ABSTRACT
The effects of vasoactive intestinal peptide (VIP) antagonists on breast cancer cells were investigated. (N-stearyl, norleucine17)VIP hybrid ((SN)VIPhyb) inhibited specific 125I-VIP binding to MCF7, SKBR3, T47D ZR75-1 and MDA-MB231 cells with high affinity (IC50 values of 0.03-0.06 microM). (SN)VIPhyb, 1 microM, inhibited the ability of 10 nM VIP to cause elevation of cAMP and to increase c-fos mRNA. Micromolar concentrations of (SN)VIPhyb inhibited the proliferation of MDA-MB231 or MCF7 cells using a MTT and clonogenic assay. Using a MTT assay, (SN)VIPhyb enhanced the ability of taxol and doxorubicin to inhibit breast cancer growth. Using nude mice bearing MDA-MB231 xenografts, VIPhyb potentiated the ability of taxol to inhibit proliferation. The results indicate that VIP receptor antagonists increase the ability of chemotherapeutic drugs to kill breast cancer cells.
