Loss of tumor suppressor Merlin results in aberrant activation of Wnt/β-catenin signaling in cancer

The molecular biology of NF2/Merlin on tumorigenesis and development

The neurofibromatosis type 2 (NF2) gene, known for encoding the tumor suppressor protein Merlin, is central to the study of tumorigenesis and associated cellular processes. This review comprehensively examines the multifaceted role of NF2/Merlin, detailing its structural characteristics, functional diversity, and involvement in various signaling pathways such as Wnt/β-catenin, Hippo, TGF-β, RTKs, mTOR, Notch, and Hedgehog. These pathways are crucial for cellular growth, proliferation, and differentiation. NF2 mutations are specifically linked to the development of schwannomas, meningiomas, and ependymomas, although the precise mechanisms of tumor formation in these specific cell types remain unclear. Additionally, the review explores Merlin's role in embryogenesis, highlighting the severe developmental defects and embryonic lethality caused by NF2 deficiency. The potential therapeutic strategies targeting these genetic aberrations are also discussed, emphasizing inhibitors of mTOR, HDAC, and VEGF as promising avenues for treatment. This synthesis of current knowledge underscores the necessity for ongoing research to elucidate the detailed mechanisms of NF2/Merlin and develop effective therapeutic strategies, ultimately aiming to improve the prognosis and quality of life for individuals with NF2 mutations.

Repeat DNA methylation is modulated by adherens junction signaling

Through its involvement in gene transcription and heterochromatin formation, DNA methylation regulates how cells interact with their environment. Nevertheless, the extracellular signaling cues that modulate the distribution of this central chromatin modification are largely unclear. DNA methylation is highly abundant at repetitive elements, but its investigation in live cells has been complicated by methodological challenges. Utilizing a CRISPR/dCas9 biosensor that reads DNA methylation of human α-satellite repeats in live cells, we here uncover a signaling pathway linking the chromatin and transcriptional state of repetitive elements to epithelial adherens junction integrity. Specifically, we find that in confluent breast epithelial cell monolayers, α-satellite repeat methylation is reduced by comparison to low density cultures. This is coupled with increased transcriptional activity at repeats. Through comprehensive perturbation experiments, we identify the junctional protein E-cadherin, which links to the actin cytoskeleton, as a central molecular player for signal relay into the nucleus. Furthermore, we find that this pathway is impaired in cancer cells that lack E-cadherin and are not contact-inhibited. This suggests that the molecular connection between cell density and repetitive element methylation could play a role in the maintenance of epithelial tissue homeostasis.

Transposon delivery for CRISPR-based loss-of-function screen in mice identifies NF2 as a cooperating gene involved with the canonical WNT signaling molecular class of hepatocellular carcinoma

Various molecular subclasses of hepatocellular carcinoma (HCC) exists, with many novel cooperating oncogenes and tumor suppressor genes involved in its tumorigenesis. The emerging importance of WNT signaling in HCC has been established. However, the intricate genetic mechanisms involved in this complex signaling pathway remains to be elucidated. Importantly, while some cooperating genes have been identified, there are still many unknown genes associated with catenin beta 1 (CTNNB1)-induced HCC. Mutations in both oncogenes and tumor suppressor genes are required for HCC tumorigenesis. The emergence of the CRISPR/Cas9 system has allowed researchers now to target both alleles efficiently. In this novel study, the Sleeping Beauty transposon system was used as a gene delivery system in vivo to stably integrate an expression cassette that carry pools of gRNAs and overexpress a mutant version of CTNNB1 into the hepatocyte genome. We identified 206 candidate genes that drive HCC tumorigenesis in the context of WNT signaling activation and, neurofibromin 2 (NF2) gene, a known tumor suppressor gene with clinical relevance was validated in this proof-of-principle study.

