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)

Intermittent parathyroid hormone (PTH) therapy increases bone mass. The purpose of this study was to determine if analogs of human PTH(1-34) (hPTH[1-34]), which differ from the native sequence in their receptor-activating properties, could promote bone formation in an ovariectomized (OVX) osteopenic rat model. We synthesized two hPTH(1-34) analogs with single substitutions for serine in the 3-position that in vitro are partial agonists in kidney. In the renal cell line OK, maximal cyclic adenosine monophosphate (cAMP) activation by [His(3)]hPTH(134) was 50%, and maximal cAMP activation by [Leu(3)]hPTH(1-34) was 20% of that produced by hPTH(1-34). Both analogs were full agonists in UMR-106 rat osteosarcoma cells and other bone-derived systems, but both had reduced potency compared with hPTh(1-34). Six-month-old retired breeder Sprague-Dawley rats were ovariectomized, and five animals underwent sham operation. On day 56 post-OVX, five sham-operated and five pre-PTH treatment OVX animals were sacrificed, and the remaining animals were randomized into 10 groups of six animals each. All other animals were injected with one of the hPTH analogs or hPTH(1-34) at 0, 4, 40, or 400 mu g/kg of body weight (BW)/day and were killed on day 84. Histomorphometry of the proximal tibia metaphysis and biochemical markers of bone turnover (osteocalcin and pyridinoline cross-links) were the primary endpoints. The cancellous bone volume was significantly lower at day 56 post-OVX (pretreatment) and at day 84 post-OVX (post-vehicle treatment) than at baseline. None of the compounds significantly increased the cancellous bone volume. Trabecular number declined after OVX and did not change with hPTH treatment. In contrast, the trabecular thickness declined after OVX but was higher after treatment with 40 mu g/kg of BW/day or 400 mu g/kg of BW/day of hPTH(1-34). In OVX rats, the mineralizing surface was higher than baseline at day 56 and fell toward control levels by day 84. All three peptides produced marked dose-related increases in the mineralizing surface and bone formation rates, but the two analogs were less potent than hPTH(1-34). Likewise, all peptides produced significant dose-related increases in the serum osteocalcin level. The osteoclast surface was not affected by OVX but was decreased with medium and high doses of hPTH(1-34). Pyridinoline cross-link excretion was not significantly affected by treatment with hPTH(1-34) but responded with a dose-dependent decrease to treatment with [His3]hPTH(1-34). These data suggest that bone selective analogs of hPTH(1-34) maintain the ability to induce bone formation but are less potent than hPTH(1-34).
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PMID:Bone-selective analogs of human PTH(1-34) increase bone formation in an ovariectomized rat model. 915 76

We used a yeast functional assay (functional analysis of separated alleles in yeast: FASAY) to determine the p53 gene status of human cell lines maintained in our laboratory. This assay enables the researcher to score wild-type p53 expression on the basis of the ability of expressed p53 to transactivate the reporter gene HIS 3 via the p53-responsive GAL 1 promoter in Saccharomyces cerevisiae. The cell lines examined were ten hepatoma, two hepatoblastoma, three in vitro immortalized fibroblast, two osteosarcoma, a chondrosarcoma, an ovarian teratocarcinoma and a colon cancer cell line. Out of 20 cell lines, 11 cell lines had mutations in both alleles of the p53 gene, and another 8 cell lines had no mutation in the p53 gene. Thus, 55% of the cell lines examined had mutations in the p53. Interestingly, PA-1 cells had both the normal and the mutant p53 alleles, showing that FASAY is a useful method for detecting the wild-type and mutated p53 genes simultaneously. As for the three liver cell lines harboring HBsAg, there was no relationship between their p53 gene status and the presence of HBsAg. Two cell lines were normal for p53 status, while the other had a mutation of the p53 gene.
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PMID:Yeast functional assay of the p53 gene status in human cell lines maintained in our laboratory. 935 23

