Background and Objective: As one of the most important components of human body, gut microbiota play a vital role in human health by participating in metabolomics and maintaining immunological homeostasis. Microbiota dysbiosis is significantly associated with initiation and progression of different diseases. Due to close anatomical and functional connection between gut and liver (gut-liver axis), gut microbiota are found to impact the development of liver diseases including hepatocellular cancer (HCC) without fully understanding mechanisms. The overall objective of present study is to investigate how microbiota modulate HCC growth by regulating intrahepatic immune response.

Methods: Administration of carbon tetrachloride in combination with transplant of oncogenic hepatocytes by intrasplenic injection was used to make an orthotopic mouse model of HCC. A specific antibiotics cocktail (ABX) was selected to inhibit some kinds of gut microbiota. 16s rRNA sequencing was used to characterize gut microbiota profile in mice with the different treatments. Magnetic resonance imaging (MRI) was used to monitor tumor growth. Adoptive transfer of tumor antigen-specific CD8+ T cells following the treatment was used to investigate how ABX administration impacted intrahepatic immune response. Flow cytometry and multiplex cytokine assay were used to detect the alteration of effector CD8+ T cell in phenotype, proliferation, and function. Immunohistochemistry (IHC) was used to investigate immune cell tumor-infiltration.

Results: The established murine model reflects the typical features of human HCC. ABX oral administration significantly changed gut microbiota composition, particularly in abundance of P. aeruginosa and Muribaculaceae. ABX-mediated alteration of gut microbiota significantly retarded HCC progression. Interestingly, ABX treatment was found to prevent adoptively transferred tumor antigen-specific CD8+ T cell from tumor-induced immune tolerance, as higher frequency of effector CD8+ T cell was detected in ABX-treated tumor-bearing mice compared to that in control tumor-bearing mice. Correspondingly, ABX treatment resulted in the increase in expression of CD69 and enhanced production of IFN-γ in tumor antigen-specific CD8+ T cells relevant to that in control mice.

Conclusion: Modulating microbiota with antibiotics is able to shape intrahepatic immune responses and therapeutically suppress tumor growth, providing a new option in HCC control.

Citation Format: Xiaoqiang Qi, Ming Yang, Joseph Stenberg, Guangfu Li, Kevin Staveley-O’Carroll. Studying the impact of gut microbiome to hepatocellular cancer in an orthotopic murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4960.