α-Melanotropin immunoreactivity in human melanoma exudate is related to necrosis

We have previously reported high immunoreactive α-MSH (IR-α-MSH) concentrations in melanoma patients’ plasma, as well as significant amounts in melanoma metastases and cells grown in culture. Necrosis within the melanoma tumour leads to a massive proteolysis of intracellular proteins and release of cell content: this might significantly contribute to the elevated IR-α-MSH plasma levels measured in melanoma patients. To test this hypothesis, we studied the necrosis-related release of MSH from human melanoma cells, using a specific radioimmunoassay. The studies of fine-needle biopsies indicated that most of the human melanoma tumour exudates tested contained very high MSH concentrations (>500pg/ml; 14/15), while plasma levels were generally normal (≤25pg/ml; 10/15). The level in an exudate from a non-melanoma tumour type was