Transfer of the IL-37b gene elicits anti-tumor responses in mice bearing 4T1 breast cancer

Aim: IL-37b has shown anti-cancer activities in addition to its anti-inflammatory properties. In this study, we investigated the effects of IL-37b on breast carcinoma growth in mice and to determine the involvement of T cell activation in the effects. Methods: IL-37b gene was transferred into mouse breast carcinoma cell line 4T1 (4T1-IL37b cells), the expression of secretory IL-37b by the cells was detected, and the effects of IL-37b expression on the cell proliferation in vitro was evaluated. After injection of 4T1 cells or 4T1-IL37b cells into immunocompetent BALB/c mice, immunodeficient BALB/c nude mice and NOD-SCID mice, the tumor growth and survival rate were measured. The proliferation of T cells in vitro was also detected. Results: IL-37b was detected in the supernatants of 4T1-IL37b cells with a concentration of 12.02+/-0.875 ng/mL. IL-37b expression did not affect 4T1 cell proliferation in vitro. BALB/c mice inoculated with 4T1-IL37b cells showed significant retardation of tumor growth. BALB/c mice inoculated with both 4T1 cells and mitomycin C-treated 4T1-IL37b cells also showed significant retardation of tumor growth. But the anti-cancer activity of IL-37b was abrogated in BALB/c nude mice and NOD-SCID mice inoculated with 4T1-IL37b cells. Recombinant IL-37b slightly promoted CD4(+) T cell proliferation without affecting CD8(+) T cell proliferation. Conclusion: IL-37b exerts anti-4T1 breast carcinoma effects in vivo by modulating the tumor microenvironment and influencing T cell activation.