ABSTRACT
Objective To investigate the effects of macrophage inflammatory protein-1α (MIP-1α) combined with molecule 4-1BB L on the tumorigenicity of hepatocellular carcinoma cells in vivo. Methods Mouse MIP-1α (mMIP-1α) expressed Hepa 1-6 cells were transfected with m4-1BBL recombinant retrovirus, the anti-histidinol cells clones were selected and amplified. The expression of m4-1BB L was confirmed by flow cytometry. The growth curve of Hepa 1-6 cells transfected with mMIP-1α and m4-1BBL alone or together was drawn and compared. C57B/L Mice were randomly divided into 7 groups, 9 mice in each group, injected with mMIP-1α+m4-1BB L Hepa 1-6 cells, m4-1BB L Hepa 1-6 cells, mMIP-1α Hepa 1-6 cells, Hepa 1-6 cells, pLXSHD Hepa 1-6 cells or PBS respectively. The tumorigenicity of hepatocellular carcinoma cells and the mice survival rate were compared between each groups. Results Hepa 1-6 mMIP-1α+m4-1BB L cells which expressed both mMIP-1α and m4-1BB L were successfully established. The expression of mMIP-1α and m4-1BB L alone or together did not affect the growth curve of Hepa 1-6 cells. Observed for 5 weeks, no tumor developed in Hepa 1-6 mMIP-1α+m4-1BB L injected mice. The tumorigenicity of Hepa 1-6 mMIP-1α+m4-1BB L was lower than that of Hepa 1-6 mMIP-1α or Hepa 1-6 m4-1BB L in vivo. The survival rate of Hepa 1-6 mMIP-1α+m4-1BBL injected mice(9/9) was higher than that of Hepa 1-6 m4-1BB L injected mice (6/9)or Hepa 1-6 mMIP-1α injected mice (1/9). Conclusion Chemokine MIP-1α combined with costimulatory 4-1BB L lowered the tumorigenicity of hepatocellular carcinoma cells in vivo, and prolonged the mice survival period.
ABSTRACT
4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a major costimulatory receptor that is rapidly expressed on the surface of CD4+ and CD8+ T cells after antigen- or mitogen-induced activation. The interaction of 4-1BB with 4-1BBL regulates immunity and promotes the survival and expansion of activated T cells. In this study, the expression of 4-1BB and 4-1BBL was examined during regeneration of the murine thymus following acute cyclophosphamide-induced involution. Four-color flow cytometry showed that 4-1BB and 4-1BBL were present in the normal thymus and were preferentially expressed in the regenerating thymus, mainly in CD4+CD8+ double-positive (DP) thymocytes. Furthermore, the CD4loCD8lo, CD4+CD8lo and CD4loCD8+ thymocyte subsets, representing stages of thymocyte differentiation intermediate between DP and single-positive (SP) thymocytes, also expressed 4-1BB and 4-1BBL during thymus regeneration but to a lesser degree. Interestingly, the 4-1BB and 4-1BBL positive cells among the CD4+CD8+ DP thymocytes present during thymus regeneration were TCR(hi) and CD69+ unlike the corresponding controls. Moreover, the 4-1BB and 4-1BBL positive cells among the intermediate subsets present during thymus regeneration also exhibited TCRhi/int and CD69+/int phenotypes, indicating that 4-1BB and 4-1BBL are predominantly expressed by the positively selected population of the CD4+CD8+ DP and the intermediate thymocytes during thymus regeneration. RT-PCR and Western blot analyses confirmed the presence and elevated levels of 4-1BB and 4-1BBL mRNA and protein in thymocytes during thymus regeneration. We also found that the interaction of 4-1BB with 4-1BBL promoted thymocyte adhesion to thymic epithelial cells. Our results suggest that 4-1BB and 4-1BBL participate in T lymphopoiesis associated with positive selection during recovery from acute thymic involution.