Comparion Of Differentially Expressed Genes In Untreated And Relapsed Acute Lymphocytic Leukemia By CDNA Microarray

Objective To investigate the differentially expressed genes betweenuntreated and relapsed acute lymphocytic leukemia(ALL),cDNA microarray wasused to compare the gene expression profiles in untreated and relapsed ALL patients.Metheods Mononuclear cell was isolated from peripheral blood or bonemarrow of 5 pairs of untreated and relapsed ALL patients.Total RNA isolated fromstudy group(relapsed)and control group(untreated)were reverse transcribed to thecDNA with the incorporation of fluorescent dye as the probes(study group labelled byCy5,and control group labelled by Cy3).The mixed probes were then hybridized tothe BioStarH-40s expression microarray prepared already.After washing,genemicroarray was scanned for the fluorescent signal and showed differences betweentwo groups. Expression levels of 3 differentially expressed genes were measured in 83ALL patients(divided into two groups:untreated and relapsed)and 36 normal subjectsby semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).SPSS 11.5 was used to analyse the results.Results 27 genes differentially expressed in more than 4 pairs of sampleswere identified by cDNA microarray technique.Among 4096 genes,9 were shown up-regulated(0.220%) and 18 down-regulated(0.439%).These differentiallyexpressed genes include:immuno-related gene,signal transduction genes,proteintranslation and synthesis-related gene, metabolism related genes,cytoskeleton andcell movement-related gene, proto-oncogene and tumor suppressor genes,DNAsynthesis and repairing genes,cell cycle genes,et al. Verified by RT-PCR,we foundthat expression levels of DAXX and TM4SF-13 genes in the relapsed patients tendto be lower than that in the untreated ones,which coincided with the results ofmicroarray. Expression levels of these 2 genes in control group were lower than thatin patients(P<0.01). Expression level of BRD-2 gene in the relapsed patients waslower than that in the untreated ones,which was opposite to the results of microarray(P<0.05).Expression level of this gene in control group was lower than that inpatients(P<0.01). Conclusion 1. cDNA microarray technique is effective in screening thegenes associated with disease.It has some positive application values in studying thegenes associated with ALL.And it can primarily screen out differentially expressedgenes of ALL. 2. At the present time,the result of microarray is notcompletely reliable.It may have false positive and false negative problems.It isnecessary to confirm the results of microarray by other methods. 3. Those genes that still differentially expressed byconfirmation were analyzed by bioinformatics.We find that some genes are known,others are unknown.