This Article Full Text Full Text (PDF) Supplementary Data Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Piechocki, M. P. Articles by Lonardo, F. Search for Related Content PubMed PubMed Citation Articles by Piechocki, M. P. Articles by Lonardo, F.

Breast Cancer Expressing the Activated HER2/neu Is Sensitive to Gefitinib In vitro and In vivo and Acquires Resistance through a Novel Point Mutation in the HER2/neu

¹ Department of Otolaryngology-Head and Neck Surgery, Wayne State University and Karmanos Cancer Center and ² Department of Pathology, Wayne State University, Detroit, Michigan

Requests for reprints: Marie P. Piechocki, Department of Otolaryngology-Head and Neck Surgery, Wayne State University, Room 423 Prentis Building of KCI, 110 East Warren Avenue, Detroit, MI 48201. Phone: 313-833-0715, ext. 2390; Fax: 313-833-7294; E-mail: piechock{at}karmanos.org.

The HER2/neu oncogene is an important diagnostic and prognostic factor and therapeutic target in breast and other cancers. We developed and characterized a breast cancer cell line (Bam1a) that overexpresses the activated HER2/neu and ErbB-3 and has a gene expression profile consistent with the ErbB-2 genetic signature. We evaluated the effects of the epidermal growth factor receptor (EGFR)/HER2 inhibitor, gefitinib, on this breast tumor line in vitro and in vivo. We characterized the effects of gefitinib on EGFR, HER2, and ErbB-3 phosphorylation by Western blot and determined the effects on downstream signaling through growth, survival, and stress pathways and the effect on proliferation, cell cycle, and apoptosis. Gefitinib treatment diminished phosphorylation of the ErbB-3 > EGFR > HER2/neu and signal transducers and activators of transcriptions in a dose-dependent fashion. Downstream mitogenic signaling through mitogen-activated protein (MAP)/extracellular signal regulated kinase kinase, p44/42 MAP kinase (MAPK) and stress signaling through c-Jun-NH₂-kinase (JNK) 1 and c-Jun was impaired (1 µmol/L, 4–24 h), leading to cytostasis and cell cycle arrest within 24 h by decreased cyclin D1, cyclin B1, and p^Ser795Rb and increased p27. Proliferation and colony formation were inhibited at 0.5 and 1 µmol/L, respectively, and correlated with altered gene expression profiles. Diminished survival signaling through Akt, induction of bim, loss of connexin43, and decreased production of vascular endothelial growth factor-D preceded caspase-3 and poly(ADP)ribose polymerase (PARP) cleavage and apoptosis (>50% 2 µmol/L, 48 h). Oral administration of gefitinib was able to prevent the outgrowth of Bam1a tumor cells from palpable lesions, shrink established tumors, eliminate HER2 and HER3 phosphorylation, and decrease MAPK and Akt signaling in vivo. A variant of the Bam1a cell line, IR-5, with acquired ability to grow in 5 µmol/L gefitinib was developed and characterized. IR-5 bears a novel point mutation in the HER2/neu that corresponds to a L726I in the ATP-binding pocket and correlates with a log decrease in sensitivity to gefitinib, increased heterodimerization with EGFR and HER3, and impaired down-regulation. Gene expression profiling of IR-5 showed increased expression of EMP-1, NOTCH-1, FLT-1, PDGFB, and several other genes that may contribute to the resistant phenotype and sustain signaling through MAPK and Akt. This model will be useful in understanding the differences between intrinsic drug sensitivity and acquired resistance in the context of therapeutic strategies that target oncogene addicted diseases. [Cancer Res 2007;67(14):6825–43]

This article has been cited by other articles:

				C. L. Dalgard, M. Gonzalez, J. E. deNiro, and J. M. O'Brien Differential MicroRNA-34a Expression and Tumor Suppressor Function in Retinoblastoma Cells Invest. Ophthalmol. Vis. Sci., October 1, 2009; 50(10): 4542 - 4551. [Abstract] [Full Text] [PDF]

				N. Normanno, A. Morabito, A. De Luca, M. C. Piccirillo, M. Gallo, M. R Maiello, and F. Perrone Target-based therapies in breast cancer: current status and future perspectives Endocr. Relat. Cancer, September 1, 2009; 16(3): 675 - 702. [Abstract] [Full Text] [PDF]

				D. Meco, T. Servidei, A. Riccardi, C. Ferlini, G. Cusano, G. F. Zannoni, F. Giangaspero, and R. Riccardi Antitumor effect in medulloblastoma cells by gefitinib: Ectopic HER2 overexpression enhances gefitinib effects in vivo Neuro-oncol, January 1, 2009; 11(3): 250 - 259. [Abstract] [Full Text] [PDF]

				P. J. Whittington, M. P. Piechocki, H. H. Heng, J. B. Jacob, R. F. Jones, J. B. Back, and W.-Z. Wei DNA Vaccination Controls Her-2+ Tumors that Are Refractory to Targeted Therapies Cancer Res., September 15, 2008; 68(18): 7502 - 7511. [Abstract] [Full Text] [PDF]

				T. Trowe, S. Boukouvala, K. Calkins, R. E. Cutler Jr., R. Fong, R. Funke, S. B. Gendreau, Y. D. Kim, N. Miller, J. R. Woolfrey, et al. EXEL-7647 Inhibits Mutant Forms of ErbB2 Associated with Lapatinib Resistance and Neoplastic Transformation Clin. Cancer Res., April 15, 2008; 14(8): 2465 - 2475. [Abstract] [Full Text] [PDF]