中文摘要：

目的：初步探讨人乳腺癌细胞MDA-MB-231特异性多肽PI的跨膜转导机制。方法：合成PI肽链,并在其N端进行FITC标记;探讨FITC-PI的跨膜转导与MHC-Ⅰ表达的关系,利用MHC-Ⅰ抗体阻断MDA-MB-231细胞和Calu-1细胞表面MHC-Ⅰ抗原,聚合酶链反应-序列特异性引物法进行基因分析;探讨FITC-PI的跨膜转导是否与小窝蛋白介导的内吞有关,抑制剂制霉菌素与MDA-MB-231细胞共培养,荧光显微镜观察以及流式细胞仪检测细胞内FITC-PI分布情况;探讨FITC-PI跨膜转导是否与2株细胞表面相同的膜蛋白有关系,膜蛋白提取试剂盒分别提取2株细胞膜蛋白,双向电泳对其进行差异性分析。结果：MHC-Ⅰ抗体阻断后,2株细胞内仍可见FITC-PI分布,基因位点分析显示2株细胞HLA-A、B位点等位基因不同;加入制霉菌素后,镜下观察及流式细胞仪检测均显示FITC-PI分布减少;双向电泳初步分析2株细胞膜蛋白图谱共有11个相同的蛋白点。结论：PI的跨膜转导机制不单一,其一,部分由小窝蛋白介导的内吞机制,其二,可能与2株细胞表面相同的膜蛋白有关系,此研究为将来继续探讨其跨膜转导机制奠定了实验基础和理论依据。

英文摘要：

Objective：To investigate transmembrane transduction mechanism of a peptide（PI）with high affinity to human breast cancer cell line MDA-MB-231.Methods：PI was synthesized and labeled with FITC at its N-terminus.The MHC-I antigen in the MDA-MB-231 cells and human lung cancer Calu-1 cells was blocked using anti-MHC-Ⅰ antibody,respectively.HLA-allele analysis was performed by polymerase chain reaction-sequence specific primers.To investigate whether the transmembrane transduction mechanism of PI is associated with the caveolin-mediated endocytosis,the distribution of FITC-PI in MDA-MB-231 cells were detected using inverted fluorescence microscope and flow cytometry after pre-incubation with an inhibitor of endocytosis,nystatin.To investigate whether the transmembrane transduction mechanism of PI is associated with the same membrane protein of the two cell lines,the membrane proteins were detected by two-dimensional electrophoresis.Results：FITC-PI was observed in the two cells with MHC-Ⅰ antigen being blocked.Gene typing-analysis revealed that the alleles of the HLA-A and B locis were different.The inhibitor nystatin suppressed FITC-PI distribution.Two-dimensional electrophoresis analysis showed that membrane protein profiles of the two cell lines had 11 same protein spots.Conclusions：The transduction of PI is mediated by the caveolin-mediated endocytosis.The same proteins of the two cell lines may be also involved in this process.This study provides experimental evidence for further investigation of the transmembrane transduction mechanism.