Fig. 6

Cross-talk regulation between N-cadherin cleavage and MMP-9 expression. a SiRNA silencing of N-cadherin disrupted the cell–cell adhesion. NPC cells were transfected with N-cadherin siRNA for 24 h, then examined by immunofluoresence staining with anti-N-cadherin antibodies and analyzed by confocal laser scanning microscopy. b Silencing of N-cadherin decreased PMA-mediated cell invasion. NPC cells were transfected with N-cadherin siRNA for 24 h, then cell invasion was investigated by Boyden chamber assay. Representative images are shown and data are presented as mean±SEM. c NPC cells were transfected with siRNA specific for MMP-9 or N-cadherin for 24 h, then exposed to PMA for 24 h. The transfected cells were cultured with and without PMA for 24 h. The expression of MMP-9 and N-cadherin in cell lysates was assessed by western blot analysis with the indicated antibodies. MMP-9 level in CM was detected by gelatin zymography. The relative expression of FL/N-cad or MMP-9 in MMP-9 siRNA- or N-cadsiRNA-transfected cells was compared with Ng (non-specific control) siRNA (Ngi) -transfected cells after PMA treatment; N = 3, ^*P<0.05