High molecular weight kininogen (HK) blocks cell spreading but not cell attachment to surfaces coated with vitronectin and other ligands of beta3 integrins. We sought to learn the structural basis of this phenomenon. Monoclonal antibodies against the histidine-rich D5 domain in the light chain of 2-chain HK abolished the inhibitory effect of 2-chain HK on spreading of MG-63 osteosarcoma cells on vitronectin-coated tissue-culture plastic. The antibodies were effective only if incubated with 2-chain HK in solution and did not abolish the anti-cell-spreading effect of 2-chain HK that was pre-adsorbed to tissue-culture plastic. Exposure of an epitope in the histidine-rich domain was less when HK was adsorbed to tissue-culture plastic (oxidized polystyrene) than when it was adsorbed to ELISA plastic (untreated polystyrene). Loss of the epitope correlated with increased anti-cell-spreading activity of HK on tissue-culture plastic. The light chain of 2-chain HK containing D5 and that containing recombinant D5 both had anti-cell-spreading activity, but only when present in solution during adhesion assays. Pre-adsorption of recombinant D5 to tissue-culture plastic resulted in a surface on which adsorbed 2-chain HK had little anti-cell-spreading activity. Binding study revealed that HKa bound to immobilized vitronectin. The histidine-rich D5 domain of light chain of HK was identified as one of the binding sites of vitronectin, suggesting that the masking of the RGD cell-binding site of immobilized vitronectin is the molecular mechanism of anti-cell-spreading effect of HKa. In contrast, low molecular weight kininogen (LK), which lacks D5, augmented cell spreading on vitronectin-coated tissue-culture plastic. Thus, HK and LK have opposing effects on VN-dependent cell adhesion. The augmenting effect of LK was greater if LK was preincubated with cells or adsorbed to the surface at pH>7.0. Analysis of fragments of LK and antibody inhibition studies localized the cell-adhesion activity to the D3 domain that is common to LK and HK. These findings indicate that the D5 domain mediates the adsorption of HK or 2-chain HK to vitronectin substratum in anti-adhesive conformations, i.e., masking of the RGD cell-binding site of vitronectin. Such conformers inhibit cell spreading on vitronectin even though a cell-adhesion site is present in D3.
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PMID:Opposing effects of low and high molecular weight kininogens on cell adhesion. 972 55

The thymidine kinases (TKs) of herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus (VZV) were expressed in human osteosarcoma cells as fusion proteins with the green fluorescent protein (GFP), and their intracellular localizations were determined. The three TK-GFP fusion products were localized in different subcellular compartments of the transfected tumor cells. HSV-1 TK-GFP was localized exclusively in the nucleus, HSV-2 TK-GFP was predominantly found in the cytosol, while VZV TK-GFP was localized in both the nucleus and the cytosol. In support of these findings, we identified a nuclear localization signal (NLS) in the N-terminal arginine-rich region of HSV-1 TK that was absent in HSV-2 and VZV TK. The first 34 amino acids proved necessary for the specific nuclear localization of HSV-1 TK and, when added to the VZV TK-GFP gene construct, also sufficed to specifically target VZV TK-GFP to the nucleus. Further analysis of this NLS through site-directed mutagenesis revealed that the basic amino acid-rich nonapeptide 25R-R-T-A-L-R-P-R-R33 is of crucial importance in the nuclear targeting of HSV-1 TK. In particular, we revealed that the presence of the arginine residues at positions 25, 26, 30, 32, and 33 is obligatory for efficient NLS functioning, whereas arginine and histidine residues outside of the nonapeptide (i.e., residues R18, R20, and H22) did not change the functional properties of the NLS.
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PMID:Differential intracellular compartmentalization of herpetic thymidine kinases (TKs) in TK gene-transfected tumor cells: molecular characterization of the nuclear localization signal of herpes simplex virus type 1 TK. 981 86

