Enhanced epidermal growth factor receptor signaling in MCF7 breast cancer cells after long-term culture in the presence of the pure antiestrogen ICI 182,780 (Faslodex)

Citation
Ra. Mcclelland et al., Enhanced epidermal growth factor receptor signaling in MCF7 breast cancer cells after long-term culture in the presence of the pure antiestrogen ICI 182,780 (Faslodex), ENDOCRINOL, 142(7), 2001, pp. 2776-2788
Citations number
57
Categorie Soggetti
Endocrinology, Nutrition & Metabolism
Journal title
ENDOCRINOLOGY
ISSN journal
00137227 → ACNP
Volume
142
Issue
7
Year of publication
2001
Pages
2776 - 2788
Database
ISI
SICI code
0013-7227(200107)142:7<2776:EEGFRS>2.0.ZU;2-K
Abstract
This paper describes the establishment of an antiestrogen-resistant MCF7 br east cancer cell subline (FASMCF) by continuous culture of the estrogen-res ponsive parental line in steroid-depleted, ICI 182,780 (Faslodex; 10(-7) M) -supplemented medium. After a 3-month period of growth suppression, cells b egan to proliferate in ICI 182,780 at rates similar to those of untreated w ild-type cells. Immunocytochemistry showed these cells to have reduced estr ogen receptor and an absence of progesterone receptor proteins. RT-PCR and transient transfection studies with estrogen response element-reporter cons tructs confirmed that ICI 182,780-suppressed estrogen response element-medi ated signaling. FASMCF cells show increased dependence upon epidermal growt h factor receptor (EgfR)/mitogen-activated protein kinase (MAPK)-mediated s ignaling. Thus, EgfR protein and messenger RNA, growth responses to transfo rming growth factor-a, and extracellular signal-regulated kinase 1/2 MAPK a ctivation levels are all increased. Unlike wild-type cells, FASMCF cells ar e highly sensitive to growth inhibition by an EgfR-specific tyrosinekinase inhibitor (TKI), ZD1839 (Iressa), and an inhibitor of the activation of MEK 1 (MAPKK), PD098059. Short-term (similar to3 weeks) withdrawal of cells from antiestrogen had no effect on growth or phenotype, whereas longer withdrawal(> 10 weeks) appea red to partially reverse the cellular phenotype with increasing estrogen re ceptor and decreasing FgfR levels. In subsequent studies FASMCF cells were maintained in TKI, where their grow th was again suppressed and secondary TKI resistance failed to develop with in the 3-month period in which initial ICI 182,780 resistance arose. Furthe rmore, wild-type cells similarly maintained in combination ICI 182,780 and TKI treatment conditions remained growth arrested (>6 months), with notable cell loss through both reduced rates of cellular proliferation and increas ed cell death.