 g/m2), carmustine (BCNU) (600 mg/m2), etoposide (2.4 g/m2), and escalating doses of DTIC (3,000 to 6,591 mg/m2) administered either as a 2- (in 23 patients) or a 6- (in 10 patients) hour infusion to determine the maximum-tolerated dose (MTD) of DTIC and the toxicity profile of this combination. RESULTS: The MTD of DTIC infused over 2 hours and given with the CBV regimen was 3,900 mg/m2, with the dose-limiting toxicity being hypotension. Seven patients experienced transient acute hypocalcemia in association with the DTIC infusion. Prolonging the DTIC infusion to 6 hours or administration of supplemental calcium did not allow further dose escalation of DTIC to occur. Other non-hematologic toxicities observed with this regimen have been reported with CBV alone. Of 25 patients assessable for tumor response at first evaluation posttransplant, 13 (52%) were in complete remission (CR), four (16%) were in partial remission (PR), five (20%) had stable disease (SD), and three (12%) had progressive disease (PROG). Of 31 patients assessable for relapse-free survival, 22 are alive with 13 in CR, one in PR, two with SD, and six with PROG at a median follow-up duration of 313 days (range, 35 to 749+). Treatment-related mortality occurred in six patients (18%). CONCLUSION: The feasibility of combining DTIC in high doses with the CBV regimen has been demonstrated. Dose-limiting hypotension is transient and reversible when DTIC is administered at 3,900 mg/m2 with CBV. Future trials to evaluate the effect of the addition of DTIC to the CBV regimen on response rate and relapse-free survival are encouraged.
Adolescent↗
5-Lipoxygenase metabolites of arachidonic acid stimulate isolated osteoclasts to resorb calcified matrices.
Bone resorption requires cooperation between osteoclasts and mononuclear accessory cells by mechanisms which have not been elucidated. Since multinucleated cells in giant cell tumors of bone have many phenotypic and functional characteristics of normal osteoclasts, we have examined the interaction between the bone-resorbing multinucleated cells and the distinct mononuclear stromal cells from these tumors. We have found that these mononuclear cells produce an activity which stimulates both giant cells from giant cell tumors and rodent osteoclasts to resorb bone in vitro. We have identified the activity and found that it represents several products of the 5-lipoxygenase pathway of arachidonic acid metabolism, namely 5-hydroxyeicosatetraenoic acid and the leukotrienes. These data indicate that 5-lipoxygenase metabolites stimulate isolated osteoclasts to resorb bone in vitro and may represent a mechanism by which mononuclear stromal cells in human giant cell tumors communicate with the giant cells. In addition, these results may explain a possible mechanism for communication between accessory cells and osteoclasts involved in normal bone resorption.
Acid Phosphatase↗
Cloning and characterization of the 5'-flanking region of the mouse tartrate-resistant acid phosphatase gene.
Little information is available on the molecular mechanisms controlling osteoclastic bone resorption. We used tartrate-resistant acid phosphatase (TRAP) to begin to investigate the regulation of bone resorption at the molecular level. TRAP is expressed at high levels in osteoclasts and may play an important role in the bone resorptive process. Therefore, we isolated the murine TRAP gene from a mouse spleen genomic library and characterized its promoter. A restriction map was generated for the 17 kb TRAP insert. A 2 kb SmaI fragment, containing the 5'-flanking region, was subcloned and the nucleotide sequence determined. Sequence analysis of the SmaI fragment revealed the presence of numerous candidate transcription factor binding sequences, including those for AP1 and H-APF-1. The H-APF-1 site matches the consensus sequence for the IL-6-regulated transcription factor. An intron was identified at -1 to -393 bp relative to the ATG. The presence of an intron was confirmed by PCR analysis of RNA isolated from murine osteoclasts. Primer extension analysis indicated the presence of a transcription initiation site at -552 bp from the ATG. The region from -1846 to 2bp relative to the ATG initiation codon drove the transient expression of a luciferase reporter gene when transfected into HRE H9 rabbit endometrial cells. PMA treatment of HRE H9 cells enhanced luciferase transcription approximately threefold. These data suggest that the TRAP promoter is complex and contains multiple regulatory elements. The availability of the TRAP promoter may also permit production of transgenic mice, which can be used to develop previously unavailable osteoclast cell lines.
Acid Phosphatase↗
In vitro cytotoxicity of hepsulfam against human tumor cell lines and primary human tumor colony forming units.
