Mitogenic activity of pituitary hormones on cell cultures of normal and carcinogen-induced tumor epithelium from rat mammary glands.

Cell suspension containing normal or tumor epithelium were readily obtained by enzymatically digesting rat mammary glands from perphenazine-treated (prolactin-hypersecreting) cycling, female virgin animals or hormone- responsive mammary tumors from animal treated with dimethylbenzanthracene. Cell suspensions were fractioned into predominantly epithelial and predominantly stromal cells by their differential rates of attachment to culture dishes. Both normal mammary and tumor epithelial cells were characterized by the presence of specific cell-junctional complexes, desmosome-like structures, surface microvilli, and their ability to synthesize casein. Serum-dependent protease activity was greater in cultures derived from tumors, and cells from such cultures grew in agarose whereas those from the non-neoplastic gland did not. The addition of prolactin to the culture medium stimulated DNA synthesis in primary or secondary epithelial cultures from tumors, whereas additional insulin and hydrocortisone with prolactin were required for similar levels of DNA synthesis in cultures from non-neoplastic glands. The fraction of cells synthesizing DNA was, however, smaller than that with 10 percent serum measured in the same time period. Both growth hormone and epidermal growth factor stimulated DNA synthesis but to a lesser extent than did prolactin. Prolactin with hydrocortisone and insulin were relatively inactive in promoting DNA synthesis of the nonepithelial cells whereas pituitary fibroblast growth factor was more active. These mitogenic effects were obtained when the hormones were added to the medium at near physiological concentrations, and paralleled the known activities of the hormones in control of mammary gland growth and development in the rat.

Loss of production of myoepithelial cells and basement membrane proteins but retention of response to certain growth factors and hormones by a new malignant human breast cancer cell strain.

Digestion of primary breast cancers and their metastases with collagenase yields cell clusters which can be selectively isolated from stromal cells and from the less malignant-looking epithelium of the primary tumors by their failure to attach as rapidly to collagen gel. Continued passage in culture of one preparation of cell clusters has yielded a continuously growing cell strain, termed Ca2-83. This strain continues to grow mainly as cell clusters with doubling times of 10 to 14 days, although some clusters eventually adhere to plastic substrata. Two morphological extremes of cell were observed, smaller polygonal or cuboidal cells and larger, often-multinucleated cells which contain fat droplets. Cell clusters grew in a gland-like pattern similar to those of the original carcinoma and formed small nodules in 50% of recipient nu/nu mice. Both morphological forms of Ca2-83 in culture or in tumor nodules stained immunocytochemically with epithelial cell-specific antisera to epithelial membrane antigens and to human keratins but not to laminin or actin. Cultures of Ca2-83 failed to synthesize laminin under conditions where its synthesis was observed in a rat myoepithelial cell line. Ultrastructural analysis of the cell clusters has identified microvilli coated with epithelial membrane antigens and junctional complexes typical of secretory epithelia in both morphological forms, but no characteristics of myoepithelial cells or basement membranes were observed. The DNA content of the cultures increased in response to serum, a bovine pituitary fraction, and insulin. Numbers of cell clusters were also increased in the presence of culture medium exposed to preadipocytes, myoepithelial- or mesothelial-like cells/stromal cells, or to prostaglandin E2.

Trypan blue: identification and teratogenic and oncogenic activities of its coloured constituents.

Three coloured substances frequently present as contaminants in commercial samples of trypan blue have been identified as those monoazo dyes in which 4-amino-3,3'-dimethyl-biphenyl, 4-amino-3,3'-dimethyl-4'-hydroxy-biphenyl or omicroc-tolidine are coupled to H-acid. These dyes have been synthesized and, together with purified samples of trypan blue, tested for teratogenic activity in mice and oncogenic activity in rats. Unpurified trypan blue was both teratogenic and oncogenic; purified trypan blue, was teratogenic but only weakly oncogenic; the monoazo dyes possessed neither activity. It is concluded that the main blue component of trypan blue is the teratogenic principle and that some as yet unidentified component of the purple fraction either is the main oncogenic principle or potentiates the action of the blue component.

Phenotypic responses of mouse mammary tumours and normal mammary epithelium cultured in collagen gels: correlation with tumour type and progression.

Mammary tumours in female BR6/Icrf mice and the corresponding contralateral normal mammary glands were disaggregated with collagenase and the epithelial structures released ('organoids') separated from other cellular components by filtration. The organoids were established in primary culture in a collagen matrix and the outgrowths obtained were studied by light microscopy and time-lapse cinemicroscopy. The pattern of three-dimensional outgrowths produced was found to be specific to the original tissue. Organoids from normal tissue formed a characteristic outgrowth designated Pattern A. Normal tissue from pregnant mice formed an additional characteristic outgrowth (Pattern A') which has not been described previously. Pregnancy-dependent tumours produced a distinctive phenotypic outgrowth designated Pattern D, whereas pregnancy-independent tumours gave a different distinctive Pattern B as well as a unique specific outgrowth designated Pattern C. Outgrowths of Pattern D from a pregnancy-dependent tumour were removed from culture and implanted into a syngeneic female mouse. Tumours arising in the host were found to be pregnancy-independent and showed phenotypic outgrowths in subsequent culture of pregnancy-independent Patterns B and C. The results show that the type of outgrowths in these cultures correlates with the biology of the tissue in vivo and that changes in tumour progression in vivo are accompanied by alterations in phenotypic outgrowths in culture.