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Nonalcoholic fatty liver disease (NAFLD) is the fastest rising cause of hepatocellular carcinoma (HCC) in Western countries; however, the molecular mechanisms that cause NAFLD-HCC remain elusive. To identify molecular drivers of NAFLD-HCC, we performed Sleeping Beauty (SB) transposon mutagenesis screens in liverspecific Pten knockout and in high-fat diet-fed mice, which are murine models of NAFLD-HCC. SB mutagenesis accelerated liver tumor formation in both models and identified 588 and 376 candidate cancer genes (CCGs), respectively; 257 CCGs were common to both screens and were enriched in signaling pathways known to be important for human HCC. Comparison of these CCGs with those identified in a previous SB screen of hepatitis B virusinduced HCC identified a core set of 141 CCGs that were mutated in all screens. Forty-one CCGs appeared specific for NAFLD-HCC, including Sav1, a component of the Hippo signaling pathway and the most frequently mutated gene identified in both NAFLD-HCC screens. Liver-specific deletion of Sav1 was found to promote hepatic lipid accumulation, apoptosis, and fibrogenesis, leading to the acceleration of hepatocarcinogenesis in liver-specific Pten mutant mice. Sav1/Pten double-mutant livers also showed a striking up-regulation of markers of liver progenitor cells (LPCs), along with synergistic activation of Yap, which is a major downstream effector of Hippo signaling. Lastly, Yap activation, in combination with Pten inactivation, was found to accelerate cell growth and sphere formation of LPCs in vitro and induce their malignant transformation in allografts. Our forward genetic screens in mice have thus identified pathways and genes driving the development of NAFLD-HCC. [ABSTRACT FROM AUTHOR]

Epithelial ovarian cancer (EOC) is a deadly cancer, and its prognosis has not been changed significantly during several decades. To seek new therapeutic targets for EOC, we performed an in vivo dropout screen in human tumor xenografts using a pooled shRNA library targeting thousands of druggable genes. Then, in follow-up studies, we performed a second screen using a genome-wide CRISPR/Cas9 library. These screens identified 10 high-confidence drug targets that included well-known oncogenes such as ERBB2 and RAF1, and novel oncogenes, notably KPNB1, which we investigated further. Genetic and pharmacological inhibition showed that KPNB1 exerts its antitumor effects through multiphase cell cycle arrest and apoptosis induction. Mechanistically, proteomic studies revealed that KPNB1 acts as a master regulator of cell cycle-related proteins, including p21, p27, and APC/C. Clinically, EOC patients with higher expression levels of KPNB1 showed earlier recurrence and worse prognosis than those with lower expression levels of KPNB1. Interestingly, ivermectin, a Food and Drug Administration-approved antiparasitic drug, showed KPNB1-dependent antitumor effects on EOC, serving as an alternative therapeutic toward EOC patients through drug repositioning. Last, we found that the combination of ivermectin and paclitaxel produces a stronger antitumor effect on EOC both in vitro and in vivo than either drug alone. Our studies have thus identified a combinatorial therapy for EOC, in addition to a plethora of potential drug targets. [ABSTRACT FROM AUTHOR]

Epithelial-mesenchymal transition (EMT) is thought to contribute to metastasis and chemoresistance in patients with hepatocellular carcinoma (HCC), leading to their poor prognosis. The genes driving EMT in HCC are not yet fully understood, however. Here, we show that mobilization of Sleeping Beauty (SB) transposons in immortalized mouse hepatoblasts induces mesenchymal liver tumors on transplantation to nude mice. These tumors show significant down-regulation of epithelial markers, along with up-regulation of mesenchymal markers and EMT-related transcription factors (EMT-TFs). Sequencing of transposon insertion sites from tumors identified 233 candidate cancer genes (CCGs) that were enriched for genes and cellular processes driving EMT. Subsequent trunk driver analysis identified 23 CCGs that are predicted to function early in tumorigenesis and whose mutation or alteration in patients with HCC is correlated with poor patient survival. Validation of the top trunk drivers identified in the screen, including MET (MET proto-oncogene, receptor tyrosine kinase), GRB2-associated binding protein 1 (GAB1), HECT, UBA, and WWE domain containing 1 (HUWE1), lysine-specific demethylase 6A (KDM6A), and protein-tyrosine phosphatase, nonreceptor-type 12 (PTPN12), showed that deregulation of these genes activates an EMT program in human HCC cells that enhances tumor cell migration. Finally, deregulation of these genes in human HCC was found to confer sorafenib resistance through apoptotic tolerance and reduced proliferation, consistent with recent studies showing that EMT contributes to the chemoresistance of tumor cells. Our unique cell-based transposon mutagenesis screen appears to be an excellent resource for discovering genes involved in EMT in human HCC and potentially for identifying new drug targets. [ABSTRACT FROM AUTHOR]