AML1 gene over-expression in childhood acute lymphoblastic leukemia.

The present study was conducted on a series of 41 Egyptian children with newly diagnosed acute lymphoblastic leukemia (ALL) to investigate TEL and AML1 abnormalities. The TEL-AML1 fusion was observed in six patients both by RT-PCR and FISH analyses, with a frequency of 22.2% among the B-lineage group, whereas TEL deletion was seen by FISH analysis in seven patients (17.1%). By FISH analysis, nine patients (22%) showed evidence of extra AML1 copies. In five of these patients the extra copies were due to non-constitutional trisomy 21, whereas in the remaining four cases they were due to tandem AML1 copies on der(21), as evidenced by metaphase FISH. Unexpectedly however, enhanced AML1 expression levels were seen by real-time quantitative RT-PCR in 18 out of the 41 ALL patients (43.9%). This high level of AML1 expression could be an important factor contributing to the pathogenesis and progression of childhood ALL. One key mechanism for over-expression seems to be the extra copies of AML1, but other mechanisms may involve an alteration of the activity of the AML1 promoter. Here, we also report two novel findings. The first is an intragenic deletion of TEL exon 7 in a case of T cell ALL. This deletion creates a frame-shift and results in a truncated protein lacking the C-terminus that includes the ETS domain. This shorter TEL is presumably unable to bind DNA. The second finding is a rearrangement of AML1 in a case of T cell ALL due to t(4;21)(q31;q22). This is the first reported chromosomal translocation where AML1is rearranged in childhood T cell ALL.     

MDR1 gene expression and treatment outcome in acute myeloid leukemia

To prospectively assess the role of MDR1 gene expression in patients with de novo acute myeloid leukemia (AML), levels of MDR1 RNA in blast cells were determined at diagnosis and correlated with treatment outcome in 63 patients. MDR1 RNA levels were negative in 29% and positive in 71% of the patients. The complete remission rate in response to induction chemotherapy was 89% for MDR1 RNA-negative patients and 53% for MDR1 RNA-positive patients (P = .008). Expression of the MDR1 gene was observed in most patients who died early or had resistant disease. Kaplan-Meier curves revealed a decrease in both disease-free survival and overall survival of patients with detectable MDR1 gene expression compared with the disease-free survival and overall survival of MDR1 RNA-negative patients (P = .029 and P = .009, respectively). These data indicate that MDR1 gene expression is an unfavorable prognostic factor and suggest that multidrug resistance is important in AML.     

Mechanisms of growth factor expression in acute myeloid leukemia (AML)

To investigate possible mechanisms of growth factor expression in acute myeloid leukemia, genes for granulocyte macrophage colony-stimulating factor (GM-CSF) were analyzed by Southern blots in 20 patients, for M-CSF in 13, for interleukin-6 (IL-6) in 14, for IL-6 receptor in 14 and for G-CSF in five patients. Only in one patient a complex rearrangement of the G-CSF gene with possible amplification was noted indicating rarity of direct alterations of growth factor genes in acute myelogenous leukemia (AML). Spontaneous m-RNA expression for GM-CSF was found in only one of 20 patients, and for IL-6 in eight of 11 patients. In vitro incubation of AML cells of eight patients with recombinant tumor necrosis factor for 24 hr revealed induction of GM-CSF m-RNA expression in three cases and GM-CSF protein expression in two of them. These data suggest that spontaneous GM-CSF production occurs rarely in AML and that monokines, such as tumor necrosis factor, may induce GM-CSF in AML cells. Therefore, interactions of AML cells with normal or malignant accessory cells may be important for autocrine stimulation in AML. Our data suggest that ectopic growth factor secretion is not the primary cause of generating AML but may contribute to progression of the disease. Alternatively, AML may represent a heterogenous group of leukemias with different etiology but similar phenotype.     

