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S Nandi

Publications and source records attributed to S Nandi.

At least 181 records · Page 10Linked to original sources
PubMed1984

How culture conditions modulate the morphofunctional differentiation of the human estradiol-sensitive mammary cell line (MCF-7).

The MCF-7 cell line grown on plastic surfaces is widely accepted as a model for hormone sensitivity in molecular biology. However, in vitro results concerning estrogen sensitivity remain controversial. In search of culture conditions most closely simulating the in vivo microenvironment we cultured MCF-7 cells on diverse substrates and in suspension culture. The different factors of the contact environment: (A) influence of diffusive medium, (B) influence of cell to cell contacts, and (C) influence of cell to substrate contacts were considered. Using morphological criteria:phase contrast microscopy, scanning and transmission electron microscopy we observed MCF-7 morphofunctional differentiation under the different culture conditions. Plastic, corneal endothelial cell extracellular matrix, and attached collagen gels imposed a planar medium-aggregate interface. The impermeability of the free surface and the intense basal tension antagonized epithelial polarization. Only at post-confluence did domes and clusters appear above the monolayer. On floating collagen gels and in suspension culture the cells established intimate cell-cell contacts over large surfaces and reconstituted tissular architecture. Three-dimensional growth conditions which approach the in vivo contact environment of epithelial cells should be used instead of the traditional monolayer cultures for assessing hormonal and pharmacological responses of human breast carcinomas.

Breast Neoplasms↗
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↗
PubMed1984

Correlation between in vitro growth and regulation of estrogen and progesterone receptors in rat mammary epithelial cells.

The present studies examine 1) the effect of enzymatic cell dissociation on the level of cytosolic estrogen receptor (ER) and progesterone receptor (PR) for normal rat mammary tissue, 2) the concentrations of ER and PR in rat mammary epithelial (RME) cells cultured within collagen gel, and 3) correlations that may exist between receptor concentration and cultured RME cell proliferation after hormonal stimulation in vitro. After cell dissociation, ER was present in mammary cells at higher concentrations than those found in the whole gland, whereas PR concentrations were similar to those in the whole gland. As characterized by Scatchard analysis, PR and, to a lesser extent, ER can be maintained in cells cultured in serum-free medium within a collagen gel matrix. ER is apparently functional at relatively low levels, since estradiol did induce PR synthesis, and cytosolic ER was reduced by estrogen administration. However, estradiol had no mitogenic effect on RME cells in this system, supporting the hypothesis that there may be a dichotomy between estrogen's effect on growth and progesterone receptor synthesis. PRL plus progesterone act synergistically to induce cell proliferation in our system, and this correlates with increased concentrations of progesterone receptors. Thus, the collagen gel system appears to provide a useful in vitro model for the study of receptor regulation and cell proliferation.

Animals↗
PubMed1983

Biosynthesis of medium-chain fatty acids by mammary epithelial cells from virgin rats.

Epithelial cells were isolated from the undifferentiated mammary glands of mature virgin female rats, and their lipogenic characteristics were studied. These cells synthesized predominantly medium-chain fatty acids, albeit at a low rate. In contrast, whole tissue from mammary glands of virgin rats synthesized predominantly long-chain fatty acids at a relatively higher rate, indicating that the lipogenic activity is dominated by the adipocyte component of the gland. Enzyme assays revealed that thioesterase II, the enzyme which regulates production of medium-chain fatty acids by the fatty acid synthetase, was present at a high activity in the undifferentiated mammary epithelial cells of virgin rats. Immunohistochemical studies confirmed this observation and showed that the regulatory enzyme was present exclusively in the epithelial cells lining the alveolar and ductal elements of the undifferentiated gland. This study demonstrates that the potential to elaborate tissue-specific medium-chain fatty acids is already expressed in the undifferentiated tissue of virgin rats and is not acquired as a result of the differentiation associated with the lactogenic phase of development. In this species mammary epithelial cells apparently synthesize predominantly medium-chain fatty acids at all stages of development, and only the overall rate of synthesis is increased on induction of the fatty acid synthetase during lactogenesis.

Animals↗
PubMed1983

Growth effect of lithium on mouse mammary epithelial cells in serum-free collagen gel culture.

