CASEIN PRODUCTION BY HUMAN BREAST-CANCER

Abstract

Casein was measured in the sera of breast cancer patients, breast tumors and breast cancer cells in long-term tissue culture using a sensitive and specific radioimmunoassay. Levels present in breast cancer sera were not elevated above control values. Eight of 47 (17%) of the tumor samples tested were positive for casein, the highest level representing 0.003% of the soluble protein. When 7 human breast cancer cell lines were assayed for casein, the results were uniformly negative even under conditions of stimulation by lactogenic hormones. Direct immunoprecipitation of labeled cellular protein supported the negative result of the radioimmunoassay. It appears that casein production is not a common characteristic of most human breast cancers.