title: [TSST-1 regulated synergistically by 5HRE and CEAp activates lymphocytes to kill CEA-positive tumor cells specifically].
abstract: OBJECTIVE
  To evaluate the inhibitory effect of lymphocytes activated by the superantigen of toxic shock syndrome toxin-1 (TSST-1), which is regulated synergistically by 5 copies of hypoxia-responsive element (5HRE) and promoter of carcino-embryonic antigen (CEAp), against the carcino-embryonic antigen (CEA)-positive human colon carcinoma cell line LoVo under hypoxia condition in vitro.
  
  
  METHODS
  The eukaryotic expressive vector was constructed with the transmembrane superantigen gene of 5HRE-CEAp-regulated TSST-1-linker-CD80TM, and was transfected into CEA-positive human colon carcinoma cell line LoVo and CEA-negative human cervical carcinoma cell line HeLa by Lipofectamine 2000. Stably transfected cell lines were selected by G418. RT-PCR was employed to examine the expression of TC mRNA. Peripheral blood lymphocytes(PBL) of healthy people were extracted and then activated by the lysates of tumor cells stably transfected with TC. Concurrently, PBL were cultured together with stably transfected tumor cells in order to kill these cells. Then the proliferative effect of TSST-1 on PBL, and the killing effect of PBL against the stably transfected tumor cells were detected by MTT.
  
  
  RESULTS
  Monoclonal LoVo and HeLa cells stably transfected with TC were successfully obtained. Expression of TC mRNA in monoclonal LoVo cells under hypoxia condition was significantly higher than those under normoxia condition as confirmed by RT-PCR. Monoclonal HeLa cells did not express TC under either hypoxia condition or normoxia condition. As is shown by MTT assay, TSST-1 expressed by the monoclonal LoVo cells could effectively activate PBL to proliferate under hypoxia condition, resulting in dose-dependent inhibition on the proliferation of LoVo cells that expressed TSST (P<0.05). But HeLa cells and wild LoVo cells could not activate PBL to proliferate. PBL could not inhibit proliferation of HeLa cells and wild LoVo cells, either.
  
  
  CONCLUSIONS
  The superantigen of TSST-1 regulated dually by 5HRE and CEAp could activate human PBL to kill CEA-positive tumor cells specifically under hypoxia condition.
authors.affiliation: Department of General Surgery, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an 710061, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Tian
authors.forename: Xue-jun
authors.initials: XJ
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics; D002272:Carcinoembryonic Antigen / Q000235:genetics / Q000502:physiology*; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004768:Enterotoxins / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008214:Lymphocytes / Q000276:immunology*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D020218:Response Elements / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018089:Superantigens / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D001427:Bacterial Toxins; D002272:Carcinoembryonic Antigen; D004768:Enterotoxins; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal