Telomerase inhibition with a novel G-quadruplex-interactive agent, telomestatin:: in vitro and in vivo studies in acute leukemia
Telomerase inhibition with a novel G-quadruplex-interactive agent, telomestatin:: in vitro and in vivo studies in acute leukemia
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DOI：
10.1038/sj.onc.1209577
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发表时间：
2006-09-21
期刊：
影响因子：
8
通讯作者：
Ohyashiki, K.
中科院分区：
文献类型：
--
作者：
Tauchi, T.;Shin-ya, K.;Ohyashiki, K.
端粒酶复合物负责端粒的维持，是一个有前途的肿瘤治疗靶点。最近，我们已经证明，治疗与G-四链体相互作用的代理，telomestatin可重复抑制端粒酶活性的BCR-ABL阳性白血病细胞系。本研究旨在探讨端粒酶抑制剂诱导急性白血病细胞凋亡的机制。我们已经发现，在端粒酶抑制素处理的U937细胞（PD20）和显性阴性DN-hTERT表达的U937细胞（PD25）中，caspase-3和聚（ADPribose）聚合酶被激活。p38丝裂原活化蛋白（MAP）激酶和MKK3/6的激活也被发现在端粒酶抑制素处理的U937细胞（PD20）和显性阴性DN-hTERT表达的U937细胞（PD25），然而，JNK和ASK 1的激活在这些细胞中没有检测到。为了研究p38 MAP激酶抑制对端粒酶抑制细胞的生长特性和凋亡的影响，我们培养了表达DN-hTERT的U937细胞，有或没有SB203580。显性阴性hTERT表达的U937细胞在PD25上停止增殖;然而，在SB 203580存在下观察到生长速率显著增加。SB 203580的处理还减少了DN-hTERT表达的U937细胞（PD25）中的凋亡诱导。这些结果表明，p38 MAP激酶在诱导端粒酶抑制的白血病细胞凋亡中具有关键作用。此外，我们评估了端粒酶抑制素对U937细胞在异种移植小鼠模型中生长的影响。在U937异种移植物中全身性腹膜内施用端粒酶抑制素降低肿瘤端粒酶水平并减小肿瘤体积。来自经端粒酶抑制素处理的动物的肿瘤组织表现出显著的细胞凋亡。用端粒酶抑制素治疗的小鼠中没有一只显示出任何毒性迹象。综上所述，这些结果奠定了基础的药物开发计划，以实现在体内的疗效和选择性的双重目标。
The telomerase complex is responsible for telomere maintenance and represents a promising neoplasia therapeutic target. Recently, we have demonstrated that treatment with a G-quadruplex-interactive agent, telomestatin reproducibly inhibited telomerase activity in the BCR-ABL-positive leukemic cell lines. In the present study, we investigated the mechanisms of apoptosis induced by telomerase inhibition in acute leukemia. We have found the activation of caspase-3 and poly-(ADPribose) polymerase in telomestatin-treated U937 cells (PD20) and dominant-negative DN-hTERT-expressing U937 cells (PD25). Activation of p38 mitogen-activated protein (MAP) kinase and MKK3/6 was also found in telomestatin-treated U937 cells (PD20) and dominant-negative DN-hTERT-expressing U937 cells (PD25); however, activation of JNK and ASK1 was not detected in these cells. To examine the effect of p38 MAP kinase inhibition on growth properties and apoptosis in telomer-ase-inhibited cells, we cultured DN-hTERT-expressing U937 cells with or without SB203580. Dominant-negative-hTERT-expressing U937 cells stopped proliferation on PD25; however, a significant increase in growth rate was observed in the presence of SB203580. Treatment of SB203580 also reduced the induction of apoptosis in DN-hTERT-expressing U937 cells (PD25). These results suggest that p38 MAP kinase has a critical role for the induction of apoptosis in telomerase-inhibited leukemia cells. Further, we evaluated the effect of telomestatin on the growth of U937 cells in xenograft mouse model. Systemic intraperitoneal administration of telomestatin in U937 xenografts decreased tumor telomerase levels and reduced tumor volumes. Tumor tissue from telomestatin-treated animals exhibited marked apoptosis. None of the mice treated with telomestatin displayed any signs of toxicity. Taken together, these results lay the foundations for a program of drug development to achieve the dual aims of efficacy and selectivity in vivo.