DEPLETION OF TP53 IN HUMAN PLURIPOTENT STEM CELLS TRIGGERS MALIGNANT-LIKE BEHAVIOUR

Human pluripotent stem cells (hPSCs) tend to acquire genetic aberrations upon culture in vitro. Common aberrations are mutations in the tumor suppressor TP53, suspected to confer a growth-advantage to the mutant cells. However, their full impact in the development of malignant features and safety of hPSCs for downstream applications is yet to be elucidated. Here, we knock-out TP53 in hPSCs using CRISPR-Cas9 and compare them with isogenic wild-type hPSCs and human germ cell tumor lines as models of malignancy. While no major changes in proliferation, pluripotency and transcriptomic profiles are found, mutant lines display aberrations in some of the main chromosomal hotspots for genetic abnormalities in hPSCs. Additionally, enhanced clonogenic and anchorage-free growth, alongside resistance to chemotherapeutic compounds is observed. Our results indicate that common TP53-depleting mutations in hPSCs, although potentially overlooked by standard analyses, could impact their behavior and safety in a clinical setting. Overall design: To explore the impact of TP53-depleting mutations, we generated Tp53-KO lines of an embryonic (H9) and induced pluripotent (LU07) stem cell lines using CRSIPR-Cas9 technology. To deepen into the impact of these mutations in the transcriptome of the different cell lines, bulk RNAseq of the lines was performed. We compared the gene expression profiles of the different cell lines and their respective KO isogenic counterparts