BDNF promotes bladder tumor growth in SCID mice

Abstract

BDNF (brain-derived neurotrophic factor) is essential for the growth of several types of neurons in the central nervous system. Recently, BDNF and other neurotrophins acting on the trk receptors have been reported to promote the growth of lung, liver and breast tumors. However, the role of BDNF in the bladder tumor growth has not been investigated. In this study, the effects of BDNF, VEGF (vascular endothelial growth factor) and combination of BDNF plus VEGF on the growth of BFTC 905 (a grade 3 bladder papillary transitional cell carcinoma) bladder cancer cells injected into the inguinal area of SCID mice and the expression of BDNF, trkB and VEGF receptors in the tumor were investigated. Weekly injection of 100 ng each of BDNF, VEGF or combination of BDNF plus VEGF into the cancer cell loading site accelerated the growth rate of tumor with the degree of effect: BDNF + VEGF > BDNF > VEGF. BDNF and VEGF, and TrkB receptors were expressed in the control and drug treated tumors by Western and immunohistochemical methods two weeks after the last treatment. Administration of BDNF siRNA (0.2 – 0.3 nmol twice weekly) into the tumors reduced the growth rate of control tumors. These results indicate that BDNF and trkB receptor play important roles in regulating the growth of BFTC 905 bladder tumor. siRNA or drugs aimed at BDNF or trkB receptor may provide an important new approach toward the treatment of bladder tumor. (supported by an intramural fund from Tzu Chi University)