Gene therapy against gynecologic cancers targeting telomerase

人类端粒酶由三个主要亚基组成，即人类端粒酶RNA （hTR）、端粒酶相关蛋白（TP1）和端粒酶逆转录酶（hTERT）。RT-PCR分析表明，hTERT在肿瘤组织和细胞系中均有表达，而hTR或TP1不仅在肿瘤中广泛表达，在正常组织中也广泛表达。因此，hTERT表达与端粒酶活性密切相关。成功克隆了hTERT基因启动子序列。特别重要的是鉴定与这些区域相互作用的转录因子并调节hTERT表达以利用其进行基因治疗。C-Myc已被证明是hTERT基因的直接反激活因子。针对c-Myc的反义策略已成功抑制癌细胞端粒酶活性，抑制肿瘤生长。作为另一种策略，我们将hTERT启动子应用于质粒或病毒载体进行基因治疗。我们构建了一个嵌合载体，其中hTERT启动子克隆在抑制细胞生长的凋亡诱导基因的上游，并将这些载体引入宫颈癌细胞。我们已经在细胞系和动物模型中证实了这些基因疗法对肿瘤生长的特异性抑制。

Human telomerase is composed of three main subunit components, human telomerase RNA (hTR), telomerase-associated protein (TP1) and telomerase reverse transcriptase (hTERT). RT-PCR analyses demonstrated that expression of hTERT was observed in cancer tissues and cell lines, while hTR or TP1 was broadly expressed not only in cancers but also in normal tissues. Thus, hTERT expression was well correlated with telomerase activity.We succeeded to clone promoter sequences of hTERT gene. Of particular importance is identification of transcription factors interacting with such regions and regulate hTERT express in utilizing it for gene therapy. C-Myc has been shown to be a direct transactivator of hTERT gene. Antisense strategy against c-Myc has been in success to inhibit telomerase activity in cancer cells and suppress the tumor growth. As another strategy, we have applied hTERT promoter to plasmid or virus vectors for gene therapy. We have constructed a chimeric vector in which hTERT promoter is cloned upstream of apoptosis-inducing genes inhibiting cell growth and introduced of these vectors into cervical cancer cells. We have confirmed the specific inhibition of tumor growth in cell lines and animal models by these gene therapies.