Abstract
The signaling pathway that is initiated by binding of epidermal growth factor receptor (EGFR) and results in sustained signaling through PI3K plays an important role in a tumor's response to ionizing radiation. The current in vitro study explored both the effects of ZD1839 (Iressa), a highly selective EGFR tyrosine kinase inhibitor, as a radiosensitiser for bile duct carcinoma cell lines and ZD1839's general effects on cell growth in the same two lines. Secondly, we ensured suppression of radiation-induced phosphorylation of EGFR by ZD1839 using an immunoprecipitation technique. Furthermore, we examined radiation-induced phosphorylation of ERK, p38, JNK, and AKT with or without inhibitor with use of Western blot techniques and performed clonogenic assays to confirm radiosensitivity in the presence of a drug. ZD1839 inhibited cell growth of both cell lines and suppressed radiation-induced phosphorylation of EGFR. After exposure to radiation, there was an increase in phosphorylation of AKT as shown by Western blot. Treatment with either ZD1839 or LY294002 (the latter, a PI3K inhibitor) suppressed phosphorylation of AKT by Western blot. Both ZD1839 and LY294002 significantly suppressed colony formation by clonogenic assay; however, U0126 (a MEK1/2 inhibitor), SB203580 (a p38 inhibitor), and SP600125 (a JNK inhibitor) had no effect on colony formation. These results suggest that AKT may be a useful target molecule for enhancement of radiotherapy effect and that ZD1839 may have an important role in combination with radiotherapy for patients with bile duct carcinoma.
MeSH terms
-
Anthracenes / pharmacology
-
Bile Duct Neoplasms / metabolism
-
Bile Duct Neoplasms / pathology
-
Butadienes / pharmacology
-
Cell Line, Tumor
-
Cell Proliferation / drug effects
-
Cell Survival / drug effects
-
Cell Survival / radiation effects
-
Chromones / pharmacology
-
Clone Cells / cytology
-
Clone Cells / drug effects
-
Clone Cells / radiation effects
-
Dose-Response Relationship, Drug
-
Enzyme Activation / drug effects
-
Enzyme Activation / radiation effects
-
Enzyme Inhibitors / pharmacology
-
ErbB Receptors / antagonists & inhibitors*
-
ErbB Receptors / metabolism
-
Gefitinib
-
Humans
-
Imidazoles / pharmacology
-
JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
-
JNK Mitogen-Activated Protein Kinases / metabolism
-
Mitogen-Activated Protein Kinases / antagonists & inhibitors
-
Mitogen-Activated Protein Kinases / metabolism
-
Morpholines / pharmacology
-
Nitriles / pharmacology
-
Oncogene Protein v-akt / antagonists & inhibitors
-
Oncogene Protein v-akt / metabolism
-
Phosphorylation / drug effects
-
Phosphorylation / radiation effects
-
Protein Kinase Inhibitors / pharmacology*
-
Pyridines / pharmacology
-
Quinazolines / pharmacology*
-
Radiation-Sensitizing Agents / pharmacology*
-
p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
-
p38 Mitogen-Activated Protein Kinases / metabolism
Substances
-
Anthracenes
-
Butadienes
-
Chromones
-
Enzyme Inhibitors
-
Imidazoles
-
Morpholines
-
Nitriles
-
Protein Kinase Inhibitors
-
Pyridines
-
Quinazolines
-
Radiation-Sensitizing Agents
-
U 0126
-
pyrazolanthrone
-
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
-
ErbB Receptors
-
Oncogene Protein v-akt
-
JNK Mitogen-Activated Protein Kinases
-
Mitogen-Activated Protein Kinases
-
p38 Mitogen-Activated Protein Kinases
-
SB 203580
-
Gefitinib