Hippo pathway targeting in uterine leiomyosarcoma

Annalisa Astolfi, PhD,  University of Ferrara
Recipient of the: $50,000 Dr. Richard and Valerie Aronsohn Memorial Research Award

Leiomyosarcoma is the most common type of uterine sarcoma (uLMS), with an annual incidence of slightly less than two women per 100,000, characterized by a very poor response to standard therapies and an aggressive clinical course regardless of initial stage at diagnosis. The genetic profile of uLMS revealed the presence of recurrent somatic oncogenic events, dominated by frequent TP53 mutations, whose impact on the development of novel therapeutic opportunities is still marginal. Therefore, the discovery of novel and more effective therapeutic options for uLMS is an area of high unmet clinical need. 

Hippo pathway is a central regulator of organ development and size, tissue repair and stem cell fate. Deregulation of the Hippo pathway and activation of its key transcription factors YAP/TAZ plays a central role in many tumor-promoting activities, from malignant transformation, invasiveness and metastatic dissemination, to chemoresistance, immune escape and self-renewal of cancer stem cells. Recently, evidence is accumulating on the cooperation between Hippo signaling and mutant TP53 promoting oncogenic transcription programs, and on the loss of p53 function resulting in uncontrolled YAP oncogenic activity in many tumor settings.

This project is aimed at exploring Hippo pathway deregulation in uLMS carrying p53 inactivation, which is the most recurrent genetic event in this tumor type. Hippo pathway deregulation and sensitivity to YAP inhibitors will be analyzed in uLMS cell lines and in other proper cell model system represented by gene-edited induced Pluripotent Stem Cells (iPSC) differentiated towards the smooth muscle lineage. iPSC will be edited by the Crispr/Cas9 approach to carry different TP53 alterations, then differentiated towards the smooth muscle progenitor lineage. Hippo signaling pathway activation and its correlation with the presence of oncogenic TP53 mutations in the smooth muscle cell lineage will be analyzed by multiple single-marker approaches and further explored through whole transcriptome sequencing in comparison to normal tissue counterparts. Selected YAP inhibitors will be tested on cell lines versus normal uterine smooth muscle cells and in gene-edited and wild-type iPSC differentiated towards smooth muscle. The effects of YAP inhibition will be assessed by anchorage-dependent and independent cell growth, cell cycle /apoptosis/autophagy assays. 

The expected outcome of the project will be to define the role of Hippo pathway deregulation in uLMS cell models, thus identifying the best candidate drugs showing promising activity in this chemo-resistant and aggressive tumor type.