Depletion of IL-8 in mammary carcinoma cells with forced expression of TFF3 abrogated the stimulatory effect of TFF3 on HUVEC migration, invasion, and tubule formation <i>in vitro</i>.

<p>(A) ELISA analysis of IL-8 protein secreted to the medium by MCF7-Vec and MCF7-TFF3 transiently transfected with control siRNA and IL-8 siRNA after 48 hours transfection. Scrambled control siRNA (siControl) was used as control. MCF7-Vec transiently transfected with scrambled control siRNA was a baseline. (B) HUVEC migration after 24 hours co-culture with MCF-7 cells with forced expression of TFF3 transiently transfected with control siRNA and IL-8 siRNA in serum-free conditions. (C) HUVEC invasion after 24 hours co-culture with MCF-7 cells with forced expression of TFF3 transiently transfected with control siRNA and IL-8 siRNA in serum-free conditions. (D) and (E) HUVEC tubule formation <i>in vitro</i> in the Matrigel after 12 hours co-culture with MCF-7 cells with forced expression of TFF3 transiently transfected with control siRNA and IL-8 siRNA in serum-free conditions. Total tubule length (D) and tubule number (E) was assessed using ImageJ analysis software. (F) Representative light photomicrographs of HUVEC tubule formation <i>in vitro</i> in the Matrigel after 12 hours co-culture of with MCF-7 cells with forced expression of TFF3 transiently transfected with control siRNA and IL-8 siRNA. **, <i>P</i> < <i>0</i>.<i>01</i> as compared with MCF7-Vec or MCF7-TFF3 transiently transfected with scrambled control siRNA, respectively. Scale bar, 200 μm.