Mouse models show that congenital neural tube defects (NTDs) can occur as a result of mutations in the platelet-derived growth factor receptor-alpha gene (PDGFRalpha). Mice heterozygous for the PDGFRalpha-mutation Patch, and at the same time homozygous for the undulated mutation in the Pax1 gene, exhibit a high incidence of lumbar spina bifida occulta, suggesting a functional relation between PDGFRalpha and Pax1. Using the human PDGFRalpha promoter linked to a luciferase reporter, we show in the present paper that Pax1 acts as a transcriptional activator of the PDGFRalpha gene in differentiated Tera-2 human embryonal carcinoma cells. Two mutant Pax1 proteins carrying either the undulated-mutation or the Gln --> His mutation previously identified by us in the PAX1 gene of a patient with spina bifida, were not or less effective, respectively. Surprisingly, Pax1 mutant proteins appear to have opposing transcriptional activities in undifferentiated Tera-2 cells as well as in the U-2 OS osteosarcoma cell line. In these cells, the mutant Pax1 proteins enhance PDGFRalpha-promoter activity whereas the wild-type protein does not. The apparent up-regulation of PDGFRalpha expression in these cells clearly demonstrates a gain-of-function phenomenon associated with mutations in Pax genes. The altered transcriptional activation properties correlate with altered protein-DNA interaction in band-shift assays. Our data provide additional evidence that mutations in Pax1 can act as a risk factor for NTDs and suggest that the PDGFRalpha gene is a direct target of Pax1. In addition, the results support the hypothesis that deregulated PDGFRalpha expression may be causally related to NTDs.
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PMID:Altered regulation of platelet-derived growth factor receptor-alpha gene-transcription in vitro by spina bifida-associated mutant Pax1 proteins. 982 22

A soluble form of tissue-nonspecific alkaline phosphatase was purified to apparent homogeneity from the culture media of Sf9 cells which had been infected with recombinant baculoviruses encoding human tissue-nonspecific alkaline phosphatase (TNSALP). To facilitate purification, an oligonucleotide consisting of 6 tandem codons for histidine and a stop codon was engineered into the TNSALP cDNA. The molecular mass of the enzyme purified through a nickel-chelate column was estimated to be 54 kDa by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. That of the native enzyme was 90 kDa as estimated by gel filtration, indicating that the purified soluble TNSALP is dimeric. The enzyme was used for production of antibodies specific for human TNSALP. Immunoblotting analysis showed a single 80-kDa band in the cell homogenate prepared from Saos-2 (human osteosarcoma) cells. However, upon digestion with peptide: N-glycosidase F, the 80-kDa TNSALP of human origin and the soluble enzyme of insect origin migrated to the same position on SDS-polyacrylamide gel, indicating that the size difference between the two enzymes is ascribed to N-linked oligosaccharides. The antibodies prepared against the purified TNSALP were found to be useful also for immunoprecipitation and immunofluorescence studies.
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PMID:A general method for rapid purification of soluble versions of glycosylphosphatidylinositol-anchored proteins expressed in insect cells: an application for human tissue-nonspecific alkaline phosphatase. 1050 77

Human immunodeficiency virus-1 Tat protein and human Cyclin T1 mediate transcriptional activation by enhancing the elongation efficiency of RNA polymerase II. Activation of transcription of the related equine infectious anemia virus (EIAV) requires a similar protein known as eTat, which does not function in human cells. Expression of equine Cyclin T1 in human cells rescues eTat function, suggesting a general mechanism of transcription activation among lentiviruses. Here we present the cloning of Cyclin T1 from canine D17 osteosarcoma cells, which support EIAV transactivation, and show that canine Cyclin T1 confers eTat transactivation to human cells. A two-amino-acid change, from 79-proline-glycine-80 to 79-histidine-arginine-80, confers on the human Cyclin T1 the ability to cooperate with eTat in transcriptional activation. These findings suggested that the regions of Cyclin T1 that interact with lentiviral Tat proteins and TAR RNA elements form an extended domain, which very likely has a conserved fold.
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PMID:Canine cyclin T1 rescues equine infectious anemia virus tat trans-activation in human cells. 1068 21

