The virus integrations in gut microbes associated with dysbiosis of microbial community in tumorigenesis of colorectal carcinoma

Patients with colorectal cancer (CRC) have a different gut microbial and viral communities from healthy individuals. But little is known about the ways and functions of interaction of virus-bacteria, let alone its correlation with the aetiology of CRC. In this study we aimed to identify the association between the genetic integration of virus-bacteria and the expansion of some microbial population during tumorigenesis of human colorectum. Using a gut metagenomics sequencing data of healthy controls, advanced adenoma and carcinoma patients, to our knowledge, we demonstrate for the first time that the viral genetic integrations in gut microbes tend to occur in CRC patients and are potentially associated with the carcinogenesis. We found that almost all of the genetic integrations were happened between bacteriophages and bacteria, which could be influenced by the abundance of the phage communities. Importantly, the integrations of phage-carried positive effective genes offered selective advantages to the commensal and potential pathogenic bacteria, as a result, potentially led to a microbial dysbiosis along with the increasing bacterial diversity in carcinoma patients. Consequently, our work opens a new way to understand the carcinogenicity in complex intestinal ecosystems.