OBJECTIVETo study the effects of TrkB-BDNF signal pathway on the synthesis and secretion of vascular endothelial growth factor (VEGF) in human neuroblastoma cells (NB).

METHODSTrkB protein expression in SY5Y cells before and after all-trans-retinoicacid (ATRA) treatment was detected by Western blot. P-TrkB protein expression in SY5Y cells before and after the treatment of ATRA along with BDNF was also detected by Western blot. VEGF concentrations in the SY5Y cell culture supernatants were measured using ELISA after the treatment with ATRA, BDNF, tyrosine kinase inhibitor K252a and PI3k inhibitor LY294002.

RESULTSTrkB protein was undetectable in SY5Y cells before ATRA treatment. After the treatment of 1, 10 and 100 nM/L ATRA for five days, TrkB protein was expressed in SY5Y cells and the TrkB protein level increased with the increasing ATRA concentration. P-TrkB protein was not expressed in SY5Y cells treated only with 10 nM/L ATRA, but it was detectable after the treatment of ATRA along with BDNF. VEGF concentrations in the group treated with ATRA+BDNF were significantly higher than those in the untreated control and the ATRA alone treatment groups (P<0.01). VEGF concentrations in the K252a pretreated ATRA+BDNF group were significantly lower than those in the group treated with ATRA+BDNF (P<0.05). VEGF concentrations in the LY294002 treatment group (ATRA+LY294002+BDNF group) were also significantly lower than those in the group treated with ATRA+BDNF (P<0.01).

CONCLUSIONSActivation of TrkB-BDNF signal pathway may increase the synthesis and secretion of VEGF in human NB cells. The synthesis and secretion of VEGF can be inhibited by blocking TrkB-BDNF signal pathway with K252a or blocking the TrkB-BDNF downstream signal pathway PI3K/Akt with LY294002.