Nogo-B receptor promotes epithelial-mesenchymal transition in non-small cell lung cancer cells through the Ras/ERK/Snail1 pathway

Nogo-B receptor (NgBR) is a specific receptor of Nogo-B that regulates vascular remodeling and angiogenesis. Previously, we found that NgBR promotes the membrane translocation and activation of Ras in breast cancer cells and enhances the chemoresistance of hepatocellular carcinoma cells to 5-fluorouracil. However, the role of NgBR in lung cancer has not yet been elucidated. In the present study, we found that NgBR knockdown inhibited epithelial-mesenchymal transition (EMT) in non-small cell lung cancer (NSCLC) cells in vitro and metastasis of NSCLC cells in vivo. In contrast, NgBR overexpression promoted EMT in and lung metastasis of NSCLC cells. At the molecular level, NgBR modulated the expression of EMT-related proteins and enhanced the protein expression of Snail1, a crucial transcription factor that represses epithelial cell protein marker E-cadherin. Moreover, we found that NgBR overexpression promoted the membrane localization of Ras and activation of downstream MEK/ERK signaling pathway and that NgBR knockdown by using a specific shRNA inversely affected the expression of EMT-related proteins in NSCLC cells. Thus, our results provide novel insights on the regulatory role of NgBR in the metastasis of NSCLC that should be investigated further for developing a therapeutic strategy for treating patients with NSCLC.