Apoptosis-inducing Effect of 8-Bromo-7-Methoxychrysin on K562 cells / 中国实验血液学杂志

This study was purposed to investigate the apoptosis-inducing effect of 8-bromo-7-methoxychrysin (BrMChR) on leukemia K562 cells as well as the variation of caspase-3 activity and phosphorylated Akt (p-Akt) expression of K562 cells during the process of apoptosis. MTT assay was used to determine the inhibitory effect of BrMChR on proliferation of K562 cells. Cell apoptosis was assayed by AO/EB staining under fluorescent microscope and flow cytometry with Annexin V-FITC/PI staining. The expression level of p-Akt was measured by Western blot. The results showed that BrMChR had the inhibitory effect on proliferation of K562 cells and could induce apoptosis of these cells in dose-dependent manner, and these effects were significantly stronger than ChR. After treatment of K562 cells with 3 µmol/L ChR for 12 hours, the apoptosis rate was only 3.68%, but the apoptosis rate of K562 cells treated with 3 µmol/L BrMChR was 21.8%. In the same time, the caspase-3 activity significantly increased (p < 0.05), but the expression of p-Akt was down-regulated (p < 0.01). It is concluded that BrMChR can induce apoptosis of K562 cells and with effect stronger than chR. P-Akt may participate in the apoptosis process of K562 cells induced by BrMChR.

The effect of ATRA-induced leukemic cell differentiation on Brd7 gene expression in leukemia cell lines / 中国实验血液学杂志

This study was purposed to investigate the relationship between brd7 gene and differentiation of leukemia cells and the role of brd7 gene in differentiation of leukemia cells. The HL-60 and K562 cell lines were induced by all-trans retinoic acid (ATRA) for 7 days, then the cell morphologic change was observed under inverted microscope with Wright-Giema staining, the expression level of CD11b was detected by flow cytometry for evaluating cell differentiation level, the expression changes of BRD7 protein before inducing differentiation and in process of cell differentiation were determined by Western blot. The results showed that ATRA could inhibit the proliferation and induce differentiation of HL-60 cells, but no differentiation in K562 cells was induced by ATRA. The level of CD11b expression in HL-60 cells was up-regulated gradually during ATRA-induced cell differentiation. The expression of BRD7 protein increased markedly along with differentiation of HL-60 cells towards granulocytes. However, BRD7 protein did not significantly alter in K562 cells in which inducing differentiation was not found. It is concluded that brd7 gene expression enhances as the HL-60 cells differentiate, underlying which the mechanism remains to clarify.

Expression and SNP analysis of BRD7 gene in acute leukemia cells / 中南大学学报(医学版)

OBJECTIVE@#To evaluate the expression level of BRD7 gene in bone marrow mononuclear cells (BMNCs) in patients with acute leukemia (AL) and to analyze BRD7 single nucleotide polymorphism(SNP).@*METHODS@#RT-PCR was used to detect BRD7 expression in patients with AL and normal bone marrow subjects. Single-strand conformation polymorphism and DNA sequence analysis were also used to identify BRD7 mutation or SNP to investigate the relation between BRD7 and AL.@*RESULTS@#BRD7 mRNA in BMNCs from 52 patients with AL and 30 control subjects was expressed. The mRNA relative expression of BRD7 in patients with AL was higher than that of the control group (P=0.001). Three SNPs (C657A,C495T and A737G) in BRD7 gene coding region (447 approximately 844 bp) were found, and A737G was coupled with C495T . The allele frequencies of SNP C657A were not significantly different between AL and the control group. The genotype and the allele frequencies of the 2 coupled SNPs were significantly different (P0.05).@*CONCLUSION@#Expression of BRD7 gene is up-regulated in AL cells. The 2 coupled SNPs (C495T and A737G ) in BRD7 gene coding region (447 approximately 844 bp) are correlated with AL, indicating that SNPs may be one of the genetic susceptibility factors of AL.

Effect of glycosylphosphatidylinositol specific phospholipase D gene expression levels on complement mediated killing of leukemic cells in patients with chronic myeloid leukemia.

BACKGROUND: To explore the disparity in glycosylphosphatidylinositol phospholipase D (GPI-PLD) expression levels between mononuclear cells of chronic myeloid leukemia (CML) and healthy controls, and clarify the certain relation of GPI-PLD expression levels to complement mediated killing of leukemic cells. METHODS: Competitive RT-PCR was used to detect quantitatively the GPI-PLD mRNA in mononuclear cells. GPI-anchored CD55 and CD59 were analyzed by flow cytometry and Western blotting. Complement-mediated lysis was assessed by staining method of trypan blue dye. RESULTS: The GPI-PLD activities and their mRNA copies in CML patients were significantly lower than those in healthy adults. At the tenth day after treatment with bone marrow transplantation (BMT), the GPI-PLD activities and copies of GPI-PLD mRNA almost recovered to the expression levels of healthy subjects. The expression of both CD55 and CD59 in CML patients were significantly higher than those in healthy subjects. After treatment with insulin (10(-7) mol/l) plus glucose (16.7 mmol/l) for 48 h, the cellular GPI-PLD activity and mRNA levels in K562 cells derived from the leukemic cells of a CML patient all increased about 3-fold. Simultaneously, the GPI-anchored CD55 and CD59 on cell surfaces were released into the culturing medium, and the killing rate of complement-mediated K562 cell lysis increased almost 3 times. CONCLUSION: The decreased GPI-PLD expression may reduce the release of GPI-anchored CD55 and CD59 in leukemia cells and finally decrease complement mediated killing of these cells in chronic phase of CML.