The genetic landscape and possible therapeutics of neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a genetic condition marked by the development of multiple benign tumors in the nervous system. The most common tumors associated with NF2 are bilateral vestibular schwannoma, meningioma, and ependymoma. The clinical manifestations of NF2 depend on the site of involvement. Vestibular schwannoma can present with hearing loss, dizziness, and tinnitus, while spinal tumor leads to debilitating pain, muscle weakness, or paresthesias. Clinical diagnosis of NF2 is based on the Manchester criteria, which have been updated in the last decade. NF2 is caused by loss-of-function mutations in the NF2 gene on chromosome 22, leading the merlin protein to malfunction. Over half of NF2 patients have de novo mutations, and half of this group are mosaic. NF2 can be managed by surgery, stereotactic radiosurgery, monoclonal antibody bevacizumab, and close observation. However, the nature of multiple tumors and the necessity of multiple surgeries over the lifetime, inoperable tumors like meningiomatosis with infiltration of the sinus or in the area of the lower cranial nerves, the complications caused by the operation, the malignancies induced by radiotherapy, and inefficiency of cytotoxic chemotherapy due to the benign nature of NF-related tumors have led a march toward exploring targeted therapies. Recent advances in genetics and molecular biology have allowed identifying and targeting of underlying pathways in the pathogenesis of NF2. In this review, we explain the clinicopathological characteristics of NF2, its genetic and molecular background, and the current knowledge and challenges of implementing genetics to develop efficient therapies.

Research progress in breast cancer stem cells: characterization and future perspectives

More and more studies have proved that there are a small number of cells with self-renewal and differentiation ability in breast tumors, namely breast cancer stem cells. Such cells play a key role in the initiation, development and migration of breast tumors. The properties of breast tumor stem cells are regulated by a range of intracellular and extracellular factors, including important signaling pathways, transcription factors, non-coding RNAs, and cytokines such as Hedgehog, Wnt, Notch, microRNA93, microRNA100, and IL-6. Tumor microenvironment (such as mesenchymal stem cells, macrophages and cytokines) plays an important role in the regulation of breast tumor stem cells. Using the keywords including "breast cancer stem cells", "signal pathway", "chemotherapy tolerance", and "non-coding RNA", "triple negative breast cancer", "inhibitors", this study retrieved the original articles and reviews published before October 3, 2021, from PubMed and WEB OF SCI database and this study performed a comprehensive review of them. After treatment, there is a correlation between the metastasis-prone nature and recurrence with breast cancer stem cells. The signaling pathway of breast cancer stem cells plays a significant role in activating the function of breast cancer cells, regulating the differentiation of breast cancer cells and controlling the division of breast cancer cells. This imbalance leads to the uncontrolled growth and development of breast cancer cells. Targeted therapy that blocks the corresponding pathway may become a new perspective for breast cancer treatment. In addition, corresponding therapeutic strategies can be used according to the expression characteristics of different molecular types of breast cancer stem cells. For ER-positive breast cancer, simultaneous endocrine therapy and targeted therapy of tumor stem cells may improve the efficacy of endocrine therapy. Trastuzumab therapy significantly reduces the risk of recurrence of HER2-positive breast cancer. For drug-resistant patients, combination therapy is required due to the different phenotypes of epithelial-mesenchymal transforming tumor stem cells. This study briefly reviews the research progress of breast cancer stem cell-related signaling pathways and their inhibitors, in order to provide a reference for breast cancer patients to obtain more effective clinical treatment.

