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G Leclercq

Publications and source records attributed to G Leclercq.

At least 109 records · Page 6Linked to original sources
PubMed1991

Comparison of tritiated estradiol and tamoxifen aziridine for measurement of estrogen receptors in human breast cancer cytosols.

We examined the estrogen receptor measurement in 265 human breast cancer cytosols by using a specific method based on [3H]tamoxifen aziridine labeling, sequential immunoadsorption with an antiestrogen receptor monoclonal antibody (H-222), sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography. These new tools of molecular endocrinology revealed an impressive estrogen receptor molecular polymorphism. Given the recent finding of a similar estrogen receptor polymorphism at the messenger RNA level by several laboratories, it is tempting to speculate about its possible biological significance. To gain insight into the potential clinical relevance of this polymorphism in terms of breast cancer hormone dependence, we compared the 265 cytosols for their [3H]tamoxifen aziridine- and [3H]estradiol-binding capacities using the above-mentioned method and the conventional dextran-coated charcoal assay. We failed to identify a specific [3H]tamoxifen aziridine electrophoretic pattern with respect to the tumor estrogen receptor content as measured by the dextran-coated charcoal assay. However, an excellent correlation overall was found between the intensities of both labeling methods. Some tumors were positive for only one of these two ligands. It will be clinically important to see whether the tumors positive for [3H]tamoxifen aziridine only correspond to the small subset of tumors (10%) which respond to tamoxifen treatment despite very low estrogen receptor levels, as measured by the dextran-coated charcoal technique.

Antibodies, Monoclonal↗
PubMed1991

IFN-gamma reverses IL-4 inhibition of fetal thymus growth in organ culture.

IL-4 is known to inhibit the growth and differentiation of 14-day-old fetal mouse thymus in organ culture. Here we report that IFN-gamma reverses this IL-4-mediated growth inhibition. Thymus lobes from 14-day-old fetuses were cultured for 12 days in medium containing 100 IU/ml rIL-4 either in the absence or presence of rIFN-gamma (100 to 1000 IU/ml). After culture, the cell yields and the absolute numbers and frequencies of the major subpopulations according the coordinate expression of CD4 and CD8 were estimated. IL-4 treatment alone was found to result in a seven-fold decrease in cell yield and an almost complete absence of the CD4+CD8+ subpopulation. Addition of IFN-gamma reversed IL-4-mediated inhibition in a dose-dependent fashion, with an optimal dose ranging from 200 to 500 IU/ml. IFN-gamma exerted this effect only when added within the first 48 h of initiating the culture. The specificity of the reversal effect was ascertained by neutralization of the effect by a neutralizing anti-IFN-gamma mAb and by lack of activity of human IFN-gamma. In the absence of IL-4, IFN-gamma had a growth-promoting effect as evident from a threefold increase in cell numbers.

Animals↗
PubMed1991

Interleukin 4 induces CD8 alpha expression on T cell receptor V gamma 5 thymocytes.

It is generally accepted that most T cell receptor (TcR) gamma/delta cells are CD4-CD8-. After in vitro culture; however, a low percentage of these cells express the CD8 alpha subunit. We show here that addition of recombinant interleukin (IL) 4 to IL 2-cultured murine TcR V gamma 5 thymocytes induces the expression of CD8 alpha; CD8 beta is not expressed. Co-addition of the anti-IL 4 mAb 11B11 abrogates the induction of CD8 alpha expression, ruling out the possibility of a contaminant. Furthermore, we demonstrate that a substantial part of freshly prepared TcR V gamma 5 thymocytes express CD8 alpha.

Animals↗
PubMed1991

Interleukin-2 stimulated T cell receptor V gamma 3 positive thymocytes do not migrate to the skin.

