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Biomedical subjects

F Capony

Publications and source records attributed to F Capony.

At least 55 records · Page 3Linked to original sources
PubMed1985

Characterization of monoclonal antibodies to the estrogen-regulated Mr 52,000 glycoprotein and their use in MCF7 cells.

The Mr 52,000 glycoprotein is regulated by estrogen and released by breast cancer cells in culture (B. Westley and H. Rochefort, Cell, 20: 352-362, 1980). This rare protein was partially purified from 25 liters of medium conditioned by MCF7 cells and injected into Biozzi's selected mice. The spleen lymphocytes of one immunized mouse was fused with the murine myeloma P3-X63-Ag8-653. Sixteen hybridomas producing monoclonal antibodies to the Mr 52,000 protein were isolated, and seven of them were cloned and purified. The seven monoclonal antibodies were all of the immunoglobulin G1 isotype, and their dissociation constants ranged from 0.35 to 2.3 nM. The antibodies specifically recognized the secreted Mr 52,000 protein as evidenced by double immunoprecipitation and by immunoblotting after electrophoretic separation and transfer. Double-determinant immunoradiometric assay indicated that the seven purified monoclonal antibodies recognized three distinct regions of the Mr 52,000 protein, and it was used to assay the Mr 52,000 protein in biological fluids. These antibodies did not react with the external plasma membrane of MCF7 cells, as shown by immunofluorescence analysis. By contrast, the cytoplasm of MCF7 cells (but not T47D and RBA cells) was stained by the peroxidase-immunoperoxidase complex after plasma membrane permeation, indicating that the protein is secreted by exocytosis rather than shed from the plasma membrane.

Animals↗
PubMed1984

The estrogen-regulated 52 K protein adn plasminogen activators released by MCF7 cells are different.

In the MCF7 human breast cancer cell line, estradiol stimulates the synthesis of a 52 K secretory glycoprotein and has been reported to increase the plasminogen activator (PA) activity in the culture medium. Since one PA isozyme has a molecular weight close to 52 000 daltons under denaturing conditions, we asked whether the 52 K protein was a PA. The PA activity released in serum-free conditioned medium was evaluated by the increase in [125I]casein digestion observed in the presence of plasminogen. The 52 K protein was estimated by analysing the released proteins on SDS-polyacrylamide gel electrophoresis. When the conditioned medium was chromatographed on concanavalin A-Sepharose, the 52 K protein was retained on the gel, but not the PA. The two proteins also appeared different on the basis of their competing efficiency in a radioimmunoassay developed to quantify the 52 K protein. An antiserum against human urokinase failed to immunoprecipitate the 52 K protein. Under our culture conditions estradiol increased 52 K, but not PA, production. These results clearly indicate that the estradiol-regulated 52 K protein is not a plasminogen activator.

Breast Neoplasms↗
PubMed1984

Immunohistochemical detection of the estrogen-regulated 52,000 mol wt protein in primary breast cancers but not in normal breast and uterus.

An estrogen regulated glycoprotein of molecular weight 52,000 is released by metastatic human breast cancer cells in culture. In order to detect this protein directly in human tissues, several high affinity monoclonal antibodies were produced against the 52,000 mol wt protein. Frozen sections of human breast cancer samples were stained by the peroxidase-anti-peroxidase method using these antibodies. In 20 of 25 samples, specific immunoperoxidase staining was observed in the cytoplasm of epithelial cells with six monoclonal antibodies to the 52,000 mol wt protein. The 5 samples that were not stained contained no detectable estrogen receptor. Epithelial cells were not stained in 6 normal mammary glands collected during reduction mammoplasties and in 9 normal uteri, whether tissues were collected during the follicular or luteal phase. The demonstration that the 52,000 mol wt estrogen regulated protein is present in the cytoplasm of some primary breast cancers but absent in normal mammary tissue and uterus indicates its possible use as a tumor marker.

Antibodies, Monoclonal↗
PubMed1983

Release of estrogen-induced glycoprotein with a molecular weight of 52,000 by breast cancer cells in primary culture.

In an attempt to find estrogen-specific responses in breast cancer, we have established primary cell culture from metastatic pleural effusions of breast cancer and have analyzed the proteins labeled by [35S]methionine and released into the culture medium using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We show that the synthesis of a Mr 52,000 glycoprotein which is released by metastatic breast cancer cells in primary cultures is stimulated by estradiol in four of six patients. This protein is similar to the Mr 52,000 protein of MCF7 cells on the basis of its mobility in one- and two-dimensional gel electrophoresis [the molecular weight of this protein was originally found to be 46,000; it is closer to 52,000 using labeled proteins from New England Nuclear as molecular weight markers], its immunoprecipitation by antisera raised against the Mr 52,000 protein, and its binding to concanavalin A. We conclude that, similar to some breast cancer cell lines, some metastatic breast cancers synthesize a Mr 52,000 glycoprotein which is regulated by estrogens and exported from the cells into the medium. This study also shows that some primary cultures established from metastatic breast cancer remain responsive to estradiol in vitro for the synthesis of specific proteins. More clinical studies are needed to prove the interest of the Mr 52,000 secreted protein as an additional marker of the hormone responsiveness of breast cancer.

Breast Neoplasms↗
PubMed1980

Synthesis of apoprotein B of very low density lipoprotein in embryonic-chick liver. Development of responsiveness of oestrogen.

The influence of exogenous oestrogen on the rate of synthesis of the apoprotein B of very-low-density lipoprotein by embryonic chick liver has been examined at various stages of development. Significant synthesis of apoprotein B was found in the absence of hormone treatment as early as day 6 of egg incubation. This basal level of apoprotein B synthesis varied from 2.5--6% of total protein synthesis. Embryos at day 10 or earlier treated with oestradiol exhibited no increase in the basal level of apoprotein B synthesis. Embryos at day 11 responded to oestradiol slightly and, from days 12 to 20, oestrogen treatment raised the relative rate of apoprotein B synthesis significantly above basal values: the maximal rate was about 16% of total protein synthesis. The anti-oestrogen tamoxifen citrate abolished the hormone-induced increase in apoprotein B synthesis and was not itself oestrogenic. The basal level of apoprotein B production was not sensitive to tamoxifen citrate, either in relatively early or in later stages of development. The basal level of apoprotein B synthesis, therefore, is oestrogen-independent and under developmental control distinct from the hormone-sensitive synthesis. The ontogeny of oestrogen-responsiveness of apoprotein B production appears to parallel the acquisition of the hepatic oestrogen-receptor system [Lazier (1978) Biochem. J. 174, 143--152].

Animals↗
PubMed1975

In vivo effect of anti-estrogens on the localisation and replenishment of estrogen receptor.

Interactions between estrogen recpetors and triaryl ethylene anti-estrogens (U-11100A, MER 25 and CI 628) were tested on immature rat uteri. The accessible and the total (accessible and occupied) estrogen receptor sites were assayed in the cytosol and nuclear extracts using charcoal adsorption. After in vivo administration of anti-estrogens, the estradiol receptor sites were occupied and subsequently transferred to the nuclear compartment. The nuclear localisation of the receptor induced by the antagonist lasted for several days, during which replenishment of the cytosol receptor occurred. The nuclear receptors transferred by anti-estrogens and labelled in vitro with [3H]estradiol, were similar to the nuclear receptor-estradiol complex formed in vivo as far as their sedimentation constants and extractability from nuclei were concerned. Although these anti-estrogens are capable to translocate the estrogen receptor to the nucleus and to induce the replenishment of the cytosol receptor, the mechanism of their antagonism and of their weak estrogenic activity is still not clear.

Animals↗