Establishment and evaluation of cell and animal models expressing BORIS subfamily 2 variant.

Background: The possibility of a cancer vaccine aimed at stimulating or mobilizing the body's immune system to control and kill tumor cells is emerging as a potential new strategy for tumor immunological therapy. CCCTC-binding Factor Like (CTCFL)/Brother of the Regulator of Imprinted Sites (BORIS), a cancer-testis antigen (CTA), has 23 mRNA splice variants classified into six subfamilies (sfs) and potentially encodes 17 distinct polypeptides. Based on our previous long-term research on hepatocellular carcinoma (HCC), we were particularly interested in whether BORIS sf2 could be a promising candidate for immunotherapy targeting liver cancer cells. Therefore, in this study, we aimed to construct an animal model to study the immunogenicity of human BORIS sf2 in murine hepatoma cells.

Methods: We established a hepatoma cell line expressing human BORIS sf2/C68 by inserting the sequences into a lentiviral vector pLVX-EF1α-IRES-Puro carrying the puromycin resistance gene. We achieved the stabilized expression of BORIS sf2/C68 in the oncogenic Hepa1c1c7 cells through lentivirus-mediated approach. The Hepa1c1c7 cells expressing the BORIS sf2/C68 (5×10/mouse) were inoculated subcutaneously into 6-week-old C57BL/6 mice to induce the formation of tumors.

Results: In the tumor formation experiment, the murine hepatoma cells expressing human BORIS sf2/C68 showed progressive growth in C57BL/6 mice. The animal model we constructed could be used to study the immunogenicity of the human BORIS sf2 in murine hepatoma cells.

Conclusions: The animals bearing BORIS sf2/C68-positive tumors may serve as an animal model for studying the therapeutic potency and safety of HCC vaccine directed at the CT-antigen BORIS sf2.