Abstract: Objective The aim of this article was to investigate the effect of silencing PARG on local immune status in colon carcinoma. Methods Lentivirus PARG-shRNA(Short hairpin RNA) was transfected into CT26 cells as experiment group, the CT26 cells without any treatment or treated with Lentivirus empty vector served as control group. Animal models for liver metastases of colon carcinoma were established by splenic subcapsular inoculation of each group of CT26 cells in Balb/c mice. The expression of PARG protein in spleen transplant tumor was detected by Western blot analysis. Immunofluorescence double labeling assay was used for the numbers detection both of B220+DEC205+DC and CD11c+CD11b+DC in the spleen. CD4+T cells and CD8+T cells in the spleen were tested by immunofluorescence single staining. All of these cells were observed by confocal laser scanning microscope. The levels of IL-10 and IL-12 in serum were measured by enzyme-linked immunosorbent assay (ELISA). Result The expression of PARG in spleen transplant tumor was reduced in PARG-silenced group compared to that in control groups(P<0.05). In PARG-silenced group, the amounts of B220+DEC205+DC were less and the numbers of CD11c+CD11b+DC were more in spleen than that in control groups(P<0.05). The numbers of CD4+T cells and the ratio of CD4+/ CD8+ in spleen of PARG-silenced group were increased compared to that in control groups(P<0.05). The serum levels of IL-10 were lower but the serum content of IL-12 were higher in PARG-silenced group than that in control groups(P<0.05). Conclusion These studies demonstrate that silencing PARG could strengthen the local immune response to colon cancer by effect on the proliferation and differentiation of DC and T cells.

Key words: PARG, cytokine, immune function, colon carcinoma