Gene expression of E2f7/8/Rb1 triple mutant liver tumors

E2F-transcription factors activate many genes involved in cell cycle progression, DNA repair, and apoptosis. Hence, E2F-dependent transcription must be tightly regulated to prevent tumorigenesis, and therefore metazoan cells possess multiple E2F regulation mechanism. The best-known is the Retinoblastoma protein (RB), which is mutated in many cancers. Atypical E2Fs (E2F7 and -8) can repress E2F-target gene expression independently of RB and are rarely mutated in cancer. Therefore, they may act as emergency brakes in RB-mutated cells to suppress tumor growth. Currently it is unknown if and how RB and atypical E2Fs functionally interact in vivo. Here, we demonstrate that mice with liver-specific combinatorial deletion of Rb and E2f7/8 have reduced life spans compared to E2f7/8 or Rb deletion alone. This was associated with increased proliferation and enhanced malignant progression of liver tumors. Hence, atypical repressor E2Fs and RB cooperatively act as tumor suppressors in hepatocytes. We propose that the complex interactions between atypical E2Fs and RB on maintenance of genetic stability underlie this context-dependency. RNA-sequencing data of four Alb-Cre-E2f7 E2f8 Rb1 conditional triple knockout liver tumors, four Alb-Cre-E2f7 E2f8 conditional double knockout liver tumors, and four age-matched wild-type mice.