Detection of casein messenger RNA in hormone-dependent mammary cancer by molecular hybridisation

Estrogen Receptors and Post-Receptor Markers in Human Breast Cancer: A Reappraisal

Several major defects in the estrogen receptor pathway have been evidenced in most human breast cancers by an immunofluorescence tracing of estradiol receptor complexes at the single cell level. Endogenous peroxidase seems a reliable postreceptor marker for estrogen-sensitive breast cancer cells. Since almost all human breast cancers appear to include both hormone-sensitive and autonomous cell populations, a combined use of endocrine and cytotoxic regimens is urged. The hormonal regulation of tumor growth parameters could be exploited in order to achieve a maximum recruitment of synchronized tumor cells at risk to chemotherapy.

Riboflavin carrier protein: a serum and tissue marker for breast carcinoma

We have earlier shown that the estrogen-modulated riboflavin carrier protein (RCP) first isolated from the chicken egg is evolutionarily conserved in mammals and is elaborated by lactating mammary gland as demonstrated with rat mammary epithelial cells in culture and confirmed by isolation of the vitamin carrier from bovine milk. In view of several earlier reports that many milk proteins as well as other estrogen-inducible proteins are up-regulated and secreted into circulation in animal models and in women with neoplastic breast disease, we analyzed serum RCP levels in a double-blind study using a specific radioimmunoassay in pre- and post-menopausal women with clinically diagnosed breast cancer at early and advanced stages of the disease and compared these levels with those in normal age-matched control volunteers. Our data reveal that the serum RCP levels in cycling breast cancer patients are 3- to 4-fold higher (p < 0.01) than those in their normal counterparts. This difference in circulatory RCP levels between cancer patients and their age-matched normal counterparts is further magnified to 9- to 11-fold (p < 0.005) at the post-menopausal stage. In addition, there seems to be a good correlation between rising RCP levels and disease progression, since significantly higher RCP concentrations (p < 0.005) are encountered in patients with advanced metastasizing breast cancer versus those with early disease. Using specific monoclonal antibodies, RCP could be localized immunohistochemically in the cytoplasm of invading neoplastic cells of lobular and ductal carcinomas of the breast, indicating that the malignant cells are probably the source of the elevated serum RCP levels in breast cancer. These findings suggest that measurement of circulatory RCP and the immunohistochemical staining pattern of RCP in biopsy specimens could be exploited as an additional marker in diagnosis/prognosis of breast cancer in women.

Modulation by concanavalin A of the hormonal response in DNA-synthetic and transcriptional activity of a mouse mammary adenocarcinoma culture

The tissue responds in culture differently to each of the tested hormones. Insulin, but not prolactin or hydrocortisone, was mitogenic to the culture, but did not alter the overall transcriptional activity pattern displayed by the insulin-free cultures. Prolactin stimulated transcriptional activity above control levels between days 2 and 6 of culture, but hydrocortisone was inhibitory to both DNA-synthetic and transcriptional activity of the culture. Upon initial 24-hr treatment with 50 micrograms/ml monovalent concanavalin A, the tissue altered its hormonal sensitivity in the examined activities, but the presence of any one of the hormones in the culture medium abolished the individual effect of concanavalin A. With hydrocortisone, however, the individual effects of the lectin and the hormone interacted in cultures treated with both compounds, suggesting a type of intracellular communication with the membrane, operative in this mammary cell line, that may involve channels of biochemical changes energized by a hydrocortisone stimulus.

Insulin responsiveness of a mouse mammary adenocarcinoma culture in the expression of two proliferation-derived cytoplasmic proteins

Insulin induced in organ culture of a mouse mammary adenocarcinoma the expression of two cytoplasmic proteins of molecular size 72 and 49 kD. In freshly excised tumor both proteins are present in relatively large amounts, but their concentration became greatly diminished during culture in insulin-free media, indicating sensitivity to post-transcriptional modification which was activated in vitro in the absence of insulin. In insulin cultures the two proteins reappeared after two culture days, their concentration becoming increased thereafter with time of culture, but their expression could not be correlated with the biphasic pattern of transcriptional activity fluctuation recorded during culture similarly to insulin-free cultures. Insulin on the other hand stimulated two waves of doubling of DNA synthesis during 6 culture days. The results demonstrate insulin responsiveness in culture of a proliferative fraction of the tumorous cell population in this adenocarcinoma line in the synthesis of two sensitive proliferation-derived cytoplasmic proteins. The possible biological significance of these proteins is discussed.