T cell receptor (TcR) V gamma 3+ thymocytes, which only develop in the fetal thymus, migrate to the skin. IL-2 stimulation of fetal day 18 murine thymocytes results in a cell population of which 45% of the cells express the TcR V gamma 3. In this study, we describe that those IL-2 cultured TcR V gamma 3+ thymocytes have the killing capacity of lymphokine activated killer cells: NK-susceptible as well as NK-resistant tumor cell lines were killed in an MHC-unrestricted manner. Because of these findings, IL-2-expanded TcR V gamma 3+ thymocytes could have a potential use in adoptive immunotherapy for skin-located tumors. Therefore, we analyzed the migration pattern of IL-2-cultured TcR V gamma 3+ thymocytes upon i.v. injection. We describe their initial entrapment in the lungs and subsequent accumulation in the liver. Localization in the skin was practically absent, and did not differ from that of IL-2 cultured adult thymocytes (mainly TcR alpha beta +). The migration pattern was identical in adult and newborn normal mice, and in adult nude mice. Analysis of the expression of asialo-GM1 revealed that it increased strongly after IL-2 culture. The relevance of this change in asialo-GM1 expression with reference to the migration upon i.v. injection is discussed. This study indicates that an improved understanding of the determinants of in vivo localization of IL-2 cultured cells may lead to improved strategies for adoptive immunotherapy of cancer.

Age Factors↗
PubMed1991

Estrogen-like activity of a subpopulation of natural antiestrogen receptor autoantibodies in man.

We recently reported that a subpopulation of immunoglobulin G (IgG) in man interacts with the hormone-binding site of estrogen receptors (ER), competes with [3H]estradiol (E2) uptake, and decreases effective ER concentrations in cell cultures. The present work further characterizes the immunological properties of these antibodies and defines their biological activity. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting techniques, enriched preparations of the natural anti-ER IgG subpopulation (IgGs) were found to specifically immunoprecipitate ER extracted from MCF-7 mammary carcinoma cells and to compete with [3H]tamoxifen-aziridine for ER binding. During 18-h incubations IgGs decreased [3H]E2 binding capacity of MCF-7 cells in a dose-dependent manner similar to E2. Like E2 but unlike antiestrogens, this biological effect corresponded to down-regulation of the receptor protein and depended on a mechanism specifically inhibited by actinomycin D. Moreover, IgGs antagonized the decrease of [3H]E2 binding capacity produced by the strong antiestrogen methyl-hydroxytamoxifen; this antagonism was additive to that of E2. On the other hand, IgGs like estrogens increased progesterone receptor concentrations and cathepsin D secretion. The biological activity of IgGs was neutralized by anti-IgG antibodies and by ICI 164,384, a "pure" steroid antagonist of E2, confirming that immunoglobulins G were responsible for this activity and acted at the E2-binding site. These observations indicate that some natural antibodies in man can function like potent estrogens on ER and mammary cells.

Autoantibodies↗
PubMed1991

[Local growth factors for breast cancer: general review and potential value for clinician].

The discovery of a panel of peptides produced by normal and cancerous cells and capable of stimulating cell growth in an autocrine and paracrine fashion has been witnessed in recent years. This article focusses on the local growth factors thought to play a role in the biology of breast cancer and reviews which growth factors' receptors have been associated with prognosis of primary breast cancer. The potential of those growth factors for the development of new anticancer treatment strategies is also briefly discussed.

Animals↗
PubMed1991

[Evaluation of the calcium content of diet by frequential self-questionnaire].

A frequential type self-questionnaire enabling evaluation of the calcium content of the diet of an individual as well as of a given population was designed on the basis of 20 different types of food (items) rich in calcium and/or frequently eaten in metropolitan France. Comparison with the weekly docket system, chosen as a reference method, validated the self-questionnaire. Similarity with the weekly docket method disappeared when the size of portions was left to one side, drinks were eliminated or only dairy products were taken into account. The self-questionnaire with its 20 items thus offers a simple and rapid method for estimation of the daily calcium intake of a given individual to within an accuracy of 20% and as result is a dietetic evaluation technique suitable for both clinical and epidemiological use.

Adolescent↗
PubMed1990

Preferential proliferation of T cell receptor V gamma 3-positive cells in IL-2-stimulated fetal thymocytes.

