BRAF-mutated serrated colorectal neoplasia drives transcriptional activation of cholesterol metabolism.

BRAF mutations occur early in serrated colorectal cancers, but their long-term influence on tissue homeostasis is poorly characterized. We investigated the impact of short-term (3 days) and long-term (6 months) expression of Braf in the intestinal tissue of an inducible mouse model. We show that Braf perturbs the homeostasis of intestinal epithelial cells, with impaired differentiation of enterocytes emerging after prolonged expression of the oncogene. Moreover, Braf leads to a persistent transcriptional reprogramming with enrichment of numerous gene signatures indicative of proliferation and tumorigenesis, and signatures suggestive of metabolic rewiring. We focused on the top-ranking cholesterol biosynthesis signature and confirmed its increased expression in human serrated lesions. Functionally, the cholesterol lowering drug atorvastatin prevents the establishment of intestinal crypt hyperplasia in Braf-mutant mice. Overall, our work unveils the long-term impact of Braf expression in intestinal tissue and suggests that colorectal cancers with mutations in BRAF might be prevented by statins.