IL-4细胞毒素对垂体腺瘤生长及其激素分泌的靶向治疗作用

IL-4 cytotoxin inhibits cell growth and hormone secretion of pituitary adenomas

目的:研究IL-4细胞毒素对垂体腺瘤细胞生长及其激素分泌的影响,并探讨其机制。方法:应用RT-PCR法和流式细胞仪检测垂体腺瘤细胞(GH3、AtT20)上IL-4受体各亚型mRNA的表达。应用MTT法检测DT4H(IL-4细胞毒素)对垂体腺瘤细胞所产生的细胞毒性效应,并经DNA片段分析、流式细胞分析、蛋白印迹分析和电镜证实。应用ELISA法检测垂体激素分泌水平的变化。在裸鼠上建立垂体腺瘤动物模型,测定治疗前后腺瘤体积和激素水平的变化。结果:垂体腺瘤细胞GH3和AtT20上均表达IL-4受体各亚型。DT4H诱导垂体腺瘤细胞所产生的细胞毒性效应呈现剂量-时间依赖关系。细胞周期分析表明DT4H能诱导细胞周期的停滞。caspase8,caspase9,caspase3,RANKL和JNK2的表达均增加,而Bcl-2的表达减少。DT4H治疗后,垂体腺瘤细胞和裸鼠垂体腺瘤的激素分泌水平明显下降,腺瘤体积明显缩小。结论:本研究首次明确IL-4细胞毒素通过caspase途径诱导垂体腺瘤细胞的凋亡、抑制垂体激素的分泌,很可能为垂体腺瘤的生物靶向治疗提供一种新的途径。

Objective： To investigate the cytotoxic effects of IL-4 cytotoxin on cell growth and hormone secretion of pituitary adenomas, and the underlying mechanism. Methods： The mRNAs of three subunits of IL-4 receptor were detected by RT-PCR, and their surface expressions were measured by flow cytometry. Cytotoxicity induced by DT4H, an IL-4 cytotoxin, in tumor cells was measured with MTT assay, and the induced apoptosis was determined by agarose gel electrophoresis. The cell cycle and apoptosis was assessed by ANNEXIN V FITC kit with PI staining. The expressions of caspase 8, caspase 9, caspase 3, Bcl-2, RANKL and JNK2 were detected by West- ern blotting. The hormone levels secreted from pituitary adenoma cells were measured by ELISA assay. The transplanted pituitary adenoma was induced in nude mice, in which the tumor volume and hormone levels were measured before and after treatment with DT4H. Results： GH3 and AtT20 cells expressed three subunits of IL-4 receptor. DT4H produced the cytotoxicity in tumor cells in concentration- and time-dependent manners. The cell cycle analysis indicated that DT4H induced cell arrest in G0/G1 phase. The expressions of caspase 8, easpase 9, caspase 3, RANKL and JNK2 were increased, while that of Bcl-2 was decreased after treatment with DT4H. In addition, the hormone levels and the tumor volume were reduced. Conclusion： We revealed for the first time that DT4H induces apoptosis of pituitary adenoma cells through easpase activation, and inhibits secretion of hormones from pituitary adenomas. It can possibly be considered as a novel therapeutic candidate for the treatment of pituitary adenomas.