The controversy surrounding the use of diphtheria toxin (DT) as a therapeutic agent against tumor cells arises mainly from its unexpected harmfulness to healthy tissues. We encoded the cytotoxic fragment A of DT (DTA) as an objective gene in the Light-On gene-expression system to construct plasmids pGAVPO (pG) and pU5-DTA (pDTA). Meanwhile, a cRGD-modified ternary complex comprising plasmids, chitosan, and liposome (pG&pDTA@cRGD-CL) was prepared as a nanocarrier to ensure transfection efficiency. Benefiting from spatiotemporal control of this light-switchable transgene system and the superior tumor targeting of the carrier, toxins were designed to be expressed selectively in illuminated lesions. In vitro studies suggested that pG&pDTA@cRGD-CL exerted arrest of the S phase in B16F10 cells upon blue light irradiation and, ultimately, induced the apoptosis and necrosis of tumor cells. Such DTA-based treatment exerted enhanced antitumor activity in mice bearing B16F10 xenografts and displayed prolonged survival time with minimal side effects. Hence, we described novel DTA-based therapy combined with nanotechnology and the Light-On gene-expression system: such treatment could be a promising strategy against melanoma.

中文翻译：

---

安全有效的白喉毒素为基础的黑色素瘤治疗：亮基因表达系统和纳米技术的结合。

关于白喉毒素（DT）用作抗肿瘤细胞治疗剂的争议主要来自其对健康组织的意外危害。我们在Light-On基因表达系统中编码DT（DTA）的细胞毒性片段A作为目标基因，以构建质粒pGAVPO（pG）和pU5-DTA（pDTA）。同时，制备了包含质粒，壳聚糖和脂质体的cRGD修饰的三元复合物（pG＆pDTA @ cRGD-CL）作为纳米载体，以确保转染效率。得益于该光开关转基因系统的时空控制和载体的优异肿瘤靶向，毒素被设计为在受照明的病变中选择性表达。体外研究表明，pG＆pDTA @ cRGD-CL在蓝光照射下使B16F10细胞中的S期停滞，最终，诱导肿瘤细胞的凋亡和坏死。这种基于DTA的治疗方法在带有B16F10异种移植物的小鼠中发挥了增强的抗肿瘤活性，并显示出延长的生存时间以及最小的副作用。因此，我们描述了结合纳米技术和Light-On基因表达系统的新型基于DTA的疗法：这种疗法可能是对抗黑素瘤的一种有前途的策略。