The Primary Study On IGSF4 Inactivation By Promoter Methylation In Leukemia Cells

The inactivation of antioncogene by methylation has become one of important pathogenesis mechanisms of leukemia. To find the new genes inactivating in leukemia by methylation has become a very valuable task. Fifty genes related to leukemia with promoter methylation have been detected by Yuli by using restriction landmark genomic scanning technology to compare the DNA methylation pattern of spleen cells of normal mice and the mice with leukemia. The mice genome is very close to mankind, so these genes found has great value for the study of Mankind leukemia. We choosed Four genes of 50 genes found, including SEMA6A, B56JGSF4 and SLIT2, to have further study to find new genes related mankind leukemia with promoter methylation.To explore whether SEMA6A, B56, IGSF4 and SLIT2 is genes related to leukemia with promoter methylation ,the expression patterns of the 4 genes were detected with RT-PCR in HL60, U937 and MoM cell. Then it was observed whether the inactived genes in leukemia cell lines were actived after the treatment with 5-aza-deoxycytosin, a kind ofdemethylation agent . Based on the results, the IGSF4 gene expression pattern was analyzed by bioinformatics technique. And RT-PCR method was used to detect IGSF4 expression pattern in the leukemia in normal bone marrow and primary leukemia cells from patients. At last, promoter methylation of IGSF4 was detected with MS-PCR in the aboved 3 cell lines as well as the primary leukemia cells from acute leukemia patients.The results showed: (1)The expression of B56 were detected all of the three involved leukemia cell lines. The deletion of SEMA6A was detected in HL60, and the deletion of SLIT2 wasdetected in the three cell lines. But SEMA6A and SLIT2 were not both actived by the demethylation treatment. The deletion of IGSF4 was detected in all of the three involved leukemia cell lines, and could be actived by the demethylation treatment. It is indicted that IGSF4 is a good candidate gene related to leukemia with promoter methylation. (2)The predict of bioinformatics technique showed that IGSF4 was expressed in the many normal and tumour tissues including bone marrow, muscle, nerve, heart, liver and so on It indicted that IGSF4 could be a gene with important physiological function. (3)The expression of IGSF4 was detected in normal bone marrow. The Incidence of IGSF4 expression is lower in the primary leukemia cells than normal bone marrow, indicating deletion of IGSF4 could be related closely to leukemia. (4)The promoter methylation was detected in all of the above 3 cell lines, which proved that the deletion of IGSF4 expression in leukemia cells was caused by promoter methylation. The general incidence of IGSF4 promoter methylation in the primary leukemia cells from the patients with leukemia was 48%. The incidence was higher in acute leukemia than chronic leukemia. There was no difference in the incidenceof IGSF4 promoter methylation between acute myelocytic leukemia and acute lymphocytic leukemia ,as well as the primary patients group and relapsed, refractory patients group. It is indicated that IGSF4 promoter methylation exsisted widespreadly in leukemia, and could be not related to prognosis.