STAT3信号通路影响人胶质瘤细胞株存活和凋亡的研究

Role of STAT3 on cell survival and apoptosis in human glioblastoma cell lines

目的 了解STAT3在星形细胞瘤中的表达情况并研究STAT3通路在胶质瘤细胞株生长、凋亡过程中的作用和相关机制。方法 通过免疫组化的方法显示星形细胞瘤手术标本中STAT3的表达情况。用AG490作用于体外培养的人胶质瘤细胞株U251、U87，通过Western blot了解STAT3蛋白在肿瘤细胞株中的表达和AG490对STAT3通路的阻断情况。观察AG490作用后胶质瘤细胞存活率的变化，并用流式细胞分析技术检测STAT3阻断后肿瘤细胞的凋亡情况。通过RT-PCR了解STAT3通路阻断后部分相关基因mRNA表达的改变。结果 STAT3在星形细胞瘤中有广泛表达，瘤内表达明显高于瘤周组织（P〈0．01）。STAT3在不同病理分级、性别、年龄组之间，差异无统计学意义（P〉0．05）。AG490作用胶质瘤细胞株后可使细胞内p-STAT3表达下降，同时肿瘤细胞存活率明显下降，肿瘤细胞凋亡比例明显升高。AG490对U251细胞存活率和凋亡的影响与AG490的浓度和作用时间有关。在AG490阻断STAT3信号通路的过程中，Mcl-1、Bcl-XL和Survivin的mRNA表达有所下降。结论 STAT3在星形细胞瘤中有广泛表达并与肿瘤细胞生长凋亡的生物学特性有着内在联系，STAT3通路有可能成为胶质瘤治疗的有用靶点。

Objective To observe the expression of STAT3 in astrocytoma and study the effects of STAT3 on cell survival rate and apoptosis in human glioblastoma cell lines. Methods Immunohistochemical detection of STAT3 was performed on 30 astrocytoma specimens. The expression patterns of STAT3 were categorized by semiquantitative method and further analyzed with nonparametric tests in groups of histopathologic grade, sex, age and region in sections. AG490 was applied to inhibit the activation of STAT3 in human glioblastoma cell lines U251 and U87. The result of the STAT3 deactivation was proved by Western blot. And the follow-up consequence on survival rate and apoptosis rate of glioma cells were observed and analyzed statistically. The changes of mRNA expression of related genes were checked by RT-PCR. Results The STAT3 positive cells were observed in all specimens. There was no significant difference in STAT3 expression in groups of histopathalogical grade, sex and age, but the expression was significantly higher within the tumor area compared with the peritumoral regions. The expression of phospho-STAT3 was cut down in U251 and U87 cell lines after the treatment of AG490, which indicated that AG490 blocked the STAT3 signaling in the glioma cell lines. AG490 also significantly decreased the survival rate of the U251 cells in a dosage and time-dependent way. While, the apoptosis rate of tumor cells markedly increased after the AG490 treatment. And more, it was revealed that the mRNA expressions of Mcl-1, Bcl-XL and Survivin were down regulated accompanied by the inhibition of STAT3 signaling. Conclusion The findings that STAT3 widely expressed in astrocytoma and involved in the survival and apoptosis of glioma cell lines contribute to the conception that STAT3 signaling is important in the pathogenesis of glioma and, therefore, possible to be a promising target in glioma therapy.