High expression of connective tissue growth factor in pre-B acute lymphoblastic leukaemia

In recent years microarrays have been used extensively to characterize gene expression in acute lymphoblastic leukaemia (ALL). Few studies, however, have analysed normal haematopoietic cell populations to identify altered gene expression in ALL. We used oligonucleotide microarrays to compare the gene expression profile of paediatric precursor-B (pre-B) ALL specimens with two control cell populations, normal CD34(+) and CD19(+)IgM(-) cells, to focus on genes linked to leukemogenesis. A set of eight genes was identified with a ninefold higher average expression in ALL specimens compared with control cells. All of these genes were significantly deregulated in an independent cohort of 101 ALL specimens. One gene, connective tissue growth factor (CTGF, also known as CCN2), had exceptionally high expression, which was confirmed in three independent leukaemia studies. Further analysis of CTGF expression in ALL revealed exclusive expression in B-lineage, not T-lineage, ALL. Within B-lineage ALL approximately 75% of specimens were consistently positive for CTGF expression, however, specimens containing the E2A-PBX1 translocation showed low or no expression. Protein studies using Western blot analysis demonstrated the presence of CTGF in ALL cell-conditioned media. These findings indicate that CTGF is secreted by pre-B ALL cells and may play a role in the pathophysiology of this disease.     

Cell cycle regulatory gene abnormalities are important determinants of leukemogenesis and disease biology in adult acute lymphoblastic leukemia

To test the hypothesis that cell cycle regulatory gene abnormalities are determinants of clinical outcome in adult acute lymphoblastic leukemia (ALL), we screened lymphoblasts from patients on a Southwest Oncology Group protocol for abnormalities of the genes, retinoblastoma (Rb), p53, p15(INK4B), and p16(INK4A). Aberrant expression occurred in 33 (85%) patients in the following frequencies: Rb, 51%; p16(INK4A), 41%; p53, 26%. Thirteen patients (33%) had abnormalities in 2 or more genes. Outcomes were compared in patients with 0 to 1 abnormality versus patients with multiple abnormalities. The 2 groups did not differ in a large number of clinical and laboratory characteristics. The CR rates for patients with 0 to 1 and multiple abnormalities were similar (69% and 54%, respectively). Patients with 0 to 1 abnormality had a median survival time of 25 months (n = 26; 95% CI, 13-46 months) versus 8 months (n = 13; 95% CI, 4-12 months) for those with multiple abnormalities (P <.01). Stem cells (CD34+lin-) were isolated from adult ALL bone marrows and tested for p16(INK4A) expression by immunocytochemistry. In 3 of 5 patients lymphoblasts and sorted stem cells lacked p16(INK4A) expression. In 2 other patients only 50% of sorted stem cells expressed p16(INK4A). By contrast, p16 expression was present in the CD34+ lin- compartment in 95% (median) of 9 patients whose lymphoblasts expressed p16(INK4A). Therefore, cell cycle regulatory gene abnormalities are frequently present in adult ALL lymphoblasts, and they may be important determinants of disease outcome. The presence of these abnormalities in the stem compartment suggests that they contribute to leukemogenesis. Eradication of the stem cell subset harboring these abnormalities may be important to achieve cure.     

Expression and prognostic value of the retinoblastoma tumour suppressor gene (RB-1) in childhood acute lymphoblastic leukaemia

In a retrospective analysis, acute lymphoblastic leukaemia (ALL) blast cells of 102 children were investigated for the expression of the retinoblastoma susceptibility (RB)-1 gene at mRNA level by dot blot hybridization and semiquantitative RT-PCR. 56 patients were analysed by dot blot hybridization and 35 representative patients out of this group by semiquantitative RT-PCR. Two additional groups of patients (23 patients with initial and 23 patients with relapsed ALL) were also investigated by semiquantitative RT-PCR. RB-1 gene expression was detectable in all investigated ALL at different levels. According to the relative mRNA expression the patients were discriminated by the median value in groups with low or high RB-1 expression. The Kaplan-Meier estimates showed that patients with low RB-1 expression had a lower probability of remaining in first remission ( P =0.03) and a significantly higher risk to succumb to their disease ( P =0.03). Furthermore, the comparison of the results between initial and relapsed ALL showed that the relapses had significantly lower RB-1 mRNA expression ( P =0.02). The overall survival of the patients was shorter in both groups when RB-1 gene expression was low. A multivariate analysis, including age, sex, immunological subtype, initial white blood cell count and RB-1 expression, identified RB-1 as an independent prognostic predictor ( P =0.017) in addition to the initial white blood cell count ( P =0.00001). In conclusion, low RB-1 expression is an unfavourable prognostic predictor in initial and relapsed childhood ALL. The RB-1 gene expression in relapsed ALL is significantly lower than in initial ALL.     

