云南白族地区乳腺癌EphA2表达检测及以T淋巴细胞为载体的Caspase-3靶向治疗的研究

白族是云南的一种主要世居少数民族，而女性是这支生力军的重要组成部分。乳腺癌是女性最常见的恶性肿瘤之一，其发病呈较快增长和年轻化趋势，严重威胁妇女的身心健康。乳腺癌的治疗仍是世界性难题，新的靶向性药物研究仍是学术热点。免疫毒素是近年来新兴的一种特异性靶向治疗药物。最近发现EphA2在多种恶性肿瘤中过度表达，可能是一个新的肿瘤标志物。本研究首先检测白族地区乳腺癌中EphA2及其配体EphrinAl的表达，利用骨髓间充质干细胞（MSCs）对肿瘤组织有趋化性的特点，以EphrinAl为导向分子，以绿脓杆菌外毒素活性片段PE38KEDL为毒素分子，通过腺病毒介导，建立分泌重组免疫毒素EphrinAl-PE38KEDL的MSCs，体外观察其对乳腺癌细胞增殖和凋亡的作用，然后植入乳腺癌动物模型，观察分泌重组免疫毒素的MSCs对乳腺癌的治疗作用，探讨骨髓MSCs作为靶向毒素基因治疗载体的可行性。

Bai nationality is one of the main peculiar minorities in Yunnan, of which the women are the important force. Breast cancer is one of the most common malignant tumors and has become the number one killer among women carcinomas, which greatly affects human health and life. It is estimated that 1.2 million of female will be diagnosed of breast cancer, with 0.5 million death annually in the world. In recent years the incidence and mortality of breast cancer are increasing rapidly, with an annual rate of approximately 0.2～0.3％. And more and more young women were affected by this disease. The treatment of the breast cancer is a hard nut to crack in the world at present, and the research on a new targeted drug is still a hot academic issue. Immunotoxins (ITs) is a new targeted agent of the highly specific nature. Recent evidence has shown that the EphA2 receptor is overexpressed in a number of human malignancies, including that of breast, prostate, melanoma and of ovary as well as in Glioblastoma multiform, and is associated with their development and progression.Thus, the EphA2 receptor may represent a very attractive target for immunotoxin therapy. For the ideal toxin-based targeted therapy for caner, one of the most important issues to be considered is how to target only tumor tissue effectively, killing cancer cells selectively, and to protect the surrounding normal tissues from side effects. In the present study, we will first examine the expression of EphA2 receptor and its ligand EphrinAl in breast cancer tissue from Yunnan Dali Bai, Han and other minority women. Then we construct an adenoviral vector encoding EphrinA1-PE38KEDL, a recombinant immunotoxin based on the EphrinA1 ligand and a truncated form of Pseudomonas exotoxin A, which could specifically target EphA2 receptor-overexpressing tumor cells. We also confirm the production of EphrinA1-PE38KEDL in the mesenchymal stem cells (MSCs) derived from the bone marrow via adenoviral transduction and the effects of these EphrinA1-PE38KEDL-carrying MSCs on the proliferation and apoptosis of the EphA2-overexprssing breast cancer cells in vitro. And then, utilizing the tumor tropism of MSCs, the MSCs that were transiently transduced with these virus will be transplanted into the animal models of breast cancer, and the anticancer effects in vivo would be observed. The aim of our study is to obtain reliable evidence that genetically modified MSCs may function as a novel therapeutic vehicle for targeted delivery of immunotoxin to malignant tumor and explore a new strategy for the site-specific treatment of breast cancer.