Cancer‑associated fibroblast‑derived LRRC15 promotes the migration and invasion of triple‑negative breast cancer cells via Wnt/β‑catenin signalling pathway regulation

Triple-negative breast cancer (TNBC) is a highly aggressive tumour subtype associated with poor prognosis. The function of leucine-rich repeat-containing protein 15 (LRRC15), a member of the leucine-rich repeat superfamily, in TNBC has not yet been elucidated. The aim of this study was to identify the combined role of LRRC15 and Wnt/β-catenin signalling pathway in the development of TNBC. The expression of LRRC15 in TNBC tissues was analysed using data from The Cancer Genome Atlas. Cell migration and invasion assays were conducted to study the function of LRRC15 in TNBC. The expression of Wnt/β-catenin signalling proteins was analysed via western blotting. The effect of LRRC15 on β-catenin nuclear localisation was measured by performing western blotting and luciferase assays. It was found that high LRRC15 expression was associated with poor prognosis in patients with TNBC. High expression of LRRC15 in cancer-associated fibroblasts (CAFs) promoted cell migration and invasion in TNBC cells. In addition, TNBC cells with LRRC15 overexpression in CAFs showed an aberrant increase in β-catenin activity concomitant with nuclear localisation of β-catenin, which inhibited its degradation. These results showed that LRRC15 promoted tumour migration and invasion in TNBC cells by regulating the Wnt/β-catenin signalling pathway.

Merlin regulates signaling events at the nexus of development and cancer

Background

In this review, we describe how the cytoskeletal protein Merlin, encoded by the Neurofibromin 2 (NF2) gene, orchestrates developmental signaling to ensure normal ontogeny, and we discuss how Merlin deficiency leads to aberrant activation of developmental pathways that enable tumor development and malignant progression.

Main body

Parallels between embryonic development and cancer have underscored the activation of developmental signaling pathways. Hippo, WNT/β-catenin, TGF-β, receptor tyrosine kinase (RTK), Notch, and Hedgehog pathways are key players in normal developmental biology. Unrestrained activity or loss of activity of these pathways causes adverse effects in developing tissues manifesting as developmental syndromes. Interestingly, these detrimental events also impact differentiated and functional tissues. By promoting cell proliferation, migration, and stem-cell like phenotypes, deregulated activity of these pathways promotes carcinogenesis and cancer progression. The NF2 gene product, Merlin, is a tumor suppressor classically known for its ability to induce contact-dependent growth inhibition. Merlin plays a role in different stages of an organism development, ranging from embryonic to mature states. While homozygous deletion of Nf2 in murine embryos causes embryonic lethality, Merlin loss in adult tissue is implicated in Neurofibromatosis type 2 disorder and cancer. These manifestations, cumulatively, are reminiscent of dysregulated developmental signaling.

Conclusion

Understanding the molecular and cellular repercussions of Merlin loss provides fundamental insights into the etiology of developmental disorders and cancer and has the potential, in the long term, to identify new therapeutic strategies.

The Role of the Spinal Wnt Signaling Pathway in HIV-Related Neuropathic Pain

Human immunodeficiency virus (HIV)-related neuropathic pain includes HIV-induced neuropathic pain (HNP) and antiretroviral therapy-induced neuropathic pain (ART-NP). A significant amount of evidence from the past few years has shown that the development of HIV-related neuropathic pain is closely related to the activation of the Wnt signaling pathway in the spinal cord. This review summarizes the function of the spinal Wnt signaling pathway in HIV-induced neuropathic pain, focusing on the role of the spinal Wnt signaling pathway in HNP, and provides a theoretical basis for further studies and the exploration of new target drugs.

The CREB-binding protein inhibitor ICG-001: a promising therapeutic strategy in sporadic meningioma with NF2 mutations

Background

Meningiomas with Neurofibromin 2 gene mutations (NF2-mutant meningiomas) account for ~40% of the sporadic meningiomas. However, there is still no effective drug treatment for the disease.

Methods

Expression profile of Merlin protein was explored through immunohistochemistry in a meningioma patient cohort (n = 346). A 20-agent library covering a wide range of meningioma relevant targets was tested using meningioma cell lines IOMM-Lee (NF2 wildtype) and CH157-MN (NF2 deficient). Therapeutic effects and biological mechanisms of the identified compound, ICG-001, in NF2-mutant meningiomas were further characterized in vitro and in patient-derived xenograft (PDX) models.

