Evidence for alpha-melanocyte-stimulating hormone (α-MSH) receptors on human malignant melanoma cells

✍ Scribed by G. E. Ghanem; G. Comunale; A. Libert; A. Vercammen-Grandjean; F. J. Lejeune

• Book ID: 102865165
• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: French
• Weight: 563 KB
• Volume: 41
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910410216

✦ Synopsis

The presence of a-MSH receptors on human melanoma has so far been suggested in the literature but not proved. We describe a reproducible and specific binding assay of a-MSH on human melanoma cells, using a high-specific-activity 1251labelled hormone (1.5 to 2 mCi/pg) with consistent receptor binding (usually exceeding 2 pg/l06cells) and stable for 3 weeks.

Asynchronized cells in suspension

were incubated for I S min at 37OC with the tracer and various concentrations of unlabelled hormones. Synthetic a-MSH was compared to $-MSH, ACTH'-24, ACTH4-10, 0-LPH, CLIP, CRF, MIF I, A'VP and 0endorphin. Out of a panel of 8 human melanoma cell lines, 3 showed specific and reproducible a-MSH binding curves. No significant binding to human fibroblast and human carcinoma cells was seen. (u-MSH, P-MSH and, to a lesser extent ACTH4lo (a part of the o(-MSH sequence) were the only peptides able to displace labelled a-MSH from its binding sites, indicating the high specificity of the MSH receptor. Affinity constants (Ka) ranged from 10' to lo9 I/mole and the estimated receptor number was 1,000 to 2,000 per cell. We conclude that some human melanoma cell lines expressed specific MSH receptors with stable affinity but which are low in number.