The effect of lithium on the growth of mammary epithelial cells from adult virgin and midpregnant BALB/c or BALB/cfC3H mice was tested in a serum-free collagen gel culture system. The serum-free medium consisted of a 1:1 mixture of Ham's F12 and Dulbecco's Modified Eagle's medium supplemented with insulin, transferrin, cholera toxin, epidermal growth factor (EGF), and bovine serum albumin fraction V (BSA V). A multifold increase in cell number occurred during 10-12 days of culture in this medium. In dose-response studies in which the concentration of each component of this serum-free medium was varied in turn, the addition of LiCL (10 mM) enhanced growth at most concentrations of each factor. However, LiCl could not enhance growth in the absence of insulin or BSA V, but could replace EGF. The optimal concentration of LiCl was 5-10 mM; higher concentrations (20-80 mM) were toxic. KCl (1-10 mM) when added to the serum-free medium slightly stimulated growth; the addition of NaCl to the medium had little effect on growth. LiCl did not enhance the growth of cells from spontaneous mammary tumors of BALB/cfC3H mice.

Animals↗
PubMed1983

The use of thioesterase II as a rat mammary epithelial cell-specific marker.

The avidin-biotin-peroxidase complex immunoperoxidase technique was employed to determine the intercellular distribution of thioesterase II in rat mammary glands. This enzyme is responsible for shifting the product specificity of the fatty-acid synthetase enzyme complex from long to medium chain fatty acids. Thioesterase II was found exclusively in the cells lining the lumen of the ductal and alveolar structures in glands from mature virgin (150 days old) and pregnant rats. The ductal cell staining intensity was considerably less than that of the alveolar cells in the mature virgin rat glands. No immunoreactive thioesterase II was found in the stromal, adipose, vascular, or myoepithelial components of the gland in the developmental stages examined. In the glands from immature virgin rats (40-45 days old) thioesterase II was again found only in the epithelial cells lining the lumen of the ductal and end-bud structures although this layer was usually more than one cell thick. Quantitative determination of thioesterase II activity in cytosol preparations revealed similar levels in mammary fragments from enzymatically-dissociated glands obtained from mature virgins and in end buds derived from immature virgins, but somewhat higher levels in mammary structures derived from late-pregnant animals. These immunohistological and biochemical results demonstrate thioesterase II's usefulness as a mammary epithelial cell-specific marker.

Animals↗
PubMed1983

Response of end bud cells from immature rat mammary gland to hormones when cultured in collagen gel.

End buds from 4- to 5-week-old rat mammary glands were isolated and cultured within a rat tail tendon collagen gel matrix. Media containing equine serum or porcine serum and cholera toxin promoted growth, but not the production of casein or thioesterase II, nor did they induce a state of differentiation as assessed by cell ultrastructure. Medium supplemented with only 5% porcine serum, insulin and cholera toxin did not support growth or differentiation. However, when prolactin, estradiol, progesterone and hydrocortisone were added to this medium, growth was stimulated greatly and a differentiated state was induced as assessed by the production of casein and thioesterase and by the appearance of a highly secretory ultrastructure.

Animals↗
PubMed1983

Comparison of the growth of normal and neoplastic mouse mammary cells on plastic, on collagen gels and in collagen gels.

The growth of normal and neoplastic mouse mammary cells was compared in primary cultures on plastic, on rat tail collagen gels and in rat tail collagen gels. Cells on plastic grew for the first few days, then stopped with only a 1- to 3-fold increase in cell number after 2 weeks in culture. Cells grown on or in collagen gels grew continuously over the 2-week culture period with up to 10-fold increase in cell number for cultures on collagen gels and a 20-fold increase for cells embedded in collagen gels. The difference in growth rates between cells grown in collagen gel and those grown on collagen gels was due, in part, to the three-dimensional growth of the colonies in collagen gel their two-dimensional growth on collagen gel. Cells grown on and in collagen gel can produce an electron-dense basal lamina-like structure which is associated with collagen IV and laminin as judged by immunofluorescence. Cells grown on plastic do not form this structure. Cis-OH-proline blocks the production of collagen and inhibits the growth of the cultured cells indicating collagen production to be involved in growth. Rat tail collagen gels are a superior substratum for the growth of mouse mammary cells and this may be related to the cells' ability to form a collagen IV-containing basal lamina-like structure.

Animals↗
PubMed1983

Growth of mammary epithelial cells from neonatally sex hormone-exposed mice in serum-free collagen gel culture.

Neonatal sex hormone treatments are known to cause an increase in mammary tumors in female mice with expressed mammary tumor virus (MTV). The growth of mammary epithelial cells from mice treated neonatally with sex hormones was studied in response to growth-stimulatory factors in a serum-free collagen gel culture system which sustains the growth of normal mammary epithelial cells. Animals were treated with hormones or oil-vehicle for the first 5 days after birth. Cells from control mice at 2 and 3 months of age showed a maximal growth response to insulin at 5-10 micrograms/ml and LiCl at 5-20 mM. Cells responded to epidermal growth factor at all concentrations used (1, 10 and 50 ng/ml). In contrast, mammary epithelial cells from mice treated neonatally with estrogen (estradiol and diethylstilbestrol (DES] showed a reduced growth response to the growth factors tested.

