PMC

Paclitaxel-induced activation of EGFR is blocked by adding neutralizing TGFα antibody. The dose of paclitaxel is 2-fold IC50. The dose of TGFα antibody is 0.15 μg/mL A.PC-9 B. H1650

PC-9/GR exon 20 sequence. A. Wild type by direct sequencing. B. 3 of 20 clones had ACG > ATG T790M mutation by clone sequencing. C. 17 of 20 clones were wild type

Growth inhibition of PC-9 and H1650 by an anti-TGFα.antibody. PC-9 and H1650 cells were grow into a 96 well plate. The following day, the cells were incubated with indicated concentration of anti-TGFα antibody for 72 h. The inhibition ratio were determined by MTT assay.

The antiproliferative effect with paclitaxel and gefitinib is sequence-dependent. A. Schema of sequential treatment. B and C. The sequence of paclitaxel followed by gefitinib produced the most potent antiproliferative effect in PC-9 and Hcc827 cells. T → G, paclitaxel followed by gefitinib. G → T, gefitinib followed by paclitaxel. T + G, concomitant paclitaxel and gefitinib. T, paclitaxel alone for 72 h. G, gefitinib alone for 72 h.

Effect of paclitaxel on EGFR phosphorylation. PC-9 and H1650 cells were exposed to 1, 2 and 3 fold IC50 dose paclitaxel for 24 h. A dose-dependent increase in EGFR phosphorylation levels were observed.

Synergism of sequence-dependent cytotoxicity between paclitaxel and gefitinib. Points, mean values of three different experiments. ○ T → G, paclitaxel followed by gefitinib. □ G → T, gefitinib followed by paclitaxel. △ T + G, concomitant paclitaxel and gefitinib. The sequence T → G produced the most potent cytotoxic growth inhibition. The T → G sequence resulted in a synergistic effect.

Sequential modulation of EGFR phosphorylation. Cells were exposed to the IC50 dose of gefitinib and paclitaxel using different sequences. *Paclitaxel significantly activated the EGFR pathway compared with control after paclitaxel exposure for 24 h (p < 0.05). # p < 0.05. The phosphorylated EGFR (p-EGFR) level after treatment with paclitaxel followed by gefitinib was lower than that for gefitinib followed by paclitaxel.

Sequential modulation of TGFα release and expression. Cells were exposed to IC50 dose of paclitaxel and gefitinib with different sequence. A, standard enzyme-linked immunosorbent assay analysis of soluble TGFα levels in PC-9, Hcc827 and H1650 cells. *p < 0.05, significantly different from control. #P < 0.05, T→G VS G→T. B, reverse transcription-polymerase chain reaction analysis of TGFα expression. *p < 0.05, significantly different from control. #P < 0.05, T→G vs. G→T.