Results

Low Merlin expression was associated with meningioma proliferation and poor clinical outcomes in a large patient series. ICG-001, a cAMP-responsive element binding (CREB)-binding protein (CBP) inhibitor, selectively suppressed tumor growth of cells with low Merlin expression. Besides, ICG-001 mediated CH157-MN and IOMM-Lee growth inhibition primarily through robust induction of the G1 cell-cycle arrest. Treatment with ICG-001 alone significantly reduced the growth of NF2-mutant xenografts in mice, as well. We also provide further evidence that ICG-001 inhibits proliferation of NF2-mutant meningioma cells at least partly through attenuating the FOXM1-mediated Wnt/β-catenin signaling.

Conclusions

This study highlights the importance of ligand-mediated Wnt/β-catenin signaling as well as its drugable potency in NF2-mutant meningioma.

Long non-coding RNA KDM5B anti-sense RNA 1 enhances tumor progression in non-small cell lung cancer

BACKGROUND

The long non-coding RNAs (lncRNAs) have been shown as a novel class of transcripts with no protein coding functions. LncRNAs can play diverse roles in cancer cell proliferation, differentiation, metastasis, and apoptosis. However, the exact contributions of lncRNA KDM5B anti-sense RNA 1 (KDM5BAS1) to non-small cell lung cancer (NSCLC) remain poorly understood.

METHODS

In current study, we have unraveled a novel function of KDM5BAS1 in NSCLC.

RESULTS

We found that KDM5BAS1 was significantly overexpressed in tumor specimens and selected cancerous cell lines. Meanwhile, higher KDM5BAS1 expression predicted poor overall survival. Increased KDM5BAS1 expression can promote proliferation or migration and inhibit apoptosis in H1838 and H1299 cells. Furthermore, knocking down of KDM5BAS1 levels can also reduce tumor growth in in vivo implantation experiments. Overexpression of KDM5BAS1 also decreased the caspase-3 immunostaining but enhanced Ki-67 staining.

CONCLUSION

Taken together, our findings indicated that KDM5BAS1 might play an oncogenic role in NSCLC and provided clues into pharmacological intervention targeting KDM5BAS1.

microRNA-383 regulates cell viability and apoptosis by mediating Wnt/β-catenin signaling pathway in non-small cell lung cancer

The aim of this study was to investigate the roles of microRNA-383 (miRNA-383) in progression of non-small cell lung cancer (NSCLC) and the potential mechanism. The expressions of miR-383 and Wnt1 protein were detected in lung cancer tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. After the transfection of miR-383 mimics, si-Wnt1 or miR-383+Wnt1, the viability and apoptosis of NSCLC cells were detected by cell counting kit-8 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, respectively. The interaction between miR-383 and Wnt1 was investigated by luciferase activity and Western blot analysis. Cells stably transfected with miR-383 mimics were inoculated into the right axillary of nude mice by subcutaneous injection. The tumor volume and weight were measured, and the expressions of miR-383, Wnt1, β-catenin, and cyclin D1 were detected by qRT-PCR and Western blot analysis. The expression of miR-383 was significantly decreased, and the level of Wnt1 was significantly increased (P < 0.05) in lung cancer tissues and cells. Upregulation of miR-383 or inhibition of Wnt1 expression inhibited the cell viability and induce apoptosis in NSCLC cells. Moreover, Wnt1 was the target gene of miR-383, and its overexpression weakened the regulatory effect of miR-383 on cell viability and apoptosis in NSCLC cells. Besides, the addition of miR-383 decreased the tumor volume and size and inhibited the expressions of Wnt1, β-catenin, and cyclin D1 at the protein level in nude mice. Collectively, miR-383 induced apoptosis and inhibited cell viability as well as tumorigenic capacity in nude mice via regulating the Wnt/β-catenin signaling pathway.

