Modulation of the expression of the VIP receptor by serum factors on the human melanoma cell line IGR39.
IGR39 cells, isolated from a human superficial melanoma, display at their surface high and low affinity receptors for the vasoactive intestinal peptide (VIP). When grown in DME medium supplemented with 10% fetal calf serum, cells display 1.6 x 10(5) high affinity (Kd 0.74 nM) and 5.6 x 10(5) low affinity (Kd 55 nM) VIP binding sites per cell. When cultured in a chemically defined medium containing EGF, transferrin, and selenium, IGR39 cells display many neurite-like extensions. Following these morphological changes, the specific [125I]VIP binding is increased four- to fivefold after 6 days in culture. This phenomenon is reversible and is the result of an increased number of VIP binding sites available at the cell surface, without modification of their affinities. The molecular mass of the binding sites is also unchanged whatever cell culture conditions. Increase in [125I]VIP binding is inversely correlated to the serum concentration in the culture medium. When added to the chemically defined medium, sera from various origins as well as some serum substitutes reduce [125I]VIP binding to the same extent as that of the serum. The total cAMP production by VIP-stimulated IGR39 cells is enhanced by a factor of six to seven when cells are cultured in serum-free medium, in good correlation with the increase of VIP binding capacity. These data suggest that factor(s) present in fetal calf serum inhibit(s) the expression of VIP receptor, thus demonstrating the importance of a strict control of cell culture conditions for in vitro studies.
Bellan
C
C
Institut de Chimie Biologique, CNRS URA 202, Université de Provence, Marseille, France.
Fabre
C
C
Secchi
J
J
Marvaldi
J
J
Pichon
J
J
Luis
J
J
D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive / Q000187:drug effects; D001798:Blood Proteins / Q000494:pharmacology*; D001802:Blood Substitutes / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006801:Humans; D009930:Organic Chemicals; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D001798:Blood Proteins; D001802:Blood Substitutes; D016895:Culture Media, Serum-Free; D009930:Organic Chemicals; D011943:Receptors, Adrenergic, beta; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; C044609:Ultroser G; D000242:Cyclic AMP