Tsc1 and Vhl loss cooperates to drive renal cell carcinoma through augmenting HIF1 and NRF2 signaling pathways

Besides the truncal VHL mutations, ccRCC is characterized by upregulated MTOR signals from both preclinical and clinical studies. To understand how upregulated MTOR signals cooperate with VHL loss in promoting kidney tumorigenesis, we generated kidney-specific deletion of Vhl and Tsc1 (Vhl;Tsc1 cDKO) in mice. The mice showed decreased life span with maximal age of 11 weeks, bilateral polycystic kidney diseases from ~3 weeks and multifocal solid renal cell carcinoma with eosinophilic cytoplasm and grade 2-3 from 7 weeks old. The mouse tumors resemble histology of the human kidney tumors with VHL and TSC1 mutations. To understand the mechanism of how Tsc1 loss cooperates with Vhl loss in promoting tumorigenesis, we performed transcriptomic, metabolomic and immunohistochemical profilings of renal cortices from age-matched wild-type, Vhl or Tsc1 single knockout, and Vhl;Tsc1 cDKO mice. Tsc1 loss cooperates with Vhl loss by augmenting the HIF1 transcriptional output, as well as altering the glutamine/glutamate metabolism, urea cycle, glycogen metabolism, and activating NRF2 signaling pathways which reprogram the cells to counteract the high oxidative stress associated with the proliferation. Our study reports a ccRCC mouse model recapitulating human ccRCC with same genetic background, provides mechanistic insights concerning cooperation between upregulated mTORC1 signals and VHL loss, generates in vivo reagents for studying ccRCC, and implicates potential clinical values. Kidney Cortices mRNA profiles of 4-week-old wild type (WT), Vhl cKO, Pbrm1 cKO, Tsc1 cKO, Vhl;Pbrm1 cDKO, and Vhl;Tsc1 cDKO mice were generated by deep sequencing, in quadruplicates, using HiSeq 4000.