Establishment of novel molecular cancer therapy targeting telomerase and its clinical appication to gynecologic tumors

端粒酶的激活在肿瘤的生长和发展中起着关键作用，部分通过维持端粒结构。事实上，端粒酶在人类癌症中的普遍表达使得端粒酶成为癌症治疗的有希望的靶点。已经描述了抑制端粒酶的遗传、药理学和反义方法;然而，在大多数情况下，仅在多次细胞分裂后观察到癌细胞死亡。在这里，使用逆转录病毒传递的人端粒酶逆转录酶（hTERT）特异性的小干扰RHA，我们成功地抑制了宫颈癌细胞系的端粒酶活性。缺乏hTERT表达的细胞表现出显著降低的端粒酶活性，并且随着传代显示缩短的端粒和端粒3 '-突出端。这些细胞经过相当数量的细胞分裂后进入复制性衰老。值得注意的是，与具有端粒酶活性的对照细胞相比，这些细胞的增殖速率显著受损，甚至在低传代细胞（PD 5）中。同样，在缺乏hTERT的低传代细胞中，小鼠的集落形成能力和致瘤性减弱。我们进一步研究了化疗和电离辐射对hTERT表达受到抑制的细胞的影响。与对照细胞相比，缺乏hTERT的细胞显示出对电离辐射或诱导DNA双链断裂的化疗剂（如拓扑异构酶抑制剂或博来霉素）的敏感性显著增加。这些研究结果表明，基于siRNA的策略可以应用于开发新的端粒酶抑制剂，其抗肿瘤作用可以与电离辐射和化疗相结合来增强。

Telomerase activation plays critical roles in tumor growth and progression in part through the maintenance of telomere structure. Indeed, the ubiquitous expression of telomerase in human cancers makes telomerase a promising target for cancer therapy. Genetic, pharmacologic and antisense methods to inhibit telomerase have been described ; however, in most cases, cancer cell death was observed only after many cell divisions. Here, using retroviral delivery of small interfering RHAs specific for the human telomerase reverse transcriptase (hTERT), we successfully inhibited telomerase activity in cervical cancer cell lines. Cells lacking hTERT expression exhibited significantly decreased telomerase activity and showed shortened telomeres and telomeric 3'-overhangs with passage. These cells entered the replicative senescence after considerable number of cell divisions. Notably, the proliferative rate of these cells was significantly impaired, compared to control cells with telomerase activity, even in low passage cells (PD 5). Likewise, colony-forming ability and tumorgenicity in mice were attenuated in low passage cells lacking hTERT. We further examined the effects of chemotherapy and ionizing radiation of cells in which hTERT expression is suppressed. Cells lacking hTERT showed a significantly increased sensitivity than control cells to ionizing radiation or chemotherapeutic agents that induce DNA double strand breaks, such as topoisomerase inhibitors or bleomycin. These findings suggest that a siRNA-based strategy can be applied to the development of novel telomerase inhibitors, whose anti-tumor effects may be enhanced in combination with ionizing radiation and chemotherapy.