Project description:The transcriptional coactivator YAP is the key downstream effector of the Hippo pathway. YAP overexpression in the developing mouse brain results in excessive expansion of the neural progenitor pool and severe perturbation of brain development. Nf2/Merlin is a tumor suppressor whose mutations are found in many human cancers. Loss of Merlin during brain development causes overexpansion of the neural progenitor pool. We used microarrays to identify the gene expression changes caused by YAP overexpression and Nf2 deletion. We used a double-transgenic system to overexpress YAP in the developing mouse brain by crossing mice carrying a doxycycline-dependent allele of YAP1-S127A (TetO-YAP1) with those expressing the reverse tetracycline-dependent transactivator rtTA under the control of the neural progenitor-specific Nestin promoter (Nes-rtTA) and feeding the dam with doxycycline-containing food (200 mg/kg) from E7.5. We conditionally deleted Nf2 using the telencephalon-specific Emx1-Cre.
Project description:The transcriptional coactivator YAP is the key downstream effector of the Hippo pathway. YAP overexpression in the developing mouse brain results in excessive expansion of the neural progenitor pool and severe perturbation of brain development. Nf2/Merlin is a tumor suppressor whose mutations are found in many human cancers. Loss of Merlin during brain development causes overexpansion of the neural progenitor pool. We used microarrays to identify the gene expression changes caused by YAP overexpression and Nf2 deletion.
Project description:Understanding of transciptome changes of endothelial cells (ECs) in mouse brain by Nf2/Merlin is unknown. Here, we performed bulk RNA sequencing to investigate the changes of expression patterns by Nf2/Merlin deletion in mouse brain ECs
Project description:Sox2 is required to maintain osteosarcoma cell tumor initiation.Knockdown of Sox2 leads tpo loss of tumorigenic properties. To examine gene expression changes upon Sox2 knockdown, we performed microarray analysis on mouse osteosarcoma cells expressing scrambled or Sox2shRNA. We found that genes upregulated upon Sox2 knockdown included osteoblast diffrentiation genes and genes down regulated included cell cycle and RNA processing genes as well as YAP-TEAD target genes. The Hippo pathway has a profound tumor suppressive role in cancer by restraining the strong growth-promoting function of YAP. We have previously shown that the stem cell transcription factor Sox2 maintains the tumorigenicity of osteosarcoma cancer stem cells (CSCs). In this report, we describe that Sox2 maintains stemness by antagonizing the Hippo pathway via direct repression of Hippo activators, Nf2 (Merlin) and WWC1 (Kibra), thereby leading to exaggerated YAP function. YAP is potently oncogenic in osteosarcoma and its depletion sharply reduces the tumorigenic CSC fraction. Low Nf2, low WWC1, and high YAP expression mark the CSC fraction of the tumor population, while the more differentiated fraction has high Nf2, high WWC1 and reduced YAP expression. This Sox2-Hippo axis is conserved and also operates in other Sox2-dependent cancers such as glioblastomas. We propose that disruption of YAP transcriptional activity reduces CSCs and could be a therapeutic strategy for Sox2- dependent tumors. Gene expression of 482 mouse lines mOS482 were analyzed by microarray. 3 replicates each of scrambled and Sox2shRNA were processed and hybridized
Project description:Meningiomas are the most common primary brain tumors in adults. Although generally benign, a subset is of higher grade, recurs even after multiple surgeries, and frequently fatal. Around half of meningiomas harbor inactivating mutations in NF2. While low-grade NF2 mutant meningiomas harbor few additional mutations in addition to NF2 inactivation, high-grade NF2 mutant tumors frequently harbor a highly aberrant genome. We and others have previously shown that NF2 inactivation leads to YAP1 activation and that YAP1 acts as an oncogene in NF2 mutant meningiomas. Here, we show that high-grade NF2 mutant meningiomas downregulate YAP1 signaling, in part through upregulating the expression of the YAP1 competitor VGLL4 and the YAP1 upstream regulators FAT3/4. Overexpression of VGLL4 resulted in the downregulation of YAP activity and the growth inhibition of low-grade NF2 mutant meningioma cells. Our results have important implications for the efficacy of therapies targeting oncogenic YAP1 in high-grade NF2 mutant meningiomas.
Project description:The Hippo pathway and its downstream effectors, the YAP and TAZ transcriptional coactivators, are deregulated in multiple different types of human cancer and are required for cancer cell phenotypes in vitro and in vivo, while largely dispensable for tissue homeostasis in adult mice. YAP/TAZ and their partner transcription factors, the TEAD1-4 factors, are therefore promising anti-cancer targets. Due to frequent YAP/TAZ hyperactivation caused by mutations in the Hippo pathway components NF2 and Lats2, mesothelioma is one of the prime cancer types predicted to be responsive to YAP/TAZ-TEAD inhibitor treatment. Mesothelioma is a devastating disease for which currently no effective treatment options exist. Here, we describe a novel covalent YAP/TAZ-TEAD inhibitor, SWTX-143, that binds to the palmitoylation pocket of all TEAD isoforms. SWTX-143 caused irreversible and specific inhibition of the transcriptional activity of YAP/TAZ-TEAD in Hippo-mutant tumor cell lines. More importantly, YAP/TAZ-TEAD inhibitor treatment caused strong mesothelioma regression in human subcutaneous xenograft models and in an orthotopic mesothelioma mouse model. Finally, SWTX-143 also selectively impaired the growth of NF2-mutant kidney cancer cell lines, suggesting that the exquisite sensitivity of mesothelioma to these YAP/TAZ-TEAD inhibitors can be extended to other tumor types with aberrations in Hippo signaling. In brief, we describe a novel and specific YAP/TAZ-TEAD inhibitor that has great potential to treat multiple Hippo-mutant solid tumor types.
