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)

Osteosarcoma in the metaphysis to epiphysis of the left femur of a 17-year-old male is reported. The lesion appeared osteolytic with sclerotic foci on roentgenographs, accompanied by an extensive tumor shadow in the surrounding soft tissue. While 60% of the tumor was necrotic, histological examination of the remaining viable tissue revealed that it consisted almost entirely of a sheet of epithelioid cells, separated by thin, fibrovascular septa with an alveolar-like pattern, suggestive of metastatic carcinoma. Only a few areas were characterized by malignant osteoid tissue intermingled with the above cells, showing significant positivity for bone-specific alkaline phosphatase and 5'-nucleotidase, thus permitting a diagnosis of osteosarcoma. Autopsy findings revealed that the metastatic foci were histologically similar to those of the primary tumor. Electron microscopy revealed poor development of cytoplasmic organelles, supporting possible derivation from an osteoblastic cell lineage at an early stage.
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PMID:Osteosarcoma with prominent epithelioid features. 280 Nov 14

Although acute alterations in Ca2+ fluxes may mediate the skeletal responses to certain humoral agents, the processes subserving those fluxes are not well understood. We have sought evidence for Ca2+-dependent ATPase activity in isolated osteoblast-like cells maintained in primary culture. Two Ca2+-dependent ATPase components were found in a plasma membrane fraction: a high affinity component (half-saturation constant for Ca2+ of 280 nM, Vmax of 13.5 nmol/mg per min) and a low affinity component, which was in reality a divalent cation ATPase, since Mg2+ could replace Ca2+ without loss of activity. The high affinity component exhibited a pH optimum of 7.2 and required Mg2+ for full activity. It was unaffected by potassium or sodium chloride, ouabain or sodium azide, but was inhibited by lanthanum and by the calmodulin antagonist trifluoperazine. This component was prevalent in a subcellular fraction which was also enriched in 5'-nucleotidase and adenylate cyclase activities, suggesting the plasma membrane as its principal location. Osteosarcoma cells, known to resemble osteoblasts in their biological characteristics and responses to bone-seeking hormones, contained similar ATPase activities. Inclusion of purified calmodulin in the assay system caused small non-reproducible increases in the Ca2+-dependent ATPase activity of EGTA-washed membranes. Marked, consistent calmodulin stimulation was demonstrated in membranes exposed previously to trifluoperazine and then washed in trifluoperazine-free buffer. These results indicate the presence of a high affinity, calmodulin-sensitive Ca2+-dependent ATPase in osteoblast-like bone cells. As one determinant of Ca2+ fluxes in bone cells, this enzyme may participate in the hormonal regulation of bone cell function.
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PMID:A high affinity, calmodulin-responsive (Ca2+ + Mg2+)-ATPase in isolated bone cells. 613 20

A total of 19 cases with bone tumors, including six osteosarcomas. three giant cell tumors of bone, one malignant fibrous histiocytoma, four nonossifying fibromas, four chondromas and one chondrosarcoma, were examined as to enzyme histochemistry; the enzymes consisted of alkaline phosphatase (ALPase), acid phosphatase (ACPase), nonspecific esterase (NSE), adenosine triphosphatase (ATPase), 5'-nucleotidase (5'-Nucl) and beta-glucuronidase (beta-Gl). Osteosarcoma was strongly positive for ALPase followed by 5'-Nucl. Giant cell tumor, malignant fibrous histiocytoma and nonossifying fibroma showed enzyme histochemistry similar to each other: multinucleated giant cells and round cells in these tumors were strongly positive for ACPase, NSE, ATPase and 5'-Nucl simulating osteoclasts and histiocytes, whereas spindle cells were positive for ATPase and 5'-Nucl in their cytoplasm and weakly positive for ACPase. Chondroma and chondrosarcoma were focally positive for ACPase and NSE; the ACPase was sensitive to tartaric acid treatment. These observations showed that ALPase activity is very characteristic to osteosarcoma, and is useful for its diagnosis. From enzyme histochemistry, giant cell tumor, malignant fibrous histiocytoma and nonossifying fibroma can be regarded as a histiocyte-derived tumor of bone in contrast to osteosarcoma and cartilaginous tumors.
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PMID:Enzyme histochemical study on bone tumors. 629 58

