Abstract 3057: Gut microbiome controls liver metastasis

Abstract

Abstract Aim: The gut microbiome can modify tumor immunity and has been suggested to be involved in the development of liver cancer. However, it remains unknown how the gut microbiome controls hepatic immune responses. This study was designed to exam the effect of the gut microbiome on liver antitumor immunity, and to study potential mechanism. Experimental procedure: Antibiotic cocktail in drinking water was given to remove mouse gut microbiota. Control mice were kept on regular water. EL4 thymoma cells were injected s.c. to induce spontaneous liver metastasis. B16 melanoma and CT26 colon cancer cells were injected intrasplenically to form liver metastasis. Lung metastasis was induced by tail injection of tumor cells. Results: Antibiotic cocktail efficiently depleted gut bacteria. Removing gut commensal bacteria did not affect the growth of primary s.c. tumors, but impaired formation of liver metastasis in different models. The inhibitory effect on liver metastasis by removing gut microbiome was found after intrasplenic injection of tumor cells to form liver metastasis using both B16 melanoma and CT26 colon cancer tumor cells. Interestingly, formation of lung metastasis caused by tail vein injection of B16 cells was not impaired by antibiotics treatment, suggesting a liver specific effect. The inhibition of liver metastasis by antibiotic treatment was absent in Rag1 knockout mice, suggesting that the mechanism is mediated by the adaptive immune system. Conclusion: Our results suggest that the gut microbiome affects the liver immune microenvironment and modulates antitumor immunity. Citation Format: Chi Ma, Qiong Fu, Tim Greten. Gut microbiome controls liver metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3057. doi:10.1158/1538-7445.AM2017-3057