Project description:The Hippo pathway and its downstream effectors, the YAP and TAZ transcriptional coactivators, are deregulated in multiple different types of human cancer and are required for cancer cell phenotypes in vitro and in vivo, while largely dispensable for tissue homeostasis in adult mice. YAP/TAZ and their partner transcription factors, the TEAD1-4 factors, are therefore promising anti-cancer targets. Due to frequent YAP/TAZ hyperactivation caused by mutations in the Hippo pathway components NF2 and Lats2, mesothelioma is one of the prime cancer types predicted to be responsive to YAP/TAZ-TEAD inhibitor treatment. Mesothelioma is a devastating disease for which currently no effective treatment options exist. Here, we describe a novel covalent YAP/TAZ-TEAD inhibitor, SWTX-143, that binds to the palmitoylation pocket of all TEAD isoforms. SWTX-143 caused irreversible and specific inhibition of the transcriptional activity of YAP/TAZ-TEAD in Hippo-mutant tumor cell lines. More importantly, YAP/TAZ-TEAD inhibitor treatment caused strong mesothelioma regression in human subcutaneous xenograft models and in an orthotopic mesothelioma mouse model. Finally, SWTX-143 also selectively impaired the growth of NF2-mutant kidney cancer cell lines, suggesting that the exquisite sensitivity of mesothelioma to these YAP/TAZ-TEAD inhibitors can be extended to other tumor types with aberrations in Hippo signaling. In brief, we describe a novel and specific YAP/TAZ-TEAD inhibitor that has great potential to treat multiple Hippo-mutant solid tumor types.
Project description:The Hippo pathway is an emerging signaling cascade involved in the regulation of organ size control. It consists of evolutionally conserved protein kinases that are sequentially phosphorylated and activated. The active Hippo pathway subsequently phosphorylates a transcription coactivator, YAP, which precludes its nuclear localization and transcriptional activation. Identification of transcriptional targets of YAP in diverse cellular contexts is therefore critical to the understanding of the molecular mechanisms in which the Hippo pathway restricts tissue growth. We used microarrays to profile the gene expression patterns upon acute siRNA knockdown of Hippo pathway components in multiple mammalian cell lines and identified a set of genes representing immediate transcriptional targets of the Hippo/Yap signaling pathway. Three mammalian cell lines (HEK293T, HepG2, HaCaT) were transfected with scramble siRNA controls or siRNAs against NF2 and LATS2, two core components of the Hippo pathway, simultaneously. Total RNAs were harvested four days after transfection to reveal the gene expression pattern unsing microarry. YAP and TAZ siRNAs were also transfected along with NF2 and LATS2 siRNAs to identify YAP/TAZ-dependent transcriptional targets upon loss of NF2/LATS2.
Project description:The Hippo-YAP signaling pathway has emerged as a major driver of tumorigenesis in a wide spectrum of human cancers. YAP functions as a transcriptional activator and while details of YAP regulation are emerging at a fast pace, it remains unknown what downstream targets are critical for YAP oncogenic functions. To establish the mechanisms involved and identify disease-relevant targets we examined the role of YAP in neurofibromatosis type 2 (NF2) using cell and animal models. YAP function is required in NF2-null Schwann cells to promote cell survival and for tumor growth, in vivo. Moreover, YAP promotes transcription of several targets including Prostaglandin-endoperoxide synthase 2 (PTGS2), which controls production of prostaglandin E2 (PGE2) and amphiregulin (AREG), a member of the epidermal growth factor family. Both AREG and PGE2 converge to activate survival signaling through EGFR, in a Src-dependent manner, thus promoting cell survival. Importantly, treatment with the COX2 inhibitor celecoxib significantly repressed the growth of NF2-null Schwann cells in vitro and tumor growth in a mouse model of NF2-associated schwnnoma.
Project description:Neurofibromatosis type 2 (NF2) is caused by mutations of the tumor suppressor MERLIN/NF2. Prior studies established Yap as the driver of proliferation and tumorigenesis upon Nf2 inactivation in a well defined, genetically engineered murine liver model. Here, we report that in this model system Nf2 tumorigenesis also involves DNA damage and inflammation via Rac1-mediated production of ROS. Ablation of Rac1 blocks Nf2 tumorigenesis in spite of hyperactivation of the cyclinD1-pRb-E2F1 pathway and profound increase in liver size associated with the loss of Rac1-dependent p53 checkpoint and senescence programs. Surprisingly, Erk, Akt and Stat3 signaling does not correlate with proliferation or tumorigenesis despite being activated in Nf2 deficient livers, indicating a lesser role of these pathways for Nf2 tumorigenesis. Because a senescence gene signature is associated with benign NF2 tumors but not with malignant NF2 mutant mesotheliomas, we conclude that senescence may underlie the benign nature of NF2.