title: NEMO modulates radiation-induced endothelial senescence of human umbilical veins through NF-κB signal pathway.
abstract: Recently several laboratories have reported that radiation induces senescence in endothelial cells. Senescent cells can secrete multiple growth-regulatory proteins, some of which affect tumor growth, survival, invasion or angiogenesis. The purpose of this study was to explore the mechanisms of radiation-induced senescence and its effects on angiogenesis in human umbilical vein endothelial cells (HUVECs). HUVECs were either pretreated with or without PS1145 prior to irradiation with 0-8 Gy. PS1145 is a novel, highly specific small-molecule inhibitor of nuclear factor kappa B essential modulator (NEMO). MTT assays showed that in HUVECs untreated with PS1145, there was an increase in the number of radiation-induced senescence-like endothelial cells 5 days after 8 Gy irradiation, while pretreatment with PS1145 significantly ameliorated the induction in senescence of HUVECs compared to the control group. Electrophoretic mobility shift assay (EMSA) showed that pretreatment with PS1145 inhibited the radiation-induced NF-κB activation, which regulates cell fate in response to genotoxic stress. In addition, Western blotting demonstrated less translocation of p65 from cytoplasm to nucleus. Furthermore, real-time polymerase chain reaction (PCR) showed that pretreatment with PS1145 inhibited the increase of mRNA expressions of interleukin-6 (IL-6) and p53-induced death domain (PIDD) protein, which have been show to play crucial roles in both senescence and apoptosis (P < 0.05). TUNEL staining revealed an increase in apoptotic HUVECs in the group pretreated with PS1145 after irradiation. The series of functional assays further showed that radiation-induced senescence-like HUVECs had malfunctions in migration, invasion and formation of capillary-like structures, compared with the sham-irradiated and untreated, irradiated groups. Taken together, these findings indicate that the angiogenic capacity of radiation-induced senescence-like HUVECs decreased, and that irradiation caused vascular endothelial cells to gain a senescence-like phenotype through the DSB/NEMO/NF-κB signal pathway. The data suggests that NEMO may be a critical switch that regulates cellular senescence and apoptosis caused by exposure to radiation, and provides new clues for the clinical potential of the combination of radiotherapy and angiogenesis inhibitors.
authors.affiliation: a  Cancer Center, Union Hospital, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Dong
authors.forename: Fan
authors.initials: F
authors.lastname: Tong
authors.forename: Cai
authors.initials: C
authors.lastname: Qian
authors.forename: Ruiguang
authors.initials: R
authors.lastname: Zhang
authors.forename: Jihua
authors.initials: J
authors.lastname: Dong
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.forename: Yu
authors.initials: Y
authors.lastname: Hu
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D016922:Cellular Senescence / Q000187:drug effects* / Q000528:radiation effects*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000528:radiation effects; D010641:Phenotype; D011725:Pyridines / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects / Q000528:radiation effects; D015398:Signal Transduction / Q000187:drug effects* / Q000528:radiation effects*
chemical_list: D053418:Death Domain Receptor Signaling Adaptor Proteins; D006575:Heterocyclic Compounds, 3-Ring; D015850:Interleukin-6; D016328:NF-kappa B; C485896:PIDD1 protein, human; C456319:PS1145; D011725:Pyridines