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B B Asch

Publications and source records attributed to B B Asch.

At least 37 records · Page 2Linked to original sources
PubMed1991

Comparative growth of normal and malignant mouse mammary epithelium cultured serum-free on a biomatrix from preadipocytes.

Growth of normal and malignant mouse mammary epithelial cells (MMEC) on a biomatrix of substrate-attached material from 3T3-L1 preadipocytes was evaluated to devise culture conditions that are suitable for transformation studies but do not involve embedding cells in a gel. The biomatrix was prepared as described by Levine and Stockdale, and serum-free medium contained bovine serum albumin, insulin, progesterone, prolactin, and linoleic acid. Each cell type produced a distinctive pattern of colony architecture in this culture system. Cells from virgin mice (vMMEC) usually formed elaborate, three-dimensional structures resembling ducts and alveoli; cells from pregnant mice (pMMEC) grew as flat monolayers; and tumor cells grew in multilayered clusters. Cell growth was monitored by an assay for succinate dehydrogenase. Similar growth rates were found through Day 8 in cultures of vMMEC and D2 carcinoma cells. Growth of vMMEC slowed thereafter, whereas tumor cells typically continued growing through Day 14 to 18. Increase in cell number during 18 days in culture was 3-, 7-, 9-, and 11-fold for cells from pregnant and virgin mice, BALB/cfC3H and D2 carcinomas, respectively. The percent cells in S phase on Day 2 of culture was 9% for pMMEC, 4 to 11% for BALB/cfC3H tumor cells, 20% for vMMEC, and 24% for D2 tumor cells. Thus, this culture system promotes extended growth of MMEC and offers several advantages over embedding cells in a collagen gel. It may therefore be applicable to in vitro transformation studies with MMEC.

Adipose Tissue↗
PubMed1991

Effects of cytoskeletal perturbation on the sensitivity of Ehrlich ascites tumor cell surface membranes to mechanical trauma.

Evidence presented previously indicated that shape changes in circulating cancer cells within the microvasculature may lead to rapid, lethal rupture of the cell surface membranes, thereby contributing to the inefficiency of this phase of hematogenous metastasis. As the cytoskeleton is known to regulate cell shape and, in at least some cases, to be attached to the surface membrane, we have determined whether or not it plays a role in inhibiting lethal, deformation-associated, mechanically induced surface membrane trauma. Thus, Ehrlich ascites tumor (EAT) cells were treated with different cytoskeleton-perturbing agents, and their susceptibility to filtration trauma on passage through Nuclepore membranes was determined. In contrast to the involvement of the cytoskeleton in nonlethal cell deformation, agents which disrupt intracellular networks of microtubules, microfilaments and intermediate filaments had little or no direct effect on EAT cell susceptibility to rapid, mechanically induced, lethal trauma.

Acrylamide↗
PubMed1990

Lipids noncovalently associated with keratins and other cytoskeletal proteins of mouse mammary epithelial cells in primary culture.

Lipids noncovalently associated with cytoskeletal (CS) proteins of mouse mammary epithelial cells (MMEC) grown in primary culture were analyzed. A CS fraction, prepared by subjecting MMEC to 1.5 M KCl and 1% Triton X-100 in phosphate buffered saline (pH 7.4), was extracted 4-6 times with chloroform/methanol. Thin-layer chromatography (TLC) indicated that in comparison to whole cell lipid extracts, CS lipids consisted mostly of neutral lipids, especially triacylglycerols and, possibly cholesteryl esters. TLC analysis of chloroform/methanol CS extracts prepared from MMEC that had been incubated 4 h in [3H]palmitate revealed similar results, with the majority of label appearing in triacylglycerols and other neutral lipids. By autoradiography of sodium dodecyl sulfate polyacrylamide gels, all of the major CS proteins appeared labelled. The major regions of autoradiographic density of the gel were excised, the protein solubilized, and the lipids extracted and subjected to TLC. Most of the radiolabel appeared at the origin and ion front and resolved as neutral lipids. In contrast, keratins of 54-55 kDa and 46 kDa appeared to be associated noncovalently with a higher ratio of polar lipids (possibly phospholipids) to nonpolar (neutral lipids). Very little radioactivity, mostly neutral lipid, was associated with actin. A previously unidentified CS component of 30 kDa had primarily noncovalently bound neutral lipid. The results are discussed in terms of the apparent interactions of keratin filaments with the plasma membrane, nuclear envelope and cytoplasmic organelles.