Animals↗
PubMed1983

Effects of phorbol esters on normal and tumorous mouse mammary epithelial cells embedded in collagen gels.

The effects of phorbol esters on mammary epithelial cells from BALB/cfC3H/Crgl "midpregnant mice" (i.e., mice at the midterm of pregnancy) and from mammary adenocarcinomas (also from BALB/cfC3H/Crgl mice) grown in a collagen gel matrix were studied. 12-O-Tetradecanoylphorbol 13-acetate (TPA), when added to the media, caused an increased proliferation of both normal and cancerous mammary epithelial cells in a dose-dependent manner. The degree of enhancement of proliferation by TPA ranged from no increase in cell number at 3% swine serum (SW) concentration to two to three times the number of cells in the control cultures when 10 or 25% SW was used. Optimal growth was obtained with a TPA concentration of 0.1 or 1.0 microgram/ml. Increasing the SW concentration (3, 5, 10, or 25%) enhanced the proliferative effect of TPA. Cholera toxin (0.01 microgram/ml) enhanced the proliferative effect of TPA on normal cells but had a variable effect on tumor cells. The addition of TPA also resulted in a morphologic change in the epithelial colonies from midpregnant mice and from mammary tumors and caused them to assume a fibroblastic appearance. The addition of 4 alpha-phorbol or 4 alpha-phorbol 12,13-didecanoate to mammary epithelial cultures had no proliferative or morphologic effect. The results demonstrate that TPA has a growth-promoting effect on normal and cancerous mouse mammary epithelial cells.

Animals↗
PubMed1982

Serum-free growth of normal and tumor mouse mammary epithelial cells in primary culture.

Freshly isolated normal and tumor mouse mammary epithelial cells embedded within a collagen gel matrix undergo sustained growth when cultured for as long as 3 wk in a serum-free medium composed of a 1:1 (vol/vol) mixture of Hepesbuffered Ham's F12 and Dulbecco's modified Eagle's medium supplemented with insulin, epidermal growth factor (EGF), transferrin, bovine serum albumin fraction V, and cholera toxin. Of these additives, only insulin, EGF, and albumin are required for the growth of most normal cells. Albumin is not always an absolute requirement for growth but greatly enhances it. Lithium has been found to stimulate the growth of normal cells and can replace EGF. The collagen matrix culture system allows sustained growth of primary cultures of both normal and neoplastic mammary epithelium in serum-free conditions. This serum-free system will be useful in identifying and investigating the role of hormones, growth factors, and nutritional factors in regulating the growth of mammary epithelial cells.

Animals↗
PubMed1982

Transplantation of mouse mammary epithelial cells grown in primary collagen gel cultures.

A technique for the transplantation of mouse mammary epithelial cells, grown in collagen gels, has been developed that demonstrates that the phenotype of the cells prior to culture was not altered by the culture conditions. Mammary epithelial cells from virgin and midpregnant C57BL/Crgl mice; virgin, midpregnant, and multiparous nonpregnant BALB/cfC3H/Crgl mice; a BALB/c hyperplastic alveolar nodule line, and mammary tumors from BALB/cfC3H/Crgl mice were embedded inside collagen gels and grown for 10 to 14 days in the presence of 25% swine serum plus cholera toxin (0.01 microgram/ml). The epithelial cells increased in number during the culture period. At the end of the culture period, the cells were removed from the collagen gels and transplanted to the gland-free mammary fat pads of 3-week-old syngeneic female mice. Culture in collagen gels increased the number of cells necessary to obtain a high percentage of mammary outgrowths as compared to cells not grown inside collagen gels. In general, mammary cells grown inside collagen gels gave rise to outgrowths, similar in phenotype to those from noncultured cells, and were representative of the tissue of origin. Mammary epithelial cells from C57BL/Crgl virgin donors grown in collagen gels for 10 to 14 days retained their ability to respond to the endogenous hormones of pregnancy and lactation of the host and formed lobuloalveolar structures full of secretion similar to the host's own mammary gland. The data indicate that the growth of mammary epithelial cells in collagen gels and subsequent transplantation into the gland-free fat pads of syngeneic hosts provides a simple system, wherein cells can be grown in vitro and their phenotypes determined in vivo.

Adenocarcinoma↗