Gene-Product Auto-Targeting to Tumor Vessels

描述（由申请人提供）：在肿瘤靶向基因递送方面已经做出了很大的努力，但尚未注意将正常组织中转染的基因转录和翻译后的治疗基因产物靶向到肿瘤中。在肿瘤中靶向基因产物对于全身基因传递是非常重要的，因为使用最成功的全身肿瘤靶向基因传递技术，只有一部分基因能够成功地传递到肿瘤中。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产生可溶蛋白，这些蛋白分泌到血液循环中，对正常细胞有害。此外，与全身定位相比，IL-12等一些基因产物与肿瘤共定位更有效（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，将从注射基因转录和翻译的治疗性基因产物靶向或锚定到肿瘤中。具体而言，将产生肿瘤血管锚定IL-12基因，编码选定的肿瘤血管锚定微肽和IL-12，并通过电脉冲给药到肿瘤中，实现肿瘤靶向基因的传递和肿瘤靶向基因产物的自动传递。假设通过肿瘤血管锚定IL-12电致治疗，增加肿瘤中IL-12的积累，减少血清中IL-12的循环，将大大降低全身毒性，促进肿瘤根除。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，选择最有效的肽来锚定从注射基因转录和翻译到肿瘤中的基因产物；2)确定肿瘤血管锚定IL-12电致治疗免疫活性荷瘤小鼠和自发性荷瘤猫肿瘤的疗效；3)测试IL-12抑制肿瘤血管生成的新机制，以及肿瘤血管锚定IL-12增强肿瘤血管生成的抑制作用。我们提出的实验有很高的成功概率，因为我们有一个优秀的模型系统，有机会获得自发肿瘤的大型动物，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.