ABSTRACT
Objective To investigate the effect of neuropilin-1 (NRP1) on radiation-induced epithelial-mesenchymal transition (EMT) by measuring the expressions of EMT-related transcription factors in the irradiated cells with different levels of NRP 1.Methods Human lung type Ⅱ epithelial cells (A549) were transfected with NRP1 over-expression lentiviral vector and NRP1 inhibition vector to construct two cell models of NRP1high-A549 and NRP1low-A549.A NRP1 knock-down cell model was also constructed by transferring siNRP1 into normal mouse lung epithelial MLE-12 cells that was validated at both protein and mRNA levels.A single dose of 10 Gy X-ray was delivered to these cell models,then total protein and RNA were extracted at 0,12,24 and 48 h after irradiation.The expressions of EMT-related transcription factors (Twist and ZEB1) and EMT markers (β3-catenin,N-cadherin,and Vimentin) in each cell model were detected by Western blot and qPCR.Results After 10 Gy irradiation,the expressions of NRP1 mRNA and protein were significantly increased in A549 and MLE-12 cells.The expressions of the mesenchymal markers (Vimentin and N-cadherin) and the transcription factors of ZEB1 and Twist were also significantly increased (A549:t=2.917,7.361,4.852,9.278,P＜0.01;MLE-12:t=9.652,31.357,30.985,17.266,P ＜0.01).The expressions of Vimentin and N-cadherin were significantly decreased in NRP1low-A549 (t =10.077,15.707,P ＜ 0.01) and siNRP1-MLE-12 cells (t =5.745,P ＜ 0.01),but the expression of epithelial marker (β3-catenin) was significantly increased in these cells.The expressions of N-Cadherin and Vimentin were significantly elevated (t =16.055,5.560,P ＜ 0.01),while β-catenin decreased significantly in NRP1high-A549 cells.After irradiation,the transcription factor of Twist in NRP1low-A549 group was significantly decreased (t=3.987,P＜0.01),while the transcription factors of ZEB1 and Twist in the NRP1high-A549 group increased in a time-dependent manner (t =11.289,2.903,P＜0.01).After irradiation,the transcription factor of ZEB1 decreased significantly in siNRP1-MLE-12 cells (t=13.449,P＜0.01),and the protein expressions of ZEB1 and Twist in siNRP1-MLE-12 cells were lower than those of control group in a time-dependent manner.Conclusions NRP1 promotes radiation-induced EMT in human and mouse epithelial cells through up-regulation of transcription factors of ZEB1 and Twist.