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

beta-Cystathionase (EC 4.4.1.8) from Bordetella avium is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the hydrolysis of L-cystine to yield pyruvic acid, NH3, and thiocysteine. The latter compound is highly toxic toward MC3T3-E1 osteogenic cells, rat osteosarcoma cells, and other cell lines maintained in tissue culture (Gentry-Weeks, C. R., Keith, J. M., and Thompson, J. (1993) J. Biol. Chem. 268, 7298-7314). Site-directed mutagenesis has established that lysine 214 of the sequence TKYVGGHSD, is primarily responsible for internal aldimine binding of PLP in the holoenzyme. Translation of the DNA sequence of the beta-cystathionase gene (metC) from B. avium, reveals 4 cysteine residues/enzyme subunit (M(r) = 42,600), and spectrophotometric analysis with 4,4'-dithiodipyridine showed that there were no disulfide linkages in the native protein. beta-Cystathionase is inhibited by sulfhydryl-reactive agents, including N-ethylmaleimide (NEM). To elucidate the mechanism of NEM inhibition, each of the 4 cysteine residues at positions 88, 117, 279, and 309 was individually replaced by alanine or glycine. The mutant proteins C88A, C117G, C279G, and C309A were purified to homogeneity, and each was assayed for enzyme activity, PLP-binding, NEM sensitivity, and susceptibility to chymotrypsin digestion. The activities of mutant proteins C88A and C279G were comparable with that of the native enzyme, and since both forms were inhibited by NEM, neither cysteine 88 nor 279 are prerequisite for enzyme activity. By elimination, cysteine residues 117 and 309 must be the targets for alkylation, and resultant inactivation of beta-cystathionase, by the -SH reactive agent. Substitution of cysteine 117 and 309 with glycine and alanine, respectively, yielded the inactive proteins C117G and C309A. PLP was not detectable in these proteins, and their absorption spectra lacked the peak (at 420 nm) that is characteristic of internal PLP-Schiff base formation. Edman degradation revealed that C117G (M(r) approximately 36,000) also lacked the first 63 amino acids comprising the N terminus of the native protein. The beta-cystathionase mutants C117G and C309A showed enhanced susceptibility to chymotrypsin digestion. Cysteine residues 117 and 309 may reside in conformationally sensitive environments, and in the native enzyme these amino acids most probably serve a structural function. Toxicity assays performed with the various mutant proteins obtained by site-directed mutagenesis established that only catalytically active forms of beta-cystathionase were were cytotoxic for tissue culture cells.
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PMID:beta-Cystathionase from Bordetella avium. Role(s) of lysine 214 and cysteine residues in activity and cytotoxicity. 770 18

The production of cysteine protease by two human osteosarcoma cell lines (MG-63 and SaOS2) was analyzed, as well as their modulation by interleukin 1beta (hIL-1 beta), interleukin 6 (hIL-6), insulin growth factor-1 (hIGF-1), oncostatin M (hOSM), leukemia inhibitory factor (hLIF) and growth hormone (hGH). Cysteine protease activities were detected using a synthetic substrate. The protease activities (especially cathepsin L activity) of both cell lines were increased significantly in the presence of hIL-1 beta, hIL-6 and hOSM. In contrast, hIGF-1 and hGH decreased these activities, and no effect was detectable in the presence of hLIF. The addition of antibodies against the gp-130 chain of the hIL-6 and hOSM receptors totally inhibited the stimulating effect of these two cytokines on cysteine protease activities. In increasing collagen type I degradation, hIL-1beta, hIL-6 and hOSM could be involved in bone resorption, whereas the inhibitory action of hIGF-1 and hGH on collagen type I degradation suggest that this factor could play a role in bone formation.
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PMID:Cysteine protease production by human osteosarcoma cells (MG63, SAOS2) and its modulation by soluble factors. 1085 75

A number of recent studies suggest that mitochondrial function is a player in tumor development and progression. In this study, we have used gene expression arrays to examine transcriptional differences between oxidative phosphorylation (OXPHOS)-competent and OXPHOS-impaired human osteosarcoma cells. Genes associated with extracellular matrix remodeling, including members of the matrix metalloproteinases (MMPs) and tissue inhibitors of the MMP (TIMP) family, urokinase plasminogen activator and its inhibitor plasminogen-activator inhibitor-1 (PAI1), and CTGF and CYR61 (members of the Cysteine-rich 61, Connective Tissue Growth Factor and Nephroblastoma-overexpressed (CCN) gene family of growth regulators), were among the ones significantly altered in the OXPHOS-deficient cells. These changes were confirmed by RT-PCR and promoter reporter assays. Alterations at the protein level for some of these factors were also observed, though at a lower magnitude, with the exception of TIMP1, where a marked change in steady-state levels of the protein was observed after induction of OXPHOS dysfunction. Repopulation of mitochondrial DNA (mtDNA)-less cells with wild-type mtDNA reduced matrigel invasion, whereas repopulation with a mutated mtDNA did not. Taken together our data suggests that OXPHOS dysfunction modulates the invasive phenotype by transcriptional regulation of genes coding for members of the MMP/TIMP system, urokinase plasminogen activator/plasminogen-activator inhibitor I and CCN proteins.
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PMID:Oxidative phosphorylation dysfunction modulates expression of extracellular matrix--remodeling genes and invasion. 1622 32

Cysteine Rich Angiogenic Inducer 61 (Cyr61) and Vascular Endothelial Growth Factor (VEGF) are signaling proteins involved in the regulation of tumor angiogenesis and progression. The purpose of this study was to investigate the clinicopathological and prognostic significance of Cyr61 and VEGF expressions in osteosarcoma. Immunohistochemical staining was performed to evaluate the expression of both the proteins in 84 osteosarcoma samples. Correlation between Cyr61/VEGF expressions and clinicopathological parameters was determined using Rank sum test and Spearman's rank correlation coefficient. Prognostic factors were identified using univariate and multivariate Cox regression analysis. The expressions of Cyr61 and VEGF were weak in 26.2% and 17.9%, moderate in 26.2% and 23.8%, and strong in 47.6% and 58.3% of osteosarcoma samples, respectively. Cyr61 and VEGF expressions moderately correlated with each other in osteosarcoma, and exhibited significant association with Enneking stage and distant metastasis. In addition, the high expression of both proteins significantly correlated with short overall survival time in these patients. The key finding in this study was that both Cyr61 and VEGF expressions were independent prognostic indicators of overall survival. In summary, our results indicate that expression of Cyr61 and VEGF may serve as important prognostic predictors in patients with osteosarcoma.
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PMID:High expression levels of Cyr61 and VEGF are associated with poor prognosis in osteosarcoma. 2864 10