Small interfering RNA suppression of transducer and activator of transcription 3 (STAT3) signaling pathway: inhibitory effect on proliferation of human esophageal squamous carcinoma cells / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the efficiency of blockage of constitutively activated STAT3 signaling by small interfering RNA (siRNA), and to explore the inhibitory effects on the proliferation of human esophageal squamous carcinoma cells (EC9706 and Eca109).</p><p><b>METHODS</b>EC9706 and Eca109 were transfected with chemical synthesized STAT3 siRNA (100 nmol/L). RT-PCR and Western blot were used to detect STAT3 mRNA and protein expression, including phosphorylated-STAT3 (p-STAT3) before and after the transfection respectively. The changes of DNA-binding activity and cell proliferation were evaluated by electrophoretic mobility gel shift assay and MTT, respectively. Stages of cell cycle were determined by flow cytometry.</p><p><b>RESULTS</b>Expression levels of STAT3 mRNA and STAT3, p-STAT3 proteins were progressively inhibited by STAT3 siRNA at various time points after transfection. STAT3-DNA-binding activity was suppressed after transfection evidenced by electrophoretic mobility gel shift assay. The cell cycle was arrested at G(0)/G(1) phase along with a significant inhibition of cell proliferation after STAT3 siRNA treatment.</p><p><b>CONCLUSION</b>STAT3 siRNA specifically and efficiently blocks the constitutively activated STAT3 signaling pathway in human esophageal squamous carcinoma cells, resulting in cell cycle arrest and proliferation inhibition.</p>

Constitutive activation of signal transducers and activators of transcription 3 and expression of its target gene products in human ESCC cell line / 南方医科大学学报

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>