急性白血病细胞HCP基因的突变分析

目的：造血细胞磷酸酶(Hematopoietic cell phosphatase，HCP)在造血细胞发育、增殖及受体介导的有丝分裂信号传导通路中发挥关键的负调节作用，在motheaten小鼠中其突变可导致粒一单核细胞严重的过度聚积和功能紊乱。本研究旨在评价HCP基因突变在急性白血病发病中的作用。方法：利用RT—PCR、SSCP及DNA序列分析技术检测了41例急性白血病、8株白血病细胞系及50例正常对照骨髓或外周血标本中HCP基因表达及突变情况。结果：RT—PCR显示所有标本中都有HCP基因表达，仅在1例急性淋巴细胞白血病细胞中发现错义突变，发生在HCP基因氨基末端的SH2结构域；此外，分别在HCP基因的69、85、86和266密码子存在多态性。结论：HCP基因突变在急性白血病中较少见，在白血病发病中可能起较小作用。     

ERK1/2 phosphorylation is an independent predictor of complete remission in newly diagnosed adult acute lymphoblastic leukemia

Extracellular signal-regulated kinase-1/2 (ERK1/2) is frequently found constitutively activated (p-ERK1/2) in hematopoietic diseases, suggesting a role in leukemogenesis. The aim of this study was to assess the expression and clinical role of p-ERK1/2 in adult acute lymphoblastic leukemia (ALL). In 131 primary samples from adult de novo ALL patients enrolled in the Gruppo Italiano per le Malattie Ematologiche dell'Adulto (GIMEMA) Leucemia Acute Linfoide (LAL) 2000 protocol and evaluated by flow cytometry, constitutive ERK1/2 activation was found in 34.5% of cases; these results were significantly associated with higher white blood cell (WBC) values (P=.013). In a multivariate analysis, p-ERK1/2 expression was an independent predictor of complete remission achievement (P=.027). Effective approaches toward MEK inhibition need to be explored in order to evaluate whether this may represent a new therapeutic strategy for adult ALL patients.     

复发/难治性急性淋巴细胞白血病患者多药耐药基因表达及临床意义

目的探讨复发/难治性急性淋巴细胞白血病(ALL)患者多药耐药基因(mdr1基因)的表达及其临床意义。方法采用Northern blot法检测K562/A02细胞株mdr1基因的表达,RT-PCR法检测42例ALL患者(ALL组)、27例非白血病患者和健康人(对照组)mdr1基因的表达水平,分析mdr1基因过度表达的临床意义。结果ALL组mdr1基因过度表达率显著高于对照组(P<0.01),其中复发/难治者高于初诊和完全缓解(CR)者(P<0.01),临床耐药者高于非临床耐药者(P<0.01);非临床耐药者CR率显著高于临床耐药者(P<0.001)。结论mdr1基因过度表达与ALL患者临床耐药密切相关,是影响预后的重要因素;mdr1基因表达可作为判断ALL患者临床耐药和预后的指标。     

