Ihalainen J, Juvonen E, Savolainen E R, Ruutu T, Palotie A
Department of Clinical Chemistry, University of Helsinki, Finland.
Leukemia. 1994 Feb;8(2):230-5.
Alterations in DNA methylation appear to be an integral part of the malignant transformation. For example, the p15 region of chromosome 11 with multiple genes related to cell growth regulation exhibits different methylation patterns in the 5' area of the calcitonin A gene in healthy bone marrow cells, and in leukemic cell populations. In this work the methylation status of the 5' area of the calcitonin gene in myeloproliferative disorders (MPD) other than chronic myeloid leukemia (CML) is studied. A total number of 37 patients with polycythemia vera, essential thrombocythemia, or myelofibrosis were studied. A control group of 18 healthy persons and patients with reactive hematologic changes was included. The DNA isolated from peripheral blood or bone marrow cells was digested with the methylation-sensitive HpaII restriction enzyme. A Southern blot was hybridized with a 1.7 kb probe specific to the 5' area of the calcitonin gene. The result was visualized autoradiographically and analyzed with a densitometer. The results have been expressed as ratios between the abnormal and normal autoradiography band intensities, referred to as the calc-value or CALC. An increase in the calc-value signifies increasing methylation. In the control group the calc-value had a mean of 0.274. The myelofibrosis patients exhibited very strong hypermethylation in the calcitonin gene 5' area, with a mean calc-value of 11.1 (median 2.6). The polycythemia vera patients showed considerable variation in their methylation status, with a mean value of 1.52. The essential thrombocythemia patients exhibited weak hypermethylation, with a mean calc-value of 0.58. A correlation between karyotypic abnormalities and hypermethylation was observed. Complicated forms of MPD exhibited higher levels of methylation than the uncomplicated disease forms.
DNA甲基化改变似乎是恶性转化的一个重要组成部分。例如，11号染色体的p15区域含有多个与细胞生长调控相关的基因，在健康骨髓细胞和白血病细胞群体中，降钙素A基因5'区域呈现出不同的甲基化模式。在这项研究中，我们研究了除慢性粒细胞白血病（CML）之外的骨髓增殖性疾病（MPD）中降钙素基因5'区域的甲基化状态。总共研究了37例真性红细胞增多症、原发性血小板增多症或骨髓纤维化患者。纳入了18名健康人和有反应性血液学改变的患者作为对照组。从外周血或骨髓细胞中分离出的DNA用甲基化敏感的HpaII限制性内切酶进行消化。用一个针对降钙素基因5'区域的1.7 kb探针进行Southern印迹杂交。结果通过放射自显影进行可视化，并使用密度计进行分析。结果以异常和正常放射自显影带强度之间的比率表示，称为calc值或CALC。calc值增加表示甲基化增加。在对照组中，calc值的平均值为0.274。骨髓纤维化患者在降钙素基因5'区域表现出非常强烈的高甲基化，平均calc值为11.1（中位数为2.6）。真性红细胞增多症患者的甲基化状态存在相当大的差异，平均值为1.52。原发性血小板增多症患者表现出微弱的高甲基化，平均calc值为0.58。观察到核型异常与高甲基化之间存在相关性。MPD的复杂形式比非复杂疾病形式表现出更高水平的甲基化。