We found that human kinin-free high-molecular-weight kininogen (kf-HK) significantly inhibited vitronectin-mediated migration (haptotaxis) and invasive potentiation (haptoinvasion) of osteosarcoma (MG-63) cells but that HK, LK, the common heavy chain of HK and LK, and the light chain (D6(H)) of HK had no inhibitory effect. Recombinant GST-D5(H) (histidine-rich region of HK) obtained from Escherichia coli. (BL21) also inhibited both haptotaxis and haptoinvasion to about 30% of the control level in a dose-dependent manner. These findings suggest that a specific region of D5(H) is responsible for the inhibition of cell haptotaxis and haptoinvasion. Among the seven synthetic peptides covering D5(H), peptide H(479)KHGHGHGKHKNKGK(493) (P-5) inhibited both haptotaxis and haptoinvasion in a dose-dependent manner, suggesting that P-5 could possibly be utilized to prevent primary and secondary metastases of tumor cells.
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PMID:Inhibition of vitronectin-mediated haptotaxis and haptoinvasion of MG-63 cells by domain 5 (D5(H)) of human high-molecular-weight kininogen and identification of a minimal amino acid sequence. 1168 5

The study was conducted to clarify the cytocidal effect of combination therapy consisting of administration of acridine orange (AO), which is a photosensitizer, and radiation therapy using in vitro and in vivo mouse osteosarcoma models. The results revealed that AO combined with low-dose X-ray irradiation of about 1-5 Gy had a strong cytocidal effect on the cultured mouse osteosarcoma cells regardless of their chemosensitivity, and that this combination therapy inhibited growth of the in vivo mouse osteosarcoma by induction of tumor necrosis. This effect was inhibited by L-histidine, but not by mannitol. These findings suggested that AO might be excited by X-rays and kill osteosarcoma cells through the release of singlet oxygen, which is toxic to living cells. This mechanism is similar to that of photodynamic therapy with AO.
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PMID:Acridine orange excited by low-dose radiation has a strong cytocidal effect on mouse osteosarcoma. 1181 48

High-dose methotrexate is a standard component of therapy for high-grade osteosarcoma. Its effectiveness may be limited by intrinsic and acquired resistance. Decreased reduced folate carrier (RFC) expression has been shown in approximately half of osteosarcomas at diagnosis. Mutations and polymorphisms in the RFC gene have been reported in various cell lines. The purpose of this study was to investigate sequence alterations in the RFC gene in osteosarcoma tumor samples. The entire coding region of the RFC gene in samples from 162 osteosarcoma patients was screened by DNA single-stranded conformational polymorphism, followed by direct sequencing of any region with altered mobility. A previously identified polymorphism at cDNA position number 174 of RFC exon 2 was observed. Sixty-one samples (37.6%) were heterozygous with both A/G at this position (His(27)/Arg(27)), 52 samples (32.2%) were homozygous with G (Arg(27)), and 49 samples (30.2%) were homozygous with A (His(27)). Fifteen (9.2%) samples were identified with other RFC sequence variants in exon 2, none of which have been reported. The sequence variants in exon 2 included a G to A substitution at cDNA position 231, a G to A substitution at cDNA position 155, a C to T substitution at cDNA position 114, and a T to C substitution at cDNA position 104, resulting in a serine to asparagine substitution at amino acid 46, a glutamate to lysine substitution at amino acid 21, an alanine to valine substitution at amino acid 7, and a serine to proline substitution at amino acid 4, respectively. A deletion of A at cDNA position 126 resulting in a frameshift was also observed. Some of these variants were observed in multiple samples. Eight samples had altered single-stranded conformational polymorphism patterns in exon 3 that were associated with nucleotide changes that altered the amino acid sequence. All of these RFC sequence variants appeared to be heterozygous. Heterozygous C/T and homozygous C also were observed at RFC cDNA position 790 in exon 3, which does not alter the amino acid coding sequence. This study shows that RFC sequence alterations are frequent in samples from osteosarcoma patients. Additional studies are under way to determine the clinical significance of these sequence alterations and their effect on methotrexate transport and resistance.
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PMID:Sequence alterations in the reduced folate carrier are observed in osteosarcoma tumor samples. 1257 57


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