Animals↗
PubMed1990

Expression of the retrotransposons, intracisternal A-particles, during neoplastic progression of mouse mammary epithelium analyzed with a monoclonal antibody.

In order to develop new probes for investigating cellular alterations accompanying neoplastic progression of mouse mammary epithelium, rat monoclonal antibodies were prepared against cytoskeletal extracts of cultured normal and malignant mouse mammary epithelial cells. One of these antibodies, VG10, reacted in immunofluorescent staining with the majority of mouse mammary epithelial cells from hyperplastic alveolar nodule outgrowth lines of hormonal, chemical, and viral etiologies and the primary adenocarcinomas arising spontaneously from the nodules. Moreover, most mammary carcinomas developing in BALB/cfC3H, BALB/cV, and 7,12-dimethylbenzanthracene-treated BALB/c mice also had cells recognized by VG10. In contrast, normal mouse mammary epithelial cells from virgin and pregnant mice were unreactive. Immunoelectron microscopy identified the reactive component in the abnormal cells as intracisternal A-particles (IAPs), endogenous retrovirions with the ability to transpose in the mouse genome. Western blotting experiments established that the VG10 antibody is specific for the Mr 73,000 gag protein of IAPs. The results indicate that expression of IAPs is a common occurrence in the evolution of malignancy in mammary epithelium of BALB/c mice and may be induced during the transformation of normal cells to the preneoplastic stage. Expression of IAPs is therefore a candidate marker for a step in neoplastic progression in this system and has the potential for contributing to the carcinogenic process.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Concurrent collapse of keratin filaments, aggregation of organelles, and inhibition of protein synthesis during the heat shock response in mammary epithelial cells.

The sequence of heat shock-induced perturbations in protein synthesis and cytoskeletal organization was investigated in primary cultures of mouse mammary epithelial cells (MMEC). Exposure of the cells to 45 degrees C for 15 min caused a marked inhibition of protein synthesis through 2 h after heart. Resumption of protein synthesis began by 4 h, was complete by 8 h, and was accompanied by induction of four major heat shock proteins (HSPs) of 68, 70, 89, and 110 kD. Fluorescent cytochemistry studies indicated that heat shock elicited a reversible change in the organization of keratin filaments (KFs) and actin filaments but had a negligible effect on microtubules. Changes in the organization of KFs progressed gradually with maximal retraction and collapse into the perinuclear zone occurring at 1-2 h after heat followed by restoration to the fully extended state at 8 h. In contrast, actin filaments disappeared immediately after heat treatment and then rapidly returned within 30-60 min to their original appearance. The translocation of many organelles first into and then away from the juxtanuclear area along with the disruption and reformation of polyribosomes were concurrent with the sequential changes in distribution of KFs. The recovery of the arrangement of KFs coincided with but was independent of the resumption of protein synthesis and induction of HSPs. Thermotolerance could be induced in protein synthesis and KFs, but not in actin filaments, by a conditioning heat treatment. Neither protein synthesis nor induction of HSPs was necessary for the acquisition of thermotolerance in the KFs. The results are compatible with the possibility that protein synthesis may depend on the integrity of the KF network in MMEC. Heat shock thus can efficiently disarrange the KF system in a large population of epithelial cells, thereby facilitating studies on the functions of this cytoskeletal component.

Actin Cytoskeleton↗
PubMed1988

Differential expression of keratins 13 and 16 in normal epithelium, benign lesions, and ductal carcinomas of the human breast determined by the monoclonal antibody Ks8.12.

