Alteration of methylation status of fragile histidine triad gene promoter in patients with myelodysplastic syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the methylation status of fragile histidine triad (FHIT) gene promoter in patients with myelodysplastic syndrome (MDS) and its clinical relevance.</p><p><b>METHODS</b>Methylation-specific PCR (MSP) was used to detect FHIT promoter methylation in bone marrow samples from 54 MDS cases.</p><p><b>RESULTS</b>Hypermethylation of FHIT promoter was detected in 26 cases (48.1%). Association was not found between FHIT gene hypermethylation and sex, hematologic parameters and chromosomal abnormalities of MDS patients, but found between FHIT gene hypermethylation and age of the MDS cases. Although significant difference was not observed in the frequencies of FHIT gene hypermethylation among patients with refractory anemia/refractory anemia with ringed sideroblasts (RA/RAS) (1/6, 16.7%), refractory anemia/refractory anemia with ringed sideroblasts (RCMD) and refractory cytopenia with multilineage dysplasia with ringed blasts (RCMD-RS) (6/19, 31.6%), refractory anemia with excess blasts-1 (RAEB-1) (7/11, 63.6%), refractory anemia with excess blasts-2 (RAEB-2) (4/7, 57.1%) and refractory anemia with excess blasts in transformation/acute myeloid leukemia (RAEBt/AML) (8/11, 72.7%)(chi-square=8.417, P=0.077), it was observed in patients in early stages (RA/RAS and RCMD) (7/25, 28.0%), advanced stages (RAEB-1 and RAEB-2)(11/18, 61.1%) and RAEBt/AML (8/11, 72.7%) (chi-square=7.938, P=0.019). Furthermore, there was a positive correlation between the frequency of FHIT gene hypermethylation and different IPSS groups (chi-square=10.110, P=0.018).</p><p><b>CONCLUSION</b>FHIT gene hypermethylation might be one of the molecular events involved in the disease progression of MDS.</p>

CD36 expression in leukemia cells checked with multi-parameter flow cytometry and its significance / 中国实验血液学杂志

The aim of study was to investigate the expression of CD36 in leukemia cells and to explore its significance in diagnosis and differential diagnosis for leukemia in patients. Blood samples from 133 cases of leukemias were analyzed by CD45/SSC double parameters and multi-color flow cytometry in order to determine the CD36 and other leukocyte differentiation antigens. The results show that the CD36 positive rate was 21.8% (29/133) in 133 cases of leukemia, 41.9% (26/62) in 62 cases of AML (acute myeloid leukemia), and none of the 54 cases of lymphocytic leukemia was positive for this antigen. The positive rate of CD36 in M(4) (8/10), M(5) (12/12) and M(6) (3/3) was significantly higher than that in M(1) (0/9), M(2) (3/12), M(3) (0/16) (all P < 0.001). The percent of positive cells of CD36 in M(5a) was significantly higher than in M(5b) (P = 0.001). A significantly negative regression was found between CD36 and CD117 in AML (r = -0.751, P = 0.005). And a significantly positive regression was found between CD36 and CD14 in M(4) and M(5b) (r = 0.870, P = 0.011). In monocyte lineage involved leukemia (MLIL), the positive rate of CD36 (92.6%, 25/27) was significantly higher than that of CD14 (48.1%, 13/27)(P = 0.001). None of the 7 cases with M(5a) was positive for CD14, but 4 of 5 cases of M(5b) were positive. The positive rate of CD117 in M(5a) was significantly higher than that of in M(5b)(P = 0.01). The positive rate of CD34 in M(5) was low (33.3%, 4/12). It is concluded that the combination of CD36 with lymphoid and myeloid antigens is helpful to the diagnosis and differential diagnosis of lymphoid, myeloid and MLIL. The positive rate of CD36 is higher than that of CD14 in MLIL.

