title: Bacterial surface display of endoglin by antigen 43 induces antitumor effectiveness via bypassing immunotolerance and inhibition of angiogenesis.
abstract: Various angiogenesis-related self-molecules have been considered to be therapeutic targets. However, the direct use of self-molecules as vaccines is not recommended because of the inherent ability of the host to develop immune tolerance. Antigen 43 (Ag43) is a surface protein found in E. coli and contains an α and a β subunits, which contains multiple T epitopes in α subunit. Here we construct a novel Ag43 surface display system (Ag43 system) to express Ag43 chimeric proteins to disrupt immune tolerance against self-molecules. The Ag43 system was constructed from an Escherichia coli strain Tan109, derived from JM109, in which the Ag43 gene was deleted and a recombinant plasmid (pETAg43') expressing a partial Ag43 gene was introduced. The extracellular domain of angiogenesis-related endoglin gene was then subcloned into plasmid pETAg43', resulting in a recombinant plasmid pETAg43'/END(e) which was then used to transform Tan109 for protein expression. We found that Ag43 and endoglin chimeric protein (Ag43'/END(e) ) was expressed on the bacterial surface. The chimeric protein could be separated from the bacterial surface by heating to 60°C and yet retain activity. We used Ag43'/END(e) as a protein vaccine and found that it could disrupt immune tolerance against endoglin by inducing significant antitumor activities and inhibit angiogenesis in several tumor models without significant side effects. These data suggest that Ag43'/END(e) chimeric protein is a potential model vaccine for active tumor immunotherapy, and that Ag43 system could be an effective tool for novel vaccine preparation to break immune tolerance to other angiogenesis-related self-molecules for cancer therapy.
authors.affiliation: Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China.
authors.forename: Feng-Ying
authors.initials: FY
authors.lastname: Huang
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Quan
authors.initials: Q
authors.lastname: Liu
authors.forename: Yue-Nan
authors.initials: YN
authors.lastname: Li
authors.forename: Rui-Zhen
authors.initials: RZ
authors.lastname: Bai
authors.forename: Yong-Hao
authors.initials: YH
authors.lastname: Huang
authors.forename: Huan-Ge
authors.initials: HG
authors.lastname: Zhao
authors.forename: Jun-Li
authors.initials: JL
authors.lastname: Guo
authors.forename: Song-Lin
authors.initials: SL
authors.lastname: Zhou
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Lin
authors.forename: Guang-Hong
authors.initials: GH
authors.lastname: Tan
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology; D019496:Cancer Vaccines / Q000276:immunology*; D018827:Carcinoma, Lewis Lung / Q000276:immunology / Q000628:therapy*; D000071063:Endoglin; D018984:Epitopes, T-Lymphocyte; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007108:Immune Tolerance / Q000276:immunology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000276:immunology / Q000628:therapy*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D019496:Cancer Vaccines; D000071063:Endoglin; C502004:Eng protein, mouse; D018984:Epitopes, T-Lymphocyte; D047908:Intracellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; C118376:antigen 43, E coli
keywords: angiogenesis; antigen 43 surface display system (Ag43 system); endoglin; immune tolerance; recombinant vaccine