Skip to main content
Log in

Trastuzumab Plus Tamoxifen: Anti-Proliferative and Molecular Interactions in Breast Carcinoma

  • Report
  • Published:
Breast Cancer Research and Treatment Aims and scope Submit manuscript

Abstract

HER2 overexpression has been associated with anti-estrogen resistance in human breast cancer, and it has been suggested that the combined treatment of an anti-HER2 antibody plus tamoxifen has enhanced anti-cancer efficacy in breast cancer. The detailed anti-proliferative interactions between trastuzumab and tamoxifen were analyzed with the isobologram and Chou and Talalay methods, which assess the presence of synergy, addition or antagonism. We used the breast cancer cell lines that are estrogen receptor (ER)-positive and HER2-positive. We also analyzed the molecular changes on the HER2 and (ER) signaling pathways that are induced by trastuzumab plus tamoxifen. In terms of cancer cell proliferation, the simultaneous combination of trastuzumab and tamoxifen on BT-474 cells was more growth inhibitory (44%) than the treatment with trastuzumab (24%) or tamoxifen (31%) alone. Isobologram analysis of simultaneous trastuzumab plus tamoxifen exposure showed, however, that there were antagonistic interactions at an effect level of 30% (IC30). Using Chou and Talalay analysis we also observed antagonistic interactions at lower levels of cell kill, although there were additive effects at highest levels of cell kill. Trastuzumab followed by tamoxifen showed antagonism at all effects levels. Tamoxifen followed by trastuzumab showed antagonism at lower levels of cell kill, and additivity at higher levels of cell kill. Similar interactions were observed using T47D cells. The molecular effects of the combined treatment with trastuzumab plus tamoxifen on the levels of HER2 and ER signaling showed that, with respect to HER2 protein levels, trastuzumab downregulated HER2 by 27%, tamoxifen upregulated HER2 by 40%, and the combination of trastuzumab plus tamoxifen did not induce changes in HER2 respect to control. With respect to HER2 mRNA, trastuzumab upregulated HER2 mRNA to 367%, tamoxifen to 166%, and the combination to 401%. With respect to HER2 phosphorylation, trastuzumab upregulated HER2 phosphorylation to 352%, tamoxifen to 202% and the combination to 633%. Epidermal growth factor receptor levels were not changed by trastuzumab or tamoxifen alone, and were upregulated to 138% by the combination. The protein levels and activity of extracellular recptor kinase were not modified by trastuzumab, tamoxifen or the combination. Finally, estrogen receptor protein and mRNA levels were downregulated to about 50% by trastuzumab, tamoxifen or the combination. Taken together, our results show that in ER-positive breast cancer cells overexpressing HER2, trastuzumab plus tamoxifen have antagonistic interactions when used in combination, and that this antagonism may be related with an increase in HER2 signaling pathways that occurs when tamoxifen is added to trastuzumab.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Tzahar E, Yarden Y: The ErbB-2/Her2 oncogenic receptor of adenocarcinomas: from orphanhood to multiple stromal ligands. Biochim Biophys Acta 1377: M25–M37, 1998

    Google Scholar 

  2. Riese DJ, Stern DF: Specifity within the EGF family/ErbB receptor family signaling network. Bioessays 20: 41–48, 1998

    Google Scholar 

  3. Slamon DJ, Clark GM, Wong SG, Levin WJ, Ullrich A, McGuire WL: Human breast cancer: correlation of relapse and survival with amplification of HER2/neu oncogene. Science 235: 177–182, 1987

    Google Scholar 

  4. Colomer R, Montero S, Lluch A, Ojeda B, Barnadas A, Casado A, Massuti B, Cortes-Funes H, Lloveras B: Circulating HER2 extracellular domain and resistance to chemotherapy in advanced breast cancer. Clin Cancer Res 6: 2356–2362, 2000

    Google Scholar 

  5. Ross JS, Fletcher JA: The HER-2/neu oncogene in breast cancer: prognostic factor, predictive factor, and target for therapy. Stem Cells 16: 413–428, 1998

    Google Scholar 

  6. Yu D, Hung M-C: Overexpression of erbB-2 in cancer and erbB-2-targeting strategies. Oncogene 19: 6115–6121, 2000

    Google Scholar 

  7. Park JW, Stagg R, Lewis GD, Carter P, Maneval D, Slamon DJ, Jaffe H, Shepard HM: Anti-p185HER2 monoclonal antibodies: biological properties and potential for immunotherapy. Cancer Treatment Res 61: 193–211, 1992

    Google Scholar 

  8. Maier LA, Xu FJ, Hester S, Boyer CM, McKenzie S, Bruskin AM, Argon Y, Bast Jr RC: Requirements for the internalization of a murine monoclonal antibody directed against the HER-2/neu gene product c-erbB-2. Cancer Res 51: 5361–5369, 1991