Thymocyte cell suspensions, prepared from mice at different ages, were cultured in vitro with human rIL-2. This stimulation resulted in a cell population that contained almost 50% TCR-gamma delta-positive cells if thymocytes were taken from fetal day 17 until just after birth. Analysis of the variable (V gamma) region used by the TCR-gamma delta cells revealed that 90% of them expressed TCR-V gamma 3, and less than 5% expressed TCR-V gamma 2. Cells positive for TCR-alpha beta were barely detectable. If fetal day 18 organ cultured thymus lobes, instead of a cell suspension, were stimulated with IL-2, no rise in the number of TCR-V gamma 3+ or TCR-delta+ cells was observed, whereas a partial outgrowth of TCR-alpha beta+ cells occurred. From day 1 after birth, the number of TCR-gamma delta cells recovered from an IL-2-stimulated thymocyte cell suspension dropped to reach a plateau of 15% of the total cell number, whereas TCR-V gamma 3+ cells became undetectable in older animals. TCR-alpha beta+ cells, on the other hand, quickly rose in cell number after birth. Kinetic analysis showed that the preferential outgrowth of TCR-V gamma 3+ cells in IL-2-stimulated fetal day 18 thymocyte cell suspensions was present from the onset of the culture; a significant proliferation of CD4 or CD8 single positive TCR-alpha beta cells was never observed. This lack of proliferation of TCR-alpha beta cells was not due to inhibition by the activated TCR-V gamma 3+ cells. Throughout the IL-2 culture, one-fourth of the TCR-V gamma 3+ thymocytes was positive for CD8. Analysis of the DNA content and the IL-2 receptor (IL-2R) p55 expression showed that during the first days of culture the TCR-V gamma 3+ cells had a much higher proliferation rate than the TCR-V gamma 3- cells, although TCR-V gamma 3+ IL2R p55+ cells could not be detected. From day 3 to 4 of culture, the proliferation rate of TCR-V gamma 3+ cells equaled that of the rest of the cells and less than 20% of the TCR-V gamma 3+ cells expressed the IL-2R p55. The biologic significance of our findings is discussed.

Animals↗
PubMed1990

Hormone sensitivity in vitro and in vivo of v-ras-transfected MCF-7 cell derivatives.

Human mammary carcinoma cell lines (MCF-7) were analysed for their hormone sensitivity before and after transfection with a v-Ha-ras oncogene or with a neomycin-resistance gene followed by selection in vitro or in vivo. Our aim was to test how the expression of the ras oncogene would influence the estradiol sensitivity of MCF-7 cells. In culture, MCF-7 cells expressing the viral p21 oncogene product, as compared to parental MCF-7 cells and their control derivatives, showed lower levels of a 67-kDa estrogen receptor. Progesterone receptors, however, remained sensitive to up-regulation by estrogens. The oncogene-expressing cells were less sensitive than all controls to stimulation of proliferation by 10(-8)M estradiol or to inhibition of proliferation by 2-CH3-4-OH tamoxifen, and this was not dependent upon the type of culture medium used. After s.c. or i.p. injection into female athymic nude mice, ovariectomized or left intact, the growth of MCF-7 cells expressing the ras oncogene product and of all control cells was sensitive to stimulation by estrogen supplementation. Conversely, cell lines derived from tumors generated with long latency in untreated athymic nude mice by v-ras-expressing MCF-7 cells showed efficient formation of quickly growing tumors in the absence of estrogen supplementation. No differences were observed in invasion and metastasis of the different MCF-7 cell types injected into athymic nude mice that were supplemented with estrogens or not.

Animals↗
PubMed1990

Inhibitory effect of murine recombinant IL-4 on thymocyte development in fetal thymus organ cultures.