Hepsulfam (sulfamic acid 1,7-heptanediyl ester, NSC 329680) is an alkylating agent currently in Phase I clinical trials. Hepsulfam was developed as an analog of busulfan, an alkylating agent that is used to treat patients with chronic myelogenous leukemia and for marrow ablation prior to bone marrow transplantation. The objective of this study was to identify the spectrum of human tumor cells that were sensitive to hepsulfam. The following three cytotoxicity assays were employed to evaluate the in vitro cytotoxic potential of hepsulfam: 1) primary human tumors were exposed to three levels of hepsulfam for a one hour or continuous exposure, and growth in soft agar was determined; 2) human non-tumor cells and tumor cell lines were compared in an assay that measured the conversion of 14C-glucose to 14CO2 as an index of viability; and 3) the toxicity of hepsulfam to hematopoietic progenitor cells was determined in a progenitor cell colony forming assay. Cytotoxicity was not observed for human tumor cells following one hour hepsulfam exposures; in contrast, marked dose-dependent cytotoxicity was observed with continuous exposures. In human tumor cell lines, the cytotoxicity of hepsulfam was compared directly with busulfan at equimolar concentrations. Hepsulfam was more cytotoxic than busulfan in all cell lines tested. Cytotoxic activity was seen in lung, melanoma, kidney, breast, colon, ovary and brain tumor cells. These results, along with the information obtained from Phase I trials, will facilitate selection of patients who could receive this agent in Phase II efficacy trials.
Antineoplastic Agents↗
Assignment of the mouse tartrate-resistant acid phosphatase gene (Acp5) to chromosome 9.
Tartrate-resistant acid phosphatase is a marker enzyme for osteoclasts, the multinucleated cell responsible for bone resorption. Interspecific somatic whole cell hybrids and karyotypically simple microcell hybrids were used to map the gene encoding tartrate-resistant acid phosphatase (Acp5) to mouse Chromosome 9. Acp5 is therefore a member of a syntenic family of genes that map to human chromosome 19p13.1-p13.3 and mouse Chromosome 9.
Acid Phosphatase↗
Role of cytokines in the regulation of bone resorption.
The process of bone remodeling involves complex interactions between the osteoclast, the primary bone-resorbing cell, and other cells in its microenvironment. These interactions can regulate bone resorption through two processes: (1) effects on the number of osteoclasts present at a given site and (2) effects on the bone-resorbing capacity of individual osteoclasts. Cells present in the osteoclast microenvironment include marrow stromal cells, osteoblasts, macrophages, T-lymphocytes, and marrow cells. These cells, as well as the osteoclast itself, produce cytokines that can affect osteoclast formation and osteoclast activity. In vitro model systems using rodent organ cultures or long-term marrow culture systems, and in vivo models have demonstrated that cytokines such as interleukin-1, M-CSF, tumor necrosis factor, and interleukin-6 can stimulate the formation and bone-resorbing capacity of osteoclasts. In contrast, cytokines such as interleukin-4, gamma-interferon, and transforming factor-beta inhibit both osteoclast formation and osteoclast activity. The relative proportions of these cytokines in the marrow microenvironment may play a critical role in regulating osteoclast activity. Knowledge of cytokines that affect osteoclast formation and activity and their capacity to modulate the bone-resorbing process should provide critical insights into normal calcium homeostasis and disorders of bone turnover such as osteoporosis and Paget's disease of bone.
Animals↗
Abnormalities in osteoclast precursors and marrow accessory cells in Paget's disease.
Paget's disease of bone is characterized by increased numbers of abnormal osteoclasts. To determine if osteoclast precursors were increased or abnormal in this disease, we examined CFU-GM, the committed granulocyte-macrophage progenitor and the most likely precursor for osteoclasts. In cultures of unfractionated marrow mononuclear cells, CFU-GM colony formation was significantly increased in Paget's marrow cultures compared to that in normal cells (356 +/- 44 vs. 271 +/- 15/10(5) cells; P < 0.05). However, when we enriched hematopoietic precursors from Paget's and normal marrow samples using an antibody that recognizes the CD34 antigen present on most hematopoietic precursors, we found that similar numbers of CFU-GM colonies were formed (87 +/- 13/10(4) cells plated vs. 83 +/- 13). Coculture experiments with highly purified hematopoietic precursors (CD34+ cells) and nonhematopoietic marrow accessory cells (CD34- cells) revealed that the growth of Paget's precursors was significantly enhanced above expected levels by normal or Pagetic CD34- cells (P < 0.05). CFU-GM colony formation was also significantly enhanced when normal CD34+ cells were cocultured with Pagetic, but not with normal, CD34- cells. In addition, CFU-GM colony-derived cells from Paget's patients were hyperresponsive to 1,25-dihydroxyvitamin D3 and could form osteoclast-like multinucleated cells with 1,25-dihydroxyvitamin D3 concentrations one tenth of that required for normal multinucleated formation (10(-11) vs. 10(-10) M). These data suggest that osteoclast precursors may be abnormal in Paget's disease, and other cells in the Pagetic marrow microenvironment may further enhance the growth and differentiation of these abnormal precursors.
