VEGF Autocrine System Is Demonstrated in Some of Acute Promyelocytic Leukemia Cases: Relationship to WBC Count at the Disease Onset.

Abstract

Abstract 4127 Aims:In acute promyelocytic leukemia (M3), a prominent production of vascular endothelial growth factor (VEGF) is reported, and the obvious angiogenesis is observed in bone marrow specimens; however, VEGF receptors (VEGFRs) are not expressed in M3 cells in general. We analyzed VEGF systems in M3 blasts. Materials and Methods:Bone marrow cells were obtained from informed M3 patients, whose mononuclear cells were prepared with density-sedimentation method. Cells were cultured for one day for the elimination of an adherent cell-fraction. RNA was extracted from the non-adherent mononuclear cell-fraction, and cDNA was synthesized. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to determine the expression of VEGF and VEGFRs. When the expression of VEGFR type-1 and -2 was demonstrated with RT-PCR, cells were analyzed on the protein level with FACS. VEGF-A levels in sera and in the conditioned media from the cultured M3 cells were determined with ELISA kit. When M3 blasts expressed VEGFR type-1, -2, and also secreted VEGF-A, a growth-inhibition by anti-VEGF antibody was assayed in in vitro cultures. Results and Discussion:In all 25 cases examined VEGF-A production was observed, in which VEGFR type-3 was not expressed in any cases. VEGFR type-1 and -2 were expressed in 3 cases, in all of which WBC count at the onset of the disease was above 20,000/μl. When VEGF antibody was added to the blast cell-cultures, the cell-growth was inhibited significantly. These observations indicate that VEGF system works on proliferation in a few of M3 cases with hyper-leukocytosis. Disclosures:No relevant conflicts of interest to declare.