慢性粒细胞白血病ZO-1基因启动子区甲基化状态分析及临床意义探讨

目的通过对慢性期及急变期慢性粒细胞白血病（CML）患者骨髓标本中人紧密连接蛋白1（ZO-1）基因启动子区甲基化状态的分析,初步探讨其在CML病情发展变化中的临床意义。方法应用甲基化特异性聚合酶链反应（MS-PCR）检测5例CML慢性期和10例CML急变期患者骨髓标本中ZO-1基因启动子区的甲基化状态。结果在5例CML-CP患者中ZO-1基因启动子区呈非甲基化状态;在7例CML-BP患者中ZO-1基因启动子区呈高甲基化状态,甲基化阳性率为70%（7/10）;1例CML患者其慢性期骨髓标本ZO-1基因启动子区呈非甲基化状态,而急变期则呈甲基化状态,经治疗恢复到慢性期时,则又表现为非甲基化状态。结论 ZO-1基因启动子区甲基化状态可能与CML病情发展变化密切相关,可能是一个提示CML急变的分子标志物。     

ABL1 methylation is a distinct molecular event associated with clonal evolution of chronic myeloid leukemia.

Methylation of the proximal promoter of the ABL1 oncogene is a common epigenetic alteration associated with clinical progression of chronic myeloid leukemia (CML). In this study we queried whether both the Ph'-associated and normal ABL1 alleles undergo methylation; what may be the proportion of hematopoietic progenitors bearing methylated ABL1 promoters in chronic versus acute phase disease; whether methylation affects the promoter uniformly or in patches with discrete clinical relevance; and, finally, whether methylation of ABL1 reflects a generalized process or is gene-specific. To address these issues, we adapted the techniques of methylation-specific PCR and bisulfite-sequencing to study the regulatory regions of ABL1 and other genes with a role in DNA repair or genotoxic stress response. In cell lines established from CML blast crisis, which only carry a single ABL1 allele nested within the BCR-ABL fusion gene, ABL1 promoters were universally methylated. By contrast, in clinical samples from patients at advanced stages of disease, both methylated and unmethylated promoter alleles were detectable. To distinguish between allele-specific methylation and a mixed cell population pattern, we studied the methylation status of ABL1 in colonies derived from single hematopoietic progenitors. Our results showed that both methylated and unmethylated promoter alleles coexisted in the same colony. Furthermore, ABL1 methylation was noted in the vast majority of colonies from blast crisis, but not chronic-phase CML. Both cell lines and clinical samples from acute-phase CML showed nearly uniform hypermethylation along the promoter region. Finally, we showed that ABL1 methylation does not reflect a generalized process and may be unique among DNA repair/genotoxic stress response genes. Our data suggest that specific methylation of the Ph'-associated ABL1 allele accompanies clonal evolution in CML.     

Rearrangement and expression of p53 in the chronic phase and blast crisis of chronic myelogenous leukemia

We tested a population of over 60 patients with chronic myelogenous leukemia (CML) for changes in the structure and expression of the p53 gene, which is located on chromosome 17. Six of 27 (22%) blast crisis samples and 3 of 5 (60%) accelerated phase samples had rearrangements of chromosome 17, whereas only 3 of 42 (7%) chronic phase patients had cytogenetic changes in chromosome 17. There was no loss of heterozygosity during the transition to blastic crisis among seven individuals who were informative for polymorphic probes for regions in or around the p53 gene on 17p. One patient in the chronic phase and one patient in the blastic phase of the 61 CML patients studied exhibited rearrangements of the p53 gene that were detectable by Southern analysis. One p53 allele was rearranged in the chronic phase patient and both p53 alleles were rearranged in the blastic phase patient. The p53 messenger RNA (mRNA) was of normal size (2.8 kb) in chronic phase and blast crisis, and the expression of the p53 gene was at least as high or higher in blast crisis as in the chronic phase of CML. The high incidence of abnormalities of chromosome 17 in blast-crisis CML found in our studies and the discovery of rearrangements of the p53 gene in two CML patients studied suggest that further study with probes for the p53 gene and anonymous polymorphic sites in chromosome 17 should be conducted in CML.     

