Microbial community profiling of human cancers

Abstract

The microbial mass present in the human species is ten times greater than that of human cells. We know now that this metagenome influences us greatly, playing a role in our metabolism, tissue development, inflammation and immunity. Certain body habitats suffer greater exposure to the outside world than others, increasing the importance of the human microbiome on such body sites. Studying the microbial profiles associated with these habitats may lead to a greater understanding of diseases caused by infectious agents, including cancer, because estimates show that microbes play a central role in about 20% of all malignancies. To study the relationship between cancer and the human microbiome we plan to: 1) characterize the bacterial diversity present in gastric juice samples from subjects with pre-malignant lesions (n=30) or with gastric cancer (n=40), compared to subjects with no relevant clinical alterations (n=30); 2) characterize the bacterial diversity present in biopsy samples of subjects with rectal adenocarcinomas (n=18) and compare them to biopsy samples of subjects with no relevant clinical alterations (n=18); and 3) evaluate temporal alterations of bacterial communities caused by the use of radiation therapy using biopsy samples of colorectal cancer patients (n=40) across 3 times points to determine if they play a role in the development of proctitis. To do so, we will use a multi-disciplinary approach that will make use of genomic aspects, such as deep sequencing of the 16S rRNA bacterial gene, and advanced bioinformatics aspects to analyse the sequencing results. At the same time, we plan to mine public sequence databases using a bioinformatics pipeline in order to assess the presence of bacterial DNA or RNA, trying to validate findings obtained previously from the 16S rRNA gene. (AU)