Gene-Product Auto-Targeting to Tumor Vessels

描述(申请人提供)：在开发肿瘤靶向基因传递方面已经做出了很大努力，但还没有注意到靶向从正常组织中转基因到肿瘤中的基因转录和翻译的治疗性基因产品。肿瘤靶向基因产物对于全身性基因传递是非常重要的，因为使用最成功的全身性肿瘤靶向基因传递技术，只有一部分基因被成功地传递到肿瘤中。靶向肿瘤中的基因产物对于肿瘤内的基因传递也很重要，因为最常用的治疗基因如TRAIL产生的可溶性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，一些基因产品，如IL-12，当与肿瘤共定位时更有效(Li，S.，JNCI，2002；Li，S.，Mol Treatment，2005)。在这项申请中，申请者将选择有效的肿瘤血管靶向多肽来靶向或锚定从注射的基因转录和翻译到肿瘤中的治疗性基因产物。具体地说，将产生编码所选肿瘤血管锚定小肽的肿瘤血管锚定的IL-12基因和IL-12，并通过电脉冲将其注入肿瘤内，以实现肿瘤靶向基因递送和肿瘤靶向基因产物的自动递送。假说是肿瘤血管锚定的IL-12电基因治疗增加了IL-12在肿瘤中的积聚，减少了IL-12在血清中的循环，从而大大降低了全身毒性，促进了肿瘤的清除。为了验证这一假说，我们将1)使用我们的高通量体内筛选系统，选择最有效的锚定基因产物的肽；2)确定肿瘤血管锚定IL-12电基因疗法对免疫活性肿瘤荷瘤小鼠和自发荷瘤猫科动物肿瘤的治疗效果；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IL-12加强抑制肿瘤血管生成的作用。我们提出的实验有很高的成功几率，因为我们有一个很好的模型系统，可以接触到自发的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.