Elevated serum-soluble interleukin-2 receptor (Tac antigen) levels in chronic myelogenous leukemia patients with blastic crisis

We examined the expression of cell-surface interleukin-2 (IL-2) receptor (Tac antigen) on peripheral blood leukemic cells and measured soluble IL-2 receptor p55(alpha) chain (sIL-2R) levels in sera from chronic myelogenous leukemia (CML) patients with blastic crisis. Flow cytofluorometric analysis performed by dual immunofluorescence in three cases demonstrated coexpression of Tac antigen with myeloid (CD13, CD14, or CD33) or lymphoid (CD10) antigen on significant proportions of peripheral blood leukemic cells. Radiolabeled IL-2-binding assay demonstrated the specific IL-2 binding sites in three cases examined. The exogenous IL-2, however, failed to induce proliferative response. A myeloid cell line, Yut-K3, established from peripheral blood leukemic cells from a CML patient with blastic crisis, also expressed cell- surface Tac antigen and CD13 concurrently. SIL-2R assay showed that Yut- K3 released a detectable amount of sIL-2R in its culture supernatant. The serum sIL-2R levels were significantly elevated (range: 2,580 to 172,000 U/mL) in 12 CML patients with blastic crisis and were slightly elevated in ten patients in chronic phase (range: 250 to 820 U/mL) and in three in accelerated phase (range: 790 to 1,305 U/mL) compared with those in 24 normal controls (range: 70 to 695 U/mL, P less than .01). These results indicated that the leukemic cells from CML patients with blastic crisis expressed and released IL-2 receptor (Tac antigen). Longitudinal studies performed in three cases of CML with blastic crisis showed that the change of serum sIL-2R level was closely associated with that of the number of peripheral blood leukocytes and blasts, the percentage of blasts and serum LDH levels, also suggesting that the serum sIL-2R level is a useful clinical indicator of the leukemic cell burden in vivo.     

慢性粒细胞白血病各期降钙素基因甲基化与染色体的研究

为了解降钙素（ＣＴ）基因在慢性粒细胞白血病（ＣＭＬ）各期甲基化与染色体的关系，用聚合酶链反应方法对４７例ＣＭＬ患者的降钙互基因甲基化状态进行分析，同时进行细胞遗传学检测，其中慢性期２４例，加速期９例，急变期１４例。在２４例慢性期ＣＭＬ中４例ＣＴ同度甲基化（１６．７％），加速期９例中６例（６６．７％），急变期１４ １２例（８５．７％），１例的系列研究也显示同一ＣＭＬ患者的ＣＴ基因甲基化状态，从慢性期     

髓系白血病中EVI1基因的表达及其临床意义

目的研究EVI1基因在成人急性髓系白血病(AML)和慢性粒细胞白血病(CML)中的表达及其临床意义。方法采用多重逆转录-聚合酶链反应(多重RT-PCR)技术分析2002年9月至2005年3月华中科技大学同济医学院附属同济医院收治的45例AML和43例CML骨髓单个核细胞中EVI1基因mRNA的表达,分析EVI1mRNA阳性白血病患者的临床特征及疗效。结果45例AML患者中有8例(17.8%)EVI1阳性,其中M11例、M23例、M54例。43例CML患者中有8例(18.6%)EVI1阳性,其中慢性期2例,占5.7%(2/35),加速期与急变期各3例,均占75.0%(3/4),加速期与急变期组的EVI1基因表达率高于慢性期组(P<0.01)。EVI1阳性的AML患者早期病死率高;EVI1基因阳性表达与CML白血病临床分期及预后相关。结论EVI1基因的高表达在髓系白血病的发生中,特别是在慢性粒细胞白血病慢性期向急性期转化中起重要作用。     

Methylation status analysis of cell cycle regulatory genes (p16INK4A, p15INK4B, p21Waf1/Cip1, p27Kip1 and p73) in natural killer cell disorders

Natural killer (NK) cell disorders are rare diseases. Genetic abnormalities of the several tumor suppressor genes, including p15INK4B, p16INK4A/p14ARF, p53, p73, and Rb genes have been reported. Deletions and point mutations of these genes are frequently detected in these diseases. It has been reported that tumor suppressor genes are inactivated by DNA methylation of the promoter region and/or first exon of the genes in a variety of human cancers. In this study we analyze the methylation status of the genes associated with cell cycle regulation, including p16INK4A, p15INK4B, p21/Waf1/Cip1, p27/Kip1, p73, and p14ARF, by methylation specific (MS) PCR and/or bisulfite sequencing. We examined 29 cases of NK cell disorders (five aggressive NK cell leukemia/lymphoma, three blastic NK cell lymphoma/leukemia, five nasal NK cell lymphoma, three myeloid/NK cell precursor acute leukemia, 13 chronic NK lymphocytosis). We found methylation of the first exon of the p16INK4A gene in two cases (one aggressive, one blastic), and methylation of the p14ARF gene in one aggressive NK cell leukemia. Bisulfite sequencing revealed that methylation of the p15 and p27 genes was rare in these disorders. MS-PCR suggested that the p73 and p21 genes were methylated in seven cases, respectively (p73: one blastic, one nasal, five chronic; p21: one myeloid/NK, one aggressive, one nasal, and four chronic); bisulfite sequencing confirmed that methylated alleles of these genes were dominant in the samples except three cases (one myeloid/NK, one aggressive, and one chronic) in which methylated alleles of the p21 genes were less than 34% of all alleles. These results suggested that inactivation of the cell cycle regulatory genes by DNA methylation could be associated with tumorigenesis in NK cell disorders, not only aggressive subtypes but also chronic subtype.     