Two Sides of the Coin: Ezrin/Radixin/Moesin and Merlin Control Membrane Structure and Contact Inhibition

The merlin-ERM (ezrin, radixin, moesin) family of proteins plays a central role in linking the cellular membranes to the cortical actin cytoskeleton. Merlin regulates contact inhibition and is an integral part of cell–cell junctions, while ERM proteins, ezrin, radixin and moesin, assist in the formation and maintenance of specialized plasma membrane structures and membrane vesicle structures. These two protein families share a common evolutionary history, having arisen and separated via gene duplication near the origin of metazoa. During approximately 0.5 billion years of evolution, the merlin and ERM family proteins have maintained both sequence and structural conservation to an extraordinary level. Comparing crystal structures of merlin-ERM proteins and their complexes, a picture emerges of the merlin-ERM proteins acting as switchable interaction hubs, assembling protein complexes on cellular membranes and linking them to the actin cytoskeleton. Given the high level of structural conservation between the merlin and ERM family proteins we speculate that they may function together.

MicroRNA-216a suppresses the proliferation and migration of human breast cancer cells via the Wnt/β-catenin signaling pathway

The aim of the present study was to investigate the potential anticancer effects of microRNA-216a on the growth of human breast cancer and the possible underlying mechanisms. The results demonstrated that serum microRNA-216a was significantly decreased in patients with breast cancer compared with healthy controls. MicroRNA-216a overexpression led to a decrease in cell proliferation and migration, as well as increases in apoptosis, caspase-3/8 activities, Bax expression and p53 protein expression in MCF-7 cells. It was also revealed that microRNA-216a suppressed Wnt and β-catenin expression in MCF-7 cells. The anticancer effects of microRNA-216a were reversed by anti-microRNA-216a by promoting the Wnt/β-catenin signaling pathway. Inactivation of the Wnt pathway increased the anticancer effects of microRNA-216a in MCF-7 cells. Collectively, the results of the present study indicated that microRNA-216a suppressed the growth of human breast cancer cells by targeting the Wnt/β-catenin signaling pathway.

Quercetin Prevents In Vivo and In Vitro Myocardial Hypertrophy Through the Proteasome-GSK-3 Pathway

PURPOSE

Quercetin, a flavonoid, has been reported to ameliorate cardiovascular diseases, such as cardiac hypertrophy. However, the mechanism is not completely understood. In this study, a mechanism related to proteasome-glycogen synthesis kinase 3 (GSK-3) was elucidated in rats and primary neonatal cardiomyocytes.

METHODS

Rats were subjected to sham or constriction of abdominal aorta surgery groups and treated with or without quercetin for 8 weeks. Angiotensin II (Ang II)-induced primary cardiomyocytes were cultured with quercetin treatment or not for 48 h. Echocardiography, real-time RT-PCR, histology, immunofluorescence, and Western blotting were conducted. Proteasome activities were also detected using a fluorescent peptide substrate.

RESULTS

Echocardiography showed that quercetin prevented constriction of abdominal aorta-induced cardiac hypertrophy and improved the cardiac diastolic function. In addition, quercetin also significantly reduced the Ang II-induced hypertrophic surface area and atrial natriuretic factor (ANF) mRNA level in primary cardiomyocytes. Proteasome activities were obviously inhibited in the quercetin-treated group both in vivo and in vitro. Quercetin also decreased the levels of proteasome subunit beta type (PSMB) 1, PSMB2, and PSMB5 of the 20S proteasome as well as the levels of proteasome regulatory particle (Rpt) 1 and Rpt4 of the 19S proteasome. In particular, the PSMB5 level in the nucleus was reduced after quercetin treatment. Furthermore, phosphorylated GSK-3α/β (inactivation of GSK-3) was decreased, which means that GSK-3 activity was increased. The phosphorylation levels of upstream AKT (PKB (protein kinase B)) and liver kinase B1/AMP activated protein kinase (LKB1/AMPKα) and those of downstream extracellular signal-regulated kinase (ERK), histone H3, β-catenin, and GATA binding protein 4 (GATA4) were reduced after quercetin treatment, while hypertrophy was reversed after treatment with the GSK-3 inhibitor.