Previous electrophoretic analysis has indicated that keratins 13 and 16 (K13 and K16) are not present in normal human breast epithelium, but K16 is expressed in some ductal carcinomas (Moll et al., Cell, 31: 11-24, 1982). K16 may thus represent a marker for identifying a subset of ductal carcinomas and for distinguishing such tumor cells from normal cells. To explore this possibility further, we have used the monoclonal antibody Ks8.12, reportedly specific for K13 and K16 (Huszar et al., Differentiation, 31: 141-153, 1986), to examine keratin expression in human breast tissues. In immunocytochemistry the antibody reacted with epithelial cells of all normal samples, hyperplasias, and fibroadenomas. The staining was moderate to strong and always heterogeneous, involving most but not all luminal cells of ducts and acini. Myoepithelial cells were never stained. Of twenty-one ductal carcinomas examined, 90% gave a very weak or no reaction. The remaining 10% of cancers exhibited moderate to strong staining in about 50% of tumor cells. Cytoskeletal polypeptides extracted from the tissues and separated by polyacrylamide gel electrophoresis were analyzed by Western blotting to identify the polypeptides recognized by Ks8.12. In samples from normal tissue and a fibroadenoma, the antibody recognized a major Mr 48,000 component, a size appropriate for K16. In extracts from a hyperplasia and two of four carcinomas, the antibody detected a Mr 54,000 polypeptide, as well as a Mr 48,000 band, properties consistent with K13 and K16, respectively. Our results provide the first evidence indicating that K16 is present in normal as well as abnormal human breast epithelium. In addition, the data suggest that K13 may be expressed in some benign lesions and ductal carcinomas of the breast. Accordingly, Ks8.12 may prove to be useful for subclassifying ductal carcinomas and for discriminating between normal and certain benign and malignant disorders of human mammary epithelium.

Antibodies, Monoclonal↗
PubMed1987

In vitro transformation of mouse mammary epithelial cells grown serum-free inside collagen gels.

Mammary epithelial cells from 4-month-old virgin BALB/c mice were cultured inside collagen gels in the following serum-free media: Dulbecco's modified Eagle's medium:Hams's F-12 (1:1) supplemented with: insulin (10 micrograms/ml), bovine serum albumin (5 mg/ml), and epidermal growth factor (5 ng/ml); insulin, bovine serum albumin, progesterone (0.05 microgram/ml), and prolactin (1 microgram/ml); insulin, bovine serum albumin, progesterone, prolactin, and linoleic acid (10 micrograms/ml). Cells proliferated in all these media. The cells were treated with 0.01 micrograms/ml of 7,12-dimethylbenz(a)anthracene or 100 micrograms/ml of N-nitroso-N-methylurea on day 3 of culture and, subsequently, at 1-week intervals for 3-6 weeks. Tetradecanoylphorbol acetate (0.1 micrograms/ml) was added to selected cultures. The cultures were maintained for up to 9 weeks; the cells were then removed from the collagen gels, placed in monolayer culture for 2 days, and removed from monolayer culture, and 5 X 10(5) cells were transplanted to each of the gland-free mammary fat pads of 3-week-old female mice. Approximately 10 weeks after transplantation, the transplanted mammary fat pads were examined for outgrowths. Cells that were not treated with carcinogen and cultured for up to 9 weeks in different serum-free media and transplanted to the gland-free mammary fat pad produced only ductal outgrowths similar in morphology to the ducts of the virgin host's mammary glands. Six treatments with 7,12-dimethylbenz(a)anthracene, of cells grown in the presence of epidermal growth factor, induced 31% spindle cell tumors, 17% ductal hyperplasias, and 5% lobuloalveolar hyperplasias. Cells that were grown in epidermal growth factor and treated three times with N-nitroso-N-methylurea produced 23% ductal hyperplasias and 17% lobuloalveolar hyperplasias. Cells grown in the presence of progesterone and prolactin and treated three times with 7,12-dimethylbenz(a)anthracene produced up to 23% lobuloalveolar hyperplasias and 12% ductal hyperplasias. Three treatments with N-nitroso-N-methylurea of cells grown in progesterone- and prolactin-containing media produced a maximum of 50% lobuloalveolar hyperplasias and 33% ductal hyperplasias. The lobuloalveolar hyperplasias have the characteristics of the precancerous hyperplastic alveolar nodules found in mouse mammary tumorigenesis. The in vitro carcinogen-induced lobuloalveolar hyperplasias were transplantable, maintained their lobuloalveolar morphology in virgin hosts, and produced carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Structural distinctions among human breast epithelial cells revealed by the monclonal antikeratin antibodies AE1 and AE3.