The purpose of this study was to compare the adenylate cyclase of a tumour (rat osteosarcoma) growing in vivo with that of fast-growing embryonic bone. In the tumour the enzyme activity per total protein or DNA (under the same assay conditions) was 6--10-fold lower than in embryonic bone. To characterize this difference, we examined the kinetic properties of the enzyme in partially purified plasma membranes from the two tissues. A purification procedure based on differential centrifugation and discontinuous-sucrose-gradient centrifugation yielded a 10-fold increase in the specific activities of adenylate cyclase and 5'-nucleotidase in bone. The same procedure yielded an enriched membrane preparation from the tumour, but, relative to 5'-nucleotidase, a loss of 30% in adenylate cyclase occurred, which could not be recovered from another fraction. Kinetic analysis revealed that the lower adenylate cyclase activity in the tumour was due to a decrease in Vmax.. There was no significant difference in Ks (approx. 0.15 mM), and in the Km for GTP and p[NH]ppG. There were marked differences, however, in the extent of stimulation by p[NH]ppG, GTP and hormone, which was greater in tumour, and in the K1 for adenosine inhibition, which was 140 microM in bone and 500 microM in tumour. Under maximum stimulatory conditions, the enzyme activity in the tumour approached that in bone. The kinetic differences between bone and tumour enzyme were decreased by detergent solubilization, suggesting that the membrane environment plays a role in the generation of the observed differences.
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PMID:Comparison of bone and osteosarcoma adenylate cyclase. Partial purification of membranes and kinetic properties of enzyme. 693 Feb 65

Alkaline phosphatase is the marker enzyme for matrix vesicles, extracellular organelles that play a major role in primary bone formation and calcification. Recently, we developed osteosarcoma x fibrosarcoma hybrids in which alkaline phosphatase expression was greatly reduced, a phenomenon known as extinction. In the present study, we used to cell hybrids, LTA-1 and LTA-5, constructed from a human osteoblast-like osteosarcoma. TE85, and a mouse fibrosarcoma, La-t-, to examine the differential distribution of alkaline phosphatase between matrix vesicles and the plasma membrane, postulated to be the parent membrane from which matrix vesicles are derived. While alkaline phosphatase in plasma membranes was extinguished, enzyme activity in matrix vesicles from LTA-1 hybrid cells was 34.2% of that present in matrix vesicles from the TE85 parent cells and 200 times that found in La-t- matrix vesicles. Matrix vesicles from LTA-5 had alkaline phosphatase levels similar to La-t-. When other membrane enzymes (phospholipase A2, 5'-nucleotidase, and Na+/K+ ATPase) were examined, hybrid matrix vesicle and plasma membrane levels were similar to those of TE85 and significantly higher than in La-t- membrane fractions. Northern analysis detected mRNA for alkaline phosphatase in TE85 cells, but not in the hybrids or La-t- cells. In contrast, reverse transcription-polymerase chain reaction (RT-PCR) revealed alkaline phosphatase mRNA in the hybrid cells, but at very low levels. Taken together, the data indicate that regulation of plasma membrane and matrix vesicle alkaline phosphatase is independent and suggest that matrix vesicle biogenesis is independent and distinct from that of plasma membrane biogenesis. Analysis of 1B- and 1L-type alkaline phosphatase mRNA by RT-PCR showed that alternate promoter usage of the alkaline phosphatase gene was not responsible for the differential localization of this enzyme in matrix vesicle. Thus, it is likely that matrix vesicle and plasma membrane alkaline phosphatase are regulated differently at a post-transcriptional level.
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PMID:Osteosarcoma hybrids can preferentially target alkaline phosphatase activity to matrix vesicles: evidence for independent membrane biogenesis. 859 37