Research Paper Volume 12, Issue 20 pp 20380—20395

Figure 5. Rab1A overexpression enhances NPC cells metastasis and HR pathway-mediated radioresistance through activating GSK-3β/Wnt/β-catenin signaling. (A and B) Expression of typical HR pathway-related proteins, including Rad51, Mer11, P-NBS1(Ser343), Rad50 and P-ATM(Ser1981) based on western blotting, comparing the four groups of CNE2 cells transfected with Rab1A shRNA and S-26 cells transfected with Rab1A overexpression vector before IR exposure or after IR (6 Gy) for the indicated time. (C) Detection of Wnt pathway-related proteins (β-catenin, GSK-3β and P-GSK-3β), HR pathway protein (Mer11) and EMT-related proteins (E-cadherin and vimentin) in the four groups of CNE2 and S-26 cells treated with or without 6 Gy of IR. GAPDH was used as a loading control. Representative images are shown from three independent experiments. (D) Schematic diagram. Upon IR exposure, overexpression of Rab1A inhibits the activity of GSK-3β via phosphorylation at Ser9. The activation of Wnt/β-catenin signaling leads to nuclear translocation of β-catenin and transcription upregulation of HR pathway-related and EMT-related genes, in turn, induce NPC cells radioresistance and metastasis. The triangular arrows suggest positive regulation and the blunt arrows suggest negative regulation.