PMID: 9003390Dec 15, 1996Paper

Tamoxifen inhibits nitrobenzylthioinosine-sensitive equilibrative uridine transport in human MCF-7 breast cancer cells

The Biochemical Journal
J Cai, C W Lee

Abstract

Tamoxifen inhibits the binding of [3H]nitrobenzylthioinosine ([3H]NBMPR) to human MCF-7 breast cancer cells with an IC50 of 8 microM. Tamoxifen at 30 microM changed the apparent Kd for [3H]NBMPR binding from 0.63 +/- 0.12 to 4.75 +/- 0.58 nM, with little effect on the Bmax (311000 +/- 76000 and 263000 +/- 46000 sites per cell for untreated and tamoxifen-treated cells respectively). Corresponding to this decrease in binding of [3H]NBMPR in the presence of tamoxifen was an inhibition of NBMPR-sensitive equilibrative transport of 50 microM [3H]uridine (IC50 7-10 microM). In the presence of 15 microM tamoxifen, the apparent K(m) for [3H]uridine transport was increased from 390 +/- 30 to 1500 +/- 250 microM, with no change in Vmax (12.0 +/- 0.1 and 11.3 +/- 4.3 microM/s for untreated and tamoxifen-treated cells respectively). The inhibitory effect of tamoxifen on NBMPR-sensitive equilibrative uridine transport was specific, as similar results were also observed in HL-60 leukaemia and EL4 lymphoma cells. Furthermore a similar concentration of tamoxifen had no effect on the NBMPR-insensitive equilibrative transport of uridine in MCF-7, HL-60 and Morris 7777 hepatoma cells, and on the Na(+)-dependent transport of uridine in murine sple...Continue Reading

Citations

Mar 8, 2000·Biochimica Et Biophysica Acta·M M Cruz SilvaJ B Custódio
Jun 3, 2014·BMC Pharmacology & Toxicology·Thuc T LeGiuseppe Pizzorno
Sep 2, 1999·Japanese Journal of Cancer Research : Gann·K NagasawaT Yokoyama
Jun 14, 2002·FEBS Letters·Imogen CoeZlatina Naydenova
May 9, 2003·Cancer Chemotherapy and Pharmacology·S A Flanagan, K A Meckling

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