Chenxi Hu1, Panrong Zhu2, Youyou Xia2, Kaiyuan Hui1, Mei Wang1, Xiaodong Jiang3,4. 1. Tumor Laboratory, Department of Oncology, The Affiliated Lianyungang Hospital of Xuzhou Medical University, No.182 North Tongguan Road, Lianyungang, 222002, China. 2. Department of Oncology, The Affiliated Lianyungang Hospital of Xuzhou Medical University, No.182 North Tongguan Road, Lianyungang, 222002, China. 3. Tumor Laboratory, Department of Oncology, The Affiliated Lianyungang Hospital of Xuzhou Medical University, No.182 North Tongguan Road, Lianyungang, 222002, China. jxdysy1970@163.com. 4. Department of Oncology, The Affiliated Lianyungang Hospital of Xuzhou Medical University, No.182 North Tongguan Road, Lianyungang, 222002, China. jxdysy1970@163.com.
Abstract
PURPOSE: To determine if inhibiting neuropilin-1 (NRP-1) affects the radiosensitivity of NSCLC cells through a vascular endothelial growth factor receptor 2 (VEGFR2)-independent pathway, and to assess the underlying mechanisms. METHODS: The expression of VEGFR2, NRP-1, related signaling molecules, abelson murine leukemia viral oncogene homolog 1 (ABL-1), and RAD51 were determined by RT-PCR and Western blotting, respectively. Radiosensitivity was assessed using the colony-forming assay, and the cell apoptosis were analyzed by flow cytometry. RESULTS: We selected two cell lines with high expression levels of VEGFR2, including Calu-1 cells that have high NRP-1 expression, and H358 cells that have low NRP-1 expression. Upon inhibition of p-VEGFR2 by apatinib in Calu-1 cells, the expression of NRP-1 protein and other related proteins in the pathway was still high. Upon NRP-1 siRNA treatment, the expression of both NRP-1 and RAD51 decreased (p < 0.01; p < 0.05). Upon ABL-1 siRNA treatment, the expression of NRP-1 was increased and the expression of RAD51 was unchanged. Calu-1 cells treated with NRP-1 siRNA exhibited significantly higher apoptosis and radiation sensitivity in radiation therapy compared to Calu-1 cells treated with apatinib alone (p < 0.01; p < 0.01). The apoptosis and radiation sensitivity in H358 cells with NRP-1 overexpression was similar to the control group regardless of VEGFR2 inhibition. CONCLUSIONS: We demonstrated that when VEGFR2 was inhibited, NRP-1 appeared to regulate RAD51 expression through the VEGFR2-independent ABL-1 pathway, consequently regulating radiation sensitivity. In addition, the combined inhibition of VEGFR2 and NRP-1 appears to sensitize cancer cells to radiation.
PURPOSE: To determine if inhibiting neuropilin-1 (NRP-1) affects the radiosensitivity of NSCLC cells through a vascular endothelial growth factor receptor 2 (VEGFR2)-independent pathway, and to assess the underlying mechanisms. METHODS: The expression of VEGFR2, NRP-1, related signaling molecules, abelson murine leukemia viral oncogene homolog 1 (ABL-1), and RAD51 were determined by RT-PCR and Western blotting, respectively. Radiosensitivity was assessed using the colony-forming assay, and the cell apoptosis were analyzed by flow cytometry. RESULTS: We selected two cell lines with high expression levels of VEGFR2, including Calu-1 cells that have high NRP-1 expression, and H358 cells that have low NRP-1 expression. Upon inhibition of p-VEGFR2 by apatinib in Calu-1 cells, the expression of NRP-1 protein and other related proteins in the pathway was still high. Upon NRP-1 siRNA treatment, the expression of both NRP-1 and RAD51 decreased (p < 0.01; p < 0.05). Upon ABL-1 siRNA treatment, the expression of NRP-1 was increased and the expression of RAD51 was unchanged. Calu-1 cells treated with NRP-1 siRNA exhibited significantly higher apoptosis and radiation sensitivity in radiation therapy compared to Calu-1 cells treated with apatinib alone (p < 0.01; p < 0.01). The apoptosis and radiation sensitivity in H358 cells with NRP-1 overexpression was similar to the control group regardless of VEGFR2 inhibition. CONCLUSIONS: We demonstrated that when VEGFR2 was inhibited, NRP-1 appeared to regulate RAD51 expression through the VEGFR2-independent ABL-1 pathway, consequently regulating radiation sensitivity. In addition, the combined inhibition of VEGFR2 and NRP-1 appears to sensitize cancer cells to radiation.
Authors: John D Hainsworth; David M Waterhouse; William C Penley; Dianna L Shipley; Dana S Thompson; Charles D Webb; F Anthony Greco Journal: Cancer Invest Date: 2013-04-24 Impact factor: 2.176
Authors: Xing Gao; Yingchao Zhao; Anat O Stemmer-Rachamimov; Hao Liu; Peigen Huang; ShanMin Chin; Martin K Selig; Scott R Plotkin; Rakesh K Jain; Lei Xu Journal: Proc Natl Acad Sci U S A Date: 2015-11-09 Impact factor: 11.205