食管鳞癌中磷酸化信号传导与转录激活因子3和髓样细胞白血病1过表达与分化相关并可增强细胞的凋亡抗性

Overexpression of p-Stat3 and Mcl-1, and their correlation with differentiation and apoptotic resistance in esophageal squamous cell carcinoma

目的 检测磷酸化信号转导与转录激活因子3（p-Stat3）和髓样细胞白血病1（Mcl-1）蛋白在食管鳞癌中的表达，探讨其在食管鳞癌发病机制中的作用及其相关性。方法采用JAK／Stat3通路抑制剂AG490或JSI-124抑制食管鳞癌细胞KYSE510中Stat3信号通路的活化，并通过转染特异性的siRNA敲降Stat3表达，流式细胞术检测细胞凋亡，Westernblot检测Star3抗凋亡靶分子Mcl-1蛋白的表达。采用组织芯片-免疫组织化学染色法检测p-Stat3（TyrT05）和Mcl-1蛋白在食管鳞癌组织中的表达情况，分析其与食管鳞癌临床病理特征之间的关系，以及二者间表达的相关性。结果抑制食管鳞癌细胞中Stat3通路的活化后，凋亡细胞比例显著升高，Mcl-1表达明显下调。111例食管鳞癌组织中，P—Stat3（Tyr705）蛋白阳性表达50例，阳性表达率为45．0％。肿瘤分化程度越低，P-Stat3的阳性表达率越高，差异有统计学意义（P=0．018）。Mcl-1蛋白阳性表达80例，阳性表达率为72．1％。肿瘤分化程度越低，Mcl-1蛋白的阳性表达率越高，差异有统计学意义（P=0．026）。p-Stat3蛋白表达与Mcl-1蛋白表达呈正相关（P=0．012）。结论部分食管鳞癌组织中存在p-Stat3和Mel—1的过表达，二者呈正相关关系，并均与肿瘤分化程度有关。异常活化的Stat3可能通过上调靶蛋白Mcl-1的表达介导食管鳞癌细胞的凋亡抗性。

Objective To detect the expression of phosphorylated-signal transducer and activator of transcription 3 （ p-Stat3 ） and myeloid leukemia-1 （ Mcl-1 ） as well as their correlation, and to investigate the functional role of Star3 and Mcl-1 in the pathogenesis of esophageal squamous cell carcinoma （ESCC）. Methods Stat3 activity in ESCC cells was inhibited with JAK/Stat3 inhibitors （AG490 or JSI-124 ）, Specific siRNA was used to inhibit the Star3 expression. Cell apoptosis was detected by flow eytometry. Expression of Mel-1 protein was determined by Western blotting. Expression of phospho-Stat3 （Tyr705） and myeloid leukemia-1 （Mcl-1） proteins in ESCC tissues was detected by tissue microarray and immunohistochemistry. The relationship between p-Stat3 or Mcl-1 aberrant expression and clinieopatholohical features of ESCC was analyzed. The correlation of their expression was also analyzed. Results Suppression of the Stat3 signaling activation in ESCC cells led to marked apoptosis, and dramatic reduction of Mel-1 protein. The positive rate of phospho-Stat3 （Tyr705） expression was 45.0% in 50/111 of the ESCC tissue samples. The lower the degree of tumor differentiation, the higher the positive rate of phospho-Stat3 （ Tyr705）, showing a significant difference （ P = 0. 018 ）. The positive rate of Mel-1 protein expression was 72.1% （80/111） , and the lower the degree of tumor differentiation was, the higher there was the positive rate of Mcl-1, with a significant difference （ P = 0. 026 ）. There was a positive correlation between the expressions of p-Stat3 and Mcl-1 proteins （ P = 0.012）. Conclusions In a subset of ESCC tissues, p-Stat3 （Tyr705） and Mcl-1 are overexpressed and positively correlated with each other, and both are correlated with tumor differentiation. Persistent activation of Stat3 contributes to apoptotic resistance in ESCC cells, and may be at least partly mediated through upregulation of Mcl-1.