Two monoclonal antikeratin antibodies, AE1 and AE3, were used in indirect immunocytochemistry to examine keratin expression in normal, benign proliferative, and malignant human breast epithelium. Both antibodies reacted strongly with most luminal cells in ducts and acini of normal gland. While AE1 did not stain myoepithelium, AE3 recognized myoepithelial cells of ducts but not acini, implying a cytoskeletal difference between the myoepithelium of these two components. Moreover, the antibodies reacted differently with the myoepithelium of intracanalicular as compared with pericanalicular types of fibroadenomas. Tumour cells of infiltrating ductal carcinomas with a prominent intraductal component stained more homogeneously with AE1 and AE3 than those without intraductal growth. The results provide evidence for two phenotypes of myoepithelial cells and for the presence of cryptic keratin epitopes in human breast epithelial cells. The finding that neither AE1 nor AE3 is a universal detector of these cells has important clinical and experimental implications.

Adenofibroma↗
PubMed1986

A keratin epitope that is exposed in a subpopulation of preneoplastic and neoplastic mouse mammary epithelial cells but not in normal cells.

Three monoclonal anti-keratin antibodies, AE1, AE3, and AE4, were used to compare the expression of keratins in normal, preneoplastic, and malignant mouse mammary epithelial cells growing in primary culture. In indirect immunofluorescence, AE1 did not stain normal cells but did stain a minority of preneoplastic and carcinoma cells. AE3 reacted with a subpopulation of epithelial cells in both the normal and abnormal cultures, except for certain cultures from one type of tumor wherein all of the epithelial cells were reactive. AE4 decorated an elaborate keratin filament network in all cultured mammary epithelial cells, regardless of neoplastic state. In double-label immunofluorescence, a guinea pig anti-keratin antiserum, which reacts preferentially with myoepithelial cells, exhibited coincident staining with AE1 in the tumor cultures and AE3 in the normal and most tumor cultures, indicating that the cells recognized by the antibodies in these populations were myoepithelial. Immunoblot experiments with cytoskeletal polypeptides extracted from the normal and tumor cells demonstrated that the set of keratins recognized by each monoclonal antibody was essentially the same in all of the cells except for a Mr 40,000 component that was present in normal cells but either absent or diminished in the cancer cells. Thus, while normal cells had Mr 40,000 and 50,000 keratins recognized by AE1, the epitope detected by this antibody was apparently concealed or "masked" in situ. AE3 reacted in immunoblots with a major keratin group (Mr 54,000-55,000) and a minor keratin (Mr 57,000), while AE4 reacted only with the Mr 54,000-55,000 keratin species. Because immunofluorescence with AE4 showed that the Mr 54,000-55,000 keratin group was present in all mammary epithelial cells, the AE3-reactive epitope must be masked in the majority of normal and tumor cells. The data therefore showed that epitopes on three major keratins, the Mr 40,000, 50,000, and 54,000-55,000 group, were "masked" in normal cells, whereas in tumor cells "masking" involved primarily the Mr 54,000-55,000 keratin. Attempts to "unmask" the epitopes recognized by AE1 in normal cells or to increase the number of cells reactive with AE3 in the normal and tumor cultures failed. Thus, certain cultured preneoplastic and neoplastic mammary cells with a myoepithelial phenotype have an altered organization of keratins that is manifested by a keratin antigenic determinant which is visible by immunocytochemistry in the abnormal cells but not in normal mouse mammary cells. This is the first demonstration that the immunoreactivity of keratins can be modified during neoplastic progression of epithelial cells.

Animals↗
PubMed1986

Mammary tumorigenesis and tumor morphology in four C3H sublines with or without exogenous mammary tumor virus.

