Chromosome copy number changes in Mad2-null-driven p53 null HCC and T-ALL samples

Mad2 and p53 loss were combined in liver or T-cells specificely leading to early onset and highly aggressive aneuploid HCC and T-ALL. Tumours were characterized for (recurrrent) copy number changes with a focus on whole chromosome abnormalities. DNA content was compared to the DNA content of sex-matched uninfiltrated control liver samples from litter mates Chromosome instability (CIN) leads to aneuploidy and copy number variations (CNVs). Even though both are hallmarks of cancer cells, aneuploidy inhibits proliferation of untransformed cells, suggesting that cancer cells have adapted to cope with CIN. The spindle assembly checkpoint (SAC) prevents CIN by monitoring chromosome attachment and sister chromatid tension in mitosis. By conditionally inactivating Mad2, an essential SAC gene, we find that SAC inactivation in T-cells or hepatocytes is remarkably well tolerated and becomes tumorigenic when placed in a p53null or p53+/- predisposed background. The resulting T-ALLs and HCCs are highly aneuploid, exhibit clonal copy number changes that are tumor specific despite ongoing CIN, indicating that CIN is a powerful driver of tumor evolution. DNA content of 29 Mad2f/f p53f/f or Mad2f/f p53f/+ Alb-Cre+ liver tumors and 9 Mad2f/f p53 f/f Lck-Cre+ T-ALLs compared to control tissue DNA