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. 1996 Dec 15;320(Pt 3):991–995. doi: 10.1042/bj3200991

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

J Cai 1, C W Lee 1
PMCID: PMC1218025  PMID: 9003390

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 splenocytes. In this paper we demonstrate that tamoxifen by itself might have some antiproliferative effects through inhibition of DNA synthesis by blocking the nucleoside salvage pathway.

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Selected References

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  1. Ben-Baruch G., Schreiber G., Sokolovsky M. Cooperativity pattern in the interaction of the antiestrogen drug clomiphene with the Muscarinic receptors. Mol Pharmacol. 1982 Mar;21(2):287–293. [PubMed] [Google Scholar]
  2. Biswas R., Vonderhaar B. K. Antiestrogen inhibition of prolactin-induced growth of the Nb2 rat lymphoma cell line. Cancer Res. 1989 Nov 15;49(22):6295–6299. [PubMed] [Google Scholar]
  3. Butta A., MacLennan K., Flanders K. C., Sacks N. P., Smith I., McKinna A., Dowsett M., Wakefield L. M., Sporn M. B., Baum M. Induction of transforming growth factor beta 1 in human breast cancer in vivo following tamoxifen treatment. Cancer Res. 1992 Aug 1;52(15):4261–4264. [PubMed] [Google Scholar]
  4. Callaghan R., Higgins C. F. Interaction of tamoxifen with the multidrug resistance P-glycoprotein. Br J Cancer. 1995 Feb;71(2):294–299. doi: 10.1038/bjc.1995.59. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Coezy E., Borgna J. L., Rochefort H. Tamoxifen and metabolites in MCF7 cells: correlation between binding to estrogen receptor and inhibition of cell growth. Cancer Res. 1982 Jan;42(1):317–323. [PubMed] [Google Scholar]
  6. Colletta A. A., Wakefield L. M., Howell F. V., van Roozendaal K. E., Danielpour D., Ebbs S. R., Sporn M. B., Baum M. Anti-oestrogens induce the secretion of active transforming growth factor beta from human fetal fibroblasts. Br J Cancer. 1990 Sep;62(3):405–409. doi: 10.1038/bjc.1990.307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Coradini D., Biffi A., Cappelletti V., Di Fronzo G. Activity of tamoxifen and new antiestrogens on estrogen receptor positive and negative breast cancer cells. Anticancer Res. 1994 May-Jun;14(3A):1059–1064. [PubMed] [Google Scholar]
  8. Croxtall J. D., Emmas C., White J. O., Choudhary Q., Flower R. J. Tamoxifen inhibits growth of oestrogen receptor-negative A549 cells. Biochem Pharmacol. 1994 Jan 20;47(2):197–202. doi: 10.1016/0006-2952(94)90006-x. [DOI] [PubMed] [Google Scholar]
  9. Darnowski J. W., Handschumacher R. E. Tissue uridine pools: evidence in vivo of a concentrative mechanism for uridine uptake. Cancer Res. 1986 Jul;46(7):3490–3494. [PubMed] [Google Scholar]
  10. Darnowski J. W., Holdridge C., Handschumacher R. E. Concentrative uridine transport by murine splenocytes: kinetics, substrate specificity, and sodium dependency. Cancer Res. 1987 May 15;47(10):2614–2619. [PubMed] [Google Scholar]
  11. Das R. B., Biswas R., Vonderhaar B. K. Characteristics of a membrane-associated antilactogen binding site for tamoxifen. Mol Cell Endocrinol. 1993 Dec;98(1):1–8. doi: 10.1016/0303-7207(93)90229-d. [DOI] [PubMed] [Google Scholar]
  12. Friedman Z. Y. The antitumor agent tamoxifen inhibits breakdown of polyphosphoinositides in GH4C1 cells. J Pharmacol Exp Ther. 1994 Oct;271(1):238–245. [PubMed] [Google Scholar]
