Helicobacter pylori infection, gastrin and cyclooxygenase-2 in gastric carcinogenesis

Figure 5 Mature amidated gastrin (G17) induces STAT3 and Akt phosphorylation in gastric cancer cells. SGC-7901 and MKN-45 cells were treated for 30 min with increasing concentrations of G17 (A), or with G17 (10 nmol/L) for the indicated time points (B), as well as pre-treated as indicated with 10 nmol/L CCK2R antagonist YM022 (C) or 40 μmol/L JAK2 inhibitor AG490 (D) or 25 μmol/L PI3K inhibitor LY294002 (E) for 1 h and then incubated with G17 (10 nmol/L) for 30 min to evaluate STAT3 and Akt phosphorylation or for 6 h to evaluate cyclooxygenase-2 (COX-2) expression. SGC-7901 and MKN-45 cells were transfected with either CCK2R-siRNA (F) or CCK2R-pCMV6 (G), followed by G17 (10 nmol/L) treatment for 30 min. Protein extracts were prepared and analyzed for total and phosphorylated forms of STAT3 or Akt by Western blot analysis using corresponding antibodies. The top panels show a representative immunoblot of six separate experiments undertaken. The histograms at the bottom represent the relative expression of phospho-STAT3 (p-STAT3) or phospho-Akt (p-Akt) or COX-2 compared with total STAT3 (t-STAT3) or total Akt (t-Akt) or tubulin, respectively. All data represent the mean ± SD of six independent experiments. ^aP < 0.05, ^bP < 0.01 vs control or NC-siRNA or pCMV6; ^cP < 0.05, ^dP < 0.01 vs G17. Reproduced from Ref [74] with permission.