Department of Molecular Biology, BK21 Graduate Program for RNA Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin 448-701, Korea.
J Microbiol Biotechnol. 2009 Sep;19(9):1070-6. doi: 10.4014/jmb.0812.692.
Telomerase reverse transcriptase (TERT), which prolongs the replicative life span of cells, is highly upregulated in 85-90% of human cancers, whereas most normal somatic tissues in humans express limited levels of the telomerase activity. Therefore, TERT has been a potential target for anticancer therapy. Recently, we described a new approach to human cancer gene therapy, which is based on the group I intron of Tetrahymena thermophila. This ribozyme can specifically mediate RNA replacement of human TERT (hTERT) transcript with a new transcript harboring anticancer activity through a trans-splicing reaction, resulting in selective regression of hTERT-positive cancer cells. However, to validate the therapeutic potential of the ribozyme in animal models, ribozymes targeting inherent transcripts of the animal should be developed. In this study, we developed a Tetrahymena-based trans-splicing ribozyme that can specifically target and replace the mouse TERT (mTERT) RNA. This ribozyme can trigger transgene activity not only also in mTERT-expressing cells but hTERT-positive cancer cells. Importantly, the ribozyme could selectively induce activity of the suicide gene, a herpes simplex virus thymidine kinase gene, in cancer cells expressing the TERT RNA and thereby specifically hamper the survival of these cells when treated with ganciclovir. The mTERT-targeting ribozyme will be useful for evaluation of the RNA replacement approach as a cancer gene therapeutic tool in the mouse model with syngeneic tumors.
端粒酶逆转录酶（TERT）可延长细胞的复制寿命，在 85-90%的人类癌症中高度上调，而人类大多数正常体细胞组织表达有限水平的端粒酶活性。因此，TERT 一直是癌症治疗的潜在靶点。最近，我们描述了一种新的人类癌症基因治疗方法，该方法基于嗜热四膜虫的 I 组内含子。这种核酶可以通过反式剪接反应特异性介导人类 TERT（hTERT）转录本与具有抗癌活性的新转录本的 RNA 替换，从而选择性地使 hTERT 阳性癌细胞退化。然而，为了在动物模型中验证核酶的治疗潜力，应该开发针对动物固有转录物的核酶。在这项研究中，我们开发了一种基于嗜热四膜虫的反式剪接核酶，可特异性靶向和替换小鼠 TERT（mTERT）RNA。这种核酶不仅可以在表达 mTERT 的细胞中，而且可以在 hTERT 阳性癌细胞中触发转基因活性。重要的是，该核酶可以选择性地诱导表达 TERT RNA 的癌细胞中自杀基因（单纯疱疹病毒胸苷激酶基因）的活性，从而在用更昔洛韦处理时特异性地阻止这些细胞的存活。该 mTERT 靶向核酶将有助于评估 RNA 替换方法作为具有同源肿瘤的小鼠模型中的癌症基因治疗工具。
