Telomerase activity and telomere length in acute and chronic leukemia, pre- and post-ex vivo culture.
Telomerase activity and telomere length in acute and chronic leukemia, pre- and post-ex vivo culture.
复制标题
DOI：
--
复制
发表时间：
2000-02
期刊：
影响因子：
11.2
通讯作者：
M. Engelhardt;K. MacKenzie;P. Drullinsky;R. Silver;M. Moore
中科院分区：
文献类型：
--
作者：
M. Engelhardt;K. MacKenzie;P. Drullinsky;R. Silver;M. Moore
我们研究了急性和慢性白血病及骨髓增生性疾病患者外周血和骨髓造血祖细胞端粒酶调控和端粒长度。共93例急性髓性白血病患者的CD 34+细胞，（AML; n = 25），慢性髓性白血病（CML; n = 21），慢性淋巴细胞白血病（CLL; n = 18），真性红细胞增多症（PV; n = 16）或骨髓增生异常综合征（MDS; n = 13）在多种细胞因子存在下在离体扩增之前和之后在19名患者中进行分析（试剂盒配体、白细胞介素-3、白细胞介素-6和粒细胞集落刺激因子加促红细胞生成素）。与来自正常供体的造血祖细胞（n = 108）相比，慢性期（CP）CML、CLL、PV和MDS的端粒酶活性（TA）增加2- 5倍。在AML、加速期（AP）和急变期（BP）-CML中，基础TA比正常高10- 50倍。CP-CML CD 34+细胞的TA在离体培养72 h内上调，1周后达到峰值，2周后降至检测值以下。相反，AP/BP-CML和AML CD 34+细胞中的TA在培养1周后下调，此后进一步降低。白血病患者CD 34+细胞的扩增能力明显低于正常人。在第1、2、3和4周，白血病个体细胞的平均扩增分别为6.5、2.3、0.6和0.2倍，而正常细胞的扩增为5至15倍。在连续扩增培养中，在扩增3-4周期间观察到0.7kbp的中值端粒损失。我们的研究结果表明，在培养的第一周期间，来自CP-CML、CLL、PV和MDS患者的CD 34+细胞和正常造血细胞中端粒酶的上调是相似的，而在AML和AP/BP-CML中，端粒酶在基线时是高的，并且在扩增培养期间下调。基线时白血病祖细胞中高水平的端粒酶可能是恶性表型和快速循环的特征。白血病细胞培养过程中端粒酶下调可能是由于正常造血功能的扩增潜力降低或抑制，或者在AML中可能是由于AML细胞的部分分化，先前显示与TA丢失相关。在离体扩增过程中端粒缩短与低水平的TA相关，特别是在慢性白血病和MDS祖细胞中，端粒酶不足以在强烈增殖过程中保护端粒bp损失。
We studied telomerase regulation and telomere length in hematopoietic progenitor cells from peripheral blood and bone marrow from patients with acute and chronic leukemia and myeloproliferative diseases. CD34+ cells from a total of 93 patients with either acute myeloid leukemia (AML; n = 25), chronic myeloid leukemia (CML; n = 21), chronic lymphocytic leukemia (CLL; n = 18), polycythemia vera (PV; n = 16), or myelodysplastic syndromes (MDS; n = 13) were analyzed before and in 19 patients after ex vivo expansion in the presence of multiple cytokines (kit ligand, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor plus erythropoietin). Compared with hematopoietic progenitor cells from normal donors (n = 108), telomerase activity (TA) was increased 2- to 5-fold in chronic phase (CP)-CML, CLL, PV, and MDS. In AML, accelerated phase (AP) and blastic phase (BP)-CML, basal TA was 10- to 50-fold higher than normal. TA of CP-CML CD34+ cells was up-regulated within 72 h of ex vivo culture, peaked after 1 week, and decreased below detection after 2 weeks. In contrast, TA in AP/BP-CML and AML CD34+ cells was down-regulated after 1 week of culture and decreased further thereafter. The expansion potential of CD34+ cells from patients with leukemia was considerably decreased compared with CD34+ cells from normal donors. The average expansion of cells from leukemic individuals was 6.5-, 2.3-, 0.6-, and 0.2-fold in weeks 1, 2, 3, and 4, respectively, whereas expansion of normal cells was 5- to 15-fold higher. In serial expansion culture, a median telomeric loss of 0.7 kbp was observed during 3-4 weeks of expansion. Our results demonstrate that up-regulation of telomerase is similar in CD34+ cells from CP-CML, CLL, PV, and MDS patients and in normal hematopoietic cells during the first week of culture, whereas in AML and AP/BP-CML, telomerase is high at baseline and down-regulated during expansion culture. High levels of telomerase in leukemic progenitors at baseline may be a feature of both the malignant phenotype and rapid cycling. Telomerase down-regulation during culture of leukemic cells may be due to the decreased expansion potential or repression of normal hematopoiesis, or in AML it may be due to the partial differentiation of AML cells, shown previously to be associated with loss of TA. Telomere shortening during ex vivo expansion correlated with low levels of TA, particularly in chronic leukemic and MDS progenitors where telomerase was insufficient to protect against telomere bp loss during intense proliferation.