Towards a CRISPR-Based Mouse Model of Vhl-deficient Clear Cell Kidney Cancer: Initial Experience and Lessons Learned

CRISPR is revolutionizing the ability to do somatic gene editing in mice for the purpose of creating new cancer models. Inactivation of the VHL tumor suppressor gene is the signature initiating event in the most common form of kidney cancer, clear cell renal cell carcinoma (ccRCC). Such tumors are usually driven by the excessive HIF2 activity that arises when the VHL gene product, pVHL, is defective. Given the pressing need for a robust immunocompetent mouse model of human ccRCC, we directly injected adenovirus-associated viruses (AAVs) encoding sgRNAs against VHL and other known/suspected ccRCC tumor suppressor genes into the kidneys of C57BL/6 mice under conditions where Cas9 was under the control of one of two different kidney-specific promoters (Cdh16 or Pax8) to induce kidney tumors. An AAV targeting Vhl, Pbrm1, Keap1 and Tsc1 reproducibly caused macroscopic ccRCCs that partially resembled human ccRCC tumors with respect to transcriptome and cell of origin and responded to a ccRCC standard of care agent, axitinib. RNAseq analysis was utilized to evaluate the expression profile produced by the targeted loss of Vhl, Pbrm1, Keap1 and Tsc1 in these mouse tumors. Unfortunately, these tumors, like those produced by earlier genetically engineered mouse ccRCCs, are HIF2-independent.