Study Of Loss Of Heterozygosity And Microsatellite Instability On Chromosome 7 In Leukemia

Acute leukemia is one of the most common malignant tumor. It is important to the diagnosis and prognosis that the studying of mechanisms of occurrence and pathogenesis of acute leukemia in molecular biology . Loss of heterozygosity(LOH)is common in tumor.Loss of heterozygosity on the long arm of chromosome 7(7q)has been frequently reported in several types of humon cancers, including hematologic malignancy. In acute leukemia,7q22-36 is regarded as the intensive region of LOH. Frequent loss of an allelic at specific chromosomal regions implicates these region as site of tumor suppressor genes that inactivated.Objective To study the frequency of loss of heterozygosity(LOH) and microsatellite instability(MSI) on chromosome 7 and to investigate the significance of MSI and LOH and celluar biological implicationMethod MSI and LOH in 33 cases of acute leukemia ,including 11 cases of acute lymphoblastic leukemia(ALL) and 22 acute myeloblastic leukemia(AML) were detected by PCR amplificiation at 4 microsatellites on 7q22-36,gel electrophoresis and silver nitrate staining technique.Results 9 cases of leukemia demonstrated LOH at one or moreloci. LOH was found in 7 cases(7/22) of acute myeloblastic leukemia(AML) and 2 cases of acute lymphoblastic leukemia(ALL). LOH was observed in 1 case of AML on D7S487;1 case of AML and 1 case of ALL on D7S523;4 cases of AML and 1 case of ALL on D7S515;3 cases of AML on D7S636.None of 33 cases of acute leukemia(AL) showed MSI. None of 20 Cases of control samples showed LOH and MSI.Conclusion The result suggest that frequency of LOH on 7q22-36 were relatively high in acute leukemia. Some tumor suppressor genes(TSGs) may be existence on chromosome 7q22-36. Microsatellite alterations of multi-locus observed in leukemia indicate that the pathogenesis and progress of leukemia isn't related to the multi-region and multi-step changes of chromosomes as those of the solid tumor.