CONCLUSION

In summary, quercetin prevents cardiac hypertrophy, which is related to proteasome inhibition and activation of GSK-3α/β. Upstream (AKT, LKB1/AMPKα) and downstream hypertrophic factors, such as ERK, histone H3, β-catenin, and GATA4, may also be involved.

miR-30a inhibits breast cancer progression through the Wnt/β-catenin pathway

BACKGROUND

miR-30a is a microRNA associated with the progression of malignant tumors such as gastric cancer, colon cancer, prostate cancer, and lung cancer, and can regulate the proliferation and migration of breast cancer (BC) cells in vitro. However, its expression, function, clinical significance and relationship with the Wnt/β-catenin pathway in human BC were still unclear.

METHODS

Immunohistochemistry, Western blotting and real-time quantitative PCR (RT-qPCR) were used to measure the expressions of miR-30a and β-catenin in 114 pairs of human BC tumor tissues and adjacent normal tissues which were collected from March 2014 to October 2015. The effect of miR-30a on the expression of β-catenin was studied in the MCF-7 cells in vitro.

RESULTS

The expression levels of miR-30a in human BC tumor tissues were significantly lower than they were in the adjacent normal tissues (P < 0.001), and significantly higher in β-catenin protein (P < 0.001), but there was no significant different in β-catenin mRNA (P = 0.3816). The immunohistochemistry results showed that β-catenin protein was only expressed on the cell membrane in paracancerous normal tissues, but β-catenin protein was expressed on the cell membrane and cytoplasm in BC tumor cells. In addition, there was a significantly negative correlation (r = -0.816, P < 0.001) between the expression miR-30a and β-catenin protein in BC tissues. The age of onset, PR expression, ER expression, and HER-2 expression of the BC patients were not related to miR-30a or β-catenin protein expression (P > 0.05). Tumor diameter, histological grade, lymph node metastasis, TNM stage, and the prognosis of BC patients (P < 0.05) were significantly related to miR-30a or β-catenin protein expression. In MCF-7 cells, miR-30a regulated the accumulation of β-catenin protein by inhibiting the expression of BCL9 in BC cells.

CONCLUSION

miR-30a was lowly expressed in breast cancer tissues and highly in β-catenin protein, and miR-30a might block the Wnt/β-catenin pathway by inhibiting the accumulation of β-catenin, and then inhibiting breast cancer progression.

Deficiency of tumor suppressor Merlin facilitates metabolic adaptation by co-operative engagement of SMAD-Hippo signaling in breast cancer

The NF2 gene encodes the tumor and metastasis suppressor protein Merlin. Merlin exerts its tumor suppressive role by inhibiting proliferation and inducing contact-growth inhibition and apoptosis. In the current investigation, we determined that loss of Merlin in breast cancer tissues is concordant with the loss of the inhibitory SMAD, SMAD7, of the TGF-β pathway. This was reflected as dysregulated activation of TGF-β signaling that co-operatively engaged with effectors of the Hippo pathway (YAP/TAZ/TEAD). As a consequence, the loss of Merlin in breast cancer resulted in a significant metabolic and bioenergetic adaptation of cells characterized by increased aerobic glycolysis and decreased oxygen consumption. Mechanistically, we determined that the co-operative activity of the Hippo and TGF-β transcription effectors caused upregulation of the long non-coding RNA Urothelial Cancer-Associated 1 (UCA1) that disengaged Merlin's check on STAT3 activity. The consequent upregulation of Hexokinase 2 (HK2) enabled a metabolic shift towards aerobic glycolysis. In fact, Merlin deficiency engendered cellular dependence on this metabolic adaptation, endorsing a critical role for Merlin in regulating cellular metabolism. This is the first report of Merlin functioning as a molecular restraint on cellular metabolism. Thus, breast cancer patients whose tumors demonstrate concordant loss of Merlin and SMAD7 may benefit from an approach of incorporating STAT3 inhibitors.

