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Biomedical subjects

M Stampfer

Publications and source records attributed to M Stampfer.

At least 55 records · Page 3Linked to original sources
PubMed1989

Vimentin rather than keratin expression in some hormone-independent breast cancer cell lines and in oncogene-transformed mammary epithelial cells.

To characterize differences in gene expression between hormone-dependent and hormone-independent mammary carcinoma, we cloned complementary DNAs of genes expressed in a hormone-independent breast carcinoma cell line that were not expressed in a hormone-dependent line. One clone, which was isolated in many copies, coded for the intermediate filament protein vimentin. A complementary DNA clone 1.8 kilobases long included the entire protein-coding region for vimentin. Vimentin was expressed by more than one-half of the hormone-independent breast carcinoma cell lines tested but not by the hormone-dependent cell lines. The cell lines which expressed vimentin expressed only low levels of cytokeratins. The correlation between vimentin expression and more advanced stages of mammary cell transformation was tested in a model system in which immortal, nontumorigenic human mammary epithelial cells or derivative lines transformed with v-ras-H or SV40 T-antigen were found not to express vimentin, whereas a derivative highly tumorigenic cell line transformed by both v-ras-H and T-antigen did express vimentin. Analysis of several other kinds of epithelial carcinoma cell lines showed only rare examples of vimentin expression.

Base Sequence↗
PubMed1989

Keratin expression in human mammary epithelial cells cultured from normal and malignant tissue: relation to in vivo phenotypes and influence of medium.

The luminal and basal epithelial cells in the human mammary gland can be distinguished in tissue sections on the basis of the pattern of keratins they express. Moreover, the invasive cells in primary carcinomas show a keratin profile that corresponds to that of the dominant luminal cell (7, 8, 18, 19). When homogeneous populations of luminal epithelial cells from milk or from breast cancer metastases are cultured the profile of keratin expression seen in vivo is maintained. We have therefore used monospecific antibodies reactive with individual keratins to examine the phenotype of cells cultured in three different media from reduction mammoplasty tissue that contains both luminal and basal cells. The phenotype of cells cultured from primary breast cancers in one of these media (MCDB170) has also been examined. In characterizing cell phenotypes, antibodies to a polymorphic epithelial mucin (PEM) expressed in vivo by luminal cells, and to smooth muscle (a) actin, expressed in vivo by basal cells, have also been used. Our results show that proliferation of different cell phenotypes is selected for in different media. In milk mix (MX) developed for growth of luminal cells from milk, only the luminal cell phenotype proliferates (for only 1 or 2 passages). In medium MCDB 170, which was developed for long-term growth of human mammary epithelial cells from reduction mammoplasty organoids, cells from the basal layer proliferate, while in MM medium the basal phenotype dominates, but a few cells with the luminal phenotype are found. Around passage 3, in medium MCDB 170, most cells senesce and a subpopulation of cells proliferates on further passage. These cells retain expression of the basal epithelial keratins but also express some features characteristic of luminal epithelial cells, suggesting that the basal layer may contain a stem cell that can develop along the luminal lineage. In culture, however, they do not express keratin 19, which in vivo is a feature of the fully differentiated luminal cell. The cells cultured from primary breast cancer in medium MCDB 170 have a similar keratin profile to that of the normal cells cultured in this medium. They do not express keratin 19, even though the invasive cells in primary cancers homogeneously express this keratin in vivo. The invasive phenotype, which in its keratin profile corresponds to the differentiated luminal cell and that of the metastatic cancer lines, cannot be cultured from primary breast cancers using MX, which supports proliferation of the corresponding normal cell.

Breast↗
PubMed1988

Expression of growth factors and oncogenes in normal and tumor-derived human mammary epithelial cells.

