La place actuelle de l'immunoanalyse en Toxicologie Clinique

in Immuno-Analyse & Biologie Spécialisée [=IBS] (1996), 11

Tamoxifen and its active metabolite inhibit growth of estrogen receptor-negative MDA-MB-435 cells

in Biochemical Pharmacology (1995), 49

Tamoxifen (TAM), the non-steroidal anti-estrogen most widely administered to breast cancer patients, acts, at least in part, by competing with estrogen receptors (ER). However, the existence of an ... [more ▼]

Tamoxifen (TAM), the non-steroidal anti-estrogen most widely administered to breast cancer patients, acts, at least in part, by competing with estrogen receptors (ER). However, the existence of an alternative mechanism of action for this drug is supported by the clinical observations that: (a) 30% of patients with ER-negative cancer cells respond to TAM, and (b) 30% of patients with ER-positive cancer cells are not sensitive to this anti-estrogen. In this study, we observed that growth of the human ER-negative breast cancer cell line MDA-MB-435 was inhibited by TAM and 4-hydroxytamoxifen (4OH-TAM) in a concentration-dependent fashion. Both monoclonal enzymoimmunoassay and Dextran Charcoal Coated Scatchard radioimmunoassay analysis demonstrated that this MDA-MB-435 cell line does not express ER. The absence of ER in MDA-MB-435 cells was also demonstrated at the mRNA level by both northern blot hybridization and reverse transcription-polymerase chain reaction techniques. MDA-MB-435 cell proliferation was not affected by 17 beta-estradiol or by the pure anti-estrogen ICI 164384, further demonstrating that the observed effects of TAM and its active metabolite on the proliferation of MDA-MB-435 cells were due to an ER-independent mechanism, yet to be identified. MDA-MB-435 thus appears to be a promising original model for the study of the alternative ER-independent mechanisms of action of TAM. [less ▲]

Comparison of six serum ferritin immunoassays and isoferritin spectrotypes in malignancies

in Annales de Biologie Clinique (1995), 53

La ciclosporine A

Conference (1995)

Toxicités aiguë et chronique des drogues toxicomanogènes

Conference (1995)

Mechanism of action of Tamoxifen

Conference (1995)

Tamoxifen activates the cell-cell adhesion function of E-Cadherin in MCF-7/6 human mammary carcinoma cells

Poster (1994)

Marqueurs tumoraux

in Focus Diagnostica (1994), 2

Le tamoxifene dans le traitement du cancer du sein

in Journal de Gynécologie, Obstétrique et Biologie de la Reproduction (1994), 23(7), 751-6

Tamoxifen is the most often prescribed non steroidal antioestrogenic agent in the world for breast cancer. Worldwide collaboration. has centralized the results, of different trials throughout the world on ... [more ▼]

Tamoxifen is the most often prescribed non steroidal antioestrogenic agent in the world for breast cancer. Worldwide collaboration. has centralized the results, of different trials throughout the world on oral adjuvant therapy in the early stages of breast cancer. A significative regression of the tumour was observed in most cases. Moreover, recent epidemiological studies suggest that tamoxifen could prevent new contralateral primary tumours. The risk of the disease should thus be reduced by the prophylactic use of antioestrogens such as tamoxifen. Investigations using a variety of models have evaluated the effect of tamoxifen on tumour promotion and cell growth. Tamoxifen-induced growth inhibition is associated with major changes in biochemical events in cultured human breast cancer cells including cell proliferation or growth factor production. Growth inhibition of oestrogen-responsive human breast cancer cells is associated with an induced secretion of autoinhibitory polypeptides (TGF beta) and an antagonistic effect on the synthesis of proliferative proteins (TGF alpha,...). The first step in the mechanism of action of the drug is binding of tamoxifen to the oestrogen receptors. Development of resistance to tamoxifen treatment is a great problem in treatment of breast cancer patients and the mechanism of resistance will require further study: under the influence of the drug, tumours could become remodelled as selected subpopulations emerge resistant-tamoxifen. The fact that some breast cancers which are oestrogen receptor-negative respond to antioestrogen suggests that parallel but separate pathways for oestrogen and antioestrogen action may exist. This paper summarizes the results of the most recent studies concerning this promising drug. [less ▲]

Méthodes de détection des drogues illicites, y compris les drogues licites détournées de leur utilisation habituelle, dans les différents milieux biologiques

Conference (1994)