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[PMC free article] [PubMed] [Google Scholar] 44. Ceftobiprole medocaril in which the combined efficacy with gefitinib is usually expected. Furthermore, we exhibited that Rab25 plays an important role in EGFR endocytosis and gefitinib therapy. and models and found a potential relationship between gefitinib response and EGFR endocytosis. We also exhibited that suppressing EGFR endocytosis could aeffect cell viability and the gefitinib response in gefitinib-insensitive lung malignancy with wtEGFR. Additonally, we also confirmed that Rab25 is usually associated with EGFR endocytosis and the gefitinib response. RESULTS Effects of gefitinib on cell survival and EGFR signaling in lung malignancy cells with wtEGFR We first proflied gefitinib response in the eight lung malignancy cell lines (H1703, Calu-1, H441, H522, SNU-1327, SNU-2292, H358 and Calu-3) with wtEGFR. Six of the eight lung malignancy cell lines (H1703, Calu-1, H441, H522, SNU-1327 and SNU-2292) were relatively insensitive to gefitinib (IC50>10 M) compared to the other two lung malignancy cell lines (H358 and Calu-3) (IC50<10 M) (Physique ?(Figure1A).1A). To examine further differential effects of gefitinib between these lung malignancy cell lines, H358 and H1703 cells were chosen as gefitinib-sensitive and -insensitive cells, respectively. In the following comparative experiments, Aspn H358 cells exhibited morphological changes, retarded wound healing and G0/G1 arrest of the cell cycle after gefitinib treatment but H1703 cells did not show any changes in cell phenotype following gefitinib treatment (Physique 1B-D). We next investigated whether the differential effects of gefitinib between these lung malignancy cell lines were associated with activation status of the EGFR signaling pathway. Interestingly, phosphorylation of EGF-induced EGFR was inhibited by gefitinib treatment in both H358 Ceftobiprole medocaril and H1703 cells regardless of the gefitinib response (Physique ?(Figure1E).1E). In gefitinib-insensitive H1703 cells, we also profiled the activation statues of multiple EGFR phosphorylation sites that regulate numerous downstream cellular signaling pathways. As shown in Physique ?Physique1F,1F, seven Ceftobiprole medocaril of ten phosphorylation sites (Tyr845, Tyr1086, Tyr1148, Tyr1173, Ser1046/1047, and Ser1070) were activated by EGF activation, but all EGFR phosphorylated sites were blocked by gefitinib treatment. Moreover, phosphorylation of AKT and ERK, well-known downstream molecules in the EGFR signaling pathway, was also inhibited by gefitinib in both H358 and H1703 cells (Physique ?(Physique1G).1G). Comparable results were detected in the other six lung malignancy cell lines (Data not shown). These results suggest the presence of an unknown mechanism that regulates the response to gefitinib in lung malignancy with wtEGFR. Open in a separate window Physique 1 Effects of gefitinib in lung malignancy cells with wtEGFR(A) Changes in cell survival caused by gefitinib were decided using MTT assay. The cells were treated with the indicated concentrations of gefitinib for 72 h. Each data point represents mean results of six impartial determinations with the standard error (SE). (B) Morphological changes caused by gefitinib were representatively analyzed in H358 and H1703 cells using light microscopy and reddish fluorescent-conjugated phalloidin staining. After a 48 h incubation with or without gefitinib (10 M), cell images were captured at a magnification of 200. Black and white arrows show the morphologically changed cells (C) Changed cell motility capacity was evaluated using a wound healing assay. The cell images after treatment with gefitinib (10 M) Ceftobiprole medocaril were captured at a magnification of 100. (D) Redistributed percentages of the cell cycle caused by gefitinib were evaluated after PI staining and circulation cytometry. Data symbolize mean results acquired from three impartial experiments. (E) Effects of gefitinib on epidermal growth factor (EGF)-induced epidermal growth factor receptor (EGFR) phosphorylation were examined using Western blot analysis. The cells were pretreated with gefitinib (10 M) under serum-free conditions for 24 h and incubated for further indicated times in the presence or absence of 100 ng/ml EGF. (F) Statuses of multiple phosphorylation sites of EGFR in H1703 cells were decided using an antibody array. Relative expression levels of phosphorylated Ceftobiprole medocaril EGFR sites were calculated with a gel doc image analyzer. The ratio of phosphorylated EGFR was normalized to total EGFR acquired from three experiments in the same membrane. Each bar is the SE. (G) The effects of gefitinib on EGF-induced phosphorylation of ERK and AKT were evaluated by Western blot analysis. EGFR endocytosis is usually associated with the gefitinib response in lung malignancy with wtEGFR Some reports show the possibility that ligand-induced internalization of EGFR, one of its degradation processes, is a potential molecular mechanism.