PLC and PI3K pathways are important in the inhibition of EGF-induced cell migration by gefitinib ('Iressa', ZD1839).
BACKGROUND
Expression of epidermal growth factor receptor (EGFR) by human breast cancer tissues is associated with poor clinical response. The EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib ('Iressa', ZD1839), is a leading example of a molecular targeted agent, and has an anti-proliferative effect on various cancer cells. But the details of the anti-cancer effect and mechanism have not been elucidated. We studied the anti-cancer effect of gefitinib in breast cancer cell lines and the intracellular pathway downstream of EGFR associated with cell migration.


METHODS
In this study, we analysed the anti-proliferative and anti-migratory effect of gefitinib in EGFR (+) breast cancer cell lines by WST-1 analysis and chemotaxis chamber analysis. We analyzed several intracellular phosphorylated pathways which are activated by mitogen activated kinases (extracellular signal-regulated protein kinase 1 and 2: MEK), phosphatidylinositol 3'-kinase (PI3K) and phpspholipase C (PLC), by blocking those pathways using inhibitors of each kinase, and also investigated the effects on the phosphorylation of myosin light chain (MLC).


RESULTS
Gefitinib inhibited proliferation in most of these cell lines. MDA-MB231 was shown to be resistant. Furthermore, proliferation of MDA-MB231 cells was not affected by EGF stimulation, but migration of MDA-MB231 cells was significantly inhibited. PI3K and PLC inhibitors blocked EGF-stimulated cell migration and MLC phosphorylation, but the MEK inhibitor did not influence cell migration.


CONCLUSIONS
Gefitinib has an anti-migratory effect on MDA-MB231 that results in an anti-proliferative effect. PI3K and PLC are important for the migration of MDA-MB231 cells, and gefitinib may inhibit migration by blocking these signalling pathways.
Shien
Tadahiko
T
Department of Surgery II, University of Okayama, 1-5-2 Shikata-cho, Okayama 700-8558, Japan. tada99@mint.ocn.ne.jp
Doihara
Hiroyoshi
H
Hara
Humikata
H
Takahashi
Hirotoshi
H
Yoshitomi
Seiji
S
Taira
Naruto
N
Ishibe
Youiti
Y
Teramoto
Jyun
J
Aoe
Motoi
M
Shimizu
Nobuyoshi
N
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology*; D045744:Cell Line, Tumor / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D009361:Neoplasm Invasiveness; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors*
D000970:Antineoplastic Agents; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D010738:Type C Phospholipases; D000077156:Gefitinib