Experimental study on the role of VEGF autocrine loop in K562 leukemia cells / 中华血液学杂志

<p><b>OBJECTIVE</b>lo investigate the effects of anti-VEGF antibody and anti-VEGF hairpin ribozyme gene on the proliferation, apoptosis and related gene expression of the leukemia K562 cells and the possible molecular mechanisms.</p><p><b>METHODS</b>K562 cells were cultured in different concentrations of anti-VEGF antibody. The recombinant eukaryotic expression plasmid (pcDNA3-RZ) containing anti-VEGF hairpin ribozyme gene and the vector-alone were introduced into K562 cells by lipofectamine mediation. Cell proliferative capacity was determined by MTT, colony formation assay and cells cycles analysis. Cell apoptosis was assayed by DNA ladder and Annexin V -FITC/PI flow cytometry.</p><p><b>RESULTS</b>The anti-VEGF antibody was able to inhibit growth and induce apoptosis of K562 cells in a dose-dependent manner. Exposure to anti-VEGF antibody at 0. 165 microg/ml for 72 hours, the cells exhibited typical DNA ladders. The apoptosis rate peaked at antibody concentration of 0. 825 microg/ml. RT-PCR showed a decrease of MRP and TOPO II expression but a relative constant expression of GST. The introduction of exogenous anti-VEGF ribozyme gene resulted in a decrease of the proliferative capacity and colony forming efficiency from (30.5 +/- 3.3) % in control group to (16.3 +/- 2.8) % in K562/RZ group, higher G1 and lower S ratio in cell cycle distribution in comparison with the control groups. Typical DNA fragmentation and higher Annexin V + ratio occurred in K562/RZ cells after treated with 0.5 micromot/L of As2O3 for 3 days, the apoptosis rate increased from 13.4% in control group to 31. 5% in As2O3 treated group.</p><p><b>CONCLUSION</b>Anti-VEGF antibody can inhibit growth, induce apoptosis and down-regulate the expression of MRP, TOPO II genes of K562 cells in vitro. Transfection with anti-VEGF ribozyme gene can inhibit the proliferation of the cells by delaying the progression G1 into S phase in cell cycles and induce cell apoptosis by down-regulating VEGF gene expression.</p>

Inhibition of K562 cell growth and tumor angiogenesis in nude mice by transfection of anti-VEGF hairpin ribozyme gene into the cells / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the effect of anti-VEGF hairpin ribozyme gene on the tumor cell growth and tumor angiogenesis in nude mice.</p><p><b>METHODS</b>The recombinant eukaryotic expression plasmid pcDNA-RZ containing anti-VEGF hairpin ribozyme gene and the empty vector plasmid pcDNA were introduced separately into K562 cells by lipofectamine mediation and positive clones were screened by G418. Ribozyme gene in K562 cells was confirmed by PCR. Fluorescent real time RT-PCR and Western blot were used to detect the expression of VEGF mRNA and protein in the leukemia cells. The tumorigenicity of transfected K562 cells were transplanted in nude mice and tumor microvascular density (MVD) were observed by morphology and vWF immunohistochemistry stain.</p><p><b>RESULTS</b>Stable expression of the ribozyme gene in K562 cells was confirmed by PCR. The level of VEGF mRNA and protein decreased dramatically in K562/RZ cells when compared with K562 or K562/PC (K562 cells transfected with empty vector) cells. The tumor volumes were (4.43 +/- 0.87), (3.96 +/- 0.94), (2.24 +/- 0.56) cm3; tumor weight was (4.43 +/- 0.87), (3.96 +/- 0.94), (2.24 +/- 0.56)g; and tumor microvascular density was 4.70 +/- 1.25, 4.67 +/- 1.31, 1.80 +/- 1.55 in K562, K562/PC and K562/RZ cell groups, respectively.</p><p><b>CONCLUSION</b>Transfection with anti-VEGF ribozyme gene can inhibit tumor growth and vessel formation by down-regulating the VEGF gene expression in K562 cells.</p>