Jeong Jin-Sook, Lee Seong-Wook, Hong Seung-Hee, Lee Yoon-Jong, Jung Haeng-Im, Cho Kyung-Sook, Seo Hye-Hyun, Lee Sang-Jin, Park Sohee, Song Min-Sun, Kim Chang-Min, Kim In-Hoo
Department of Pathology and Medical Research Center for Cancer Molecular Therapy, Dong-A University College of Medicine, Busan, Korea.
Clin Cancer Res. 2008 Jan 1;14(1):281-90. doi: 10.1158/1078-0432.CCR-07-1524.
Our previous studies suggested that human telomerase reverse transcriptase (hTERT) RNA-targeting trans-splicing ribozyme could be a useful tool for cancer gene therapy. Here, we investigated whether adenoviruses harboring this ribozyme can be systemically delivered to mice, and whether they selectively mark tumors expressing hTERT and sensitize them to ganciclovir treatments.
We constructed adenoviral vectors containing modified hTERT-targeting trans-splicing ribozyme with downstream reporter gene (Ad-Ribo-LacZ) or suicide gene (Ad-Ribo-HSVtk) driven by a cytomegalovirus promoter. The tumor-specific trans-splicing reaction and the tumor-killing effect of adenoviruses harboring ribozyme were investigated both in vitro and in vivo using mice with intrahepatic colon cancer metastasis via systemic administration. The safety of systemic administration of the viruses was also evaluated.
We showed that Ad-Ribo-LacZ, when injected i.v., performs a highly specific trans-splicing reaction on hTERT mRNA and that it selectively marks tumors expressing hTERT in mice. More importantly, i.v. injection of Ad-Ribo-HSVtk plus ganciclovir significantly reduced tumor burden, with minimal liver toxicity, in mice with metastatic liver cancer, compared with the untreated group (P = 0.0009). Moreover, animals receiving Ad-Ribo-HSVtk showed improved survival compared with controls (P < 0.0001).
This study shows that systemically delivered adenovirus harboring trans-splicing ribozyme can recognize cancer-specific transcripts and reprogram them to combat the cancer cells. Use of trans-splicing ribozymes seems to be a potentially useful gene therapy for cancer.
我们之前的研究表明，靶向人端粒酶逆转录酶（hTERT）RNA的反式剪接核酶可能是癌症基因治疗的一种有用工具。在此，我们研究了携带这种核酶的腺病毒是否可以全身递送至小鼠，以及它们是否能选择性标记表达hTERT的肿瘤并使其对更昔洛韦治疗敏感。
我们构建了腺病毒载体，其包含由巨细胞病毒启动子驱动的、带有下游报告基因（Ad-Ribo-LacZ）或自杀基因（Ad-Ribo-HSVtk）的修饰型靶向hTERT的反式剪接核酶。通过全身给药，在体内外使用肝内结肠癌转移小鼠模型，研究携带核酶的腺病毒的肿瘤特异性反式剪接反应和肿瘤杀伤作用。还评估了病毒全身给药的安全性。
我们发现，静脉注射Ad-Ribo-LacZ时，它会对hTERT mRNA进行高度特异性的反式剪接反应，并能在小鼠体内选择性标记表达hTERT的肿瘤。更重要的是，与未治疗组相比，静脉注射Ad-Ribo-HSVtk加更昔洛韦可显著降低转移性肝癌小鼠的肿瘤负荷，且肝毒性最小（P = 0.0009）。此外，接受Ad-Ribo-HSVtk治疗的动物与对照组相比，生存期有所延长（P < 0.0001）。
本研究表明，全身递送的携带反式剪接核酶的腺病毒能够识别癌症特异性转录本并对其进行重编程以对抗癌细胞。使用反式剪接核酶似乎是一种潜在有用的癌症基因治疗方法。
