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Objective: To evaluate the in vivo antitumor effect of anti-brain derived neurotrophic factor (BDNF) monoclonal antibody (MoAb) on a human myeloma xenograft animal model., Methods: The xenograft tumor model was established in the nonobese diabetic/severe combined immunodeficiency (NOD/ SCID) mice by subcutaneous injection of human myeloma cell line RPMI 8226. The antibodies were injected intraperitoneally at a dose of 20 microg/mouse at day 1, day 2, day 3 after tumor cell inoculation or at a dose of 100 microg/mouse once a week after tumors were developed. The histologic and cytologic examination were performed to confirm the development of plasmacytomas. The microvascular densities (MVD) in tumors were analyzed by immunohistochemistry. The effect of anti-BDNF MoAb on the proliferation of RPMI 8226 cells in vitro and on endothelial cell network formation in the co-culture system were determined by 3H-thymidine incorporation assay and Matrigel network formation assay, respectively., Results: The xenograft NOD/SCID animal model had high capacity for growth of RPMI 8226 subcutaneous tumors and presented pathologic features of plasmacytomas. After subcutaneous injection of RPMI 8226 cells, all mice developed localized tumors in (20 +/- 2) d. On 20 microg anti-BDNF MoAb 3 consecutive treatment, the mean tumor-free time was extended to (30 +/- 6) d and survival was significantly prolonged compared with IgG-treated group [(57 +/- 7) d vs (48 +/- 4) d, P < 0.05]. When mice died naturally, the tumors size in anti-BDNF MoAb treated ones was also reduced compared with control group [(157.9 +/- 21.6) mm3 vs (405.5 +/- 35.2) mm3, P < 0.05]. When the antibody treatment (100 microg/mouse) underwent from 27 th to 60 day once a week after tumor inoculation, the local tumor growth was inhibited partially and necrosis and infiltration were observed in the tumors. The median MVD in the antibody-treated mice (100 microg/mouse) was 11 vessels/0.216 mm2. The IgG treated mice had no decrease in MVD of subcutaneous tumors compared with untreated mice. In vitro, anti-BDNF MoAb (1.5 microg/ml) significantly but partially inhibited HUVEC network formation induced by RPMI 8226 (68.2% reduction) and significantly inhibited RPMI 8226 proliferation, too. The IgG (1.5 microg/ml) treated mice had no significant effect on both of two assays., Conclusions: Anti-BDNF monoclonal antibody could inhibit growth and angiogenesis in subcutaneous myeloma tumors. BDNF is a potential therapeutic target in MM.

Patients with multiple myeloma (MM) have increased bone marrow angiogenesis, but the angiogenic properties of myeloma cells and the mechanism of MM-induced angiogenesis have not been completely clarified. The brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, TrkB, have been identified as critical factors in the regulation of vessel formation. In this study, we demonstrate that patients with MM had increased BDNF and vascular endothelial growth factor (VEGF) in their peripheral blood. We also found in particular that a decreased BDNF level was correlated with the remission of MM. BDNF was expressed by the human myeloma cell line RPMI8226 and primary myeloma cells, and TrkB was expressed by human umbilical vein endothelial cells (HUVEC) at the protein levels. In a coculture system, we observed that both RPMI8226 cells and primary myeloma cells induced the migration and formation of a net-like structure in HUVEC. The anti-BDNF monoclonal antibody significantly but partially restrained the angiogenesis effect of MM cells. Moreover, in an experimental model of angiogenesis in vivo, BDNF and VEGF significantly promoted vessel formation in Matrigel plug compared to the control. These effects were also blocked by anti-BDNF monoclonal antibody. Finally, our in vitro results were supported by the in vivo finding in human myeloma xenograft NOD/SCID models. Anti-BDNF mAb treatment resulted in inhibition of tumor growth, decreased vessel density, and tumor necrosis. Our study suggested that the BDNF/TrkB signaling pathway could be involved, at least in part, in MM-induced angiogenesis.

In order to explore the probability of curcumin treating multiple myeloma (MM) via the inhibition of angiogenesis, the expressions of brain derived neurotrophic factor (BDNF) and its specific receptor in human MM cells and endothelial cells were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The angiogenic activity was evaluated by endothelial cell migration assay and tubule formation assay in vitro. The results showed that exogenous BDNF significantly induced endothelial cell tubule formation and endothelial cell migration, these two effects were inhibited by curcumin. Furthermore, BDNF was detected in the MM cell and TrkB was detected in the endothelial cell and curcumin depressed the mRNA expression of BDNF and TrkB in the dose- and time-dependent manners. It is concluded that BDNF is a novel angiogenesis protein. Curcumin interrupts the interaction between multiple myeloma cells and endothelial cells by reducing TrkB expression in endothelial cells and inhibiting BDNF production in multiple myeloma cells, eventually, resulting in inhibition of angiogenesis. This is probably one part of the mechanism of the curcumin treating MM via the inhibition of angiogenesis.

Objective: To investigate the expression of brain-derived neurotrophic factor (BDNF) in multiple myeloma (MM) cells and the correlation between BDNF and MM angiogenesis., Methods: The expressions of BDNF mRNA transcripts and protein in MM cell lines (RPMI 8226, KM3) were determined by RT-PCR and Western blot, respectively, BDNF levels in culture supernatant by enzyme-linked immunosorbent assay. Proliferation of human umbilical vein endothelial cells (HUVEC) mixed with MM culture medium at different concentrations was examined by MTT assay. The effects of MM culture medium on HUVEC migration and tube formation were studied by modified Boyden chamber assay and tube formation assay, respectively., Results: BDNF was expressed in and secreted by MM cell lines RPMI 8226 and KM3. BDNF concentrations in culture supernatants were within the range of its biological activity. MM culture medium induced a concentration-dependent proliferation of HUVEC. The number of HUVEC at a concentration of 50% KM3 culture medium and at full KM3 culture medium were (1.85 +/- 0.23)-fold and (2.16 +/- 0.29) -fold increase, respectively (P <0.05), compared with that of control. The proliferative activity of HUVEC was reduced on the addition of BDNF antibody to the culture medium. MM culture medium also stimulated the migration and differentiation of HUVEC in vitro, the chemotactic index of HUVEC at a concentration of 50% KM3 culture medium and at full KM3 culture medium were 1.85 +/- 0.23 and 2.16 +/- 0.29, respectively (P < 0.05). Full KM3 culture medium also stimulated capillary-like tube formation in HUVEC (P <0.01), and addition of anti-human BDNF antibody neutralized these effects significantly., Conclusion: MM cell lines expressed and secreted biologically active BDNF, which may be involved, at least in part, in MM angiogenesis.