Multidrug resistance 1 gene expression and AgNOR in childhood acute leukemias

The multidrug resistance 1 (MDR1) gene product, P-glycoprotein (Pgp/p170) is a membrane protein, which acts as an ATP dependant efflux pump that expels a wide variety of organic compounds including chemotherapeutic agents from the cell. Pgp over expression has been demonstrated to be linked with poor treatment outcome and poor prognosis in a number of malignant tumors. AgNORs is a simple, reliable and inexpensive method of evaluating the proliferative activity of a tumor. We have studied MDR1 expression and AgNORS in 41 cases of acute leukemia in children. In this study, AgNOR counts in patients with acute lymphoblastic leukemia (ALL) L2 subtype (FAB classification) were significantly higher as compared to the ALL L1 subtype. Similarly, mean AgNOR count in the acute myeloid Leukemia (AML) M2 subtype was significantly higher as compared to the ALL L1 subtype. However, there was no correlation between AgNOR and treatment outcome or between AgNOR counts and MDR1 expression in any of the subtypes of acute leukemia included in this series. In AML, MDR1 gene expression was found to be related to reduced remission induction rates and hence poorer prognosis. In ALL, our study has shown no difference in remission induction between MDR1 positive and MDR1 negative cases. This would suggest that factors other than MDR1 may be of relevance in Pediatric ALL.     

AML1 gene amplification: a novel finding in childhood acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVE: We previously found a high-level amplification in chromosomal region 21q22 in two children with acute lymphoblastic leukemia (ALL) using comparative genomic hybridization. The same region harbors the AML1 gene. The aim of the present study was to investigate whether AML1 is a target gene in these amplifications. DESIGN AND METHODS: Bone marrow samples were obtained from 112 childhood ALL patients. The copy number of AML1 was studied using fluorescent in situ hybridization with a dual color DNA probe specific for the AML1 and TEL genes. RESULTS: Three of the patients had 3-to-8 fold amplification of AML1 and showed a high-level amplification of 21q22 by comparative genomic hybridization. In two of them the extra copies were shown to be located tandemly in a derivative of chromosome 21. Thirty-seven of the patients (33%) had 1-to-2 extra copies of AML1, most probably reflecting the incidence of trisomy 21 and tetrasomy 21. The TEL-AML1 fusion was less frequent in the patients with extra copies of AML1 (7/40; 18%) than in the patients with no extra copy (24/72; 33%). None of the three patients with 3-to-8 fold amplification of AML1 showed the fusion or loss of TEL. INTERPRETATION AND CONCLUSIONS: Our findings suggest that the AML1 gene is a target gene in the 21q22 amplicon in childhood ALL. To understand the role, if any, of the AML1 amplification in leukemogenesis, further studies are needed.     

Hypermethylation of the calcitonin gene in acute lymphoblastic leukaemia is associated with unfavourable clinical outcome

We analysed calcitonin (CALC1) gene hypermethylation using semiquantitative differential polymerase chain reaction in 105 patients with adult (n = 49) and childhood (n = 56) acute lymphoblastic leukaemia (ALL), and studied the association of CALC1 hypermethylation with clinical presentation features and disease outcome. We also investigated the possible relationship between CALC1 methylation status and expression of the cell cycle inhibitor gene p57KIP2. We observed CALC1 hypermethylation in bone marrow cells from 43% (45 out of 105) of ALL patients. Clinical, molecular and laboratory features did not differ significantly between hypermethylated and hypomethylated patients, only T-cell lineage was associated with hypermethylation (14% vs. 47%, P = 0025). Complete remission rate was similar in both groups although hypermethylated patients had a higher relapse rate (68% vs. 19%, P < 0.00001) and mortality rate (55% vs. 36%, P = 0.06) than hypomethylated patients. Estimated disease-free survival (DFS) at 6 years was 66.1% for hypomethylated patients and 5.3% for hypermethylated patients (P < 0,00001). Multivariate analysis from potential prognostic factors demonstrated that CALC1 methylation status was an independent prognostic factor in predicting DFS (P = 0.0001). Separate analysis of adult and childhood ALL patients showed similar results to the whole series. In addition, hypermethylated patients showed downregulation of p57KIP2 expression. Our results suggest that CALC1 gene hypermethylation is associated with an enhanced risk of relapse independently of known poor-prognostic factors and we describe, for the first time, a possible implication of the p57KIP2 gene in the genesis and prognosis of ALL.     

