title: Trastuzumab-induced HER reprogramming in "resistant" breast carcinoma cells.
abstract: Although trastuzumab (Herceptin) is an important advance in the treatment of breast cancer, a significant proportion of patients do not respond to trastuzumab either alone or in combination with chemotherapy. In this study, we observe that epidermal growth factor receptor (EGFR) and HER3 expression is substantially increased after long-term trastuzumab exposure of HER2-positive breast carcinoma-derived cell lines that show primary resistance to trastuzumab. Furthermore, long-term trastuzumab exposure of trastuzumab-resistant cell lines induces de novo sensitivity to the EGFR-targeted agents gefitinib or cetuximab in two of three cell lines accompanied by increased EGFR expression. Together, these results indicate that primary trastuzumab resistance is not synonymous with lack of responsiveness to trastuzumab and, importantly, suggest that trastuzumab priming may sensitize trastuzumab-resistant tumors to other HER family-directed therapeutics.
authors.affiliation: Division of Medical Oncology, Yale Cancer Center, Yale University, New Haven, Connecticut, USA.
authors.forename: Murli
authors.initials: M
authors.lastname: Narayan
authors.forename: Jason A
authors.initials: JA
authors.lastname: Wilken
authors.forename: Lyndsay N
authors.initials: LN
authors.lastname: Harris
authors.forename: Andre T
authors.initials: AT
authors.lastname: Baron
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Kimbler
authors.forename: Nita J
authors.initials: NJ
authors.lastname: Maihle
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D006801:Humans; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D000068878:Trastuzumab