Therapeutic Injection of a C-Type CpG ODN Induced an Antitumor Immune Response in C57/BL6 Mice of Orthotopically Transplanted Hepatocellular Carcinoma

Synthetic CpG oligodeoxynucleotides (ODNs), as TLR9 agonists, have been found to play a possible role in antitumor effect. In order to determine the effect of YW002, known as a C-type CpG ODN, on the treatment of hepatocellular carcinoma (HCC), which is one of the most aggressive carcinomas, we chose to inject YW002 at the doses of 12.5 µg and 25 µg per mouse 7 days post-tumor challenge. The survival rate of mice was recorded every day. On day 14 postinjection, five mice in each group were bled and randomly sacrificed. The level of IFN-γ or TNF-α in the serum was detected and lymphocyte infiltration in the tumor tissue; the ratios of CD8(+) T cells and CD4(+) T cells in the spleen of mice were also analyzed. The results indicated that treatment with YW002 could raise the survival rate and delay tumor growth in the mice with orthotopically transplanted HCC. Furthermore, the treatment improved the antitumor immune response through increasing the T-cell infiltration in tumor and the ratio of CD4(+), CD8(+), and NK cells in the spleen. In addition, the concentration of IFN-γ was raised, and the level of TGF-β was depressed. Our data suggested that CpG ODN might be a proper medicament in a monotherapeutic regimen for treatment of HCC.