  13. Furr B. J., Jordan V. C. The pharmacology and clinical uses of tamoxifen. Pharmacol Ther. 1984;25(2):127–205. doi: 10.1016/0163-7258(84)90043-3. [DOI] [PubMed] [Google Scholar]
  14. Gout P. W., Beer C. T., Noble R. L. Prolactin-stimulated growth of cell cultures established from malignant Nb rat lymphomas. Cancer Res. 1980 Jul;40(7):2433–2436. [PubMed] [Google Scholar]
  15. Grem J. L. Biochemical modulation of fluorouracil by dipyridamole: preclinical and clinical experience. Semin Oncol. 1992 Apr;19(2 Suppl 3):56–65. [PubMed] [Google Scholar]
  16. Grem J. L., Fischer P. H. Alteration of fluorouracil metabolism in human colon cancer cells by dipyridamole with a selective increase in fluorodeoxyuridine monophosphate levels. Cancer Res. 1986 Dec;46(12 Pt 1):6191–6199. [PubMed] [Google Scholar]
  17. Hawkins R. A., Roberts M. M., Forrest A. P. Oestrogen receptors and breast cancer: current status. Br J Surg. 1980 Mar;67(3):153–169. doi: 10.1002/bjs.1800670302. [DOI] [PubMed] [Google Scholar]
  18. Horwitz K. B. Mechanisms of hormone resistance in breast cancer. Breast Cancer Res Treat. 1993;26(2):119–130. doi: 10.1007/BF00689685. [DOI] [PubMed] [Google Scholar]
  19. Howell S. B., Mansfield S. J., Taetle R. Thymidine and hypoxanthine requirements of normal and malignant human cells for protection against methotrexate cytotoxicity. Cancer Res. 1981 Mar;41(3):945–950. [PubMed] [Google Scholar]
  20. Jarvis S. M. Nitrobenzylthioinosine-sensitive nucleoside transport system: mechanism of inhibition by dipyridamole. Mol Pharmacol. 1986 Dec;30(6):659–665. [PubMed] [Google Scholar]
  21. Jordan V. C. Overview from the International Conference on Long-Term Tamoxifen Therapy for Breast Cancer. J Natl Cancer Inst. 1992 Feb 19;84(4):231–234. doi: 10.1093/jnci/84.4.231. [DOI] [PubMed] [Google Scholar]
  22. Kayyali R., Marriott C., Wiseman H. Tamoxifen decreases drug efflux from liposomes: relevance to its ability to reverse multidrug resistance in cancer cells? FEBS Lett. 1994 May 16;344(2-3):221–224. doi: 10.1016/0014-5793(94)00378-5. [DOI] [PubMed] [Google Scholar]
  23. Kon O. L. An antiestrogen-binding protein in human tissues. J Biol Chem. 1983 Mar 10;258(5):3173–3177. [PubMed] [Google Scholar]
  24. Kroeger E. A., Brandes L. J. Evidence that tamoxifen is a histamine antagonist. Biochem Biophys Res Commun. 1985 Sep 16;131(2):750–755. doi: 10.1016/0006-291x(85)91302-6. [DOI] [PubMed] [Google Scholar]
  25. Laurence J., Cooke H., Sikder S. K. Effect of tamoxifen on regulation of viral replication and human immunodeficiency virus (HIV) long terminal repeat-directed transcription in cells chronically infected with HIV-1. Blood. 1990 Feb 1;75(3):696–703. [PubMed] [Google Scholar]
  26. Lee C. W., Cheeseman C. I., Jarvis S. M. Na+- and K+-dependent uridine transport in rat renal brush-border membrane vesicles. Biochim Biophys Acta. 1988 Jul 7;942(1):139–149. doi: 10.1016/0005-2736(88)90283-0. [DOI] [PubMed] [Google Scholar]
  27. Lee C. W., Cheeseman C. I., Jarvis S. M. Transport characteristics of renal brush border Na(+)- and K(+)-dependent uridine carriers. Am J Physiol. 1990 May;258(5 Pt 2):F1203–F1210. doi: 10.1152/ajprenal.1990.258.5.F1203. [DOI] [PubMed] [Google Scholar]