Antigens, CD↗
Tartrate-resistant acid phosphatase gene expression as a facile reporter gene for screening transfection efficiency in mammalian cell cultures.
The efficiency of DNA transfection into mammalian cell cultures has been monitored using a variety of reporter assays. However, the common procedures are expensive, time-consuming and usually cannot identify the transfected cell population directly. In the present communication we describe a simple, inexpensive and efficient method to directly identify DNA transfection in mammalian cells using tartrate-resistant acid phosphatase (TRAP) gene expression. The method involves the transfection of a plasmid (pCT3), which contains TRAP cDNA driven by a CMV promoter, into mammalian cells. The cells can then be stained for TRAP activity, and the transfection efficiency can be determined by simply counting the positively transfected cells in a defined area with a microscope. This method permits screening of mammalian cells for transfection efficiency in multi-well plates. After waiting 30-40 minutes to allow the TRAP assay to saturate, wells can be scored in 1-2 minutes with little difficulty in detecting the transfected cells.
Acid Phosphatase↗
Comparison of engraftment and acute GVHD in patients undergoing cryopreserved or fresh allogeneic BMT.
Coordination of marrow donation for allogeneic BMT is a common logistical problem. The use of cryopreserved donor marrow would facilitate scheduling and avoid potential problems due to donor employment, injury, infection or death. We analysed results of 10 matched related BMTs performed with cryopreserved donor marrow and compared them with 33 matched related BMTs using fresh bone marrow over a 4 year period. No difference in time to engraftment of granulocytes and platelets or transfusion requirements were demonstrated for the two groups. However, there was less GVHD in patients who received cryopreserved donor marrow (chi 2, p = 0.03; Fisher's exact test (two-sided) p = 0.067) despite comparable risk factors. The reason for this difference is unclear. Our results indicate that the use of cryopreserved bone marrow for allogeneic BMT patients is at least equivalent to the use of fresh bone marrow. A prospective randomized trial is needed to determine if a true difference exists in the incidence or severity of acute GVHD and to determine if recurrence rate is different between the two groups.
Acute Disease↗
Interleukin-6: an osteotropic factor?
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Humans↗
Effects of stem cell factor on osteoclast-like cell formation in long-term human marrow cultures.
Stem cell factor (SCF) is a newly described hematopoietic growth factor that stimulates the growth of primitive hematopoietic progenitors and mast cells. Since the osteoclast precursor is hematopoietic in origin, we tested SCF for its capacity to stimulate the formation of osteoclast-like multinucleated cells (MNC) in long-term human marrow cultures. These MNC express an osteoclast phenotype and form resorption lacunae on calcified matrices. Addition of SCF alone (0.1 pg/ml to 100 ng/ml) to long-term marrow cultures did not increase MNC formation. However, treatment of these cultures sequentially with SCF for 1 week followed by 1,25-(OH)2D3 for the second and third weeks of culture significantly enhanced MNC formation. [3H]Thymidine incorporation studies showed that SCF increased the proliferation of MNC precursors. These data suggested that SCF was acting on early MNC precursors. We then tested the capacity of SCF to stimulate the formation of colonies of committed precursors for osteoclast-like MNC. SCF (20 pg/ml to 20 ng/ml) enhanced osteoclast precursor formation in unfractionated bone marrow mononuclear cells but was unable to increase osteoclast precursor formation when a highly purified population of hematopoietic precursors was used as the target cells for SCF. These data suggest that SCF works in concert with other factors produced by nonhematopoietic marrow cells to increase the precursor pool for osteoclasts and that other factors, such as 1,25-(OH)2D3, complete the differentiation process to the mature osteoclast.
Analysis of Variance↗
Interleukin 6. A potential autocrine/paracrine factor in Paget's disease of bone.
