The biochemical and immunocytochemical characterisation of an antigen on the membrane of basal cells of the epidermis

Clinical and biological significance of HSP89 alpha in human breast cancer

In order to isolate and characterize genes whose expression may be altered in breast malignancy, we screened a cDNA library with a polyclonal anti-serum against breast-cancer-metastasis membranes and isolated several immunopositive clones. One of these, AJ1, was analyzed in detail and found to be expressed at varying levels as a 3.3-kb mRNA in all of 143 breast cancers. High expression was associated with lymph-node involvement (p = 0.03). Comparison between high- and low-expressing groups showed a significant difference at 4 and 6 years for both overall (p = 0.004 and p = 0.002 respectively) and disease-free (p = 0.0001 and p = 0.04 respectively) survival, but not at 11 years. AJ1 was expressed at much lower levels in non-malignant biopsies as compared with malignant tissue (p = 0.001). Expression was observed in breast-cancer cell lines MCF-7, ZR-75-1, T47D, MDA-MB-231 and HBL 100. Partial sequence analysis of the 620 bp clone showed complete homology with human heat-shock protein 89 alpha. In addition to being heat-inducible in all the breast cell lines examined, AJ1 levels were increased by estradiol (blocked by cyclohexamide and tamoxifen), EGF, oxytocin and vasopressin in a time-dependent manner in MCF-7 cells and by estradiol, EGF, prolactin and hydrocortisone in T47D cells. In MDA-MB-231 cells, EGF caused down-regulation of AJ1 mRNA levels. The increasing evidence for the association of heat-shock proteins with steroid receptors suggests that AJ1 may play an important role in the control of estrogen-receptor transcriptional activity in breast cancers.

Relationship of growth factors and differentiation in normal and neoplastic development of the mammary gland

The different mammary cell lines described herein appear to be representative of the cell types found in both normal glands and benign tumors of rats and humans. The epithelial cell lines can differentiate to both alveolar-like and myoepithelial-like cells in culture. The epithelial cell lines and particularly those cell lines representing intermediate stages in the myoepithelial differentiation pathway are candidates for the epithelial stem cells found in rat and possibly in human terminal ductal structures. The systemic mammatrophic hormones that are thought to control the growth of the mammary gland in vivo have little or no stimulatory effect alone on the growth of normal and neoplastic rat mammary cells in culture. The pituitary growth factors (fibroblast growth factor [FGF] and pituitary-derived mammary growth factor [PMGF],) and the growth factors released from the different cell lines, (stromal prostaglandin E2 [PGE2] and myoepithelial transforming growth factor alpha [TGF-alpha]) are much more potent mitogenic agents for the mammary cell lines. The ability of FGF and epidermal growth factor (EGF) -related molecules to simulate growth of the different mammary cell types in culture correlates with the presence of their high-affinity receptors. Thus these growth factors are promising candidates for some of the primary effectors of mammary growth in vivo. Malignant mammary epithelial cells have a greatly reduced rate of growth compared to their normal and benign counterparts. They also fail to differentiate or to respond to PMGF but can still respond to PGE2 and TGF-alpha. In addition, highly malignant variants appear capable of adapting to a new growth environment in vivo. This suggests that simple molecular explanations based solely on the autostimulation of cell growth may not be sufficient to explain some of the properties of the slowly growing, highly malignant cells.

Differentiation of simian virus 40 transformed human mammary epithelial stem cell lines to myoepithelial-like cells is associated with increased expression of viral large T antigen

Cloned simian virus 40 (SV40)-transformed human breast epithelial cell lines can differentiate to myoepithelial-like cells, and these can be isolated as clonal cell lines. Immunofluorescent and immunocytochemical analysis of such cell lines growing on plastic surfaces, collagen gels, and as tumor-nodules in nude mice indicate that all the cell lines produce SV40 large T antigen, but that the production of this antigen is qualitatively increased in the myoepithelial-like cells and cell lines. The myoepithelial-like cell lines produce 4-6 times more immunoprecipitable large T antigen than the parental epithelial cells. The amount of mRNA for large T antigen is also increased by 3.5-5-fold in the myoepithelial-like cell lines when analysed by dot-blot or by Northern hybridisations. Thus, differentiation along the myoepithelial-like cell pathway is associated in these SV40-transformed cells with increased expression of the viral large T antigen. It is suggested that immortalization of primary breast epithelial cell cultures may be, in part, due to the expression of large T antigen preventing processes of terminal keratinization.

