Growth and molecular interactions of the anti-EGFR antibody Cetuximab and the DNA cross-linking agent cisplatin in gefitinib-resistant MDA-MB-468 cells: New prospects in the treatment of triple-negative/basal-like breast cancer

  • Authors:
    • Cristina Oliveras-Ferraros
    • Alejandro Vazquez-Martin
    • Eugeni López-Bonet
    • Begoña Martín-Castillo
    • Sonia Del Barco
    • Joan Brunet
    • Javier A. Menendez
  • View Affiliations

  • Published online on: December 1, 2008     https://doi.org/10.3892/ijo_00000106
  • Pages: 1165-1176
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Abstract

Three prominent hallmarks of triple-negative/basal-like breast carcinomas, a subtype of breast cancer gene phenotype associated with poor relapse-free and overall survival, are overexpression of the epidermal growth factor receptor (EGFR), hyperactivation of the MEK/ERK transduction pathway and high sensitivity to DNA-damaging agents. The cytotoxic interaction between EGFR inhibitors (monoclonal antibodies such as Cetuximab and small molecule tyrosine kinase inhibitors such as gefitinib) and DNA cross-linking agents (e.g. platinum derivatives) might represent a promising combination for the treatment of triple-negative/basal-like breast tumors that are dependent upon EGFR/MEK/ERK signaling. We evaluated the growth and molecular interactions of the anti-EGFR antibody Cetuximab (Erbitux®) and the DNA cross-linking agent cisplatin (cis-diammedichloroplatinum; CDDP) in the gefitinib-resistant MDA-MB-468 breast cancer cell line, an in vitro model system that shows many of the recurrent basal-like molecular abnormalities including ER-PR-HER2-negative status, TP53 deficiency, EGFR overexpression, PTEN loss and constitutive activation of the MEK/ERK pathway. Unlike other basal-like breast cancer models, MDA-MB-468 cells do not carry mutations of the key DNA repair gene BRCA1. Concurrent treatment with sub-optimal doses of Cetuximab significantly enhanced CDDP-induced apoptotic cell death. However, an isobologram-based mathematical assessment of the nature of the interaction revealed a loss of synergism when employing a high-dose of Cetuximab. Since BRCA1 depletion has been found to decrease DNA damage repair and cell survival in MDA-MB-468 cells when treated with DNA-damaging drugs, we employed ELISA-based quantitative analyses to measure BRCA1 protein levels in CDDP+/− Cetuximab-treated cells. Cetuximab as single agent was as efficient as CDDP at increasing BRCA1 protein expression. Interestingly, Cetuximab co-exposure significantly antagonized the ability of CDDP to up-regulate BRCA1 expression. Low-scale phosphor-proteomic approaches [i.e. phospho-receptor tyrosine kinase (RTK) and phospho-mitogen-activated protein kinases (MAPKs) Array Proteome Profiler™ capable of simultaneously identifying the relative levels of phosphorylation of 42 different RTKs and 23 different MAPKs and other serine/threonine kinases, respectively] revealed the ability of Cetuximab, as single agent, to paradoxically induce hyper-phosphorylation of EGFR while concomitantly deactivating p42/44 (ERK1/ERK2) MAPK. Unexpectedly, ELISA-based quantitative analyses of EGFR protein content demonstrated that simultaneous exposure to Cetuximab and optimal doses of CDDP completely depleted EGFR protein in MDA-MB-468 cells. Although these findings preclinically support, at least in part, ongoing clinical trials for ‘triple-negative/basal-like’ metastatic breast cancer patients who are receiving either Cetuximab alone versus Cetuximab plus carboplatin (http://www.clinicaltrials.gov/ct/show/NCT00232505), the unexpected ability of CDDP to promote a complete depletion of the Cetuximab target EGFR further suggests that treatment schedules, Cetuximab/CDDP doses and BRCA1 status should be carefully considered when combining anti-EGFR antibodies and platinum derivatives in triple-negative/basal-like breast carcinomas.

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December 2008
Volume 33 Issue 6

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Oliveras-Ferraros C, Vazquez-Martin A, López-Bonet E, Martín-Castillo B, Del Barco S, Brunet J and Menendez JA: Growth and molecular interactions of the anti-EGFR antibody Cetuximab and the DNA cross-linking agent cisplatin in gefitinib-resistant MDA-MB-468 cells: New prospects in the treatment of triple-negative/basal-like breast cancer. Int J Oncol 33: 1165-1176, 2008.
APA
Oliveras-Ferraros, C., Vazquez-Martin, A., López-Bonet, E., Martín-Castillo, B., Del Barco, S., Brunet, J., & Menendez, J.A. (2008). Growth and molecular interactions of the anti-EGFR antibody Cetuximab and the DNA cross-linking agent cisplatin in gefitinib-resistant MDA-MB-468 cells: New prospects in the treatment of triple-negative/basal-like breast cancer. International Journal of Oncology, 33, 1165-1176. https://doi.org/10.3892/ijo_00000106
MLA
Oliveras-Ferraros, C., Vazquez-Martin, A., López-Bonet, E., Martín-Castillo, B., Del Barco, S., Brunet, J., Menendez, J. A."Growth and molecular interactions of the anti-EGFR antibody Cetuximab and the DNA cross-linking agent cisplatin in gefitinib-resistant MDA-MB-468 cells: New prospects in the treatment of triple-negative/basal-like breast cancer". International Journal of Oncology 33.6 (2008): 1165-1176.
Chicago
Oliveras-Ferraros, C., Vazquez-Martin, A., López-Bonet, E., Martín-Castillo, B., Del Barco, S., Brunet, J., Menendez, J. A."Growth and molecular interactions of the anti-EGFR antibody Cetuximab and the DNA cross-linking agent cisplatin in gefitinib-resistant MDA-MB-468 cells: New prospects in the treatment of triple-negative/basal-like breast cancer". International Journal of Oncology 33, no. 6 (2008): 1165-1176. https://doi.org/10.3892/ijo_00000106