The ERM family member Merlin is required for endometrial gland morphogenesis

Disruption of endometrial gland formation or function can cause female infertility. Formation of endometrial glands via tubulogenesis of luminal epithelial cells requires the establishment and maintenance of cell polarity and cell adhesion. The FERM domain-containing protein Merlin coordinates epithelial cell polarity and cell adhesion and is critical for epithelial tissue function in the skin and kidney. We now demonstrate a requirement for Merlin in endometrial gland development. Conditional deletion of Merlin in the endometrium results in female infertility caused by the absence of gland formation. Interestingly, we observed glandular epithelial markers within discrete groups of cells in the Merlin-deficient luminal epithelium. Wnt signaling, a pathway necessary for endometrial gland development is maintained in Merlin-deficient endometrium, suggesting the glandular fate program is active. Instead, we observe increased levels of apical actin and markers indicative of high membrane tension on the basal surface of the Merlin-deficient luminal epithelium. These findings suggest that the structural integrity of the luminal epithelium during gland formation is required for appropriate endometrial tubulogenesis and tissue function. Moreover, our work implicates Merlin-dependent regulation of mechanical tension in the proper formation of endometrial gland architecture and function.

The association of NF2 (neurofibromin 2) gene polymorphism and the risk of medulloblastomas

To explore the relationship between NF2 promoter gene mutation and the risk of medulloblastomas (MBs). We collected tissues from 16 MB patients and 7 age-matched non-MB controls. Gene sequencing, qPCR (real-time quantitative polymerase chain reaction), IHC (immunohistochemistry), and WB (Western blot) were used to analyze the changes in the NF2 gene sequence and expression between patients and controls. We found that NF2 promoter gene mutations occurred in MB patients. The NF2 mRNA expression was higher in the controls than in patients (p = 0.03 < 0.05); however, the results of IHC and WB demonstrated that the NF2 protein expression was significantly higher in patients than in the controls (IHC: p = 0.0001; WB: p = 0.01). There was no significant difference in the CRL4 mRNA and protein levels. In addition, NF2 protein was mainly expressed in the nucleus in MB patients, while the NF2 protein was mainly expressed in the cytoplasm in the controls. NF2 promoter mutations exist in MB patients. NF2 mRNA expression was higher in controls than patients; whereas NF2 protein level was higher in patients than in controls.

Traditional and systems biology based drug discovery for the rare tumor syndrome neurofibromatosis type 2

Neurofibromatosis 2 (NF2) is a rare tumor suppressor syndrome that manifests with multiple schwannomas and meningiomas. There are no effective drug therapies for these benign tumors and conventional therapies have limited efficacy. Various model systems have been created and several drug targets have been implicated in NF2-driven tumorigenesis based on known effects of the absence of merlin, the product of the NF2 gene. We tested priority compounds based on known biology with traditional dose-concentration studies in meningioma and schwann cell systems. Concurrently, we studied functional kinome and gene expression in these cells pre- and post-treatment to determine merlin deficient molecular phenotypes. Cell viability results showed that three agents (GSK2126458, Panobinostat, CUDC-907) had the greatest activity across schwannoma and meningioma cell systems, but merlin status did not significantly influence response. In vivo, drug effect was tumor specific with meningioma, but not schwannoma, showing response to GSK2126458 and Panobinostat. In culture, changes in both the transcriptome and kinome in response to treatment clustered predominantly based on tumor type. However, there were differences in both gene expression and functional kinome at baseline between meningioma and schwannoma cell systems that may form the basis for future selective therapies. This work has created an openly accessible resource (www.synapse.org/SynodosNF2) of fully characterized isogenic schwannoma and meningioma cell systems as well as a rich data source of kinome and transcriptome data from these assay systems before and after treatment that enables single and combination drug discovery based on molecular phenotype.

