以HUMSCs为载体的多重靶向高转移乳腺癌的腺病毒基因治疗系统研究

Metastasis of breast cancer is the leading cause of failure to chemotherapy and lack of effective treatment. Get advantage of tumor-targeted characteristics, low immunogenicity of human umbilical cord blood derived mesenchymal stem cells(HUMSCs), we utilized HUMSCs as the vehicle of lentivirus for tumor targeted therapy and get satisfactory effect. Moreover, sTRAIL that expressed by adenovirus was comfirmed to overcome TRAIL resistance in our previous work. To improve the effectiveness and safety of the virus therapy system, by means of the condition that CXCR4 promoter is active in metastatic breast cancer cells as well as in the homing course of mesenchymal stem cells, we utilize the CXCR4 promoter to control the expression of E1A gene to achieve in vivo delivery of adenovirus to metastatic site of breast cancer and conditional replication of adenovirus in desired tumor cells. And we construct the cistron that is sTRAIL expression under the control of CMV promoter, in this means, adenovirus side effect would be help in overcoming TRAIL resistance in tumor cells and the sTRAIL molecular would be enriched in the local tumor site, augmenting the anti-tumor effect as well as in CXCR4(-) breast cancer cells. Our therapeutic system aimed to realize multi-targeted therapy: HUMSCs homing to tumor site, adenovirus conditional replication and the selective anti-tumor effect of sTRAIL while avoiding unsafety events. Above all, our work would provide a new solution to metastatic breast cancer and gene therapy in clinical practice.

乳腺癌转移是导致治疗失败的主因,且尚缺乏有效的治疗手段。我们之前利用HUMSCs可向肿瘤部位归巢的特点将其作为病毒治疗的载体取得了良好的疗效；此外，腺病毒表达的sTRAIL已被我们证实可克服肿瘤细胞对sTRAIL的耐受。本研究利用CXCR4启动子在HUMSCs及转移性乳腺癌细胞中均具活性的条件，以HUMSCs装载腺病毒系统，通过CXCR4启动子控制腺病毒基因E1A的表达，实现HUMSCs装载的腺病毒向乳腺癌及其转移灶的定向运输及在目的细胞中的条件型复制；同时插入由CMV启动子启动的sTRAIL片段，通过腺病毒的旁观者效应和sTRAIL的特异性抗肿瘤作用，克服sTRAIL耐受，实现对肿瘤细胞的选择性杀伤。本治疗系统可实现HUMSCs向肿瘤部位的定向归巢、腺病毒的条件型复制及治疗性蛋白的靶向杀伤等多重靶向作用，同时我们还将对它的安全性进行评价，为乳腺癌转移及肿瘤基因治疗探索新的方式。

乳腺癌转移是导致治疗失败的主因,且尚缺乏有效的治疗手段。我们之前利用HUMSCs可向肿瘤部位归巢的特点将其作为病毒治疗的载体取得了良好的疗效；此外，腺病毒表达的sTRAIL已被我们证实可克服肿瘤细胞对sTRAIL的耐受。本研究克隆并鉴定了CXCR4启动子在转移性乳腺癌细胞及HUMSCs（不同低氧诱导条件下）中的转录活性；验证了乳腺癌细胞CXCR4/CXCL12自分泌轴，在乳腺癌细胞体外培养及与HUMSCs共培养系统中可检测到CXCL12的分泌，共培养系统中乳腺癌细胞可诱导HUMSCs的趋化迁移，且该作用可被CXCR4抑制剂AMD3100所拮抗；克隆sTRAIL片段并成功构建Promoter(CXCR4)-sTRAIL腺病毒系统，初步证实了该腺病毒系统对乳腺癌的抗肿瘤作用。目前在进行携带E1A基因的慢病毒系统改造，力求减低腺病毒感染对HUMSCs的毒性，并兼顾本治疗系统的靶向作用，今后还将对本治疗系统进行安全性进行评价，为乳腺癌转移及肿瘤基因治疗探索新的方式。

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