Effects of mitochondrial stress on intestinal tumor development depends on Apc status

Mitochondrial stress triggers both metabolic and transcriptomic reprogramming but its effects on tumor development remains unclear. It is also unknown whether the genetic status has any influence on the capacity of mitochondrial stress to control tumor development. To explore these issues, we generated a mouse model lacking the lipid transfer protein Stard7 in intestinal epithelial cells (IECs) and assessed tumor development in both Wnt-dependent tumor initiation and in inflammation-driven tumor development. The loss of Stard7 in both models of intestinal tumors impaired mitochondrial Complex I activity, led to a severe metabolic and lipidomic reprogramming and potentiated mTORC1 activation. As a result, levels of enzymes involved in serine biosynthesis were enhanced in Stard7-deficient IECs showing or not constitutive Wnt signaling. Strikingly, despite similar molecular signatures upon Stard7 deficiency in intestinal crypts showing or not constitutive Wnt signaling, Stard7 contributed to tumor development in AOM/DSS-treated mice but inhibits Wnt-driven cancer initiation in the intestine. Apc+/Min mice lacking Stard7 in IECs developed more tumors in the distal colon. Collectively, our results suggest that the Apc genetic status critically controls the effects of mitochondrial stress on intestinal tumor development.