| Leukemia is a complex genetic disease characterized by the accumulation of multiple molecular alterations. Functional studies of leukemia specific genes are crucial to our understanding of its complexity and polymorphism. Current diagnostic and prognostic classifications are insufficient to reflect the whole heterogeneity of leukemia. Recent advances in human genome research and high-throughput microarray technologies make it possible finally to tackle the molecular complexity of malignant diseases. Genomic analysis has the potential to reveal the comprehensive transcriptional alterations that dictate fundamental biological processes such as signal transduction in response to specific stimuli, cell growth, differentiation, and apoptosis. Since the technique of microarray has been employed in the classic discovery of acute leukemia in 1999, more and more data revealed that although numerous alterations of gene groups might be accumulated in the progression of this disease, the number of key genetic alterations is limited. As a high throughput, rapid and parallel technique in analyzing gene expression, oligonucleotide microarray serves as an ideal method in the research of leukemia classic predictors and classic discovery.In our studies, two supervised methods of analysis were used to identify the several best discriminating genes between the following cohorts: patients with leukemia versus their sibling donors; acutemyelogenous leukemia (AML) versus acute lymphoblastic leukemia (ALL).1. Identification of acute leukemia - specific genes from leukemia recipient/ sibling donor pairs by distinguishing study with oligonucleotide microarrayObjective With the use of oligonucleotide microarray, gene expression profiles were analyzed in bone marrow /leucopheresis peripheral blood samples of 9 acute leukemia patients and their sibling donors. Method To identify acute leukemia - specific genes, we prospectively analyzed the expression profiles of 163 genes in acute leukemia patients and their sibling donors. The oligonucleotide primers were designed, synthesized and spotted on the chemical-material-coated-glass plates in array. The total RNAs were isolated and reversely transcribed into cDNAs with the incorporations of fluorescent dUTP. Samples were then hybridized on the oligonucleotide microarray. Results In four ALL patient/donor pairs, we identified 5 up-regulated (RIZ, STK-1, T-cell leukemia/lymphoma 1A, Cbp/p300, Opl8)and 1 down-regulated genes(hematopoietic proteoglycan core protein). In five patients with AML-M4 or AML-M5/donor pairs, 6 up-regulated(STAT5B, ligand p62 for the Lck SH2, CST3, LTC4S, myeloid leukemia factor 2 and epb72)and 1 down-regulated genes(CCR5)were detected. Conclusion Basis on distinguishing study of recipient/ sibling donor pairs, a set of 13 up-regulated or down-regulated genes have been identified. The results have further confirmed these key disease-specific genetic alterations and significant gene expressionprofiles in acute leukemia.2. Molecular class discovery and class prediction of acute leukemiasObjective Distinguishing ALL from AML is crucial for successful chemotherapy. Although the distinction between AML and ALL has been well established by morphology, histochemistry, immunophenotyping as wellas cytogenetic analysis, current diagnostic and prognostic classifications are insufficient to reflect the whole clinical heterogeneity of leukemia subtypes. Genoraic analysis has become a crucial aspect of leukemia classification and diagnosis. Methods In this study, the oligonucleotide microarray was employed to analyze the class discovery and class prediction with 16 acute leukemia samples according to their gene expression signal values. In order to find out related genes to distinguish AML and ALL samples, the Tclass system (A tumor classification system developed by Bioinformations) has been used. The similarity of gene expression profiles among 16 acute leukemia samples has been analysis by CLUSTER and TREEVIEW program. Results From this study of ALL/AML cla... |
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