TrkB altered sensitivity to CDDP in HNSCC.

<p><b>A</b>. UMSCC1 cells were transfected with a vector containing wild-type TrkB (TrkB) or an empty vector (EV). Cells were then exposed to CDDP for addressing increasing resistance of TrkB over-expressed UMSCC1 to CDDP. MTT cell viability assay was conducted to determine the IC50 values. <b>B.</b> expression efficacy was confirmed by Western Blot analysis. BDNF expression level was also determined. <b>C.</b> Expression levels of XiAP, Bim, MDR1, GST-p, and N-cadherin were determined with over-expressed UMSCC1 cells. Both OSC-19 and HN-5 cells were stably transfected with a short-hairpin RNA construct targeting TrkB (TrkB shRNA) or a non-targeting, short-hairpin RNA construct (NT shRNA). <b>D.</b> Both HN-5P and HN-5CR cells were then treated with various concentration of CDDP and analyzed to address the effect of TrkB down-regulation on sensitivity to CDDP by suppressing TrkB expression. <b>E.</b> Down-regulation of TrkB expression was confirmed by Western blot analysis. Cell lysates of suppressing TrkB were separated with SDS-PAGE and membrane was incubated with BDNF, Bim, XiAP, and MDR1 antibodies. Expression levels of TrkB, BDNF, Bim, XiAP, and MDR1 were normalized with GAPDH.