[Constitutive activation of signal transducers and activators of transcription 3 and expression of its target gene products in human ESCC cell line]

Abstract

Objective: To 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.

Methods: Western 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.

Results: Western 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.

Conclusion: STAT3 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.