Hormone and methylxanthine action on breast epithelial cells.

Human mammary carcinoma cells and normal mouse breast epithelial cells desensitized as the result of treatment with beta-adrenergic agonists. Accumulation of cAMP in the same cells was affected only slightly by caffeine and there was no detectable desensitization or hypersensitization as a result of that treatment. However, as in many other cell types, caffeine was an effective inhibitor of adenosine action. These observations do not support the hypothesis made by Minton and his co-workers (1), that treatment of breast epithelial cells with agents that increase cAMP accumulation leads to hypersensitization rather than desensitization.