ABL oncogene amplification with p16(INK4a) gene deletion in precursor T-cell acute lymphoblastic leukemia/lymphoma: report of the first case

Gene amplification is a relatively rare event in hematologic malignancies. The ABL gene on chromosome band 9q34 is a proto-oncogene and is the well-known translocation partner of the BCR gene on 22q11 giving rise to t(9;22)(q34;q11), which is the hallmark of chronic myeloid leukemia and is the most common chromosomal abnormality in adult acute lymphoblastic leukemia (ALL). Amplification of ABL is an exceedingly rare event, with only less than 5 cases reported in the literature. The p16(INK4a) (or CDKN2A) gene on 9p21 is a tumor suppressor gene, and deletion thereof is recently recognized as one of the most common genetic abnormalities in ALL. The authors herein describe an 8-year-old male patient with precursor T-cell ALL harboring both ABL gene amplification and p16(INK4a) gene deletion. Fluorescence in situ hybridization (FISH) analysis using BCR/ABL probes revealed five or more ABL signals, indicating amplification in 51.5% of interphase nuclei. FISH using p16(INK4a) gene probes showed heterozygous p16(INK4a) deletion in 71.0%. On conventional cytogenetic analysis, however, only 10 metaphases were available, which showed the normal karyotype, 46,XY[10], serving no evidence for the findings on FISH. This is the first report of an ALL case with ABL amplification, and the authors speculate that both ABL proto-oncogene amplification and the p16(INK4a) tumor suppressor gene deletion have been implicated in leukemogenesis in the present case, although whether the ABL amplification truly contributes to the leukemogenesis or merely an epiphenomenon representing underlying genomic instability remains to be determined.     

Downregulation of DBC1 expression in acute lymphoblastic leukaemia is mediated by aberrant methylation of its promoter

The DBC1 gene is a potential tumour suppressor gene that is commonly hypermethylated in epithelial cancers. We studied the role of promoter hypermethylation in the regulation of DBC1 in acute lymphoblastic leukaemia (ALL) cell lines and 170 ALL patients at diagnosis. Abnormal methylation of DBC1 was observed in all ALL cell lines and in 17% of ALL patients. Moreover, DBC1 methylation was associated with decreased DBC1 expression, while treatment of ALL cells with 5-Aza-2'-deoxycytidine resulted in demethylation of the promoter and upregulation of DBC1 expression. Fluorescence in situ hybridisation identified the deletion of one allele of DBC1 in some ALL cell lines, which indicated that the lack of DBC1 expression was due to deletion of one allele and methylation of the other. In conclusion, these results demonstrate, for the first time, that the expression of DBC1 is downregulated in a percentage of patients with ALL due to the hypermethylation of its promoter and/or gene deletion.     

白血病患者Prame基因的表达及其与WT1基因比较的临床意义

目的：探讨Prame(黑色素瘤特异性抗原)在白血病患者中的表达及其临床意义。方法：应用逆转录—聚合酶链反应(RT—PCR)测定58例白血病患者Prame mRNA的表达，并与WTl mRNA的表达相比较。结果：急性髓细胞性白血病(AML)患者Prame阳性表达率为52．2％，急性淋巴细胞性白血病(ALL)患者Prame阳性表达率为66．7％，慢性粒细胞性白血病(CML)急性变患者Prame阳性表达率为55．6％；慢性及加速期CML患者ll例、l0名正常人外周血及l0例非血液病患者骨髓细胞均未见Prame mRNA表达，其中l例AML和5例ALL患者Prame阳性而WT1阴性。对2例Prame阳性和4例Prame、WTl均阳性的患者短期随访发现所有患者化疗后Prame均有不同程度的下降。l例复发患者Prame表达再次升高且早于WTl l个月，余3例白血病患者Prame和WTl表达的波动呈正比。结论：免疫抗原Prame是白血病的一个重要标记基因，与病程进展密切相关，有望成为白血病微小残留病灶检测和进行白血病免疫治疗的靶基因。     

