A major problem in cancer therapy is tumor drug resistance such as is found with antifolates (e.g., methotrexate [MTX]). We are specifically interested in the role of the human folate receptor (hFR) in MTX resistance. To investigate whether transfection of hFR results in increased MTX uptake and increased drug sensitivity, human mammary carcinoma (MCF-7) cells and Chinese hamster ovary cells (C...

A biochemical basis for the LEClO mutant phenotype of Chinese hamster ovary cells has been identified. Independent LEClO mutants, originally selected for resistance to the toxicity of ricin, have been shown to exhibit reduced binding of la61-ricin at the cell surface. Although this is indicative of structural changes in cellsurface carbohydrates, labeling of plasma membranes with galactose o~id...

A 48-h treatment with vinyl acetate (0.05-1 mM) induced a drastic increase in sister chromatid exchanges (SCEs) and (in first division cells) structural chromosome aberrations in cultured human lymphocytes. The effects were more pronounced in cultures of isolated lymphocytes than in whole-blood cultures. A distinct dose-dependent induction of SCEs similarly occurred in Chinese hamster ovary cel...

DNA lesions, cytotoxicity, and cellular uptake of CaCrO4 were com pared in Chinese hamster ovary, in mouse embryo fibroblast C3H10T'/2, and in human osteosarcoma cells. The concentration of CaCrO4 that reduced colony formation by 50% was 2or 3-fold less in human osteo sarcoma cells than in C3H 10T'/2 or Chinese hamster ovary cells. Alkaline elution studies showed that CaCrO4 induced DNA single ...

Kampo formulations are traditional herbal medications used in China and Japan for many centuries to treat diarrheal diseases such as cholera. Our studies were undertaken to identify and verify by chemical synthesis the active components that inhibited cholera toxin (CT), the virulence factor secreted by Vibrio cholerae, the causative agent of cholera. The Kampo formulation, Daio-kanzo-to, inhib...

DNA lesions, cytotoxicity, and cellular uptake of CaCrO4 were compared in Chinese hamster ovary, in mouse embryo fibroblast C3H10T1/2, and in human osteosarcoma cells. The concentration of CaCrO4 that reduced colony formation by 50% was 2- or 3-fold less in human osteosarcoma cells than in C3H10T1/2 or Chinese hamster ovary cells. Alkaline elution studies showed that CaCrO4 induced DNA single s...

The cytotoxic and pharmacological properties of hyperthermia and cis-diamminedichloroplatinum(II) (DDP) were studied in DDP-sensitive and DDP-resistant Chinese hamster ovary cells in vitro. Cytotoxicity was measured by cell survival using colony formation assay and cellular platinum levels were determined by atomic absorption spectrophotometry. Hyperthermia potentiated DDP cytotoxicity in both ...

Mammalian cell cultures are the preferred expression systems for the production of biopharmaceuticals requiring posttranslational processing. Usually, cell cultures are cultivated in medium supplemented with serum, which supports cell proliferation, viability, and productivity. However, due to scientific and regulatory concerns, serum-free conditions are required in recombinant protein producti...