EVIDENCE FOR γ-MSH-LIKE IMMUNOREACTIVITY IN ECTOPIC ACTH-PRODUCING TUMORS

Abstract

Using a specific radioimmunoassay for γ-MSH, a predicted peptide in the cryptic N-terminal portionof the adrenocorticotropin-β-lipotropin precursor, γ-MSH-like immuno reactivity (γ-MLI) was detected in two ectopic ACTH producing tumors. Gel chromatographic studies on Bio-Gel P-60 revealed oneor two peaks of γ-MLI; one was eluted near the elution position of β-LPH, compatible with γ-MLI in human pituitary and the other emerged near the position of β-endorphin. These results indicate that ectopic ACTH-producing tumors elaborate not only ACTH, β-endorphin but also γ-MLI.