Mdr1 gene expression and mutations in Ras proto-oncogenes in acute myeloid leukemia

Resistance to cytotoxic therapy and development of refractory disease in acute myeloid leukemia (AML) is frequently associated with the expression of mdr1/P-gp. In the last years many potential signaling pathways leading to modulation of mdr1 expression have been described. Thus, it has been assumed that activated Ras may influence mdr1 expression. This activation can be realized by mutations in the Ras oncogene leading to constitutive signaling. Ras mutations are observed in many human cancers, including AML. Recently, we could show a negative correlation between Ras mutations and mdr1 expression in blast samples of AML patients. Taking this up the potential possibilities of Ras influence on mdr1 activity and their implications on treatment outcome in AML are discussed.     

AML1-ETO融合基因转阴对急性髓细胞白血病预后的影响

目的:探讨AML1-ETO融合基因阳性表达的急性髓细胞白血病（acute myelocytic leukemia,AML）患者治疗后融合基因转阴及转阴时间长短对AML患者预后的影响。方法:对2012年1月1日至2016年12月31日在中国医科大学附属盛京医院住院治疗的35例初诊AML1-ETO融合基因阳性AML患者的临床资料进行回顾性分析,总结其形态学、免疫学和分子生物学特征,用 Kaplan-Meier 曲线评估患者生存情况。结果:35例患者男女比例 1.33∶1,中位年龄为34岁(15~71岁)。中位随访时间为16(4~61)个月,诱导缓解率为82.9%,3个疗程或以上缓解占14.3%(n=5),始终未缓解占2.9%(n=1),复发率35.3％(n=12),复发中位时间 12（6~20）个月。其中11例治疗后融合基因转阴,包括3个月内转阴占63.6%（n=7）,大于3个月转阴占36.4%（n=4）。单因素分析表明AML1-ETO融合基因转阴患者OS和PFS高,预后较好,AML1-ETO融合基因转阴时间长短对患者长期生存的影响无统计学意义（P=0.707）。结论:AML1-ETO融合基因转阴的AML患者预后较好,AML1-ETO融合基因转阴时间长短对患者的长期生存无明显影响。     

急性髓性白血病患者LRP、MRP基因表达

目的：研究急性髓性白血病ＬＲＰ基因、ＭＲＰ基因表达与疗效的关系，方法：用ＲＴ－ＰＣＲ法检测３７例急性髓性白血病ＬＲＰ基因、ＭＲＰ基因表达，按此两种基因表达分成ＬＲＰ－／ＭＲＰ－、ＬＲＰ－ＭＲＰ＋、ＬＲＰ＋／ＭＲＰ－、ＬＲＰ＋／ＭＲＰ＋共４组，统计比较各组疗效。结果：与ＬＲＰ－／ＭＲＰ－组比较，其余３组疗效较低，其中ＬＲＰ＋／ＭＲＰ－组、ＬＲＰ＋／ＭＲＰ＋组存在显著差异，但ＬＲＰ＋／ＭＲＰ＋组与ＬＲ     

Relevance of mdr1 gene expression in acute myeloid leukemia and comparison of different diagnostic methods.

In an attempt to determine the incidence and clinical relevance of mdr1 gene expression in acute myeloid leukemia (AML), we examined 126 specimens obtained from adult patients with de novo AML by slot blot and immunocytochemistry. We found a high incidence of mdr1 gene expression in newly diagnosed patients (27% by immunocytochemistry and 43% by slot blot). No difference was observed between newly diagnosed patients and relapsed patients. However, patients with resistant disease showed statistically higher incidence of mdr1 gene expression compared to the untreated and relapsing patients (60% versus 27% by immunocytochemistry, p 0.005; and 73% versus 45% by slot blot, p less than 0.05). The expression of mdr1 gene correlated significantly with clinical drug resistance: 62% of patients positive for mdr1-mRNA and 68% of patients positive for P-glycoprotein (P-gp) eventually developed resistance to chemotherapy, while this was the case for a lower percentage of patients who did not express mdr1 gene (only 23% by slot blot analysis, p = 0.0052, or 24% by immunocytochemistry, p = 0.0009). A combined parameter, mdr1-mRNA/P-gp, had a very high prognostic value in terms of specificity and sensitivity. All nine patients (100%) who were mdr1-mRNA+/P-gp+ progressed to clinical drug resistance afterward, whereas 11 of 13 (85%) patients who were mdr1-mRNA-1 P-gp- entered complete remission and only two patients later developed drug resistance (p = 0.0005). It could thus be used as a reliable parameter in clinical settings.     

