Xavier Dolcet

Endometrial cancer progression driven by PTEN-deficiency requires miR-424(322)~503

Abstract Endometrial cancer is the most frequent type of cancer in the female reproductive tract. Loss-of-function alterations in PTEN, leading to enhanced PI3K/AKT activation, are among the most frequent molecular alterations in endometrial cancer. Increased PI3K/AKT signaling resulting from PTEN loss promotes cellular proliferation and confers resistance to TGFβ-mediated apoptosis, a key regulator of endometrial homeostasis. In this study, we have analyzed the role of miRNAs in driving these altered cellular responses. A comprehensive transcriptomic analysis of miRNA expression revealed the upregulation of several miRNAs caused by PTEN deficiency and/or TGFβ stimulation. The miR-424(322)~503 cluster drew our attention due to its involvement in regulating apoptosis and proliferation. However, miR-424(322)~503 cluster has a paradoxical role in cancer, exhibiting either oncogenic and tumor suppressive functions depending on cell type or context. To ascertain the function of miR-424(322)~503 in endometrial carcinogenesis caused by PTEN deficiency, we generated a double Pten/miR-424(322)~503 knock-out mice. We demonstrate that loss of miR-424(322)~503 impairs proliferation of both wild type or Pten deficient endometrial organoids by interfering with growth factor and PI3K/AKT signaling. Furthermore, the absence of miR-424(322)~503 restores TGFβ-induced apoptosis, which is otherwise compromised by PTEN deficiency. In vivo, Pten/miR-424(322)~503 knock-out mice exhibit reduced endometrial cancer progression compared to Pten deficient mice through a cell-autonomous mechanism.

In Vivo Intra‐Uterine Delivery of TAT‐Fused Cre Recombinase and CRISPR/Cas9 Editing System in Mice Unveil Histopathology of Pten/p53‐Deficient Endometrial Cancers

AbstractPhosphatase and TENsin homolog (Pten) and p53 are two of the most frequently mutated tumor suppressor genes in endometrial cancer. However, the functional consequences and histopathological manifestation of concomitant p53 and Pten loss of function alterations in the development of endometrial cancer is still controversial. Here, it is demonstrated that simultaneous Pten and p53 deletion is sufficient to cause epithelial to mesenchymal transition phenotype in endometrial organoids. By a novel intravaginal delivery method using HIV1 trans‐activator of transcription cell penetrating peptide fused with a Cre recombinase protein (TAT‐Cre), local ablation of both p53 and Pten is achieved specifically in the uterus. These mice developed high‐grade endometrial carcinomas and a high percentage of uterine carcinosarcomas resembling those found in humans. To further demonstrate that carcinosarcomas arise from epithelium, double Pten/p53 deficient epithelial cells are mixed with wild type stromal and myometrial cells and subcutaneously transplanted to Scid mice. All xenotransplants resulted in the development of uterine carcinosarcomas displaying high nuclear pleomorphism and metastatic potential. Accordingly, in vivo CRISPR/Cas9 disruption of Pten and p53 also triggered the development of metastatic carcinosarcomas. The results unfadingly demonstrate that simultaneous deletion of p53 and Pten in endometrial epithelial cells is enough to trigger epithelial to mesenchymal transition that is consistently translated to the formation of uterine carcinosarcomas in vivo.