    Google Scholar 

  9. Yarden Y: Agonistic antibodies stimulate the kinase encoded by the neu protooncogene in living cells but the oncogenic mutant is constitutively active. Proc Natl Acad Sci USA 87: 2569–2573, 1990

    Google Scholar 

  10. Carter P, Presta L, Gorman CM, Ridway JBB, Henner D, Wong WLT, Rowland AM, Kotts C, Carver ME, Shepard HM: Humanization of an anti-p185HER2 antibody for human cancer therapy. Proc Natl Acad Sci USA 89: 4285–4289, 1992

    Google Scholar 

  11. Tokuda Y, Ohnishi Y, Shimamura K, Iwasawa M, Yoshimura M, Ueyama Y, Tamaoki N, Tajima T, Mitomi T: In vitro and in vivo anti-tumour effects of humanised monoclonal antibody against c-erbB-2 product. Br J Cancer 73: 1362–1365, 1996

    Google Scholar 

  12. Baselga J, Norton L, Albanell J, Kim YM, Mendelsohn J: Recombinant humanized anti-HER2 antibody (Herceptin) enhanced the antitumor antivity of placlitaxel and doxorubicin against HER2/neu overexpressing human breast cancer xenografts. Cancer Res 58: 2825–2831, 1998

    Google Scholar 

  13. Pegram M, Hsu S, Lewis G, Pietras R, Beryt M, Sliwkowski M, Coombs D, Baly D, Kabbinavar F, Slamon D: Inhibitory effects of combinations of HER-2/neu antibody and chemotherapeutic agents used for treatment of human breast cancers. Oncogene 18: 2241–2251, 1999

    Google Scholar 

  14. Vogel CL, Cobleigh MA, Tripathy D, Gutheil JC, Harris LN, Fehrenbacher L, Slamon DJ, Murphy M, Novotny WF, Burchmore M, Shack S, Stewart SJ, Press M: Efficacy and safety of trastuzumab as a single agent in first-line treatment of HER2-overexpressing metastasic breast cancer. J Clin Oncol 20: 719–726, 2002

    Google Scholar 

  15. Slamon D, Leyland-Jones B, Shak S, Paton V, Bajamonda A, Fleming T, Eiemann W, Wolter J, Norton L: Addition of Herceptin (humanized anti-HER2 antibody) to first line chemotherapy for HER2 overexpressing metastasic breast cancer (HER2+/MBC) markedly increases anticancer activity: a randomized, multinational controlled phase II trial. Proc Am Assoc Clin Oncol 17: 98, 1998

    Google Scholar 

  16. Vollenwieder-Zerargui L, Barrelet L, Wong Y, Lemarchand-Beraud I, Gomez F: The predictive value of estrogen and progesterone receptors concentrations on the clinical behavior of breast cancer in women. Clinical correlation of patients. Cancer 57: 1171–1180, 1986

    Google Scholar 

  17. Newby JC, Johnston SRD, Smith IE, Dowsett M: Expression of epidermal growth factor receptor and C-erb B2 during the development of tamoxifen resistance in breast cancer. Clin Cancer Res 3: 1643–1651, 1997

    Google Scholar 

  18. Kurokawa H, Lenferink AEG, Simpson JF, Pisacane PI, Sliwkowski MX, Forbes JT, Arteaga CL: Inhibition of HER2/neu (erbB-2) and mitogen-activated protein kinases enhaces tamoxifen action against HER2-overexpressing, tamoxifen-resistant breast cancer cells. Cancer Res 60: 5887–5894, 2000

    Google Scholar 

  19. Janes PW, Daly RJ, deFazio A, Sutherland RL: Activa-tion of the Ras signaling pathway in human breast cancer cells overexpressing erbB-2. Oncogene 9: 3601–3608, 1994

    Google Scholar 

  20. Kato S, Endoh H, Masuhiro Y, Kitamoto T, Uchiyama S, Sasaki H, Masushige S, Gotoh Y, Nishida E, Kawashima H, Metzger D, Chambon P: Activation of the estrogen receptor through phosphorylation by mitogen-activated protein kinase. Science 270: 1491–1494, 1995

    Google Scholar 

  21. Bunone G, Briand PA, Miksicek RJ, Picard D: Activation of the unliganded estrogen receptor by EGF involves the MAP kinase pathway and direct phosphorylation. EMBO J 15: 2174–2183, 1996

    Google Scholar 

  22. Lupu R, Lippman ME: The role of erbB-2 signal transduction pathways in human breast cancer. Breast Cancer Res Treat 27: 83–93, 1993

