RESUMO
BACKGROUND/AIMS: Signal transducers and activators of transcription (STATs) are a family of transcription factors that are activated in response to cytokines and growth factors. STAT3 activation has been implicated in modulating the activity of downstream mediators, such as Bcl-xL and matrix metalloproteinase-2 (MMP-2). The aim of this study was to investigate the immunohistochemical expression of STAT3, B-cell lymphoma-extra large (Bcl-xL), and MMP-2 proteins according to histopathological parameters in colon adenocarcinomas, including lymph node metastasis, tumor differentiation, the TNM stage and the tumor size. METHODS: Immunohistochemical staining with monoclonal STAT3, Bcl-xL, and MMP-2 antibodies was performed on paraffin-embedded specimens from 20 colon adenomas and 39 adenocarcinomas. RESULTS: The expression of STAT3, Bcl-xL, and MMP-2 was increased in the adenocarcinomas as compared with the adenomas (p<0.001). STAT3 expression was stronger in tumors with a distant metastasis than in tumors without a distant metastasis (p=0.012). A larger tumor size was related to an increase in STAT3 expression (p=0.035). CONCLUSIONS: STAT3, Bcl-xL, and MMP-2 may play important roles in the tumorigenesis of colorectal carcinoma. STAT3 may be indicative of a poor prognosis due to its correlation with distant metastases and a larger tumor size.