The microbiome in colorectal metastases: nature and impact on local immune and inflammatory response, disease evolution and response to therapy

Despite evidence associating colorectal cancer (CRC) and microbiome, its role in metastatic CRC remains
unexplored. In this project, we aim to characterize bacterial colonization of CRC metastases matched with
primary tumors, surrounding normal tissues and evaluate its relationship with tumor characteristics, including
molecular subtype, pattern of histological growth, local immune response and alteration in T-cell antigen
presentation, as well as its impact on disease outcome. A large series of frozen tumor samples from several
sources will be analyzed by a combination of direct identification of bacterial species by 16S rRNA profiling,
RNA-seq, in situ hybridization with broad-spectrum and strain-specific probes to identify, quantify and locate
bacteria, and multiplexed immunofluorescence coupled to computerized image analysis to characterize the
immune and inflammatory infiltrate. This project will provide much-needed insights in the role of the microbiome
and immune microenvironment in metastatic tumor development and maintenance, as well as disease outcome
and therapy response.