Pharmacological interplay between breast cancer resistance protein and gefitinib in epidermal growth factor receptor signaling.
BACKGROUND
It has been previously shown that gefitinib reverses breast cancer resistance protein (BCRP)-mediated drug resistance. Here, the impact of BCRP on gefitinib-mediated inhibition in epidermal growth factor receptor (EGFR) signaling is evaluated.


METHODS
Sensitivity to gefitinib was determined by growth inhibition assay, and intracellular gefitinib levels were measured with HPLC. Western blotting was performed to detect EGFR signaling molecules.


RESULTS
BCRP reduced intracellular gefitinib levels and attenuated inhibitory activities of gefitinib to EGF-dependent EGFR signalings including downstream MAPK and Akt pathways in gefitinib-sensitive PC-9 cells. However, gefitinib did not inhibit MAPK and Akt signalings in KB-3-1 and HCT-116 cells, and BCRP-mediated gefitinib-resistance shown in PC-9 cells was not observed in gefitinib-insensitive KB-3-1 and HCT-116 cells.


CONCLUSIONS
BCRP transports gefitinib and suppresses its inhibitory effects on EGFR phosphorylation. However, effects of BCRP on gefitinib activity in the EGFR signaling and on gefitinib-resistance were limited in the gefitinib-sensitive cells only.
Division of Chemotherapy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512, Japan.
Kazuhiro
K
Katayama
Kazuhiko
K
Shibata
Junko
J
Mitsuhashi
Kohji
K
Noguchi
Yoshikazu
Y
Sugimoto
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D019008:Drug Resistance, Neoplasm; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000077156:Gefitinib; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D000077156:Gefitinib