Nuclear export inhibition activates TP53 pathways and is a potent therapeutic strategy in atypical teratoid rhabdoid tumors
Tessa O House, Irina Alimova, Shawna Larsen, Gillian Murdock, Angela Pierce, Breauna Brunt, Stefania Tocci, Sofia Krykunenko, Marissa Coppola, Anat Erdreich-Epstein, Ron Firestein, Natalie J Serkova, Rajeev Vibhakar, Jessica W TsaiAbstract
Background
Atypical teratoid/rhabdoid tumor (ATRT) is an aggressive central nervous system tumor mostly affecting young children. Improved and less toxic therapies for children with ATRT are imperative due to the toxicities associated with current treatments. Furthermore, existing therapies do not address the underlying genetic drivers of ATRT. In this study, we sought to determine whether exportin-1 (XPO1) is a genetic dependency and therapeutic target in ATRT.
Methods
We utilized an integrative approach harnessing patient-derived ATRT cell lines, functional genomics, pharmacologic assays, transcriptomics, and in vivo intracranial xenograft models to systematically test the hypothesis that XPO1 is a novel dependency in ATRT.
Results
Analysis of RNA-sequencing datasets revealed high XPO1 expression in ATRT cells compared to other pediatric brain tumor cell lines. Both CRISPR/Cas9 genetic knockdown and pharmacologic inhibition of XPO1 using six selective inhibitors of nuclear export (SINEs) in patient-derived ATRT cells led to significant reduction in cell viability and proliferation. Furthermore, we observed increased apoptosis, G0 phase cell cycle arrest, and upregulation of TP53 signaling pathways in cells treated with the SINE selinexor. Consistently, our transcriptomic data revealed the upregulation of apoptosis and TP53 signaling pathways and concomitant depletion of cell cycle gene sets. In vivo, selinexor in combination with radiation and cyclophosphamide led to significant reduction in tumor volume and increased animal survival in intracranial ATRT xenograft models.
Conclusions
Our data reveal XPO1 as a novel genetic dependency and potent therapeutic target in ATRT.