To further demonstrate the p73 mediated alternative pathway we pharmacologically

Treatment of MCF 7 COX cells with the Cox 2 inhibitor NS398 decreased their invasive potential, indicating that Cox 2 expression contributes to the invasive activity of MCF 7 DOX cells. We next determined the effects of the Cox 2 inhibitor NS398 KU-55933 価格 on activities of MMP 9, MMP 2, and uPA secreted from MCF 7 DOX cells using plasminogen fibrinogen and gelatin zymography assays. We found that the activity of MMP 9 and uPA was inhibited by 50 uM NS398, a con centration that did not affect MCF 7 DOX cell prolif eration, The effect of Cox 2 expression on invasiveness of MCF 7 DOX cells was confirmed by blocking Cox 2 expression using siRNA.<br><br> Consistent with the results of the Cox 2 inhibitor experiment, transfection of siRNA targeting Cox 2 sup pressed migration of MCF 7 DOX cells in an in vitro migration assay, Effect of the EGFR pathway Linifanib 臨床試験 on Cox 2 mediated invasion of MCF 7 DOX cells Having identified Cox 2 as an important regulator of invasiveness of MCF 7 DOX cells, we next asked which upstream pathway modulates the expression of Cox 2 in this cell line. Because EGFR has been reported to regu late Cox 2 expression, we hypothesized that activa tion of the EGFR pathway may induce Cox 2 expression. First, we examined the basal expression level of EGFR in a subset of breast cancer cell lines. Western blot analysis showed high levels of EGFR expression in the doxorubicin resistant MCF 7 DOX and MDA MB 231 cells, which were invasive and had elevated Cox 2 expression, We next tested the role of the EGFR pathway on induction of Cox 2 expression by treating cells with EGF and blocking these pathways using EGFR specific siRNA.<br><br> Cox 2 expression was markedly suppressed when both MCF 7 DOX and MDA MB 231 cells were transfected with EGFR specific siRNAs, In addition, Western blot analyses of MCF 7 DOX cells revealed that Cox 2 expression was induced within 2 h of EGF treatment, We further confirmed that blocking the EGFR pathway purchase LY3009104 suppressed Cox 2 expression using a selective EGFR tyrosine kinase inhibi tor, gefitinib. Treating cells for 24 h with gefitinib effec tively suppressed EGF induced Cox 2 expression in MCF 7 DOX cells, We then tested the effects of the EGFR inhibitor on invasion of MCF 7 DOX cells. Gefitinib decreased the invasive potential of MCF 7 DOX cells, indicating that EGFR contributes to invasiveness of MCF 7 DOX cells by upregulating Cox 2.<br><br> Effect of EGFR on PI3K Akt and MAPK mediated Cox 2 expression in MCF 7 DOX cells Because EGFR controls several other pathways, such as the PI3K Akt and MAPK pathways, we next investigated which downstream pathway was involved in EGFR mediated Cox 2 expression. As expected, treating MCF 7 DOX cells with EGF for 8 h to induce Cox 2 expression activated both the PI3K Akt and MAPK pathways, To confirm the role of the PI3K Akt and MAPK pathways in Cox 2 expression, we stu died the effect of the PI3K Akt inhibitor LY294002 and the MAPK inhibitor U0126 on EGF induced expression of pAkt and Cox 2 in MCF 7 DOX cells. Western blot analysis showed that LY294002 and U0126 dramatically suppressed activation of pAkt and pERK1 2, respec tively, and downregulated EGF induced Cox 2 expres sion, To investigate the role of the PI3K Akt pathway in invasiveness of MCF 7 DOX cells, we deter mined whether blocking the PI3K Akt pathway would inhibit invasion of MCF 7 DOX cells in an in vitro inva sion assay.