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Biomedical subjects

M E Monaco

Publications and source records attributed to M E Monaco.

40 records · Page 3Linked to original sources
PubMed1977

Casein production by human breast cancer.

Casein was measured in the sera of breast cancer patients, in breast cancer tumors, and in 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 forty-seven (17%) of the tumor samples tested were positive for casein, the highest level representing 0.003% of the soluble protein. When seven human breast cancer cell lines were assayed for casein, the results were uniformly negative even under conditions of stimulation by lactogenic hormones. In addition, direct immunoprecipitation of labeled cellular protein supported the negative result of the radioimmunoassay. Thus it appears that casein production is not a common characteristic of most human breast cancers.

Breast Neoplasms↗
PubMed1977

Effects of estrone, estradiol, and estriol on hormone-responsive human breast cancer in long-term tissue culture.

The effects of estrone, estradiol, and estriol on MCF-7 human breast cancer are compared. In this estrogen-responsive cell line, all three estrogens are capable of inducing equivalent stimulation of amino acid and nucleoside incorporation. Estriol is capable of partially overcoming antiestrogen inhibition with Tamoxifen (lCl 46474), even when antiestrogen is present in 1000-fold excess. Antiestrogen effects are completely overcome by 100-fold less estriol. Studies of metabolism of estrogens by MCF-7 cells revealed no conversion of estriol to either estrone or estradiol. All three steroids bind to a high-affinity estrogen receptor found in these cells. The apparent dissociation constant is lower for estradiol than for estrone and estriol, but all three bind to an equal number of sites when saturating concentrations are used. Tritiated estrogens used in binding studies were shown to be radiochemically pure. We conclude that estriol can bind to estrogen receptor and stimulate human breast cancer in tissue culture. Our data do not support an antiestrogenic role for estriol in human breast cancer.

Binding, Competitive↗
PubMed1976

Hormone responsive human breast cancer in long-term tissue culture: effect of insulin.

The mechanisms of steroid and peptide hormone action in human breast cancer are poorly understood. We have previously characterized a cell line of human breast cancer in long-term tissue culture that possesses various steroid hormone receptors and responses, providing a model for the study of steroid hormone action. The present studies describe a human breast cancer in vitro that responds to physiologie concentrations of insulin with an increased rate of macromolecular synthesis and growth. Thymidine and uridine incorporation in cells in serum-free medium are stimulated by 10(-11) M insulin and are maximal with 10(-8) M. Leucine incorporation is stimulated by 5 X 10(-11) M insulin and is maximal with 10(-9) M. Significant stimulation of uridine and leucine incorporation is evident by 3 hr and maximal by 10 hr. A 10-hr lag period exists for insulin stimulation of thymidine incorporation, which is maximal form 14 to 24 hr. The effect of 10(-8) M insulin on macromolecular synthesis is accompanied by a 69% increase above controls in the number of cells after 24 hr. The effect on macromolecular synthesis is observed in glucose-free medium. Insulin's effect on protein synthesis is not blocked by inhibition of RNA synthesis with actinomycin D. Glucocorticoids partially inhibit the action of insulin in these cells. This system provides a model for studying insulin action, and suggests that some human breast cancer may show growth regulation by insulin.

Breast Neoplasms↗