The expression of genes which may be involved in the regulation of human mammary epithelial cell growth [transforming growth factors alpha and beta] and tumorigenesis [c-myc, erbB2, epidermal growth factor receptor (EGFR), Ha-ras, pS2] has been compared in similarly cultured normal cell strains and tumor cell lines. We have found that the normal breast cells produce high levels of EGFR mRNA, which are translated into nearly 10(5) low affinity epidermal growth factor-binding molecules/cell. In the estrogen receptor-negative lines examined, the EGFR gene was expressed at levels comparable to those in the normal cells. In contrast, EGFR and transforming growth factor alpha mRNAs were reduced in estrogen receptor-positive tumor lines compared to estrogen receptor-negative lines and normal cells. Steady state mRNA levels for transforming growth factor beta, erbB2, c-myc, and Ha-ras in the normal cells were greater than or comparable to those in all of the breast tumor lines. Furthermore, in the absence of gene amplification, only one of the genes examined (i.e., pS2) was overexpressed in a subset of the tumor cells compared to their normal counterparts. Several reports by other investigators have described overexpression of some of these genes in breast biopsies and in tumor lines in studies lacking normal controls. Thus, our results, in which the same genes were not overexpressed compared to normal cells unless amplified, underscore the importance of including appropriate normal controls in studies aimed at defining aberrant patterns of gene expression in tumor cells.

Breast↗
PubMed1985

Growth of diploid cells from breast cancers.

Cell cultures were derived from normal and cancerous breast tissues and from metastases by methods that selected for relatively adherent epithelial aggregates. Karyotypic analyses of first or second passage cultures yielded predominantly normal diploid cells. Nonclonal aberrations were more common in tumor-derived than in normal cultures. Three of the cultures that originated from metastases were characterized by abnormal clones. These results support observations based on DNA content, which indicate that a considerable fraction of breast cancers are composed predominantly of diploid cells. They differ greatly from chromosomal findings in long-term cultures of tumor effusions and thus emphasize the karyotypic diversity that can be found in tumors from a single tissue of origin--the breast.

Adolescent↗
PubMed1984

Thioesterase II, a new marker enzyme for human cells of breast epithelial origin.

Metabolic, enzymologic, and immunohistochemical techniques have been used to show that a human cell line of breast epithelial origin synthesized medium chain fatty acids via the ubiquitous fatty acid synthetase and a mammary-specific chain-terminating enzyme, thioesterase II. Previous studies in our laboratory with rodents indicated that thioesterase II is expressed exclusively in mammary epithelial cells, an observation consistent with the physiologic role of the enzyme in milk fat synthesis. Results of the present study suggest that the enzyme exhibits a similar cell specificity in its expression in humans and that the specificity is maintained in normal and neoplastic tissues. Thus thioesterase II was detected immunohistochemically in normal human breast epithelia derived from both lactating and nonlactating breast tissue, in cultured cells derived from both primary breast epithelial tumors and from a metastatic tumor of breast origin, and in several human breast epithelial cell lines; the enzyme could not be detected in HeLa cells, in a colon carcinoma, or in a mammary myoepithelial cell line. These findings raise the possibility that thioesterase II may be of use as a diagnostic tool to identify human tumors of breast epithelial origin.

Adolescent↗
PubMed1981

Analysis of expression of human mammary epithelial antigens in normal and malignant breast cells at the single cell level by flow cytofluorimetry.

The expression of cell-type specific antigens on the surface of human mammary epithelial cells (HME antigens) is analyzed at the single cell level by flow cytofluorimetry. Methods are described to deal with two technical difficulties that have hampered the quantitation of surface antigens on cells from primary cultures by flow cytofluorimetry, namely, cell clumping and the presence of several cell types. By staining the cells simultaneously with two different fluorescent markers: the cell surface HME antigens with fluorescein-tagged antibodies (green fluorescence) and the cell DNA with propidium iodide (red fluorescence), it was possible to determine the expression of HME antigens per unit DNA, analyze their expression on breast cells in mixed populations, and analyze their expression in different phases of the cell cycle. The HME antigens were diminished in malignant breast epithelial cells as compared to their normal counterpart.

Antigens, Surface↗
PubMed1980

Growth of normal human mammary cells in culture.

