The inducible expression of dominant-negative epidermal growth factor receptor-CD533 results in radiosensitization of human mammary carcinoma cells.
Ionizing radiation activates the epidermal growth factor receptor (EGFR) and downstream signaling involving the cytoprotective mitogen-activated protein kinase (MAPK) pathway. In our effort to investigate the role of EGFR in cellular responses to radiation, we generated mammary carcinoma cell clones, MCF-TR5-EGFR-CD533 and MDA-TR15-EGFR-CD533, that inducibly express EGFR-CD533, a truncated EGFR mutant lacking mitogenic and transformation activity. EGFR-CD533 expression inhibits radiation- and EGF-induced EGFR autophosphorylation and MAPK activation and, therefore, functions as a dominant-negative mutant without blocking the expression of EGFR or erbB-2, another member of the erbB receptor Tyr kinase family. Expression of EGFR-CD533 only minimally inhibited cell growth and did not alter radiosensitivity to single radiation exposures. However, repeated 2 Gy radiation exposures of cells, under conditions of EGFR-CD533 expression, essentially abolished their ability for subsequent cell growth. These results identify the inhibition of EGFR function through genetic manipulation as a potential therapeutic maneuver. The concept of such an intervention would be the radiosensitization of cells by counteracting a radiation-induced cytoprotective proliferation response.
Department of Radiation Oncology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond 23298-0058, USA.
J N
JN
Contessa
D B
DB
Reardon
D
D
Todd
P
P
Dent
R B
RB
Mikkelsen
K
K
Valerie
G D
GD
Bowers
R K
RK
Schmidt-Ullrich
D001943:Breast Neoplasms; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000494:pharmacology; D066246:ErbB Receptors / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D006801:Humans; D007700:Kinetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D066246:ErbB Receptors; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004318:Doxycycline