OBJECTIVETo investigate the correlation of expressions of STAT3 and p-STAT3 with epithelial mesenchymal transition(EMT)-associated protein E-cadherin in colorectal cancer, and to examine the association of above expressions with tumor invasion and metastasis of colorectal cancer.

METHODSImmunohistochemistry assay ElivisionTM plus was used to detect the expressions of STAT3, p-STAT3 and E-cadherin protein in colorectal cancer tissue samples of 50 cases and their corresponding adjacent non-tumor tissues. Association of these protein expressions with tumor invasion and metastasis was analyzed with χ(2) test. Correlation of STAT3 and p-STAT3 with E-cadherin was analyzed with Spearman method.

RESULTSPositive expression rates of STAT3, p-STAT3 and E-cadherin protein in colorectal cancer tissues were 72%(36/50), 76%(38/50) and 26%(13/50), which were significantly higher compared to adjacent normal intestinal mucosa tissues [24%(12/50), 26%(13/50) and 68%(34/50), all P<0.05]. STAT3, p-STAT3 and E-cadherin expressions were associated with tumor differentiation, tumor invasion depth, tumor size, lymph node metastasis, TNM staging (all P<0.05). In colorectal cancer tissues, STAT3 protein expression was positively correlated with p-STAT3 expression. STAT3 and p-STAT3 expressions in colorectal cancer tissues were negatively correlated with E-cadherin expression(P<0.05).

CONCLUSIONSTAT3 and p-STAT3 may be involved in tumor EMT through inhibition of E-cadherin expression, leading to the development of colorectal cancer.