【摘要】 为探讨急性白血病DNA甲基转移酶(MTase)活性改变的规律及其与降钙素(CT)基因甲基化发生率的关系,采用~3H标记同位素示踪微量分析法测定白血病细胞MTase的活性;应用甲基化敏感的限制性内切酶消化,结合设有内外参照的多聚酶链反应(PCR)技术检测CT基因甲基化率(CTMR);采用半定量反转录PCR法测定MTase的mRNA表达水平。发现29例急性白血病病人骨髓单个核细胞CTMR平均值为(47.2±22.O)％,明显高于正常人骨髓单个核细胞对照组。15例急性白血病MTase活性平均值为(9.1±4.6)％,较非恶性血液病对照组明显为高;11例缓解期白血病MTase活性平均值(4.1±2.6)％,与对照组无明显区别;3/4例急性白血病治疗缓解后MTase活性下降。5例急性白血病同时测定CTMR及MTase,发现其CTMR及MTase均显著高于对照组。4种白血病细胞系CTMR较对照分别高19-36倍,MTase活性高14-48倍,MTasemRNA表达高41-134倍。结果提示:MTase活性增高及CT基因高甲基化是急性白血病的高发现象。MTase活性增高可能是白血病细胞CT基因高甲基化的原因。MTase mRNA表达增高可能是白血病细胞MTase活性增高的原因。抑制MTase活性,开辟治疗白血病的新途径是值得探索的课题。更多还原

【Abstract】 To study DNA-methyltransferase (MTase) activity in leukemia cells and its relations with the calcitonin gene methylation rate (CTMR), mononucleated cells of bone marrow were detected for MTase activity by a mi-croassay technique and caltitonin gene methylation rate by PCR with methylation sensitive restriction endonucle-ase digestion, as well as expression level of MTase gene by RT-PCR. Results showed: ①Mean MTase activity in group of 15 cases with acute leukemia was (9.1 ±4.6)%, 4-fold higher than that in 11 subjects with no hematological malignancies which was (2.1±1.6)%, and the value from 11 acute leukemia patients in complete remission was (4.1±2.6)%, which was the same range in the control group. ②The mean CTMR of 29 patients with acute leukemia was (47. 2 ± 22. 0) %, higher than that of the control group, which was (2.2 ± 3.3)% (P<0.05). ③The mean values of MTase activity and CTMR in 5 patients with acute leukemia were (8.4±2.8)% and (49.4 ± 18.9)% respectively, both of them higher than that of control which were (2.1 ± 1.6)% and(2.2±3.3)% respectively (P<0.05). In four human leukemia cell lines, HL-60, K562, CEM and KG la, CTMR was 19 - 36 fold higher than that of control; the activity of MTase was 14 - 48 fold than that of control; and gene expression of MTase was 41 - 134 fold higher than that of control. It was suggested that increased MTase activity perhaps happened frequently in acute leukemia, which might be a reason for calcitonin gene hypermethylation; high expression of MTase gene might account for its increasing activity; and it is worth studying,if modification of DNA methylation pattern would be a useful way for treatment of leukemia.更多还原