Production and secretion of two vasoactive peptides, endothelin-1 and adrenomedullin, by a colorectal adenocarcinoma cell line, DLD-1

Production and secretion of endothelin-1 (ET-1) and adrenomedullin (ADM) by a cultured human colorectal adenocarcinoma cell line, DLD-1, were studied by radioimmunoassay and Northern blot analysis. Both immunoreactive (IR)-ET and IR-ADM were detected by radioimmunoassay in the culture medium of DLD-1 (IR-ET 0.86 ± 0.05 fmol/10⁵ cells/ 24 h; IR-ADM 1.20 ± 0.09 fmol/10⁵ cells/24 h; n = 5, mean ± SEM). An analysis by reverse-phase high-performance liquid chromatography (HPLC) of the IR-ET in the culture medium showed a major immunoreactive peak in the position of ET-1. Reverse-phase HPLC of the IR-ADM in the medium showed three immunoreactive peaks, one of which eluted in the position of human ADM. Northern blot analysis showed the expression of ET-1 mRNA and ADM mRNA in the DLD-1 cells. Treatment with interferon-γ (1-100 U/ml) for 24 h decreased the IR-ET levels in the culture medium but significantly increased IR-ADM levels. This study has shown the production and secretion of two vasoactive peptides, ET-1 and ADM, by DLD-1 colorectal adenocarcinoma cells. The secretion of IR-ET was decreased by treatment with interferon-γ. These findings suggest possible pathophysiologic roles for ET-1 and ADM in colon mucosal epithelial cells and tumors derived from them.