Immature B cell malignancies synthesize VEGF, VEGFR-1 (Flt-1) and VEGFR-2 (KDR).

Expression of VEGF and VEGFR support a role for angiogenic pathways in the pathogenesis of some hematological malignances. Our goal was to determine if expression of these angiogenic molecules also extend to childhood precursor B cell acute lymphoblastic leukemia (pre-B ALL). We now show that transcripts of VEGF, and its receptors VEGFR-1 and VEGFR-2 are concomitantly expressed in both ALL cell lines and primary pre-B ALL. Western blot and ELISA consistently detected VEGF protein in the supernatants of the cell lines. Similarly, VEGFR-1 and VEGFR-2 proteins are also detectable by FACS analysis. Interestingly, the expression of the receptors in immature B cells is limited to the intra-cytoplasmic compartment and may suggest either internalization of the receptors or a block in trafficking of the receptor to the surface.