Combined inhibition of IGFR enhances the effects of gefitinib in H1650: a lung cancer cell line with EGFR mutation and primary resistance to EGFR-TK inhibitors.
OBJECTIVE
H1650 non-small cell lung cancer (NSCLC) cells display primary resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) although they have a deletion mutation on exon 19 of the EGFR gene. We investigated the effect of inhibition of both insulin-like growth factor receptor (IGFR) and EGFR signaling considering that IGFR signaling pathway has been implicated in the development and progression with therapeutic resistance of various cancers including lung cancer.


METHODS
Three human NSCLC cell lines with an EGFR mutation of PC-9, HCC827 and H1650 were used for experiment. Cell viability and proliferative activity were assessed by MTT and three-dimensional culture assay. Combination index was obtained by CalcuSyn software. The change of EGFR- and IGFR-related signals was evaluated by western blots.


RESULTS
H1650 cells were 1,000 times more resistant to gefitinib and erlotinib than HCC827 and PC-9 cells possessing the same EGFR mutation. Phosphatase and tensin homolog loss and sustained phosphorylation of Akt in spite of treatment with gefitinib were evident only in H1650 cells. Interestingly, IGFR phosphorylation was decreased by gefitinib in HCC827 and PC-9 cells while being maintained in H1650 cells. Combined treatment with the IGFR inhibitors alpha-IR3 and AG1024 enhanced gefitinib-induced growth inhibition and apoptosis, and down-regulated phosphorylation of Akt, EGFR and IGFR.


CONCLUSIONS
Combined inhibition of IGFR signaling enhances the growth inhibitory and apoptosis-inducing effects of gefitinib, suggesting that this approach could be useful to overcome the primary resistance to EGFR-TKIs in lung cancer.
Choi
Yun Jung
YJ
Department of Internal Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Science, 215-4 Gongneung-dong, Nowon-gu, Seoul, 139-706, Korea.
Rho
Jin Kyung
JK
Jeon
Byung-suk
BS
Choi
Su Jin
SJ
Park
Su Cheol
SC
Lee
Seung Sook
SS
Kim
Hye-Ryoun
HR
Kim
Cheol Hyeon
CH
Lee
Jae Cheol
JC
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005091:Exons / Q000235:genetics; D000077156:Gefitinib; D017353:Gene Deletion; D018773:Genes, erbB-1 / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007202:Indicators and Reagents; D018969:Insulin-Like Growth Factor Binding Proteins / Q000037:antagonists & inhibitors*; D008175:Lung Neoplasms / Q000188:drug therapy*; D009154:Mutation / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis / Q000235:genetics; D011799:Quinazolines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
D000970:Antineoplastic Agents; D007202:Indicators and Reagents; D018969:Insulin-Like Growth Factor Binding Proteins; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D000077156:Gefitinib