The effect of rIL-4 on early T cell development in fetal thymus organ culture was studied by two-color immunofluorescence and by proliferation assays. Addition of IL-4 to an organ culture of 14-day-old fetal BALB/c thymus resulted in a decreased cell yield (less than 15% as compared to the control culture) and in a complete inhibition of CD4+CD8+ thymocytes after 12 days of culture. This IL-4 effect was time dependent as shorter times (less than 6 days) resulted in a thymic development comparable to the untreated control. When thymuses at later stages of gestation were treated with IL-4, the inhibition was less pronounced. The inhibitory activity of IL-4 was abrogated by the anti-IL-4 mAb 11B11, ruling out the possibility of a contaminant. Organ cultured 14-day-old fetal thymocytes treated with IL-4 during 12 days responded vigorously to IL-2 alone and to IL-4 + PMA + ionomycin. Taken together, these results indicate that IL-4 affects the intrathymic T cell development at an early stage.

Animals↗
PubMed1990

Expansion of large granular lymphocytes in IL-2-driven 14-day-old fetal thymocytes in organ culture.

These experiments were designed to evaluate the role of cytokines in early T cell development within the thymus. By using a thymic organ culture model, we have studied the influence of high dose of IL-2 (10 to 1000 IU/ml) on the cell populations that are generated during 12 days starting from a thymic rudiment of 14-day-old mouse embryo. The IL-2 treatment resulted in the expansion of Thy-1+/-, CD4-, CD8-, CD3-, Fc gamma RII+, CD5 (Lyt-1)-, HSA-, Pgp- 1+, Mel-14- population. These cells had the morphology of large granular lymphocytes and displayed broad cytotoxic activity. In addition, IL-2-treated organ cultures had a dramatic decrease in CD4+CD8+ thymocytes, a marked reduction in TCR-alpha beta+ thymocytes--even more pronounced in the TCR-V beta 6+ and TCR-V beta 8+ thymocytes--and no significant changes in the number of TCR-gamma delta+ as compared to control organ cultures.

Animals↗
PubMed1990

Metabolism of tamoxifen by isolated rat hepatocytes. Identification of the glucuronide of 4-hydroxytamoxifen.

Metabolism of 4-hydroxytamoxifen by hepatocytes isolated from rats administered with phenobarbital and examination by TLC of the components not extractable into ethyl acetate revealed 4-hydroxytamoxifen beta-glucuronide; its identity was confirmed by comparison of its 1H NMR spectrum with that of synthetic material. This conjugate was also formed on metabolism of tamoxifen. It bound to cytosolic oestrogen receptors with only one thousandth the affinity of 4-hydroxytamoxifen and gave a correspondingly very weak inhibition of growth of the MCF-7 human breast cancer cell line. Therefore, in contrast to reported observations on the 3-glucuronide of oestradiol, the MCF-7 cells were unable to hydrolyse 4-hydroxytamoxifen glucuronide and on this evidence, formation of this metabolite is solely a deactivation pathway.

Animals↗
PubMed1990

Psychosocial correlates of oestrogen and progesterone receptors in breast cancer.

Psychosocial correlates of hormone receptor status in primary breast cancers were investigated in 93 consecutive patients. Life event, coping style, and psychological adjustment self-report scales were completed. The 75 patients with receptor-positive (oestrogen and/or progesterone) tumours were better adjusted psychologically than the 18 patients with receptor-negative lesions. These findings may explain the relations that have been found between psychosocial variables and survival.

Adaptation, Psychological↗
PubMed1990

Direct evidence for partial target specificity in lymphokine-activated killer thymocytes.

Thymocytes were removed from mice at different times before and after birth, and their phenotype and killing repertoire were analysed after stimulation with human recombinant interleukin 2 (IL-2). Whereas three different tumour targets were killed by all lymphokine-activated killer (LAK) populations tested, EL4 lymphoma cells were only killed by LAK cells derived from thymocytes after, but not before, birth. Cold-target competition tests showed that LAK thymocytes recognized antigenic structures on EL4 cells that are different from those on other tumour targets. Analysis of EL4 target killing after removal of different subsets from LAK cells revealed that the major part of this killing is exerted by CD8+ cells. Our findings are additional and more direct evidence for partial target specificity in LAK cells.

