EP1.03-11 Mechanisms of Gefitinib Plus Pemetrexed on Human Non-Small Cell Lung Cancer

Abstract

Resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI) is often acquired in non-small cell lung cancer (NSCLC) patients during treatment. We previously demonstrated that combined treatment with EGFR-TKI gefitinib plus chemotherapy improved progression-free survival (PFS) in NSCLC patients carrying sensitive EGFR mutations. Pharmacological interaction between gefitinib and pemetrexed was evaluated in NSCLC cell line PC-9 using MTT assay. The influence of combined treatment with gefitinib plus pemetrexed on gene expression profiles and signaling pathways has been investigated using microarray and Ingenuity Pathway Analysis (IPA). Synergistic inhibitory effect between gefitinib and pemetrexed was observed in NSCLC cell line PC-9. Figure 1A suggested representative proliferation inhibitory effects of gefitinib, pemetrexed and combined treatment for 48 hours. Figure 1B showed CI values of concurrent gefitinib-pemetrexed treatment in PC-9 NSCLC cell line. CI values at ED50, ED75 and ED90 were shown. Furthermore, widespread gene expression changes and critical signaling pathways were induced significantly by combined treatment in PC-9 cells. Figure 2A was heatmap of gene expression prolifes in human NSCLC PC-9 cell line treated with gefitinib (blue), pemetrexed (purple) or gefitinib-pemetrexed combination (orange) with the criteria P<0.05 and ▏fold change ▏>1.5. Genes and samples were listed in rows and columns, respectively. A colour standard for data normalization was shown at the bottom with green representing downregulated genes while red representing upregulated genes. In Figure 2B, pathway enrichment of differential expressed genes was analysed using Ingenuity Pathway Analysis (IPA). Signaling pathways shown here were based on a P<0.0001. Figure 2C showed heatmap of critical pathways affected by combined treatment as compared to gefitinib single treatment. Heatmap colour represented the Z-score of signalling pathways. Z-score>0 meant the signalling pathway was stimulated by related treatment while Z-score<0 meant the signalling pathway was inhibited by related treatment.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Gene expression profiles revealed potential signaling pathways contributing to the synergism.