Gene-Product Auto-Targeting to Tumor Vessels

描述（由申请人提供）：在开发肿瘤靶向基因递送方面已经做出了很大努力，但是没有注意到靶向从正常组织中转染的基因转录和翻译到肿瘤中的治疗性基因产物。靶向基因产物在肿瘤中的定位对于系统性基因递送非常重要，因为使用最成功的系统性肿瘤靶向基因递送技术，只有一部分基因被成功地递送到肿瘤中。靶向肿瘤中的基因产物对于肿瘤内基因递送也很重要，因为最常用的治疗基因如TRAIL产生分泌到血液循环中并且对正常细胞有害的可溶性蛋白质。此外，与全身定位相比，一些基因产物如IL-12在与肿瘤共定位时更有效（Li，S.，JNCI，2002; Li，S.，Mol Therapy，2005）。在本申请中，申请人将选择有效的肿瘤血管靶向肽来靶向或锚定从注射基因转录和翻译的治疗基因产物进入肿瘤。具体地，将产生编码所选择的肿瘤血管锚定小肽和IL-12的肿瘤血管锚定IL-12基因，并将其通过电脉冲施用到肿瘤中，以实现肿瘤靶向基因递送和肿瘤靶向基因产物自动递送。假设通过使用肿瘤血管锚定的IL-12电基因疗法增加IL-12在肿瘤中的积累和减少IL-12在血清中的循环，将大大降低全身毒性并增强肿瘤根除。为了验证这一假设，我们将1）使用我们的高通量体内筛选系统选择用于锚定基因产物的最有效的肽，所述锚定基因产物从注射的基因转录和翻译到肿瘤中; 2）确定肿瘤血管锚定IL-12电基因疗法用于治疗免疫活性荷瘤小鼠和自发荷瘤猫科动物中的肿瘤的治疗功效;以及3）测试IL-12抑制肿瘤血管生成的新机制，以及通过肿瘤血管锚定的IL-12增强肿瘤血管生成的抑制。我们提出的实验成功的概率很高，因为我们有一个很好的模型系统，可以接触到自发携带肿瘤的大型动物，以及完成任务所需的所有资源。

DESCRIPTION (provided by applicant): Great effort has been made in developing tumor-targeted gene delivery, but no attention has been given to targeting the therapeutic gene products that are transcribed and translated from genes transfected in normal tissues into tumors. Targeting gene product in tumors is very important for systemic gene delivery because only a portion of genes are successfully delivered into tumors by using the most successful systemic tumor-targeted gene delivery technology. Targeting gene product in tumors is also important for intratumoral gene delivery because the most commonly used therapeutic genes like TRAIL yield soluble proteins that are secreted into the blood circulation and are harmful to normal cells. Moreover, some gene products such as IL-12 are more effective when co-localized with tumors, compared to systemic localization (Li, S., JNCI, 2002; Li, S., Mol Therapy, 2005). In this application, the applicant will select the effective tumor vessel-targeted peptides to target or anchor the therapeutic gene product transcribed and translated from the injected gene into tumors. Specifically, tumor vessel- anchored IL-12 gene encoding the selected tumor vessel-anchored mini-peptide and IL-12 will be generated and will be administered into tumors via electric pulses to achieve the tumor-targeted gene delivery and the tumor-targeted gene-product auto-delivery. The hypothesis is that the increased IL-12 accumulation in tumor and reduction of IL-12 circulation in serum by using tumor vessel-anchored IL-12 electrogenetherapy will greatly reduce systemic toxicity and enhance tumor eradication. To test this hypothesis, we will 1) select the most effective peptides for anchoring gene product that are transcribed and translated from the injected gene into tumors using our high throughput in vivo screening system; 2) Determine the therapeutic efficacy of tumor vessel-anchoring IL-12 electrogenetherapy for treating tumors in immunocompetent tumor-bearing mice and spontaneous tumor bearing felines; and 3) test a novel mechanism by which IL-12 inhibits tumor angiogenesis and by shich tumor vessel-anchored IL-12 enhances the inhibition of tumor angiogenesis. The experiments that we propose have a high probality of success because we have an excellent model system in place, the access to spontaneous tumor- bearing large animals, and all the resources necessary to complete the task.