title: Cancer-derived immunoglobulin G promotes tumor cell growth and proliferation through inducing production of reactive oxygen species.
abstract: Cancer cells have been found to express immunoglobulin G (IgG), but the exact functions and underlying mechanisms of cancer-derived IgG remain elusive. In this study, we first confirmed that downregulation of IgG restrained the growth and proliferation of cancer cells in vitro and in vivo. To elucidate its mechanism, we carried out a co-immunoprecipitation assay in HeLa cells and identified 27 potential IgG-interacting proteins. Among them, receptor of activated protein kinase C 1 (RACK1), ras-related nuclear protein (RAN) and peroxiredoxin 1 (PRDX1) are closely related to cell growth and oxidative stress, which prompted us to investigate the mechanism of action of IgG in the above phenomena. Upon confirmation of the interactions between IgG and the three proteins, further experiments revealed that downregulation of cancer-derived IgG lowered levels of intracellular reactive oxygen species (ROS) by enhancing cellular total antioxidant capacity. In addition, a few ROS scavengers, including catalase (CAT), dimethylsulfoxide (DMSO), n-acetylcysteine (NAC) and superoxide dismutase (SOD), further inhibited the growth of IgG-deficient cancer cells through suppressing mitogen-activated protein kinase/extracellular-regulated kinase (MAPK/ERK) signaling pathway induced by a low level of intracellular ROS, whereas exogenous hydrogen peroxide (H2O2) at low concentration promoted their survival via increasing intracellular ROS levels. Similar results were obtained in an animal model and human tissues. Taken together, our results demonstrate that cancer-derived IgG can enhance the growth and proliferation of cancer cells via inducing the production of ROS at low level. These findings provide new clues for understanding tumor proliferation and designing cancer therapy.
authors: Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Department of Pathology, Shantou University Medical College, Shantou, China.
authors: J
authors: J
authors: Wang
authors: D
authors: D
authors: Lin
authors: H
authors: H
authors: Peng
authors: Y
authors: Y
authors: Huang
authors: J
authors: J
authors: Huang
authors: J
authors: J
authors: Gu
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003593:Cytoplasm / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D007074:Immunoglobulin G / Q000378:metabolism*; D047468:Immunoprecipitation; D054464:Peroxiredoxins / Q000378:metabolism; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000378:metabolism
chemical_list: D000975:Antioxidants; D007074:Immunoglobulin G; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; C515940:PRDX1 protein, human; D054464:Peroxiredoxins; D020931:ran GTP-Binding Protein