PMID- 19020749 OWN - NLM STAT- MEDLINE DCOM- 20090202 LR - 20181201 IS - 1019-6439 (Print) IS - 1019-6439 (Linking) VI - 33 IP - 6 DP - 2008 Dec TI - 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. PG - 1165-76 AB - 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. FAU - Oliveras-Ferraros, Cristina AU - Oliveras-Ferraros C AD - Catalan Institute of Oncology (ICO), Dr Josep Trueta University Hospital of Girona, E-17007 Girona, Catalonia, Spain. FAU - Vazquez-Martin, Alejandro AU - Vazquez-Martin A FAU - Lopez-Bonet, Eugeni AU - Lopez-Bonet E FAU - Martin-Castillo, Begona AU - Martin-Castillo B FAU - Del Barco, Sonia AU - Del Barco S FAU - Brunet, Joan AU - Brunet J FAU - Menendez, Javier A AU - Menendez JA LA - eng SI - ClinicalTrials.gov/NCT00232505 PT - Journal Article PT - Research Support, Non-U.S. Gov't PL - Greece TA - Int J Oncol JT - International journal of oncology JID - 9306042 RN - 0 (Antibodies, Monoclonal) RN - 0 (Antibodies, Monoclonal, Humanized) RN - 0 (BRCA1 Protein) RN - 0 (BRCA1 protein, human) RN - 0 (Cross-Linking Reagents) RN - 0 (Protein Kinase Inhibitors) RN - 0 (Quinazolines) RN - 0 (Receptors, Estrogen) RN - 0 (Receptors, Progesterone) RN - 0 (TP53 protein, human) RN - 0 (Tumor Suppressor Protein p53) RN - EC 2.7.10.1 (EGFR protein, human) RN - EC 2.7.10.1 (ERBB2 protein, human) RN - EC 2.7.10.1 (ErbB Receptors) RN - EC 2.7.10.1 (Receptor, ErbB-2) RN - EC 2.7.12.2 (Mitogen-Activated Protein Kinase Kinases) RN - EC 3.1.3.67 (PTEN Phosphohydrolase) RN - EC 3.1.3.67 (PTEN protein, human) RN - PQX0D8J21J (Cetuximab) RN - Q20Q21Q62J (Cisplatin) RN - S65743JHBS (Gefitinib) SB - IM MH - Antibodies, Monoclonal/administration & dosage MH - Antibodies, Monoclonal, Humanized MH - Antineoplastic Combined Chemotherapy Protocols/*pharmacology MH - Apoptosis/*drug effects MH - BRCA1 Protein/metabolism MH - Breast Neoplasms/enzymology/metabolism/*pathology MH - Cell Line, Tumor MH - Cell Proliferation/*drug effects MH - Cetuximab MH - Cisplatin/administration & dosage MH - Cross-Linking Reagents/administration & dosage MH - Dose-Response Relationship, Drug MH - *Drug Resistance, Neoplasm MH - Drug Synergism MH - ErbB Receptors/*antagonists & inhibitors/metabolism MH - Female MH - Gefitinib MH - Humans MH - Mitogen-Activated Protein Kinase Kinases/metabolism MH - PTEN Phosphohydrolase/deficiency MH - Phosphorylation MH - Protein Kinase Inhibitors/administration & dosage MH - Quinazolines/*pharmacology MH - Receptor, ErbB-2/deficiency MH - Receptors, Estrogen/deficiency MH - Receptors, Progesterone/deficiency MH - Tumor Suppressor Protein p53/deficiency MH - Up-Regulation EDAT- 2008/11/21 09:00 MHDA- 2009/02/03 09:00 CRDT- 2008/11/21 09:00 PHST- 2008/11/21 09:00 [pubmed] PHST- 2009/02/03 09:00 [medline] PHST- 2008/11/21 09:00 [entrez] PST - ppublish SO - Int J Oncol. 2008 Dec;33(6):1165-76.