Reduction mammoplasty tissue was used to obtain short-term cultures of human epithelial cell populations. Digestion of tissue with collagenase and hyaluronidase resulted in cell clusters (organoids) resembling ductal and alveolar structures; these could be separated by filtration from the stromal components. Epithelial outgrowth from these organoids was greatly enhanced by the addition of conditioned medium from other human epithelial and myoepithelial cell lines. Additionally, the mammary epithelial growth was stimulated by insulin, hydrocortisone, epidermal growth factor, and steroid hormones. With this enriched nutritional environment, active cell division could be maintained for 1 to 3 months and cells could be serially subcultured 1 to 4 times.

Breast↗
PubMed1975

Impairment of autonomically mediated heart rate control in patients with cardiac dysfunction.

Patients with cardiac disorders have defective parasympathetic control of heart rate. To evaluate the possibility of similar changes in sympathetic control of heart rate, we compared reflex chronotropic responses to 80 degree upright tilt and nitroglycerin-induced hypotension in 31 cardiac patients and 7 normal individuals before and after partial parasympathetic blockade with atropine. Tilting revealed an attenuation of the normal heart rate increase in patients; the magnitude of this defect was greatest in patients with more severe symptoms (class III) and evidence of left ventricular dysfunction (the heart rate increase averaged 25 plus or minus 3 beats/min in normal subjects, 12 plus or minus 2 beats/min in class I-II patients, and 7 plus or minus 1 beats/min in class III patients). Class III symptoms due to mechanical causes (mitral stenosis), however, were not associated with this defect. A marked reduction in heart rate rise with hypotension was seen only in those class III patients without mitral stenosis (0.4 plus or minus 0.1 beats min-minus 1 mm Hg-minus 1 vs. 3.0 plus or minus 0.5 beats min-minus 1 mm Hg-minus 1 in normal subjects). This abnormality also persisted after atropine administration, thus confirming a defect in the sympathetic as well as the parasympathetic component of baroreceptor-mediated reflex heart rate control in patients with cardiac dysfunction. Infusions of isoproterenol produced equivalent rises in heart rate in patients and normal individuals, excluding a reduction in beta-receptor responsiveness as a cause of impaired sympathetic influence. Norepinephrine depletion, however, is a well-recognized concomitant of cardiac failure. It is possible that the reduction in sympathetically mediated heart rate responses results in part from depletion of the sympathetic neurotransmitter.

Adolescent↗
PubMed1974

Translation of vesicular stomatitis messenger RNA by extracts from mammalian and plant cells.

RNA was isolated from polyribosomes of vesicular stomatitis virus (VSV)-infected cells and tested for its ability to direct protein synthesis in extracts of animal and plant cells. In cell-free, non-preincubated extracts of rabbit reticulocytes, the 28S VSV RNA stimulated synthesis of a protein the size of the vesicular stomatitis virus L protein whereas the 13 to 15S RNA directed synthesis of the VSV M, N, NS, and possibly G proteins. In wheat germ extracts, 13 to 15S RNA also directed synthesis of the N, NS, M, and possibly G proteins. Analysis of extracts labeled with formyl [(35)S]methionine showed that the 28S RNA directed the initiation of synthesis of one protein, whereas the 13 to 15S RNA directed initiation of at least four proteins. It is concluded that the 28S RNA encodes only the L protein, whereas the 13 to 15S RNA is a mixture of species, presumably monocistronic, which code for the four other known vesicular stomatitis virus proteins.

Animals↗
PubMed1973

Identification of the vesicular stomatitis virus large protein as a unique viral protein.

Previous studies have noted the existence of a 190,000-dalton vesicular stomatitis virus (VSV) protein called the large (L) protein. To determine whether this protein is a nonspecific aggregate, a precursor to the other VSV proteins, or a unique viral protein, its synthesis relative to the other VSV proteins was studied under conditions of inhibition of initiation of protein synthesis. Also, its tryptic peptides were compared to those of the other VSV proteins. In both cases the results were consistent with the identification of the large protein as a unique viral protein.

Animals↗