Objective        To determine the effect of cucurbitacin E (CuE) on the proliferation and migration of human colonic cancer Caco-2 cells

and to determine the underlying molecular mechanism in the action.       Methods      The cultured Caco-2 cells were treated with CuE at 0.001

0.01

0.1

1 and 10 μmol/L respectively. CCK-8 assay was used to detect the proliferation of Caco-2 cells. The migration of Caco-2 was analyzed by scratch assay and transwell chamber assay. Fluorescence assay was employed to determine the relative contents of  F-actin and G-actin. Laser confocal microscopy was used to observe the cytoskeleton F-actin. Western blot assay was used to detect the protein expression of cofilin

phosphorylated cofilin

LIM domain kinase 2 (LIMK2) and phosphorylated LIMK2.       Results        CCK-8 assay

scratch assay and transwell chamber assay showed CuE of 0.1

1 and 10 μmol/L significantly inhibited the proliferation and migration of Caco-2 cells in a dose-dependent and time-dependent manner (P0.05). Fluorescence assay showed after 0.1 μmol/L CuE treatment resulted in a significant increase of G-actin content (P0.05)

dynamic imbalance of F-actin/G-actin

and the treatment for 1

2

6

12 and 24 h caused the disruption of cytoskeleton F-actin in Caco-2 cells. Western blot analysis demonstrated that the protein expression of cofilin

phosphorylated cofilin and phosphorylated LIMK2 were decreased in the Caco-2 cells after the treatment of different concentrations of CuE (P0.05)

while the expression of LIMK2 had no significant change compared with control.       Conclusion        CuE may disrupt the cytoskeleton actin by inhibiting LIMK/cofilin signaling pathway

and further lead to inhibit the proliferation and migration in human colonic cancer Caco-2 cells.