Pagetic osteoclasts are greatly increased in number and size and have increased numbers of nuclei per cell compared to normal osteoclasts. The mechanisms responsible for enhanced osteoclast formation in Paget's disease are unknown. We have used our recently described model system for pagetic osteoclast formation to evaluate culture media conditioned by these atypical multinucleated cells (MNC) to determine if pagetic osteoclasts produce an autocrine or paracrine factor that enhances osteoclast formation. Conditioned media from long-term bone marrow cultures from patients with Paget's disease stimulated osteoclast-like MNC formation in normal marrow cultures. At least part of this activity could be ascribed to interleukin 6 (IL-6). In contrast, conditioned media from normal marrow cultures contained lower levels of IL-6 and did not stimulate formation of osteoclast-like MNC. 7 of 8 bone marrow plasma samples taken from involved bones and 18 of 27 peripheral blood serum samples from Paget's patients had high levels of IL-6. Normal marrow plasma and peripheral blood serum had no or very low levels of IL-6. These results suggest that IL-6 produced by marrow and/or bone cells in patients with Paget's disease may be an autocrine/paracrine factor for pagetic osteoclasts.
Biological Assay↗
Evidence for an autocrine/paracrine role for interleukin-6 in bone resorption by giant cells from giant cell tumors of bone.
Interleukin-6 (IL-6) is a multifunctional cytokine whose role in osteoclastic bone resorption has not been clearly defined. Therefore, we have used giant cells, which express many features of osteoclasts, from giant cell tumors of bone as a model to examine the role that IL-6 may play in human osteoclastic bone resorption. We found that conditioned medium from 24-h cultures of highly purified giant cells (10(6)/ml) contained large amounts of IL-6 (37.9 +/- 8.8 ng/ml), similar to the amount of IL-6 produced by tumor stromal cells (29.8 +/- 11.5 ng/ml). Giant cells and stromal cells from giant cell tumors expressed IL-6 mRNA, as indicated by polymerase chain reaction analysis and in situ hybridization studies, and immunohistochemical techniques demonstrated that the giant cells expressed IL-6 receptors. The addition of a neutralizing antibody to IL-6 significantly decreased the area of dentine resorbed by purified giant cells in a dose-dependent manner, and the addition of IL-6 to cultures of purified giant cells pretreated with anti-IL-6 restored the resorbing capacity of the giant cells. These data suggest that IL-6 may act as both an autocrine and a paracrine factor for human osteoclasts and play an important role in the bone-resorbing capacity of these cells.
Base Sequence↗
Effects of TNF and lymphotoxin on bone cells.
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Animals↗
Osteotropic factor responsiveness of highly purified populations of early and late precursors for human multinucleated cells expressing the osteoclast phenotype.
Recently we have adapted human long-term bone marrow cultures to form multinucleated cells (MNC) that express the osteoclast phenotype and used semisolid culture techniques to identify early (bipotent) and late (unipotent) mononuclear precursors for these MNC. The early precursor can form both osteoclast-like MNC and macrophage polykaryons; the late precursor forms only osteoclast-like MNC. In this study we examined the effects of osteotropic hormones and cytokines of MNC formation from highly purified populations of these early or late mononuclear precursor cells. MNC expressing the osteoclast phenotype were identified by their cross-reactivity with the 23c6 monoclonal antibody, which preferentially identifies osteoclasts. 1,25-(OH)2D3 (10(-8) M), IL-1 beta (10 u/ml), and IL-6 (100 pg/ml) stimulated formation of 23c6-positive MNC from highly purified populations of early or late precursor cells. In contrast, PTH (50 ng/ml) did not act directly on late precursor cells but only stimulated 23c6-positive MNC formation from early precursors. These results show that (1) 1,25-(OH)2D3, IL-1 beta, and IL-6 can stimulate 23c6-positive MNC formation from a highly enriched population of early and late precursors, and (2) PTH does not act on late precursors but may act indirectly on the late precursors.
Calcitriol↗
Assays for bone resorption and bone formation.
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Animals↗
Interleukin-3. Its biology and potential uses in pediatric hematology/oncology.
The hematopoietic growth factor interleukin (IL)-3 is a potent regulator of blood cell proliferation. It promotes the survival, proliferation, and development of hematopoietic stem cells and committed progenitor cells of the granulocyte-macrophage, erythrocyte, eosinophil, basophil, megakaryocyte, mast cell, and lymphocyte lineages. In addition, IL-3 enhances mature myeloid cell functions such as phagocytosis and activation of basophils and eosinophils, as well as monocyte cytotoxicity. The first phase of clinical trials suggested that IL-3 may augment myelopoiesis in a number of clinical conditions. It may be efficacious for treatment of primary marrow disorders, including myelodysplastic syndromes and aplastic anemia. However, replacement therapy with IL-3 alone is probably not sufficient to obtain maximal stimulation of myelopoiesis. Preclinical and clinical studies published to date suggest that sequential use or combinations of growth factors will be needed to obtain optimal hematopoietic responses.
Animals↗