Mammary tumorigenesis was surveyed in retired breeding females in four sublines of the C3H strain: in standard milk-transmitted early oncogenic mouse mammary tumor virus (MMTV)-infected C3H/He and C3H/Ki mice, and in standard milk-transmitted early oncogenic MMTV free C3Hf/He and C3Hf/Ki mice. All of 58 C3H/Ki mice and 98% (306 of 309) of the C3H/He mice developed palpable mammary tumors at average ages of 276 and 284 days, respectively. Thirty-one % (47 of 152) of the C3Hf/Ki mice and 77% (168 of 218) of the C3Hf/He mice developed palpable mammary tumors at average ages of 798 and 757 days, respectively. The mammary tumors removed from C3H/He and C3H/Ki mice were all adenocarcinomas of epithelial origin, and all contained MMTV. The mammary tumors removed from C3Hf/He and C3Hf/Ki mice were either adenocarcinomas or sarcomas. The carcinomas were of epithelial origin and all expressed the late oncogenic endogenous MMTV. The sarcomas were of histiocyte or fibrocyte origin and contained neither virus particles nor MMTV antigenic markers. It is concluded that exogenous standard milk-transmitted oncogenic MMTV oncogenesis in C3H mice is not modified by host genetic factors. In contrast, late oncogenic endogenous MMTV oncogenesis is influenced both by host genetic control of the expression of the late oncogenic MMTV provirus and by the location of the proviral genes in the germline DNA.

Adenocarcinoma↗
PubMed1986

Conservation of epithelial cell phenotypes during hematogenous metastasis from mammary carcinomas.

The phenotypic heterogeneity of epithelial cells during hematogenous metastasis from primary mammary carcinomas of BALB/cfC3H mice was examined. Antisera to keratins were used in immunofluorescence assays to identify epithelial and myoepithelial cells. Both cell types were located in frozen sections of not only the primary lesions but also pulmonary metastases. Tumor cells disseminating to the lungs were recovered from the bloodstream of tumor-bearing mice with the use of a quantitative density gradient centrifugation procedure. Carcinoma cells were detected in the circulation of 62% of mice at the time of assay, but all tumors examined had released cells into the circulation at some point in their history. Epithelial cells and myoepithelial cells were detected simultaneously in 21% of mice, whereas other mice had only epithelial cells (16%) or myoepithelial cells (25%) in their circulation at the time of assay. Single cells and multicellular emboli of each cell type were disseminated, together with similar numbers of heterogeneous emboli containing both epithelial and myoepithelial cells. The evidence shows that the presence of both mammary epithelial and myoepithelial cells in pulmonary metastases from mouse mammary carcinomas can be accounted for by their hematogenous delivery as differentiated cells.

Animals↗
PubMed1985

Expression of keratins and other cytoskeletal proteins in mouse mammary epithelium during the normal developmental cycle and primary culture.

Mammary epithelium is composed of ductal, alveolar, and myoepithelial cells, and undergoes dramatic responses in growth, differentiation, and function to hormonal stimuli during the four stages of the mammary developmental cycle represented in virgin, pregnant, lactating, and involuting animals. To determine if progression of the epithelium through the cycle is accompanied by changes in cytoskeletal composition, particularly the keratins, the polypeptides in cytoskeletal extracts from BALB/c mouse mammary tissues were analyzed by one- and two-dimensional gel electrophoresis combined with immunoblots using polyclonal and monoclonal antikeratin antibodies. The major polypeptides in cytoskeletal fractions enriched in intermediate filaments included seven acidic and three basic components ranging in molecular weight from 40,000 to 90,000. Two major polypeptides of Mr 50,000 and 40,000, along with two minor components of Mr 57,000 and 55,000 were identified as keratins. The polypeptide profiles of mammary glands from virgin, pregnant, lactating, and involuting mice were very similar, indicating a remarkable stability of cytoskeletal composition during hormonal shifts and periods of minimal or maximal cell growth and differentiated function. The data also suggest that ductal and alveolar cells express the same set of cytoskeletal polypeptides, including keratins. Mammary cells grown in primary culture exhibited a loss or reduction in most of the basic polypeptides, a large increase in an acidic Mr 55,000 keratin, and the appearance of a prominent acidic polypeptide of Mr 46,000. The latter results demonstrate that keratin expression in mouse mammary epithelial cells is subject to regulation by certain environmental factors.

Animals↗
PubMed1985

Heterogeneity of keratin expression in mouse mammary hyperplastic alveolar nodules and adenocarcinomas.