    Google Scholar 

  23. Witters LM, Kumar R, Chinchilli VM, Lipton A: Enhanced anti-proliferative activity of the combination of tamoxifen plus HER-2-neu antibody. Breast Cancer Res Treat 42: 1–5, 1997

    Google Scholar 

  24. Menéndez JA, Barbacid MM, Montero S, Sevilla E, Escrich E, Solanas M, Cortés-Funes H, Colomer R: Effects of gamma-linolenic acid and oleic acid on paclit-axel cytotoxicity in human breast cancer cells. Eur J Cancer 37: 402–413, 2001

    Google Scholar 

  25. Menéndez JA, Ropero S, Barbacid MM, Montero S, Solanas M, Escrich E, Cortés-Funes H, Colomer R: Synergistic interaction between vinorelbine and gamma-linoleic acid in breast cancer cells. Breast Cancer Res Treat 72: 203–219, 2002

    Google Scholar 

  26. Berembaum MM: What is synergy? Pharmacol Rev 41: 93–141, 1989

    Google Scholar 

  27. Chou T-C, Talalay P: Quantitative analysis of dose-effect relationships: the combined Effects of multiple drugs or enzyme inhibitors. Adv Enzyme Regul 22: 27–55, 1984

    Google Scholar 

  28. Larsen SS, Egeblad M, Jäättelä M, Lykkesfeldt AE: Acquired antiestrogen resistance in MCF-7 human breast cancer sublines is not accomplished by altered expression of receptors in the ErbB-family. Breast Cancer Res Treat 58: 41–56, 1999

    Google Scholar 

  29. Diel P, Smolnikar K, Michna H: The pure antiestrogen ICI 182780 is more effective in the induction of apoptosis and down regulation of BCL-2 than tamoxifen in MCF-7 cells. Breast Cancer Res Treat 58: 87–97, 1999

    Google Scholar 

  30. Saceda M, Grunt TW, Colomer R, Lippman ME, Lupu R, Martin MB: Regulation of estrogen receptor concentration and activity by an erb/Her ligand in breast carcinoma cell lines. Endocrinology 137: 4322–4330, 1996

    Google Scholar 

  31. Kunisue H, Kurebayashi J, Otsuki T, Tang CK, Kurosumi M, Yamamoto S, Anaka K, Doihara H, Shimizu N, Sonoo H: Anti-HER2 antibody enhances the growth inhibitory effect of anti-oestrogen on breast cancer cells expressing both oestrogen receptors and HER2. Br J Cancer 82: 46–51, 2000

    Google Scholar 

  32. Sliwkowski MX, Lofgren JA, Lewis GD, Hotaling TE, Fendly BM, Fox JA: Nonclinical studies adressing the mechanism of action of trastuzumab (Herceptin). Semin Oncol 26(suppl 12): 60–70, 1999

    Google Scholar 

  33. Antoniotti S, Maggiora P, Dati C, De Bortoli M: Tamoxifen up-regulates c-erbB-2 expression in oestrogen-responsive breast cancer cells in vitro. Eur J Cancer 28: 318–321, 1992

    Google Scholar 

  34. Alimandi M, Romano M, Curia MC, Muraro R, Fedi P, Aaronson SA, DiFiore PP, Kraus MH: Cooperative signaling of ErbB3 and ErbB2 in neoplastic transforma-tion and human mammary carcinomas. Oncogene 10: 1813–1821, 1995

    Google Scholar 

  35. Lewis GD, Figari I, Frendly B, Wong WL, Carter P, Gorman C, Shepard HM: Differential responses of human tumor cell lines to anti-p185HER2 monoclonal antibodies. Cancer Immunol Immunother 37: 255–263, 1993

    Google Scholar 

  36. Oh AS, Lorant LA, Holloway JN, Miller DL, Kern FG, El-Ashry D: Hyperactivation of MAPK induces loss of ER? expression in breast cancer cells. Mol Endocrinol 15: 1344–1359, 2001

    Google Scholar 

  37. Grunt TW, Saceda M, Martin MB, Lupu R, Dittrich E, Krupitza G, Harant H, Huber H, Dittrich C: Bidirectional interactions between the estrogen receptor and the c-erbB-2 signaling pathways: heregulin inhibits estrogenic effects in breast cancer cells. Int J Cancer 63: 560–567, 1995

    Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Ramon Colomer.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ropero, S., Abel Menéndez, J., Vázquez-Martín, A. et al. Trastuzumab Plus Tamoxifen: Anti-Proliferative and Molecular Interactions in Breast Carcinoma. Breast Cancer Res Treat 86, 125–137 (2004). https://doi.org/10.1023/B:BREA.0000032981.20384.c6

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1023/B:BREA.0000032981.20384.c6

Navigation