VIP receptor activity and signal transduction in the cancerous progression of the mammary epithelium

Specitic VIP receptors with high affinity for the neuropeptide were identified in humam mammary epithelial cells in culture, at various stages of the neoplastic transformation. These [ 125 I] VIP binding sites are functionally coupled to the production of cAMP in normal humam mammary epithelial cells (HMEC) in primary culture (3.2-told stimulation, EC 50 =2.2×10 -10 VIP) and SV40 large T-immortalized and transformed humam mammary epithelial ST cell lines (2-to 9-told stimulation of basal cAMP levels, EC 50 =1.1-1.8×10 -10 M VIP)