The keratins and other cytoskeletal proteins expressed by normal, preneoplastic, and malignant mammary tissues in BALB/c mice and by cells in primary cultures established from these tissues were analyzed and compared. The preneoplastic lesions were hyperplastic alveolar nodules (HAN) derived originally from mice treated by hormonal stimulation (D2), exposed to a chemical carcinogen (C4), or spontaneously expressing mouse mammary tumor virus (CV2) and maintained by serial transplantation. All tumors were mammary adenocarcinomas which developed as primary neoplasms from the HAN outgrowth lines. Cytoskeletal extracts were prepared from the tissues and cultured cells and subjected to two-dimensional polyacrylamide gel electrophoresis. Comparison of the major polypeptides in the normal and abnormal tissue extracts revealed considerable similarities in the cytoskeletal profiles. Three basic and seven acidic polypeptides ranging in molecular weight from 40,000 to 90,000 were regularly identified. However, notable differences were also found. A Mr 55,000 keratin (IEF 55) was prominent in one HAN, the D2, and all tumor tissues but not in normal gland. Likewise, a Mr 46,000 polypeptide (IEF 46), which has been tentatively identified previously as a keratin, was absent in normal epithelium but present in all abnormal tissues except the C4 and CV2 HAN. A Mr 58,000 polypeptide (NEPHGE 58) was not detected in normal gland or the C4 lesions but was found in all other abnormal tissues. The overall pattern of polypeptides in cytoskeletal extracts from normal and abnormal mammary cells in primary culture resembled that of the corresponding tissue but also had important differences. In all cell cultures, IEF 46 and IEF 55 were major species, while the larger and more basic components were markedly reduced. A Mr 56,000 polypeptide (NEPHGE 56) was detected only in C4 HAN and C4 and CV2 tumor cells. Trace or small, variable amounts of a Mr 57,000 basic keratin (NEPHGE 57) were present in normal and D2 tissues and cultured cells. NEPHGE 57 was dramatically increased in C4 and CV2 tissues and cultured cells and may be related to expression of squamous metaplasia and keratinization which are characteristic of these lesions. Although production of IEF 46 and IEF 55 may be associated with neoplastic progression of mammary epithelium, particularly in vivo, the association is not exclusive since normal cells express these polypeptides when grown in primary culture. In addition, correlations between altered keratin expression and the mode of induction of the mammary lesions were not obvious.

Adenocarcinoma↗
PubMed1983

A secreted phosphoprotein marker for neoplastic transformation of both epithelial and fibroblastic cells.

A wide variety of virally and spontaneously transformed fibroblasts secrete a major transformation-related phosphoprotein with a molecular weight (MW), depending on the species of origin, of about 62,000 (62K). Markedly elevated extracellular levels of this major 32P-labelled protein are not simply linked to exponential growth but instead are associated directly with transformation. The phosphoprotein is not antigenically related to p60src, p60c-src or simian virus 40 (SV40) non-viral T antigen, and it is further distinguishable from SV40 non-viral T antigen (pp 53) on the basis of its electrophoretic mobility. In this study we have compared a variety of normal and transformed epithelial cells for secretion of this 32P-labelled protein and have found that this marker distinguishes neoplastic from preneoplastic and normal mouse mammary epithelium and also identifies highly tumorigenic cells derived from guinea pig bile duct epithelium and rat liver epithelium. Because the classical phenotypic properties commonly associated with transformation of fibroblasts cannot be generally used to discriminate tumorigenic from non-tumorigenic epithelial cells, this phosphoprotein, which identifies tumorigenic cells of both fibroblastic and epithelial origin, is likely to be of particular importance.

Acetoxyacetylaminofluorene↗
PubMed1983

Mitochondrial inclusions in selenium-treated mouse mammary epithelial cell lines.

