The treatment of mouse colorectal cancer by oral delivery tumor-targeting Salmonella.
Systemic administration of Salmonella to tumor-bearing mice leads to its preferential accumulation in tumor sites, the enhancement of host immunity, and the inhibition of tumor growth. However, the underlying mechanism for Salmonella-induced antitumor immune response via oral delivery remained uncertain. Herein, we used mouse colorectal cancer (CT26) as tumor model to study the therapeutic effects after oral delivery of Salmonella. When orally administered into tumor-bearing mice, Salmonella significantly accumulated in the tumor sites, inhibited tumor growth and extended the survival of mice. No obvious toxicity was observed during orally administered Salmonella by examining body weight and inflammatory cytokines. As indoleamine 2, 3-dioxygenase 1 (IDO) is a crucial mediator for tumor-mediated immune tolerance, we examined the expression of IDO. We demonstrated that Salmonella inhibited IDO expression in mouse cancer cells. Furthermore, immunohistochemical studies of the tumors revealed the infiltration of neutrophils and T cells in mice treated with Salmonella. In conclusion, our results indicate that Salmonella exerts its tumoricidal effects and stimulates T cell activities by inhibiting IDO expression. Oral delivery of Salmonella may, represent a potential strategy for the treatment of tumor.
Department of Environmental Engineering and Science, Feng Chia University Taichung 40407, Taiwan.
Wei-Kuang
WK
Wang
Department of Environmental Engineering and Science, Feng Chia University Taichung 40407, Taiwan ; Graduate Institute of Basic Medical Science, School of Medicine, China Medical University Taichung 40404, Taiwan.
Meng-Fan
MF
Lu
Graduate Institute of Basic Medical Science, School of Medicine, China Medical University Taichung 40404, Taiwan.
Yu-Diao
YD
Kuan
Graduate Institute of Basic Medical Science, School of Medicine, China Medical University Taichung 40404, Taiwan ; Department of Microbiology, School of Medicine, China Medical University Taichung 40404, Taiwan.
Che-Hsin
CH
Lee
3-dioxygenase 1; Colorectal cancer; Salmonella; T cell; indoleamine 2; oral delivery; tumor-targeting