Adrenocorticotropin, β-Lipotropin, β-Endorphin, and Corticotropin-Releasing Factor-Like Activity in an Adrenocorticotropin-Producing Nephroblastoma

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Abstract
A rare case of an ACTH-producing nephroblas-toma is reported in a 5-yr-old girl. The tumor obtained at surgery contained 505 ng/g wet wt immunoreactive ACTH and 85 ng/g bioactive ACTH. A corticotropin-releasing activity equivalent to 0.03 NIAMD-rat-HE-RP-1/mg wet tissue was demonstrated in tumor extracts using rat pituitary cell cultures. Immunoreactive (IR) ACTH, β-lipotropin (β-LPH), and β-endorphin were assayed in eluate fractions from a Sephadex G-75 gel filtration of tumor extracts. The major IR ACTH peak eluted in the void volume, indicating so-called big ACTH. Another peak eluting between the void volume and human β-LPH presumably represents intermediate ACTH (23 K ACTH). A small peak of IR ACTH was eluted in the region of human ACTH-(1–39). The major IR β-LPH peak was observed in the region of big ACTH and β-LPH. The major β-endorphin peak coeluted with big ACTH and a small peak was observed in the region of β-LPH, but there was no significant peak in the β-endorphin region. This suggests that the tumor produced mainly big ACTH and that 23 K ACTH and yS-LPH were also produced, but productions of ACTH-(1–39) and β-endorphin were greatly hindered, probably by the lack of peptidases. The results showed that big ACTH displaced ACTH-(l–39), β-LPH, and β-endorphin from their antibody. It suggests that big ACTH contains a common precursor molecule of ACTH-(l–39), β-LPH, and β-endorphin.

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