Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Measurements of free cystolic Ca2+ ([Ca2+]i) and Ba2+ ([Ba2+]i) concentrations with Fura 2 were used to identify and characterize the properties of a depolarization-activated Ca2+ and Ba2+ entry in the plasma membrane of osteoblast-like cells. The presence of this pathway was demonstrated in two osteoblastic cell lines, UMR-106 and MC3T3-E1 and osteoblasts isolated from rat long bone and rat neonatal calvariae. Subsequent characterization of the pathway was performed in the osteosarcoma cell line UMR-106. Depolarization of the cells with high medium K+ was followed by an increase in [Ca2+]i which was dependent on medium Ca2+. Ba2+ ions depolarized the cells and were transported by this pathway. Mg2+ ions interfered with Ca2+ and Ba2+ entry. At 140 mM KCl and 1 mM MgCl2, the pathway could be saturated with Ca2+ or Ba2+. The apparent affinity for Ca2+ was 0.78 mM and for Ba2+ 1.82 mM. Ca2+ or Ba2+ entry into the cells was blocked by low concentrations of nicardipine, diltiazem, verapamil, and La3+. In the absence of an increase in [Ca2+]i or [Ba2+]i, the pathway inactivated within about 5 min after depolarization. When [Ca2+]i or [Ba2+]i was allowed to increase, the pathway inactivated within about 20 s. These properties suggest that Ca2+ and Ba2+ entry are mediated by an L-type, depolarization-activated Ca2+ channel in osteoblasts. The activity of these channels changes little with an increase or decrease in cell volume. Thus, it is concluded that these pathways do not provide the Ca2+ entry pathway required for initiation of volume decrease by osteoblasts.
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PMID:Properties of the depolarization-activated calcium and barium entry in osteoblast-like cells. 249 47

Antibodies specific for membrane-associated antigens of human osteosarcoma cells were isolated from sera of 12 patients with osteosarcoma (OS). Affinity columns were prepared by coupling purified membrane antigens from cultured human OS cell lines (TE-85 or LM) to CBrN-activated Sepharose 4B. The antigens were prepared by discontinuous sucrose gradient ultracentrifugation, papain digestion, and DEAE column chromatography. Diluted serum was passed over the affinity columns, and the adsorbed proteins were eluted with 2.5 M MgCl2 (pH 6.5). Immunodiffusion, indirect immunofluorescence, and complement fixation were used to assay antibody activity in the eluate. Specific anti-OS activity was found in the immunoglobulin (Ig) fraction isolated from the sera of the 12 OS patients, as confirmed by blocking experiments. No anti-OS antibody activity was found in sera from healthy individuals or patients with breast carcinoma, clear cell liposarcoma, or leukemia in this study. The anti-OS activity of the isolated Ig from OS patients was abolished after absorption with cultured human OS cells from lines LM, TE-85, or G292 but not after absorption with cells from lines WI-38 (embryonic lung), TE-32 (rhabdomyosarcoma), CAMA-1 or SW527 (breast carcinoma), or M-14 (melanoma). Absorption with rabbit antihuman IgG but not with rabbit antihuman IgM immunobeads completely eliminated the antibody activity.
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PMID:Osteosarcoma patients: isolation of serum antibodies by affinity chromatography. 679 43