SAMHD1基因在初诊急性髓细胞白血病患者中的表达及其临床意义

目的:探讨SAMHD1基因在初诊急性髓细胞白血病（AML)患者中的表达及其临床意义。方法:实时定量PCR方法检测13例成人初诊AML患者与7例非恶性血液病患者SAMHD1 mRNA的表达,分析其临床意义。利用SPSS统计学方法分析SAMHD1基因表达高低与初诊白血病患者临床和实验室特征之间的相关性,采用Kaplan-Meier法以及COX回归模型进行多因素生存分析。结果:SAMHD1基因在AML患者中的表达低于非恶性血液病患者（P＜0.05）,且SAMHD1基因表达高低与患者性别、年龄、初诊时WBC、HGB、PLT、骨髓原始细胞百分比分布差异均无统计学意义;SAMHD1表达高低在预后良好与预后不良组间差异比较有统计学意义（P＜0.05),其中低表达组的OS低于高表达组。结论:SAMHD1基因在AML与非恶性血液病患者中表达差异具有统计学意义,且其可作为影响初诊AML患者OS的独立预后因素。     

WT1 isoform expression pattern in acute myeloid leukemia

WT1 plays a dual role in leukemia development, probably due to an imbalance in the expression of the 4 main WT1 isoforms. We quantify their expression and evaluate them in a series of AML patients.Our data showed a predominant expression of isoform D in AML, although in a lower quantity than in normal CD34+ cells. We found a positive correlation between the total WT1 expression and A, B and C isoforms. The overexpression of WT1 in AML might be due to a relative increase in A, B and C isoforms, together with a relative decrease in isoform D expression.     

Gene expression profiling in acute myeloid leukemia.

Over the last decades, significant advances have been made in the knowledge and treatment of acute myeloid leukemia (AML). The WHO has recognized this new information by incorporating into its classification morphologic, immunophenotypic, genetic, and clinical features in an attempt to define biologically and clinically relevant entities. Nevertheless, well-defined cytogenetic subgroups exhibit considerable heterogeneity, and in many AML subtypes the pathogenic event is still not known. A classification system based on the underlying molecular pathogenetic abnormalities would be ideal, but such detailed knowledge is not yet available. Novel approaches in genomics, such as surveying the expression levels of thousands of genes in parallel using DNA microarray technology, open possibilities to further refine the studies on AML. Today, gene expression profiling in AML is becoming well established and has already been proven to be valuable in diagnosing different cytogenetic subtypes, discovering novel AML subclasses, and predicting clinical outcome. Recently, gene expression profiling studies in AML showed a remarkable level of concordance in findings, which may ultimately lead to an increasingly refined molecular taxonomy. While many challenges remain to be overcome, a combination of gene expression profiling with other microarray-based applications, high-throughput mutational analyses and proteomic approaches will not only significantly contribute to the classification and therapeutic decision making of AML, but also give important insights into the true pathobiologic nature of this type of leukemia.     

Clinical implications of gene expression profiling of acute myeloid leukemia

Since the first demonstration in 1999 that gene expression profiling could distinguish between different variants of acute leukemia, several studies have analyzed patients with acute myeloid leukemia on the basis of cytogenetics, morphologic subgroups, secondary mutations such as FLT3, prognosis, and therapeutic response. This review examines some of these data and attempts to discuss whether these analyses will have clinical applications in diagnosis, prediction of prognosis and response to therapy, disease classification, or individually targeted therapy. It is probable that all these areas will reach the clinical environment eventually, but in the short to medium term, microarrays will be involved only in diagnosis.