急性淋巴细胞白血病患者FLT3基因及FLT3/ITD基因突变的检测及临床意义

目的:研究急性淋巴细胞白血病(ALL)患者FLT3基因及其内部串联重复(ITD)突变情况。方法:采用多聚酶链反应(PCR)联合单链构象多态性(SSCP)方法检测76例不同免疫分型ALL患者FLT3基因及FLT3/ITD基因突变。结果:76例ALL患者经PCR扩增发现46例(60.5%)FLT3基因检测阳性,其中前前B细胞ALL、前B细胞ALL、成熟B细胞ALL及T细胞系ALL患者FLT3基因检测阳性率分别为88.2%(15/17),73.9%(17/23),40.0%(6/15)和23.5%(4/17);前前B细胞ALL和前B细胞患者ALL FLT3基因检测阳性率80.0%,显著高于成熟B细胞ALL(40.0%)(P<0.01);B细胞系ALL患者FLT3基因检测阳性率为69.1%,显著高于T细胞系ALL患者(23.5%)(P<0.01)。76例ALL患者中仅有2例(2.6%)出现FLT3/ITD基因突变,此2例均为伴有2种髓系抗原表达,免疫学检查诊断为急性混合细胞白血病患者,均伴有外周血高白细胞数、骨髓中高白血病细胞比例及预后较差。结论:B细胞系ALL和T细胞系ALL患者均可检测出FLT3基因,但B细胞系ALL患者FLT3基因检测阳性率显著高于T细胞系ALL;B细胞系ALL中细胞分化越成熟则FLT3基因检测率阳性越低。ALL患者一般不出现FLT3/ITD基因突变,FLT3/ITD基因突变检测可能有助于急性白血病基因分型及预后判断。     

Deletion of the human retinoblastoma gene in primary leukemias

As an initial step in evaluating the role of tumor suppressor genes in leukemogenesis, we surveyed primary leukemia cells from 130 patients for possible deletion of the retinoblastoma susceptibility (Rb) gene by Southern blot analysis. Two of them clearly showed homozygous deletion of Rb alleles. The first patient was a pre-B acute lymphoid leukemia (ALL) associated with a cytogenetic translocation: t(14;16)(q24;q22). The deletion was located at the 3' portion of the Rb gene, very close to the site of Rb gene deletion recently identified in an ALL cell line. The absence of Rb110 protein was further confirmed by Western blot analysis. The second patient was a chronic myelomonocytic leukemia (CMMoL), terminated in acute blastic transformation. Deletion of the 5' portion of Rb gene was found in leukemic cells in the chronic stage. The results indicated that inactivation of the Rb gene occurred in certain cases of leukemia. Its significance warrants further study.     

CD2 antigen expression on leukemic cells as a predictor of event-free survival after chemotherapy for T-lineage acute lymphoblastic leukemia: a Children's Cancer Group study

We examined the prognostic impact of CD2 antigen expression for 651 patients with T-lineage acute lymphoblastic leukemia (ALL), who were enrolled in front-line Childrens Cancer Group treatment studies between 1983 and 1994. There was a statistically significant correlation between the CD2 antigen positive leukemic cell content of bone marrow and probability of remaining in bone marrow remission, as well as overall event-free survival (EFS) (P = .0003 and P = .002, log-rank tests for linear trend). When compared with patients with the highest CD2 expression level (> 75% positivity), the life table relative event rate (RER) was 1.22 for patients with intermediate range CD2 expression level (30% to 75% positivity) and 1.81 for "CD2-negative" patients (< 30% positivity). At 6 years postdiagnosis, the EFS estimates for the three CD2 expression groups (low positivity to high positivity) were 52.8%, 65.5%, and 71.9%, respectively. CD2 expression remained a significant predictor of EFS after adjustment for the effects of other covariates by multivariate regression, with a RER of 1.47 for CD2- negative patients (P = .04). Analysis of T-lineage ALL patients shows a significant separation in EFS after adjustment for the National Cancer Institute (NCI) age and white blood cell (WBC) criteria for standard and high-risk ALL (P = .002, RER = 1.67). The determination of CD2 expression on leukemic cells helped identify patients with the better and poorer prognoses in both of these risk group subsets. For standard risk T-lineage ALL, CD2-negative patients had a worse outcome (P = .0007, RER = 2.92) with an estimated 5-year EFS of 55.9% as compared with 78.3% for the CD2-positive patients. Thus, CD2 negativity in standard risk T-lineage ALL identified a group of patients who had a worse outcome than high-risk T-lineage ALL patients who were CD2 positive. The percentage of CD2 antigen positive leukemic cells from T- lineage ALL patients is a powerful predictor of EFS after chemotherapy. This prognostic relationship is the first instance in which a biological marker in T-lineage ALL has been unequivocally linked to treatment outcome.