Pathology Presents: Dr. Susan Bullman
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Susan Bullman, PhD
Human Biology Division
Fred Hutchinson Cancer Research Center
- Faculty Sponsor
Dr. Ray Monnat
Susan Bullman, PhD
Assistant Professor, Human Biology Division, Fred Hutchinson Cancer Research Center
“The Intratumoral Microbiota: A Role in Cancer Initiation and Progression”
Why assess the microbiota in human cancers? If a bacterial agent can directly or indirectly contribute to cancer initiation or progression, then these organisms are viable targets for cancer prevention and treatment.
In human cancers, malignant cells are surrounded by a complex microenvironment encompassing a range of non-transformed cells, but also a diverse collection of microorganisms. A growing body of evidence demonstrates the role of the microbiota in modulating inflammatory environments and promoting tumor growth and metastasis. Genomic analyses have consistently revealed an enrichment of the invasive bacterium Fusobacterium nucleatum in human colorectal tumors relative to non-cancerous colorectal tissues. Exogenous F. nucleatum infection in animal and cellular models has also supported its cancer-promoting role. We demonstrate that Fusobacterium species and their co-occurring microbiota persist in liver metastasis and in patient-derived xenografts of Fusobacterium-positive CRC. Antibiotic treatment of mice harboring these patient colon cancer xenografts led to a significant reduction in tumor Fusobacterium load, cancer cell proliferation, and overall tumor growth, suggesting that microbiome modulation could change the course of this disease. Our current research centers on mapping the cellular distribution of the microbiota within the tumor microenvironment and assessing the interplay between the microbiota and cancer therapeutics. I will also use an evidence-based approach to highlight recent key manuscripts in this field and discuss key questions that should be addressed moving forward.