  28. Lee C. W. Decrease in equilibrative uridine transport during monocytic differentiation of HL-60 leukaemia: involvement of protein kinase C. Biochem J. 1994 Jun 1;300(Pt 2):407–412. doi: 10.1042/bj3000407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Lee C. W., Goh L. B., Tu Y. Sensitivity to inhibition by N-ethylmaleimide: a property of nitrobenzylthioinosine-sensitive equilibrative nucleoside transporter of murine myeloma cells. Biochim Biophys Acta. 1995 Aug 31;1268(2):200–208. doi: 10.1016/0167-4889(95)00081-3. [DOI] [PubMed] [Google Scholar]
  30. Lee C. W., Sokoloski J. A., Sartorelli A. C., Handschumacher R. E. Induction of the differentiation of HL-60 cells by phorbol 12-myristate 13-acetate activates a Na(+)-dependent uridine-transport system. Involvement of protein kinase C. Biochem J. 1991 Feb 15;274(Pt 1):85–90. doi: 10.1042/bj2740085. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Lopes M. C., Vale M. G., Carvalho A. P. Ca2(+)-dependent binding of tamoxifen to calmodulin isolated from bovine brain. Cancer Res. 1990 May 1;50(9):2753–2758. [PubMed] [Google Scholar]
  32. Mac Neil S., Dawson R. A., Crocker G., Tucker W. F., Bittiner B., Singleton J. G., Hunter T., Tierney D. F. Antiproliferative effects on keratinocytes of a range of clinically used drugs with calmodulin antagonist activity. Br J Dermatol. 1993 Feb;128(2):143–150. doi: 10.1111/j.1365-2133.1993.tb15143.x. [DOI] [PubMed] [Google Scholar]
  33. O'Brian C. A., Liskamp R. M., Solomon D. H., Weinstein I. B. Inhibition of protein kinase C by tamoxifen. Cancer Res. 1985 Jun;45(6):2462–2465. [PubMed] [Google Scholar]
  34. Pinedo H. M., Zaharko D. S., Bull J. M., Chabner B. A. The reversal of methotrexate cytotoxicity to mouse bone marrow cells by leucovorin and nucleosides. Cancer Res. 1976 Dec;36(12):4418–4424. [PubMed] [Google Scholar]
  35. Plagemann P. G., Wohlhueter R. M., Woffendin C. Nucleoside and nucleobase transport in animal cells. Biochim Biophys Acta. 1988 Oct 11;947(3):405–443. doi: 10.1016/0304-4157(88)90002-0. [DOI] [PubMed] [Google Scholar]
  36. Sutherland R. L., Murphy L. C., San Foo M., Green M. D., Whybourne A. M., Krozowski Z. S. High-affinity anti-oestrogen binding site distinct from the oestrogen receptor. Nature. 1980 Nov 20;288(5788):273–275. doi: 10.1038/288273a0. [DOI] [PubMed] [Google Scholar]
  37. Taylor O. M., Benson E. A., McMahon M. J. Clinical trial of tamoxifen in patients with irresectable pancreatic adenocarcinoma. The Yorkshire Gastrointestinal Tumour Group. Br J Surg. 1993 Mar;80(3):384–386. doi: 10.1002/bjs.1800800341. [DOI] [PubMed] [Google Scholar]
  38. Vonderhaar B. K., Banerjee R. Is tamoxifen also an anti-lactogen? Mol Cell Endocrinol. 1991 Aug;79(1-3):C159–C163. doi: 10.1016/0303-7207(91)90088-a. [DOI] [PubMed] [Google Scholar]
  39. Wiebe V. J., Osborne C. K., McGuire W. L., DeGregorio M. W. Identification of estrogenic tamoxifen metabolite(s) in tamoxifen-resistant human breast tumors. J Clin Oncol. 1992 Jun;10(6):990–994. doi: 10.1200/JCO.1992.10.6.990. [DOI] [PubMed] [Google Scholar]
  40. Wiseman H., Quinn P., Halliwell B. Tamoxifen and related compounds decrease membrane fluidity in liposomes. Mechanism for the antioxidant action of tamoxifen and relevance to its anticancer and cardioprotective actions? FEBS Lett. 1993 Sep 6;330(1):53–56. doi: 10.1016/0014-5793(93)80918-k. [DOI] [PubMed] [Google Scholar]
  41. Young J. D., Jarvis S. M. Nucleoside transport in animal cells. Biosci Rep. 1983 Apr;3(4):309–322. doi: 10.1007/BF01122895. [DOI] [PubMed] [Google Scholar]

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