High expression of the receptor tyrosine kinase Tie-1 in acute myeloid leukemia and myelodysplastic syndrome

The tyrosine kinase receptor Tie-1 has been shown to play a role in angiogenesis and hematopoiesis. We evaluated the level of expression and clinical significance of Tie-1 protein in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We used western blot analysis to confirm and radioimmunoassay to quantify Tie-1 protein expression in bone marrow samples obtained from untreated patients having AML (66 patients) or MDS (29 patients). Samples obtained from these patients contained significantly higher levels of Tie-1 protein than did control samples (P<0.001). Also, Tie-1 levels were significantly higher in AML patients than MDS patients (P<0.0001). Tie-1 levels did not correlate with complete remission or survival duration in patients having either disease. These data suggest that Tie-1 expression is increased in AML and MDS but that the level of expression does not influence the response to current therapy. The role of Tie-1 overexpression in the reported increased vascularity in the bone marrow of AML and MDS patients requires further investigation.