Objective  To determine p-STAT3 expression in 65 cases of colorectal cancer and its correlation with Snail and MMP2 and to explore the mechanism of p-STAT3 activation in colorectal cancer cells by inhibiting its activation in vitro.

  Methods   Immunohistochemical technique was adopted to examine the expression levels of p-STAT3, Snail, and MMP2. MTT assay was used to explore the effects of diluting AG490, which does not affect cell proliferation. Western blot was used to examine the expression levels of p-STAT3, STAT3, Snail, and MMP2. Wound healing assay was employed to evaluate the migration of colorectal cancer cells.

  Results  p-STAT3 expression was significantly correlated with Snail and MMP2 expression. Moreover, p-STAT3 expression was significantly correlated with TNM stage, lymph node metastasis, and distant metastasis in colorectal cancer tissues (P < 0.05) but not with tumor differentiation. Treatment with 10 μM AG490 for 48 h did not significantly affect cell proliferation in the control and experimental groups (P > 0.05). STAT3 expression was not significantly changed when p-STAT3 expression was inhibited by AG490. Meanwhile, the expression levels of Snail and MMP2 were down-regulated, and the migration ability of colorectal cancer cells was significantly reduced.

  Conclusion  p-STAT3 promotes colorectal cancer metastasis by regulating the process of epithelial-mesenchymal transition.