Transient, DNA-free in vivo CRISPR/Cas9 genome edition for flexible modelling of endometrial carcinogenesis

The CRISPR/Cas9 technology has emerged as a powerful tool to generate mouse models of disease. Endometrial cancer is the most common malignancy of the female genital tract. In the present study, we have developed a pipeline for the generation of somatically engineered mouse models of endometrial cancer by in vivo electroporation-mediated delivery of Cas9 ribonucleoprotein into the uterine cavity. By using mT/mG dual-fluorescent reporter mice, we show that this system allows an efficient genomic edition specifically in epithelial endometrial cells. As a proof of its applicability for endometrial cancer modeling, we designed Cas9 ribonucleoprotein targeting Pten, the most frequently tumor suppressor gene mutated in this type of cancer. Pten-targeting ribonucleoprotein delivery into the uterine cavity caused loss of expression of PTEN protein in epithelial endometrial cells that resulted in the development of endometrial lesions. We also validated this technique for gene edition in other important endometrial driver genes such as p53 or Fbxw7. By co-targeting LoxP sites of mT/mG reporter mice and Pten, we demonstrate the generation of differentially edited cell populations that may be a useful tool to model tumoral heterogeneity. Moreover, the combination of CRISPR/Cas9 technology in mT/mG dual-reporter mice and light-sheet microscopy represents an interesting approach for in vivo cancer cell tracing. This methodology opens a new door for future rapid, flexible, customizable and multiplexable in vivo modeling of endometrial cancer.