Restoring beta1 integrin activation function in K562 cells transfected with antisense VEGF121 cDNA / 中国实验血液学杂志

To investigate the effect of vascular endothelial growth factor (VEGF) on beta1 integrin (VLA-4 and VLA-5) activation ability in K562 cells transfected with antisense VEGF121 cDNA, K562 cells were transfected with antisense (As), sense (S) and vector (V, pcDNA(3)). Flow cytometry was used to evaluate the expression rate of VLA-4 (CD49d/CD29) and VLA-5 (CD49e/CD29) and beta1 integrin activation ability in the transfected K562 cells. The results showed that the expression rates of VLA-4 and VLA-5 were more than 92% in the transfected K562 cells and there was no difference among the K562/V, K562/S and K562/As cells. However, beta1 integrin activated 9EG7 expression rate in K562/As cells was higher than that in K562/V cells [(75.6 +/- 10.5)% vs (41.2 +/- 2.1)%, P < 0.01)] after activation with beta1 integrin activator 8A2. It is concluded that function of beta1 integrin to be activated is restored in K562 cells transfected with antisense VEGF121 cDNA.

Expression of Vascular Endothelial Growth Factor in the Bone Marrow Cells from Adult Chronic Myelogenous Leukemia / 中国实验血液学杂志

Vascular endothelial growth factor (VEGF) is one of the main angiogenic cytokines and plays an important role in the development of human solid tumors. However, it is not clarified whether VEGF governs the progress of the chronic myelogenous leukemia (CML). This study is to estimate VEGF expression in the bone marrow cells from normal and adult CML patients and various leukemic cell lines. Reverse transcription-polymerase chain reaction (RT-PCR) was used for detection of VEGF mRNA. VEGF concentrations in the cell cultural supernatant and the plasma from normal and CML patient bone marrows were determined by enzyme linked immunosorbent assay (ELISA). VEGF mRNA was positive in 67 of 72 cases of bcr/abl(+) CML patient bone marrow cells (93.1%), in 5 of 10 CML patients post Allo-BMT bone marrow cells (50%), and in 6 of 10 normal bone marrow cells (60%), the expression rate of VEGF mRNA in CML patients bone marrow cells was higher than that in CML patients post Allo-BMT and normal bone marrow cells. VEGF mRNA also expressed in the HL-60, K562, CEM, KG1a, NB4, and Nalm6 cells, but not in the Jurkat cells. The mean VEGF concentration in the plasma (380.6 pg/ml) from 22 untreated CML patients was 9 folds higher than that from 9 CML patients post Allo-BMT (38.0 pg/ml). The mean VEGF concentration in the cultural supernatant (499.8 pg/ml) of 17 newly diagnosed CML bone marrows was 2.5-folds higher than that in 11 normal donors (141.3 pg/ml). The CML marrow cells secrete more VEGF than normal marrow cells do. Our results suggest that the abnormality of VEGF transcription and translation expression may play an important role in the development of CML.

Low Concentrations of STI571 Enhances beta1 Integrin Mediated Inhibitory Effect on Proliferation of Myeloid Progenitors in Ph(+)Chronic Myeloid Leukemia / 中国实验血液学杂志

To investigate whether ABL specific tyrosine kinase specific inhibitor STI571 can restore beta1 integrin mediated negative effect on Ph(+) chronic myeloid leukemia(CML), the inhibitory effect of beta 1 integrin activator (beta1 integrin activating antibody 8A2, cytokines such as GM-CSF, G-CSF and SCF) and/or FN on the granulocyte-macrophage colony forming unit (CFU-GM) from 16 patients with Ph(+)CML and 13 normal individuals were examined; the bone marrow mononuclear cells (BMMNC) before and after ABL kinase specific inhibitor STI571 pretreatment (0.1 micro mol/L for 30-60 minutes) were target cells in this study. The roles which VLA4 and VLA5 played in this process were evaluated through blocking assay. The results showed: (1) beta1 integrin activator(s) or FN alone have no effect on CFU-GM from CML or normal bone marrow mononuclear cells before or after STI571 pretreatment, nor STI571 pretreatment itself. (2) The inhibitory effect of beta1 integrin activator(s) plus FN on CML CFU-GM are significantly lower than that on normal CFU-GM. (3) The inhibitory effect of beta1 integrin activator(s) plus FN on CML CFU-GM after STI571 pretreatment is comparable to that on normal CFU-GM. (4) Monoclonal antibody to VLA4 and VLA5 or to total beta1 integrins almost completely abrogate the above effect of STI571. The results suggested enhancing beta1 integrin mediated negative effect on myeloid progenitors in Ph(+)CML is one of the therapeutic mechanisms of STI571 on Ph(+)CML.