Extracellular calcium concentration is critically important for normal function of the body. Recently, reports have shown that cells derived from parathyroid glands contain an extracellular calcium receptor that is responsive to changes in extracellular calcium. Bone is intimately involved in calcium homeostasis; therefore, we sought to test the hypothesis that extracellular calcium has direct effects on bone cells. Extracellular calcium was increased by the addition of varying concentrations of CaCl2 (0.4-2.0 mM) to the control medium. An increase in extracellular calcium increased cell proliferation, as assessed by 3H-thymidine incorporation, in a number of cell types including normal human bone cells derived from vertebrae (HBV155) and a number of human osteosarcoma cell lines. The increase in cell proliferation by elevated CaCl2 was dose dependent, whereas MgCl2 was not effective at the doses tested (up to 2 mM added MgCl2). To test the hypothesis that the mitogenic activity of elevated extracellular calcium involved a growth factor, levels of insulin-like growth factor II (IGF-II) were measured in the conditioned medium of HBV155 cells by radioimmunoassay after removal of binding proteins by size exclusion chromatography. The effects of an increase in extracellular calcium by 1 mM were: 1) increased culture media levels of IGF-II within 1 h of treatment, 2) the increase in IGF-II levels reached a maximum after 8 h of treatment, and 3) IGF-II levels were still elevated after 24 h of treatment. Furthermore, a blocking monoclonal antibody against IGF-II abolished the increased cell proliferation in HBV155 cells following elevation of extracellular calcium. Taken together, these findings suggest that an increase in extracellular calcium results in an increase in IGF-II which is required for the subsequent increase in cell proliferation.
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PMID:Effects of extracellular calcium on insulin-like growth factor II in human bone cells. 859 42

Cell-fibronectin interactions, mediated through several different receptors, have been implicated in a wide variety of cellular properties. Among the cell surface receptors for fibronectin, integrins are the best characterized, particularly the prototype alpha5beta1 integrin. Using [125I]iodine cell surface labeling or metabolic radiolabeling with sodium [35S]sulfate, we identified alpha5beta1 integrin as the only sulfated integrin among beta1 integrin heterodimers expressed by the human melanoma cell line Mel-85. This facultative sulfation was confirmed not only by immunoprecipitation reactions using specific monoclonal antibodies but also by fibronectin affinity chromatography, two-dimensional electrophoresis, and chemical reduction. The covalent nature of alpha5beta1 integrin sulfation was evidenced by its resistance to treatments with high ionic, chaotrophic, and denaturing agents such as 4 M NaCl, 4 M MgCl2, 8 M urea, and 6 M guanidine HCl. Based on deglycosylation procedures as chemical beta-elimination, proteinase K digestion, and susceptibility to glycosaminoglycan lyases (chondroitinase ABC and heparitinases I and II), it was demonstrated that the alpha5beta1 heterodimer and alpha5 and beta1 integrin subunits were proteoglycans. The importance of alpha5beta1 sulfation was strengthened by the finding that this molecule is also sulfated in MG-63 (human osteosarcoma) and HCT-8 (human colon adenocarcinoma) cells.
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PMID:Post-translational modifications of alpha5beta1 integrin by glycosaminoglycan chains. The alpha5beta1 integrin is a facultative proteoglycan. 913 4

Magnesium-based implants exhibit various advantages such as biodegradability and potential for enhanced in vivo bone formation. However, the cellular mechanisms behind this possible osteoconductivity remain unclear. To determine whether high local magnesium concentrations can be osteoconductive and exclude other environmental factors that occur during the degradation of magnesium implants, magnesium salt (MgCl2) was used as a model system. Because cell lines are preferred targets in studies of non-degradable implant materials, we performed a comparative study of 3 osteosarcoma-derived cell lines (MG63, SaoS2 and U2OS) with primary human osteoblasts. The correlation among cell count, viability, cell size and several MgCl2 concentrations was used to examine the influence of magnesium on proliferation in vitro. Moreover, bone metabolism alterations during proliferation were investigated by analyzing the expression of genes involved in osteogenesis. It was observed that for all cell types, the cell count decreases at concentrations above 10 mM MgCl2. However, detailed analysis showed that MgCl2 has a relevant but very diverse influence on proliferation and bone metabolism, depending on the cell type. Only for primary cells was a clear stimulating effect observed. Therefore, reliable results demonstrating the osteoconductivity of magnesium implants can only be achieved with primary osteoblasts.
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PMID:Comparison of the reaction of bone-derived cells to enhanced MgCl2-salt concentrations. 2548 35