[Low Concentrations of STI571 Enhances beta1 Integrin Mediated Inhibitory Effect on Proliferation of Myeloid Progenitors in Ph(+)Chronic Myeloid Leukemia]
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.
Bai
Ren-Kui
RK
People's Hospital and Institute of Hematology, Beijing University, Beijing 100044, China.
Chen
Shan-Shan
SS
Liu
Yan-Rong
YR
Li
Jin-Lan
JL
Fu
Jia-Yu
JY