Dynamic reorganisation of intratumoural bacterial florae during colorectal cancer progression

Colorectal cancer (CRC) exhibits distinct bacterial community compositions compared to healthy mucosae, which intimately correlate with CRC clinical outcomes. There is a lack of explanation for the inducements of microbiota remodelling.

FISH experiments and 16S rRNA sequencing were conducted to determine the inducements of various bacterial colonisation within tissues. Community cultivation was conducted to estimate the capacity of tumours to remodel bacterial communities. Metagenomic analyses were utilised to determine the remodelled communities of CRC with distant metastasis. Scratch tests and three-dimensional (3D) cultivation were employed to investigate the influence of specific taxa on tumour cell behaviours.

Colorectal tumours exhibit heterogeneous and individualised preferences in constantly remodelling intratumoural bacterial florae. Various degrees of colorectal gland differentiation within tumours cause heterogeneous intratumoural bacterial colonisation. CRC progression further alters bacterial community composition. Particularly, Prevotella is significantly enriched in the newly established communities colonising the primary foci of metastatic CRC. Furthermore, Prevotella intermedia (P. intermedia) promotes the invasion, migration, and ectopic tumorigenesis of CRC cells.

Individual evaluation of the preference of tumours in microbiota may pave the way to the development of CRC therapeutic strategies, and Prevotella is an emerging genus worthy of clinical attention.