title: Enhancement of superantigen activity and antitumor response of staphylococcal enterotoxin C2 by site-directed mutagenesis.
abstract: Bacterial superantigen staphylococcal enterotoxins (SEs) tremendously stimulate polyclonal T cells bearing particular TCR Vbeta domains when binding to MHC II molecules, suggesting that they could be a candidate of new antitumor agent. SEC2, an important member of superantigen family, has been used in clinical trial as an immunotherapy agent for cancer treatment in China, and obtained some encouraging effects. However, the presence of immunosuppression and endotoxic activity limits the therapeutic dosage of SEC2, and influences its antitumor effect in clinic. Therefore, the enhancement of superantigen activity and antitumor effect of SEC2 could effectively make compensation for the disadvantages mentioned above. In this study, a superantigen SEC2(T20L/G22E) mutant was generated by site-directed mutagenesis, and efficiently expressed in E. coli BL21(DE3). The results showed that SEC2(T20L/G22E) mutant exhibited a significantly enhanced superantigen activity and antitumor response, compared with native SEC2 in vitro. Further toxicity assay in vivo indicated that SEC2(T20L/G22E) mutant had no significant increase in emetic and pyrogenic activity compared with SEC2, which suggested that the mutant SEC2(T20L/G22E) could be used as a potentially powerful candidate for cancer immunotherapy, and could make compensation for the deficiency of native SEC2 in clinic.
authors.affiliation: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Wang
authors.forename: Mingkai
authors.initials: M
authors.lastname: Xu
authors.forename: Huiwen
authors.initials: H
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Chenggang
authors.initials: C
authors.lastname: Zhang
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002415:Cats; D045744:Cell Line, Tumor / Q000187:drug effects; D003967:Diarrhea / Q000139:chemically induced; D004354:Drug Screening Assays, Antitumor; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000502:physiology / Q000627:therapeutic use / Q000633:toxicity; D005260:Female; D005334:Fever / Q000139:chemically induced; D007167:Immunotherapy / Q000379:methods; D008114:Liver Neoplasms, Experimental / Q000276:immunology / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D010865:Pilot Projects; D017354:Point Mutation; D011817:Rabbits; D011897:Random Allocation; D013211:Staphylococcus aureus / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D013329:Structure-Activity Relationship; D018089:Superantigens / Q000235:genetics / Q000276:immunology*; D014839:Vomiting / Q000139:chemically induced
chemical_list: D004768:Enterotoxins; D018089:Superantigens; C034959:enterotoxin C, staphylococcal