免疫电镜方法研究P-gp、p53蛋白、Bcl-2蛋白在肺癌组织中的表达

Immunoelectron microscopic analysis of P-glycoprotein,p53, and Bcl-2 proteins expressions in lung cancer

目的 从超微水平了解P gp、p5 3蛋白、Bcl 2蛋白在肺癌组织中的表达 ,探讨它们与多药耐药 (multidrugresistance ,MDR)的关系和可能的作用机制。 方法 8例非小细胞肺癌 (NSCLC)手术标本和 7例小细胞肺癌 (SCLC)经支气管镜活检标本 ,用免疫电镜方法包埋后 ,以PAG标记抗体方法检测P gp、p5 3蛋白、Bcl 2蛋白的表达。 结果 P gp主要位于胞膜和胞浆内质网附近 ;p5 3主要位于细胞核异染色质上 ,胞浆中也有存在 ;Bcl 2分布与线粒体和内质网有关。三者在 15例肺癌中的表达率分别为 33 3% (5 / 15 )、6 0 0 % (9/ 15 )和 2 6 7% (4 / 15 )。 8例手术获得的正常肺组织标本中 ,3种蛋白表达均为阴性。 5例P gp阳性的标本中 ,4例为NSCLC ,仅 1例为化疗后的SCLC。 结论 用免疫电镜方法检测 ,P gp、p5 3蛋白、Bcl 2蛋白在肺癌中有一定的表达。P gp与p5 3、p5 3与Bcl 2的表达无相关性。P gp主要位于胞膜 ,支持其膜上药物输出泵的功能 ,其表达在肺癌的MDR中起一定作用 ,但不是惟一因素。

Objective To determine the ultrastructural localization of P-gp, p53 protein, and Bcl-2 protein in lung cancer cells,their relation to multidrug resistance and possible mechanisms of action. Methods Expression of P-gp, p53, and Bcl-2 proteins was examined in 8 NSCLC surgical specimens and 7 SCLC bronchoscopically biopsied specimens using postembedding PAG immunolabelling technique for electron microscopy. Results P-gp was detected on the cell membrane and the periphery of endoplasmic reticulum(ER). P53 protein was observed not only in the nuclei associated with heterochromatin but also in the cytosol. Bcl-2 protein immunoreactivity was associated with mitochondria and ER. P-gp, p53, and Bcl-2 were detected in 5(33%), 9(60%), and 4(26.7%) out of the 15 samples examined,respectively. In 8 normal lung tissues, these three proteins were detected. Of 5 P-gp positive samples 4 were NSCLC, only 1 was SCLC after chemotherapy. Conclusion P-gp, p53, and Bcl-2 proteins are detectable immuno-electron microscopically in lung cancer cells. No correlation in expression existed between of p53 and P-gp, nor did that between p53 and Bcl-2. The plasma membrane localization of P-gp supports its action as a transmembrane drug efflux pump. P-gp may play a role in MDR in lung cancer.