Potentiation of the Cell Growth Inhibitory Effect of β Interferon by Mopidamole

It was suggested that the antitumor effect of the interferons is based in part on their ability to stimulate increased cAMP production. We have explored the interaction of human fibroblastic β interferon (HFIF) with a cAMP decomposition inhibitory pyrimido-pyrimidine derivative, Mopidamole (RA-233) in cultures of neoplastic and normal cell lines. Mopidamole potentiated the growth inhibitory effect of HFIF in cultures of ES-1 malignant melanoma cells, LNCaP prostatic carcinoma cells, RT-4 transitional carcinoma cells, HT-29 colon adenocarcinoma cells and in diploid fibroblast Cells.