title: Infiltration of tumor-reactive transforming growth factor-beta insensitive CD8+ T cells into the tumor parenchyma is associated with apoptosis and rejection of tumor cells.
abstract: BACKGROUND
  TGF-beta is a potent immunosuppressant. High levels of TGF-beta produced by cancer cells have a negative inhibition effect on surrounding host immune cells and leads to evasion of the host immune surveillance and tumor progression. In the present study, we report a distinct ability of tumor reactive, TGF-beta-insensitive CD8+ T cells to infiltrate into established tumors, secrete relevant cytokines, and induce apoptosis of tumor cells.
  
  
  METHODS
  CD8+ T cells were isolated from the spleens of C57BL/6 mice, which were primed with irradiated mouse prostate cancer cells, the TRAMP-C2 cells. After ex vivo expansion, these tumor reactive CD8+ cells were rendered TGF-beta-insensitive by infection with a retroviral (MSCV)-mediated dominant negative TGF-beta type II receptor (TbetaRIIDN). Control CD8+ cells consist of those transfected with the GFP-only empty vector and naïve CD8+ T cells. Recipient mice were challenged with a single injection of TRAMP-C2 cells 21 days before adoptive transfer of CD8+ T cells was performed. Forty days after the adoptive transfer, all animals were sacrificed. The presence of pulmonary metastases was evaluated pathologically. Serial slides of malignant tissues were used for immunofluorescent staining for different kinds of immune cell infiltration, cytokines, and apoptosis analysis.
  
  
  RESULTS
  Pulmonary metastases were either eliminated or significantly reduced in the group receiving adoptive transfer of tumor-reactive TGF-beta-insensitive CD8+ T cells (3 out of 12) when compared to GFP controls (9 out of 12), and naïve CD8+ T cells (12 out of 12). Results of immunofluorescent studies demonstrated that only tumor-reactive TGF-beta-insensitive CD8+ T cells were able to infiltrate into the tumor and mediate apoptosis when compared to CD4+ T cells, NK cells, and B cells. A large amount of cytokines such as perforin, nitric oxide, IFN-gamma, IL-2, TNF-alpha were secreted in tumor tissue treated with tumor-reactive TGF-beta-insensitive CD8+ T cells. No immune cells infiltration and cytokine secretion were detected in tumor tissues treated with naïve T cells and GFP controls.
  
  
  CONCLUSIONS
  Our results demonstrate the mechanism of anti-tumor effect of tumor-reactive TGF-beta-insensitive CD8+ T cells that adoptive transfer of these CD8+ T cells resulted in infiltration of these immune cells into the tumor parenchyma, secretion of relevant cytokines, and induction of apoptosis in tumor cells. These results support the concept that tumor-reactive TGF-beta-insensitive CD8+ T cells may prove beneficial in the treatment of advanced cancer patients.
authors.affiliation: Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA, and Institute of Urology, The First Hospital, Peking University, Beijing, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Jang
authors.forename: Ximing
authors.initials: X
authors.lastname: Yang
authors.forename: Irwin
authors.initials: I
authors.lastname: Park
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
authors.forename: Shilajit
authors.initials: S
authors.lastname: Kundu
authors.forename: Michael
authors.initials: M
authors.lastname: Pins
authors.forename: Borko
authors.initials: B
authors.lastname: Javonovic
authors.forename: Timothy
authors.initials: T
authors.lastname: Kuzel
authors.forename: Seong-Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Luk
authors.initials: L
authors.lastname: Van Parijs
authors.forename: Norm
authors.initials: N
authors.lastname: Smith
authors.forename: Larry
authors.initials: L
authors.lastname: Wong
authors.forename: Norman M
authors.initials: NM
authors.lastname: Greenberg
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Guo
authors.forename: Chung
authors.initials: C
authors.lastname: Lee
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000276:immunology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008175:Lung Neoplasms / Q000556:secondary; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011471:Prostatic Neoplasms / Q000276:immunology* / Q000473:pathology; D013047:Specific Pathogen-Free Organisms; D016212:Transforming Growth Factor beta / Q000276:immunology*
chemical_list: D016207:Cytokines; D016212:Transforming Growth Factor beta