Velez Reyes, German2021-09-242021-09-242019-06https://hdl.handle.net/11299/224614University of Minnesota Ph.D. dissertation. June 2019. Major: MD/PhD Program. Advisor: David Largaespada. 1 computer file (PDF); ix, 92 pages.Cancer is a devastating and intriguing disease. Innovations in screening and treatment have reduced cancer rates and mortality in the last decade. However, we are at a crossroads to better understand the molecular mechanisms and the genetic events that result in malignant transformation of human tumors. Drug resistance is on the rise and malignancies that recur are more difficult to treat. It is our goal to understand the genetic mechanisms and the pathways that drive and promote human tumor malignant transformation. In order to understand these mechanisms, we have used two different approaches: a mouse in vivo liver and a human in vitro Schwan cell cancer model. We hypothesized that loss-of-function mutations and/or copy number loss in novel Schwann cell tumor suppressor genes results in the activation of multiple pathways that aid in the malignant transformation of neurofibromas into MPNSTs. In the liver, we hypothesized that RSPO2-driven oncogenic activity occurs via Hippo/YAP signaling. In the peripheral nerve, we designed a medium-throughput screening methodology using CRISPR/Cas9 technology to validate a previous in vivo Sleeping Beauty (SB) screen. We were able to confirm the results of the screen and discovered that multiple pathways are activated in Schwann cell tumors. This occurs as a result of copy number alterations and tumor suppressor gene loss. Activation of Wnt, Rho, PI3K/mTOR, Hippo, and Shh appear to be hallmarks of neoplasms of Schwann cell tumors. Interestingly, we also found that loss of normal chromatin folding is a mechanism of aberrant oncogenic expression. In the liver we have made use of the Fah mouse model to show that RSPO2-induced liver tumors depend on Hippo/YAP signaling. We also discovered that removal of YAP results in reduced tumor burden. Our studies shed light into the future of cancer treatment and motivate further research. Our data indicates that some liver and peripheral nerve cancers may be vulnerable to targeted therapy. Combination therapy in conjunction with an informed individual’s tumor genetic landscape is a reasonable way to treat human cancers. In this thesis we outlined our screening methods, MPNST genes, and the pathways they activate. We also show that RSPO2 works via YAP. Our screening methods show a streamlined way to validate candidate tumor suppressor genes and oncogenes in order to push forward discovery of targeted therapies to alleviate the heavy burden of cancer.enThesis or Dissertation