Figure 5.

W2014-S significantly enhanced gefitinib sensitivity in vitro. (A) Cell proliferation and IC50 values of gefitinib at different concentrations for 72 h were measured in PC-9 and PC-9/GR cells. Each point represented the mean ± SEM, n=3. (B) The different expressions of pY705-STAT3, STAT3, pY1068-EGFR and EGFR in PC-9 and PC-9/GR cells were measured by western blot. (C) The silent effect of siRNA to STAT3 in PC-9/GR cells were detected by cell counting and western blot. Each point represented the mean ± SEM, n=3. ^*P < 0.05, ^**P < 0.01. (D) Cell viability of STAT3 knockdown was measured in PC-9/GR cells. Data were expressed as mean ± SEM, n=3. ^*P < 0.05, ^**P < 0.01, *^**P < 0.001. (E) Cell proliferation of gefitinib (2 μM) and/or W2014-S (1 μM) for 72 h was measured in PC-9/GR cells. Data were expressed as mean ± SEM, n=3. ^*P < 0.05. (F) Numbers of colonies of PC-9/GR cells treated with W2014-S (0.5 μM) and/or gefitinib (2 μM) were measured by colony formation assay. Data were expressed as mean ± SEM, n=3. ^*P < 0.05, ^**P < 0.01, *^**P < 0.001. (G) Transwell cell invasion assay was used to detected cell invasion of PC-9/GR cells treated with W2014-S (1 μM) and/or gefitinib (2 μM) for 24 h. Data were expressed as mean ± SEM, n=3. ^*P < 0.05, ^**P < 0.01, *^**P < 0.001. (H-I) PC-9/GR cells were treated with W2014-S (1 μM) and/or gefitinib (2 μM) for 72 h and apoptosis was measured by flow cytometry. PI means propidium iodide. The figures were modified due to the lower font size of labels in original picture. (J) The protein levels of pY705-STAT3, STAT3, pY1068-EGFR and EGFR in PC-9/GR cells treated with W2014-S (1 μM) and/or gefitinib (2 μM) for 24 h. Data were expressed as mean ± SEM, n=3. ^*P < 0.05, ^**P < 0.01, *^**P < 0.001.