Isolation of simian virus 40-transformed human mammary epithelial stem cell lines that can differentiate to myoepithelial-like cells in culture and in vivo

Simian Virus 40 (SV40) transformation of primary cultures of human mammary epithelial cells has yielded a cloned epithelial-like cell line and a representative, single-cell subclone. Although apparently homogeneous, both cloned cell lines can also yield small numbers of three other cell types. The more-elongated cell type can be obtained directly by replating cells from the medium of the epithelial-like cell cultures or by picking and culturing single cells to form representative lines. Immunofluorescent and immunocytochemical analysis of these cell lines growing on plastic or as tumor-nodules in nude mice for epithelial membrane antigens, various cytokeratins, various actins, laminin, Type IV collagen, the common acute lymphoblastic leukemia antigen (CALLA), and a 135-kDa glycoprotein confirm the epithelial nature of the epithelial-like cells and suggest a myoepithelial origin for the more-elongated cell type. Ultrastructural analysis largely confirms the results, although the myofilamental bundles can be scanty in the growing myoepithelial-like cells. The other two cell types are possibly related to the keratinizing and casein-secreting cells seen in the epithelial tumor-nodules before and after mating the mice, respectively. The myoepithelial-like cells produce 5- to 17-fold more laminin, Type IV collagen, CALLA, and the 135-kDa glycoprotein than the epithelial cells, and all of these antigens are preferentially found on myoepithelial cells in vivo. It is suggested that the SV40-transformed epithelial cell is an immortalized form of human mammary stem cell which can differentiate in culture and in vivo to myoepithelial-like cells.

Cell-surface peptidases as modulators of growth and differentiation

Some of the many cell-surface antigens defined by the CD (cluster differentiation) nomenclature have lately emerged as proteins with well-characterised enzymic activities. One important example is CD10 or CALLA (common acute lymphoblastic leukaemia antigen), which is identical to endopeptidase-24.11, an enzyme with an important role in the hydrolysis of biologically active peptides. CD13 and CD26 are also surface peptidases. These enzymes, which have a wide distribution on the surfaces of various cell types, may have specific roles in the control of growth and differentiation in both haemopoietic and epithelial cell systems.

Characterisation of a messenger RNA selectively expressed in human breast cancer

A complementary DNA library from MCF-7 cells was screened using 32P-cDNA derived from a breast carcinoma and from normal breast tissue. From 10(5) plaques (20% of library) we obtained a clone (Md2) which was differentially expressed in the carcinoma. The distribution of its corresponding transcript of 6-700 nucleotides was examined in normal and neoplastic cells, by filter and in situ hybridisation. We observed localisation of 35S-Md2 to the tumour cells of breast cancers with no significant reaction over stromal or vascular elements or on normal ductal epithelia. M13 sequencing showed Md2 to be 250 nucleotides in length, of which 197 were homologous to the 3'-untranslated region and a short open reading frame of the pS2 gene (Masiakowski et al., 1982). Md2 mRNA was found principally in breast carcinoma cell lines and tumours, with low levels in benign breast disease and no expression in non-breast squamous cell lines. Approximately 43% (23/54) of carcinomas contained this mRNA (varying from + to + + + + level); it was present in 20/38 (53%) of ER positive carcinomas compared to 3/16 (19%) of ER negative carcinomas. In 21 patients who had undergone primary endocrine therapy for recurrent disease expression of Md2 in the primary tumour correlated with the subsequent response to treatment (P = 0.041) and was of similar predictive value as ER status. Both tests correctly predicted outcome in about 76% of cases.

Expression of membrane glycoproteins in normal keratinocytes and squamous carcinoma cell lines

Con A acceptor glycoproteins were analyzed by 2D-PAGE and 125I-Con A overlay in three squamous carcinoma cell lines and compared with those in the simian virus (SV40)-transformed keratinocyte cell line SVK-14 and in normal keratinocytes. The majority of the glycoproteins identified by this technique were expressed at similar levels in all of the cells examined, independent of the culture conditions used. A cell surface glycoprotein gp34 (MW 34 kDa, pI 5.1) was increased in the tumor cells compared with normal keratinocytes and expression varied with the culture density. Another glycoprotein, gp21 (MW 21 kDa, pI 6.3), was found to be increased in expression in normal keratinocytes and stratified hyperconfluent cultures of squamous carcinoma cell lines. This paper describes the potential of this technique to identify membrane glycoproteins which may be expressed as a function of proliferation or differentiation.

Characterization of human mammary cell types in primary culture: immunofluorescent and immunocytochemical indicators of cellular heterogeneity

