Evidence for increased alpha MSH receptor binding in the F1 variant of B16 melanoma cells grown in dialyzed fetal calf serum.
The specific binding of an alpha MSH analogue (Ac-[Nle4, D-Phe7] alpha MSH4-11 NH2) was enhanced in the presence of 10% dialyzed fetal calf serum (FCS) as compared with 10% FCS (nondialyzed) in the F1 variant of B16 melanoma cells. The replenishment of dialyzed serum with adrenocorticotrophic hormone (ACTH) or insulin had no effect on the increased level of alpha MSH receptor binding in these cells. However, 10 nM alpha MSH or 1 microM ACTH under identical conditions significantly decreased the level of alpha MSH binding. Competitive binding studies involving the alpha MSH analogue revealed that the specificity of the receptor was restricted to the complete molecule of alpha MSH, our analogue, beta MSH and ACTH1-24, ACTH4-10, which contains the amino acid sequence responsible for biological activity, showed a very low affinity for the receptor. Furthermore, we observed an interesting phenomenon unique to dialyzed FCS in that once the cells were grown to confluence and melanin was produced, the cells were no longer viable. However, in McCoy's medium, which is deficient in tyrosine, the cells did not produce melanin and remained viable.
McQuillan
A
A
Lady Davis Institute for Medical Research, Sir Mortimer B. Davis, Jewish General Hospital, Montreal, Quebec, Canada.
Hutchinson
M
M
Panasci
L C
LC
D000818:Animals; D002417:Cattle; D002460:Cell Line; D005312:Fetal Blood; D014644:Genetic Variation; D008546:Melanoma, Experimental / Q000235:genetics / Q000473:pathology* / Q000648:ultrastructure; D011979:Receptors, Pituitary Hormone / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D000521:alpha-MSH / Q000378:metabolism
D011979:Receptors, Pituitary Hormone; D000521:alpha-MSH; C029446:MSH receptor