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)

An osteoblast-like human osteosarcoma cell line (U2-OS) has been shown to possess a vitamin K-dependent carboxylation system which is similar to the system in human HepG2 cells and in liver and lung from the rat. In an 'in vitro' system prepared from these cells, vitamin K1 was shown to overcome warfarin inhibition of gamma-carboxylation carried out by the vitamin K-dependent carboxylase. The data suggest that osteoblasts, the cells involved in synthesis of vitamin K-dependent proteins in bone, can use vitamin K1 as an antidote to warfarin poisoning if enough vitamin K1 can accumulate in the tissue. Five precursors of vitamin K-dependent proteins were identified in osteosarcoma and HepG2 cells respectively. In microsomes (microsomal fractions) from the osteosarcoma cells these precursors revealed apparent molecular masses of 85, 78, 56, 35 and 31 kDa. When osteosarcoma cells were cultured in the presence of warfarin, vitamin K-dependent 14C-labelling of the 78 kDa precursor was enhanced. Selective 14C-labelling of one precursor was also demonstrated in microsomes from HepG2 cells and from rat lung after warfarin treatment. In HepG2 cells this precursor was identified as the precursor of (clotting) Factor X. This unique 14C-labelling pattern of precursors of vitamin K-dependent proteins in microsomes from different cells and tissues reflects a new mechanism underlying the action of warfarin.
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PMID:The vitamin K-dependent carboxylation system in human osteosarcoma U2-OS cells. Antidotal effect of vitamin K1 and a novel mechanism for the action of warfarin. 238 86

Tissue factor (TF), a transmembrane glycoprotein expressed by numerous cell types, plays a critical role in the initiation of blood coagulation at sites of vascular injury. Activated products of the coagulation cascade may then enhance the inflammatory responses associated with wound healing. In the present investigation the ability of rat osteosarcoma (ROS) cells to express TF activity was examined following their growth on tissue-culture polystyrene (TCPS) and selected orthopedic biomaterials (titanium and zirconium alloys, and stainless steel). ROS cells exhibited significant TF activity as evidenced by the conversion of Factor X to Factor Xa in the presence of TF, Factor VIIa, and Ca2+. Factor Xa concentrations ranged from 1.0 fM per cell at 10 min to 6.0 fM per cell after 60 min. Additionally, ROS cells stimulated with calcium ionophore (A23187) exhibited approximately twice the activity of non-stimulated cells when grown on TCPS but not on the metallic substrates. ROS cells (stimulated or unstimulated) adherent to the zirconium alloy generated lower amounts of Factor Xa compared to those bound to the other alloys and unstimulated cells grown on TCPS. These results indicate that ROS cells cultured on these synthetic surfaces differentially express procoagulant activity and that cells grown on TCPS, but not the metallic alloys, exhibit increased TF activity in response to stimulation by calcium ionophore. This procoagulant activity may potentiate subsequent inflammatory responses associated with the use of orthopedic biomaterials and thereby influence the tissue compatibility of the implant.
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PMID:Tissue factor expression by rat osteosarcoma cells adherent to tissue culture polystyrene and selected orthopedic biomaterials. 986 Jan 71

Tissue factor (TF), a transmembrane glycoprotein, plays a role in the initiation of blood coagulation at sites of vascular injury. Activated products of coagulation may then enhance inflammatory responses. The present investigation assesses the ability of rat osteosarcoma (UMR-106) cells cultured on titanium alloy (Ti6Al4V) to express differential surface TF activity in response to cyclic mechanical strain. Strains ranged from -2000 micro-strain to +2000 micro-strain, and durations from 5, 10, and 20 min per day over 5 days to 24 h continuous stimulation. ROS cells exhibited significant TF activity as demonstrated by the conversion of Factor X to Factor Xa. Strains of +2000 micro-strain with 5-20-min duration exhibited decreased TF activity with duration from 1.4E-04 nM/cell to 8.7E-05 nM/cell. Additionally, ROS cells stimulated with calcium ionophore (A23187) exhibited at least twice the activity of nonstimulated cells. Strains of +1340 micro-strain with 5-20-min duration exhibited an increasing trend with 4.15E-05 nM/cell to 7.38E-05 nM/cell. Strain direction had no significant effect on TF activity. Thus, both mechanical and chemical stimuli induce differential expression of TF activity by ROS cells cultured on Ti6Al4V, a phenomenon that may potentiate or regulate the inflammatory responses associated with the implantation of orthopedic biomaterials.
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PMID:Cyclic mechanical strain alters tissue-factor activity in rat osteosarcoma cells cultured on a titanium substrate. 1529 23