Reduction of the anti-metabolic and anti-proliferative effects of methotrexate by 17 beta-oestradiol in a human breast carcinoma cell line, MDA-MB-436

Clarke, R.; Van Den Berg, H.W.; Kennedy, D.G.; Murphy, R.F.

European Journal of Cancer and Clinical Oncology 19(1): 19-24


ISSN/ISBN: 0277-5379
PMID: 6682774
Accession: 006280228

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The modifying influence of 17.beta.-estradiol on the anti-metabolic and growth inhibitory actions of methotrexate (MTX) was studied in a human brest cancer cell line, MDA-MB-436. This cell line contains detectable estrogen receptors but is progesterone receptor-negative. 17.beta.-Estradiol (10-10-10-6 M) failed to influence DNA synthetic rate as assessed by [3H]-TdR or [3H]-UdR incorporation and cell proliferative rate was similarly unaffected. Although by these criteria 17.beta.-estradiol failed to elicit a biological response in the MDA-MB-436 cell line, 10-6 M 17.beta.-estradiol significantly reduced the anti-metabolic and anti-proliferative actions of MTX. In the presence of 17.beta.-estradiol approximately twice the concentration of MTX was required to inhibit cell proliferation to the same extent as was observed following exposure to MTX alone. This partial reversal of MTX effects was accompanied by a 20% reduction in the steady-state intracellular MTX concentration when cells were exposed to the drug in the presence of 10-6 M 17.beta.-estradiol.