Relationship between Mutations of the Epidermal Growth Factor Receptor Gene and Drug-Resistance to Gefitinib in Human Lung Cancer in vitro.

To explore cell lines' difference of drug-resistance to gefitinib and the underlying mechanism. Human lung cancer cell lines of PC9, PC9/AB2, PC9/AB11, PC9/BB4 were treated in vitro, exons 18-21 of EGFR gene were sequenced and EGFR gene mRNA levels were measured. Four cell lines' drug resistance difference of gefitinib were validated. All the four cell lines had the 15 bp deletion at exon 19, and AB11 had A to G point-mutation at exon 20. PC9 EGFR gene in the sensitive cell line was expressed much higher than that in 3 resistance cell lines by real-time PCR. There is significant difference of drug-resistance to gefitinib existed among the lung cancer cell lines PC9, PC9/AB2, PC9/AB11 and PC9/BB4. The mutations changes of expressive level of EGFR gene might be correlated with the acquired drug-resistance to gefitinib in lung cancer cell lines.