OBJECTIVETo investigate the expression of signal transducers and activators of transcription 3 (STAT3) and its target gene products including vascular endothelial growth factor (VEGF) and Bcl-2 in two human esophageal squamous cell carcinoma (ESCC) cell lines for understanding whether STAT3 signaling transduction pathway was constitutively activated in ESCC cell lines.

METHODSWestern blotting was used to determine the protein levels of STAT3, p-STAT3 (activated STAT3), VEGF and Bcl-2 in two ESCC cell lines (EC9706 and Eca109). Nuclear proteins from the ESCC cell lines were extracted to evaluate the DNA-binding activity by electrophoretic mobility gel shift assay (EMSA). RT-PCR was used to detect the mRNA of STAT3, VEGF and Bcl-2.

RESULTSWestern blotting and RT-PCR revealed that STAT3, VEGF and Bcl-2 protein and mRNA were overexpressed in the two ESCC cell lines, which contained constitutively activated STAT3 signaling transduction pathway. The results of EMSA of the nuclear protein showed high DNA-binding activity of STAT3.

CONCLUSIONSTAT3 signaling transduction pathway is constitutively activated in human ESCC cell lines, suggesting that STAT3 may play a critical role in the carcinogenesis of the esophagus.