Gut microbiota protect against colorectal tumorigenesis through lncRNA Snhg9.

The intestinal microbiota is a key environmental factor in the development of colorectal cancer (CRC). Here, we report that, in the context of mild colonic inflammation, the microbiota protects against colorectal tumorigenesis in mice. This protection is achieved by microbial suppression of the long non-coding RNA (lncRNA) Snhg9. Snhg9 promotes tumor growth through inhibition of the tumor suppressor p53. Snhg9 suppresses p53 activity by dissociating the p53 deacetylase sirtuin 1 (SIRT1) from the cell cycle and apoptosis regulator 2 (CCAR2). Consequently, the depletion of the microbiota by antibiotics causes upregulation of Snhg9 and accelerates CRC progression. Moreover, Snhg9 is functionally conserved. Human SNHG9 promotes tumor growth via the same mechanism as mouse Snhg9, despite their low sequence similarity.