Animals↗
PubMed1990

Estrogenic and antiestrogenic down-regulation of estrogen receptor levels: evidence for two different mechanisms.

Preincubation of MCF-7 cells with estradiol (E2) produces a decrease of 3H-E2 binding capacity ("processing"); the strong antiestrogen methylhydroxytamoxifen (MHT) is also effective but with a approximately 100 fold lower efficiency. Parallel immunological measurement of estrogen receptor contents of the cells (ER-EIA from Abbott) revealed that the mechanisms by which these ligands operate are not of the same nature. Thus, while E2 produced a loss of the ER peptide, MHT increased it; indicating an accumulation of a non-binding form of the receptor under its treatment. Measurement of the binding capacity of the cells for 3H-ORG 2058 showed a decrease of PgR concentration after pre-incubation with MHT which contrasted with the classical E2-induced increase of the receptor. MHT at relatively low concentrations also antagonised the E2-induced decrease of 3H-E2 binding capacity; this property did not result from a difference in chemical structure between the ligands since bisphenol a weak estrogenic analogue of MHT failed to show a similar antagonistic activity. This property confers to MHT the ability to reduce the efficiency of E2 to induce PgR. Finally, actinomycin D a known antagonist of the E2-induced processing was found to be totally ineffective towards the MHT processing. This clearly confirmed that the term "processing" covers at least two distinct mechanisms.

Breast Neoplasms↗
PubMed1990

[Immunocytochemical assay of estrogen receptors in puncture products of breast carcinomas].

In a pilot study, estrogen receptors (ER) were assayed on 42 surgically removed breast tumors by the following 3 methods: biochemical assay with dextran coated charcoal (DCC), Abbott immunoenzymatic (ER-EIA) and immunocytochemical (ER-ICA) technics. DCC and ER-EIA were performed on biopsy specimens while ER-ICA was run on cytocentrifugated cells obtained by fine needle aspiration (FNA). ER contents were expressed according to an index taking into account the proportion of colored neoplastic cells and the intensity of staining. Statistical correlation coefficient (Spearman and Kendall) concordance, sensitivity and specificity between the results were calculated (ER - ICA/ER - EIA: P less than 0.001, r = 0.38, concordance = 83%, sensitivity = 86%, specificity = 77%; ER - ICA/DCC: P less than 0.05, r = 0.22, concordance = 77%, sensitivity = 85%, specificity = 63%; ER - EIA/DCC: P less than 0.001, (r = 0.60). As previously reported, both immunoassays showed good agreement. The weaker but nevertheless significant correlation found with reference DCC may be due to the heterogeneity of tumoral ER content. This hypothesis is supported by the variability of ER - ICA assays on multiple FNA performed in 16 cases from our series. Use of multidirectional FNA slightly improved the results. Nevertheless, ER - ICA appear to be a good semi-quantitative method and might be helpful in the follow-up of metastasis treated with anti-estrogen, especially in small lesions not assayable by DCC.

Adenocarcinoma↗
PubMed1989

Determination of 2-methyl derivatives of tamoxifen in cell culture medium using high-performance liquid chromatography and electrochemical detection.

The 2-methyl derivatives of tamoxifen (2-methyltamoxifen and 2-methyl-4-hydroxytamoxifen) were extracted from a cell culture medium at pH 5.4 (Earle's Minimum Essential Medium) with an internal standard (tamoxifen) on a phenyl sorbent cartridge. The compounds were then separated by high-performance liquid chromatography on a nitrile column eluted with acetonitrile-methanol-0.05 M sodium dihydrogenphosphate (19:4:11.6:69,v/v) containing 0.11 mmol/l disodium EDTA and determined by electrochemical detection at +1.1 V vs. Ag/AgCl/3 M NaCl. The absolute detection limits were 50 pg for 2-methyl-4-hydroxytamoxifen and 100 pg for tamoxifen and 2-methyltamoxifen at a sensitivity of 1 nA/V.

Breast Neoplasms↗