IL-6 promotes RKIP and STAT 3 transcription and phosphorylation; H. pylori infection induces STAT3 transcription and phosphorylation.

(A) Western blot analysis of AGS cells treated with the indicated concentrations of IL-6 and for 6 hours. Densitometry was performed and for pRKIP expression, our results indicate a 1.8 fold incerase of pRKIP (average intensity 0.59 vs 1.051) in cells treated with 25 ng/ml IL-6 and a 1.35 fold increase (average intensity 0.59 vs 0.772) in cells treated with 50 ng/ml IL-6. For RKIP expression, our results indicate a 0.8 fold incerase of pRKIP (average intensity 0.69 vs 0.563) in cells treated with 25 ng/ml IL-6 and a 1.05 fold increase (average intensity 0.69 vs 0.745) in cells treated with 50 ng/ml IL-6 when normalized to actin at each time point. (B) Western blot analysis of AGS co-cultured with H. pylori and examined for pY705 STAT3 for the indicated times; (C) STAT3 luciferase reporter transcriptional assay of AGS cells co-cultured with H. pylori at the indicated MOI; (D) STAT3 luciferase reporter assay of AGS cells transiently transfected with STAT3 for 24 h and co-cultured with H. pylori and/or treated with IL-6 for 6 h. A paired t-test was performed to analyze the increase or decrease in STAT3 transcription of experimental samples when compared to empty vector (EV): *IL-6, p<0.0003; **STAT3, p<0.009; *** H. pylori p<0.0005; **** STAT3 and H. pylori p<0.0000023.