Parenchymal organoidal structures that were obtained from collagenase digestion of reduction mammoplasty specimens of apparently normal human breasts have been grown in short-term primary cultures, either on plastic or on floating gels of polymerized rat-tail collagen. Three morphologically distinct major cell types are readily observed in both systems: cuboidal cells, which occupy apical positions on collagen gels; larger, epithelioid, or basal cells on gels; and elongated cells which penetrate into the gel. In addition, a fourth cell type, that of large, flat cell, is observed less readily by phase contrast microscopy on the surface of cultures grown on plastic. Immunofluorescent and immunocytochemical staining of cultures on plastic or histologic sections of cultures on gels have been undertaken with antisera and other histochemical reagents that stain the different parenchymal cell types in vivo. Thus antisera to epithelial membrane antigen(s), monoclonal antibodies (MABs) to the defatted mammary milk fat globule membrane, peanut lectin, and keratin MAB LE61, which preferentially stain the epithelial cells of ducts in vivo, also stain the cuboidal/apical cells in vitro. The large, flat cells are stained intensely by the first three reagents but not by the last one. Antisera to collagen IV, laminin, fibronectin, actin, keratin MAB LP34, MABs to the common acute lymphoblastic leukemia antigen, and MAB LICR-LON-23.10, which showed enhanced staining for the ductal myoepithelial cells in vivo, also stain the epithelioid/elongated cells in vitro. However, the effect of the last four reagents is reduced considerably in most elongated cells, and MAB LP34 stains the large, flat cells intensely. Heterogeneous cells of intermediate morphologies and staining patterns between the cuboidal cells and large, flat cells are related to mammary epithelial cells. whereas the large epithelioid/elongated cells have some characteristics of myoepithelial cells, and that intermediate forms may exist in culture between the two parenchymal cell types.

Human breast epithelial xenografts: an immunocytochemical and ultrastructural study of differentiation and lactogenic response

Fragments of ductal and lobular epithelium ('organoids') produced by collagenase digestion of reduction-mammoplasty specimens were injected into athymic 'nude' mice. These heterospecific tissues were accepted without rejection, and the presence of xenografts was confirmed by cytology, immunocytochemistry and chromatin staining. Lactation, as confirmed by immunocytochemical and ultrastructural criteria, was observed in the grafted human epithelium during murine pregnancy at both intra- and extra-mammary sites.

Analysis of differentiation antigens on normal and carcinogen-altered rat epithelial cells in vivo and in culture

Two murine monoclonal antibodies, 3BG8 and 9BG8, which were raised against a rat tracheal squamous-cell-carcinoma cell line, recognize cell-surface antigens on normal rat squamous epithelium (skin, esophagus, vagina, and cornea) as well as on carcinogen-exposed, immortalized, rat tracheal epithelial cells. Monoclonal antibody 3BG8 binds to a 115-kilodalton cell-surface protein on undifferentiated basal cells of the epithelium, while the binding of the other antibody, 9BG8, occurs in both differentiated and undifferentiated populations of normal squamous epithelium and squamous cell carcinomas. Undifferentiated tracheal carcinomas bound only the 3BG8 antibody. No binding of either antibody was detected on normal tracheal mucociliary epithelium. Only under conditions that induce squamous differentiation of rat tracheal epithelium was binding of 3BG8 and 9BG8 detected. For reasons which are not clear at present, 9BG8 dramatically inhibits the growth of normal tracheal and esophageal cells in primary culture, whereas only 3BG8 affects the growth of carcinogen-altered tracheal cell lines. Based on antigen characterization and distribution, it is concluded that the 3BG8 and 9BG8 epitopes are localized on differentiation antigens which differ from others that have been previously described.

Display of three-parametric data acquired by a flow cytometer

A program for producing contour maps of three-parameter flow cytometric data is described. The program is written in Pascal and can be implemented on any microcomputer with a graphics screen.

Stem cells and the development of mammary cancers in experimental rats and in humans

Evidence based on immunocytochemical staining and ultrastructure suggests that morphological gradations between epithelial and myoepithelial cells, and possibly between epithelial cells and alveolar-like cells occur in terminal ductal structures of rat and human mammary glands. The benign carcinogen-induced rat and benign human mammary tumors can contain epithelial, myoepithelial-like and alveolar-like cells, whereas the malignant counterparts mainly contain only epithelial-like cells. Clonal epithelial cell lines from normal rat mammary glands, benign tumors, and SV40-transformed human mammary glands can differentiate to either myoepithelial-like or alveolar-like cells. In those of the rat, the differentiation processes occur in steps: intermediate cells along the myoepithelial-like pathway resemble intermediates in terminal ductal structures in vivo, and can also generate certain well-differentiated mesenchymal elements of the original tumours. Differentiation of the benign rat cells to alveolar-like cells with mammatrophic hormones and retinoids in vitro leads to a reduction in their tumor-forming ability in vivo. Cell lines from malignant rat mammary tumors of increasing metastatic potential and from human ductal carcinomas largely fail to yield myoepithelial-like or alveolar-like cells and are relatively slow-growing. Growth of the rat mammary epithelial cells in culture is stimulated by a pituitary-derived mammatrophic growth factor (PMGF), prostaglandin E2, and alpha-transforming growth factor; the response of the malignant cell lines to PMGF is reduced. It is suggested that stem cells exist in the rat and human glands that are capable of differentiating to the other major cell types of the mammary parenchyma, and that during the carcinogenic process they generate genetically unstable cells which lose their ability to differentiate and attempt to maximise their intrinsically slow growth rate.