Aberrant methylation of the major breakpoint cluster region in chronic myeloid leukemia

Isolated hypomethylated sites exist in the major breakpoint cluster region (M-bcr) where most Philadelphia chromosome (Ph) breakpoints are located. Twenty of 50 (40%) chronic myeloid leukemia (CML) patients were found to have aberrant hypermethylation of these sites on the rearranged M-bcr when compared with control marrows. The aberrancy correlated strongly with M-bcr breakpoint location; 19 of 20 cases had breakpoints located 5' of the M-bcr Sca I site, and 28 of 30 cases with normal M-bcr methylation had breakpoints located 3' of the M-bcr Sca I site. Sequence analysis of the Ph M-bcr breakpoints failed to find an M- bcr nucleotide position that delineated the transition between abnormally and normally methylated cases, indicating that the translocation of a critical M-bcr sequence was not responsible for the methylation abnormality. In 3 of 8 CML patients, cells without the t(9;22) were found to have abnormally methylated, unrearranged M-bcrs. The data indicate that abnormally methylated rearranged M-bcrs are present in CML cases with Ph breakpoints 5' of the M-bcr Sca I site and that the M-bcr in Ph- cells of patients with CML may also be abnormally methylated.     

bcr—abl融合基因在慢性粒细胞白血病诊治中的意义

目的探讨定量检测bcr-abl融合基因在慢性粒细胞白血病（CML）诊断、治疗及微小残留病变监测中的意义。方法应用实时定量PCR（RQ—PCR）方法检测145例CML患者bcr—abl融合基因的表达情况。结果abl和bcr-abl的标准曲线相关系数均大于0．99,批内差及批间差均小于4％;11例不同分期的CML患者同时检测外周血和骨髓中bcr—abl水平,8例外周血较骨髓低,3例较骨髓高;急变期的bcr—abl表达情况较加速期和慢性期均明显增高。结论RQ—PCR技术检测bcr—abl融合基因准确可靠,对于评价疗效、监测微小残留病变以及预测疾病进展具有重要的临床应用价值。     

Proliferation and Differentiation in Diffusion Chambers of Marrow,Blood and Spleen Cells from Patients with Chronic Myeloid Leukaemia during Chronic Phase and Blastic Transformation

The proliferative and differentiating capacity was compared between immature normal marrow cells and marrow, blood or spleen cells from patients with chronic myeloid leukaemia (CML) in chronic and blastic phases. Low density cells highly enriched in myeloblasts and promyelocytes were cultured in diffusion chambers (DC) and implanted into the peritoneal cavity of mice pretreasted with cyclophosphamide. In CML of chronic phase cell production was higher than normal with the exception of spleen cells. Total cell production was lower in blastic phase than in CML chronic phase. The [³H]-TdR labelling index of myeloblasts of blastic phase CML increased considerably upon implantation in DC consistent with re-entry into active proliferation. Immature normal cells give rise mostly to macrophages while the corresponding CML cells of chronic phase give a much higher PMN production with peaks after 12–18 d. Also in CML of blastic crisis the blasts differentiate into mature PMNs, but the maturation time is shortened with peaks of PMNs after 5–10 d. DC cultures of spleen cells from patients with CML showed a less differentiating capacity with a very low PMN production compared to cultures of marrow or blood cells. Our results indicate intrinsic differences in growth and maturation capacity between normal immature granulopoietic cells and cells from patients with CML of chronic phase or blastic crisis. The results may also indicate intrinsic differences between spleen, blood or marrow cells in CML.     

Quantitative measure of c-abl and p15 methylation in chronic myelogenous leukemia: biological implications

We used a sensitive, quantitative bisulfite PCR assay, methylation sensitive single nucleotide primer extension (Ms-SNuPE), to measure methylation of the 5' CpG islands of c-abl and p15 in chronic myelogenous leukemia (CML) patients during progression. We found that the Pa promoter of c-abl was methylated in 81% (17/21) of the white blood cells (WBCs) of CML patients, which correlates with previous reports. In contrast, WBCs from healthy donors, acute myelogenous leukemias, acute lymphocytic leukemias, and myelodysplastic syndromes were unmethylated at the c-abl Pa promoter locus. We also observed p15 hypermethylation in 24% (8/34) of CML cases. Methylation of the p15 but not c-abl Pa promoters was associated with CML progression (P = 0.047 vs 0.46), and the two events were independently acquired. We conclude that de novo methylation of c-abl and p15 both occur in CML, and analysis of DNA methylation changes using the bisulfite-based MS-SNuPE assay allows both a sensitive and quantitative assessment of these molecular events compared to other methods currently utilized. (Blood. 2000;95:2990-2992)