Figure 3. Activation of Slit2/Robo1 signaling promotes the growth of intestinal tumors.

Following methylene blue staining, the small intestines from the Apc^Min/+ and Apc^Min/+;Slit2 mice were examined macroscopically (A). Overexpression of Slit2 significantly increased the number (B) and size (C) of the tumors. Overexpression of Slit2 resulted in a marked increase in cell proliferation as shown by enhanced BrdU uptake in the tumor tissues of Apc^Min/+;Slit2 mice (D). The results of IHC were better presented quantitatively using IPP software (D, right panel). On the other hand, inactivation of the Slit2/Robo1 signaling by siRNA-mediated gene knockdown led to a reduced proliferation of SW620 and SW480 cells (n=6 per group); conversely, overexpression of Slit2 or Robo1 caused an increased proliferation of HCT-116 cells (E). The results of methylene blue staining and IHC staining are representative of 11 mice per group (All mice were 24-week-old). The statistical data were expressed as the mean ±S.D. **: P < 0.01, and ***: P < 0.001. Scale bars: 20 μm.