Differential metabolic adaptations define responses of winner and loser oncogenic mutant stem cells in skin epidermisin vivo

Abstract

AbstractSkin epithelial stem cells detect and correct aberrancies induced by oncogenic mutations. Different oncogenes invoke different mechanisms of epithelial tolerance: while wild-type cells outcompete β-catenin-Gain-of-Function (βcatGOF) mutant cells, HrasG12Vmutant cells outcompete wild-type cells1,2. Here we ask how metabolic states change as wild-type stem cells interface with mutant cells, and how this ultimately drives different cell competition outcomes. By adapting our live-imaging platform to track endogenous redox ratio (NAD(P)H/FAD) with single cell resolution in the same mice over time, we show that wild-type epidermal stem cells maintain robust redox ratio despite their heterogeneous cell cycle states. We discover that both βcatGOF and HrasG12Vmodels lead to a rapid drop in redox ratios. However, the “winner” cells in each model (wild-type in βcatGOF and mutant in HrasG12V), rapidly recover their redox ratios, irrespective of the mutation induced. Using mass spectrometry (13C-LC-MS/MS)3, we find that both mutants increase flux through the oxidative tricarboxylic acid cycle, but the “winner” HrasG12Vcells and the “loser” βcatGOF cells modulate glycolytic flux differently. Hence, we reveal the metabolic adaptations that define the hallmarks of winners and losers during cell competitionin vivoand uncover the nodes of regulation unique to each cell fate.