Cells In Serum-containing Medium Research Articles

γ-Glutamyltranspeptidase activity in a human pancreatic cancer cell line (HPC-Y1) in serum-free chemically defined medium

gamma-Glutamyltranspeptidase (gamma-GTP) activity was found in a human pancreatic cancer cell line, HPC-Y1, cultivated in a serum-free chemically defined medium. The gamma-GTP stained in the cytoplasms as fine granules and was produced constantly in a protein-free chemically defined medium. The detergent- or protease-solubilized gamma-GTP of HPC-Y1 cells in serum-free medium was compared with the gamma-GTPs extracted from HPC-Y1 cells in serum-containing medium, human pancreatic carcinoma and normal human pancreas. Their molecular weights, electrophoretic mobilities, affinity to Concanavalin A-Sepharose and isoelectric points were almost identical. No cancer specific properties in the gamma-GTP derived from human pancreatic carcinoma cell line were found by these analyses. However, the serum-free spent medium of HPC-Y1 cells was useful for purifying the gamma-GTP secreted from the human pancreatic carcinoma cell line, since it is not necessary to separate the contaminated serum components that are usually added for cell cultures and the extraction procedures could induce minor structural change and/or artificial modification of gamma-GTP.

Epidermal growth factor inhibits growth of A431 human epidermoid carcinoma in serum-free cell culture.

A medium consisting of a rich basal nutrient mixture supplemented with bovine insulin (10 micrograms/ml), human transferrin (10 micrograms/ml), human cold-insoluble globulin (5 micrograms/ml), and ethanolamine (0.5 mM) supported the growth of the A431 human epidermoid cell line in the absence of serum with a generation time equal to that of cells in serum-containing medium. Addition of epidermal growth factor (EGF) to this culture medium at concentration mitogenic for other cell types resulted in a marked inhibition of A431 cell growth. Inhibitory effects of EGF were observed at 1 ng/ml and near-maximal effects were observed at 10 ng/ml. The inhibitory effect of EGF could be reversed by the omission of EGF in subsequent medium changes and could be prevented by the addition of anti-EGF antibody to the culture medium. Inhibition of A431 cell growth by EGF also could be demonstrated in serum-containing medium.

Serum catecholamines desensitize beta-adrenergic receptors of cultured C6 glioma cells.

C6 glioma cells grown in medium containing fetal bovine serum have a decreased beta-adrenergic receptor number and beta-receptor-stimulated cyclic AMP accumulation as compared to cells grown in a serum-free, defined medium. The decreased number of receptors and decreased cAMP accumulation are attributable to a suppression of receptor binding and response by serum as opposed to increases produced by growth in the defined medium. Serum, when added to cells grown in the absence of serum, stimulated cellular cyclic AMP levels to 2-3 times basal levels. This direct stimulatory effect was blocked by incubation of the cells with the beta-adrenergic antagonist propranolol and was partially reversed by dialysis of the serum. In contrast, addition of serum to cells that have been grown with serum fails to stimulate cyclic AMP accumulation. The decrease in receptors following growth in serum can be mimicked by growing cells in serum-free medium in the presence of beta-adrenergic agonists such as isoproterenol or norepinephrine. Radioenzymatic assays indicate that fetal bovine serum contains approximately 0.3 nM norepinephrine and lower concentrations of epinephrine. It thus appears that growth of C6 cells in serum-containing media desensitizes the beta-adrenergic receptor/cyclic AMP system of these cells. This desensitized state appears to result primarily from the action of catecholamines present in serum. These data indicate that retained catecholamines are one component in serum that can modify expression of beta-adrenergic receptors and hormonal response of cultured glioma cells.

Mouse T Cell-Mediated Cytolysis Specifically Triggered by Cytophilic Xenogeneic Serum Determinants: A Caveat for the Interpretation of Experiments Done under “Syngeneic” Conditions

Abstract We have demonstrated by using a combination of in vivo priming and in vitro incubation that the injection into mice of cultured cells can lead to the development of cytolytic T cells as a function of the serum used for growing the injected cells. Moreover, mere injection of xenogeneic serum followed by in vitro incubation of the primed cells in serum-containing medium led to the development of cytolytic T cells. The induction and the cytolysis phases of this system had distinct characteristics. For the induction of the development of cytolytic cells, cytophilic xenogeneic serum determinants were necessary and were recognized in a specific way. For cytolysis, T cells were required, which recognized unidentified antigens (but apparently not xenogeneic serum determinants) at the surface of syngeneic or allogeneic target cells. In addition, different strains of mice had different patterns of reactivity in this system. These results are discussed from two points of view. First, they lead us to issue a serious caveat for the interpretation of experiments done in “syngeneic” conditions, when the sensitizing cells have been in contact with xenogeneic serum. Second, we underline the interest of this system for further studies on the induction of T cell-mediated cytolysis.