Nakajima A, Tauchi T, Sashida G, Sumi M, Abe K, Yamamoto K, Ohyashiki J H, Ohyashiki K
First Department of Internal Medicine, Tokyo Medical University, Shinjuku-ku, Japan.
Leukemia. 2003 Mar;17(3):560-7. doi: 10.1038/sj.leu.2402825.
Telomerase is a ribonucleoprotein enzyme that maintains protective structures at the ends of eukaryotic chromosomes. We examined the impact of telomerase inhibition by the dominant-negative human catalytic subunit of telomerase (DN-hTERT) on the biological features of acute leukemia. We introduced vectors encoding dominant- negative (DN)-hTERT, wild-type (WT)-hTERT, or a control vector expressing only a drug-resistant marker into a telomerase-positive human acute lymphoblastic leukemia cell line, HAL-01. Expression of DN-hTERT dramatically inhibited telomerase activity, leading to apoptotic cell death. Mutant telomerase expression also enhanced daunorubicin-induced apoptosis. Nude mice (n=5 per group) received subcutanous implants of HAL-01 cells expressing the control vector or DN-hTERT or WT-hTERT. Implantation of HAL-01 cells expressing control vector (n=5) rapidly produced tumors, whereas implantation of those expressing DN-hTERT (n=5) did not. Thus, telomerase inhibition both growth of HAL-01 cells in vitro and tumorigenic capacity in vivo. Furthermore, the G-quadruplex-interactive telomerase-specific inhibitor, telomestatin, shortened the telomere length and induced apoptosis in freshly isolated primary acute leukemia cells. These results suggest that antitelomerase therapy may be useful in some acute leukemias in combination with antileukemic agents such as daunorubicin.
端粒酶是一种核糖核蛋白酶，可维持真核染色体末端的保护结构。我们研究了端粒酶的显性负性人催化亚基（DN-hTERT）对急性白血病生物学特性的端粒酶抑制作用。我们将编码显性负性（DN）-hTERT、野生型（WT）-hTERT或仅表达耐药标记的对照载体导入端粒酶阳性的人急性淋巴细胞白血病细胞系HAL-01中。DN-hTERT的表达显著抑制了端粒酶活性，导致凋亡性细胞死亡。突变型端粒酶表达也增强了柔红霉素诱导的凋亡。裸鼠（每组n = 5）皮下植入表达对照载体或DN-hTERT或WT-hTERT的HAL-01细胞。植入表达对照载体的HAL-01细胞（n = 5）迅速产生肿瘤，而植入表达DN-hTERT的细胞（n = 5）则未产生肿瘤。因此，端粒酶抑制既影响HAL-01细胞的体外生长，也影响其体内致瘤能力。此外，G-四链体相互作用的端粒酶特异性抑制剂端粒抑素缩短了新鲜分离的原发性急性白血病细胞的端粒长度并诱导凋亡。这些结果表明，抗端粒酶疗法与柔红霉素等抗白血病药物联合应用可能对某些急性白血病有用。
