HFD activated FAO mediates intestinal stemness and tumorgenicity I

Obesity is an established risk factor for cancer in many tissues such as the gastrointestinal tract. In the mammalian intestine, a pro-obesity high fat diet (HFD) promotes tumorigenesis in part by enhancing intestinal stem cell (ISC) numbers, proliferation and function. Although Ppar (Peroxisome proliferator-activated receptor) nuclear receptor activity has been proposed to mediate some of these effects in HFD ISCs, the exact role that different Ppar family members play in this process is unclear. Here, we find that in loss-of-function in vivo models, both Ppar family members alpha and delta contribute to the HFD response in ISCs. Mechanistically, both PPARs do so by robustly inducing a downstream fatty acid oxidation (FAO) metabolic program. Notably, pharmacologic and genetic disruption of CPT1a (the rate limiting enzyme of FAO) blunts the HFD phenotype in ISCs. Furthermore, just as HFD ISCs depend on CPT1a-mediated FAO, inhibition of CPT1a dampens the pro-tumorigenic consequences of a HFD on early tumor incidence and progression in the intestine. These findings demonstrate that inhibition of a HFD activated FAO program creates a therapeutic opportunity to counter the effects of a HFD on ISCs and intestinal tumorigenesis.