The effects of selenium on three mammary epithelial cell lines (YN-4, WAZ-2t, and CL-S1) grown in vitro were examined by immunocytochemical and transmission electron microscopy technique. The primary effect of selenium at the ultrastructural level was the appearance of electron-dense inclusions within the mitochondrial matrix. The mitochondrial inclusions were seen in all three cell lines, although most readily induced in YN-4 cells, the cell line which is most sensitive to selenium-mediated growth inhibition. Selenium at 5 x 10(-8) and 5 x 10(-6) M did not alter cytoplasmic microtubules or intermediate filament networks, as determined by immunocytochemical staining. Immunocytochemical staining for cytoplasmic filaments and microtubules, and transmission electron microscopy observations, supported the contention that cells from all three cell lines were epithelial in origin, since they contained abundant desmosomes and were uniformly positive for keratin intermediate filaments. Whereas line YN-4 was negative for vimentin intermediate filaments, a minority (5 to 24%) of the cells in lines CL-S1 and WAZ-2t stained positively. In addition, the tumorigenicity of these three cell lines was assessed by in vitro growth assays and in vivo transplantation assays. Cell lines YN-4 and WAZ-2t, but not line CL-S1, were tumorigenic in syngeneic mice. All tumors were mammary adenocarcinomas. Cytochalasin B-induced multinucleation assay and growth as multicellular spheroides correlated positively with in vivo tumorigenicity, whereas saturation density and growth in low Ca2+ medium were not correlated with tumorigenicity. It is speculated that one of the early effects of selenium-mediated growth inhibition may be a modulation of mitochondrial function.

Animals↗
PubMed1981

Identification of mouse mammary epithelial cells by immunofluorescence with rabbit and guinea pig antikeratin antisera.

Few markers are available to identify the three types of mammary epithelial cells--ductal, alveolar, and myoepithelial--especially in pathological conditions and in cell cultures. We have used antisera to human keratins in immunofluorescence to facilitate the identification of the three mouse mammary epithelial cell types. In frozen tissue sections and primary cell cultures, a rabbit antikeratin antiserum specifically stained cytoplasmic filaments in all three types of epithelial cells. A guinea pig antiserum against the same keratin preparation, however, reacted preferentially with filaments in myoepithelial cells and readily detected this cell type in normal, dysplastic, and malignant mammary tissues and cell cultures. Neither antisera reacted with fibroblasts or any other mesenchymal cells. The combined use of the two antikeratin antisera thereby permits rapid surveys of tissue sections and cultures for the localization of not only all epithelial cells but also the subpopulation of myoepithelial cells. Moreover, when mammary cultures established from late-pregnant or lactating mice were stained simultaneously with guinea pig antikeratin and rabbit anticasein antisera, three populations of epithelial cells were mutually exclusive: those stained by anticasein antiserum, those stained by guinea pig antikeratin antiserum, and those stained by neither, consistent with properties of alveolar, myoepithelial, and ductal cells, respectively. These antisera thus offer a tool for studying different epithelial cell types during mammary development, tumorigenesis, and malignant progression.

Animals↗
PubMed1981

Interactions of normal, dysplastic, and malignant mammary epithelial cells with fibronectin in vivo and in vitro.

Previous studies have demonstrated that normal and malignant mouse mammary cells are indistinguishable in many surface-related properties that often denote transformation of other cell types such as fibroblasts. In the present investigation, the interactions of normal, dysplastic, and malignant mammary epithelial cells with fibronectin in tissues and cultures were examined by indirect immunofluorescence. Cells lining the lumina of ducts and alveoli in normal and dysplastic mouse and human mammary tissues abutted a layer of fibronectin along their basal surfaces that included the region of the basement membrane and the underlying stroma. Moreover, double staining for keratin and fibronectin revealed that myoepithelial cells were surrounded by the matrix protein. In contrast, tumor cells in adenocarcinomas and ductal carcinomas were not directly associated with fibronectin. The accumulation of fibronectin in primary cultures prepared from mouse mammary tissues paralleled the distribution seen in vivo. A matrix of fibronectin formed beneath normal and preneoplastic mammary cells within 4 to 6 days after plating, whereas tumor cells were negative, regardless of the age or density of the culture. This correlation with in vivo results did not extend to cells of established mammary tumor culture lines which readily accumulated pericellular networks of fibronectin. Addition of exogenous fibronectin to primary cultures enhanced formation of a basal matrix by normal cells but had no effect on the negative status of the tumor cells. The results indicate that mammary tumor cells in tissues and in primary cultures have an altered capacity to interact with fibronectin. However, this alteration is not necessarily expressed by established mammary tumor cell lines.

Animals↗