Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methotrexate (MTX), a folate antagonist and anticancer agent, was linked covalently to murine monoclonal anti-HLA IgG1 antibody (H-1) with the use of dextran T-40 as a multivalent carrier. As determined spectrophotometrically, the conjugate was composed of 9.20 mol MTX per 1 mol antibody. Of the substituted MTX, 46.3% (4.30 mol MTX per 1 mol antibody) exhibited inhibitory activity on dihydrofolate reductase. The MTX conjugated to H-1 [MTX-(H-l)] showed significantly stronger cytotoxicity against HLA-bearing cells than cells lacking HLA (p less than 0.001) in cultivation after a 2-hour exposure to the drugs. In the same experiment, free MTX showed equivalent cytotoxicity to cells both bearing and lacking HLA. When cells were cultivated for 3 days with the drugs, MTX-(H-l) also showed significantly stronger cytotoxicity than free MTX or MTX-control IgG conjugate against HLA-bearing cells (p less than 0.001), and the MTX-(H-l), MTX-control IgG, and free MTX showed equivalent cytotoxicity to cells lacking HLA. Our results indicate that the MTX-(H-l) conjugate binds to the cell surface antigen by its antibody action and exerts greater MTX cytotoxicity than free MTX in vitro.
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PMID:Production of a monoclonal antibody-methotrexate conjugate utilizing dextran T-40 and its biologic activity. 620 74

Osteosarcoma, the most common bone malignancy with a peak incidence at adolescence, had no survival improvement since decades. Persistent problems are chemo-resistance and metastatic spread. We developed in-vitro osteosarcoma models resistant to chemotherapy and in-vivo bioluminescent orthotopic cell-derived-xenografts (CDX). Continuous increasing drug concentration cultures in-vitro resulted in five methotrexate (MTX)-resistant and one doxorubicin (DOXO)-resistant cell lines. Resistance persisted after drug removal except for MG-63. Different resistance mechanisms were identified, affecting drug transport and action mechanisms specific to methotrexate (RFC/SCL19A1 decrease, DHFR up-regulation) for MTX-resistant lines, or a multi-drug phenomenon (PgP up-regulation) for HOS-R/DOXO. Differential analysis of copy number abnormalities (aCGH) and gene expression (RNAseq) revealed changes of several chromosomic regions translated at transcriptomic level depending on drug and cell line, as well as different pathways implicated in invasive and metastatic potential (e.g., Fas, Metalloproteinases) and immunity (enrichment in HLA cluster genes in 6p21.3) in HOS-R/DOXO. Resistant-CDX models (HOS-R/MTX, HOS-R/DOXO and Saos-2-B-R/MTX) injected intratibially into NSG mice behaved as their parental counterpart at primary tumor site; however, they exhibited a slower growth rate and lower metastatic spread, although they retained resistance and CGH main characteristics without drug pressure. These models represent valuable tools to explore resistance mechanisms and new therapies in osteosarcoma.
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PMID:In-Vitro and In-Vivo Establishment and Characterization of Bioluminescent Orthotopic Chemotherapy-Resistant Human Osteosarcoma Models in NSG Mice. 3131 71