Genome-Wide CRISPR Screen for Essential Cell Growth Mediators in Mutant KRAS Colorectal Cancers

Targeting mutant KRAS signaling pathways continues to attract attention as a therapeutic strategy for KRAS-driven tumors. In this study, we exploited the power of the CRISPR-Cas9 system to identify genes affecting the tumor xenograft growth of human mutant KRAS (KRAS^MUT) colorectal cancers. Using pooled lentiviral single-guide RNA libraries, we conducted a genome-wide loss-of-function genetic screen in an isogenic pair of human colorectal cancer cell lines harboring mutant or wild-type KRAS. The screen identified novel and established synthetic enhancers or synthetic lethals for KRAS^MUT colorectal cancer, including targetable metabolic genes. Notably, genetic disruption or pharmacologic inhibition of the metabolic enzymes NAD kinase or ketohexokinase was growth inhibitory in vivo In addition, the chromatin remodeling protein INO80C was identified as a novel tumor suppressor in KRAS^MUT colorectal and pancreatic tumor xenografts. Our findings define a novel targetable set of therapeutic targets for KRAS^MUT tumors. Cancer Res; 77(22); 6330-9. ©2017 AACR.

Global Proteome and Phospho-proteome Analysis of Merlin-deficient Meningioma and Schwannoma Identifies PDLIM2 as a Novel Therapeutic Target

Loss or mutation of the tumour suppressor Merlin predisposes individuals to develop multiple nervous system tumours, including schwannomas and meningiomas, sporadically or as part of the autosomal dominant inherited condition Neurofibromatosis 2 (NF2). These tumours display largely low grade features but their presence can lead to significant morbidity. Surgery and radiotherapy remain the only treatment options despite years of research, therefore an effective therapeutic is required.

Unbiased omics studies have become pivotal in the identification of differentially expressed genes and proteins that may act as drug targets or biomarkers. Here we analysed the proteome and phospho-proteome of these genetically defined tumours using primary human tumour cells to identify upregulated/activated proteins and/or pathways. We identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to human Schwann and meningeal cells respectively. Using functional enrichment analysis we highlighted several dysregulated pathways and Gene Ontology terms. We identified several proteins and phospho-proteins that are more highly expressed in tumours compared to controls. Among proteins jointly dysregulated in both tumours we focused in particular on PDZ and LIM domain protein 2 (PDLIM2) and validated its overexpression in several tumour samples, while not detecting it in normal cells. We showed that shRNA mediated knockdown of PDLIM2 in both primary meningioma and schwannoma leads to significant reductions in cellular proliferation.

To our knowledge, this is the first comprehensive assessment of the NF2-related meningioma and schwannoma proteome and phospho-proteome. Taken together, our data highlight several commonly deregulated factors, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma.

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Proteome and phosphoproteome of Merlin-deficient schwannomas and meningiomas were analysed.

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Comparative studies highlighted several pathways relevant for therapeutic intervention.

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PDLIM2 was identified as a novel, commonly upregulated protein in both tumours.

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PDLIM2 knockdown led to a significant reduction in proliferation in both cell types.

Loss or mutation of the protein Merlin causes a genetic condition known as Neurofibromatosis 2 (NF2) characterised by the growth of schwannomas and meningiomas.

We analysed several of these tumour samples and identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to normal controls. We identified PDZ and LIM domain protein 2 (PDLIM2) as overexpressed in both tumour types and further showed that knockdown of PDLIM2 leads to significant reductions in cellular proliferation.

Taken together, our data highlight several deregulated signalling pathways, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma.

Loss of tricellular tight junction protein LSR promotes cell invasion and migration via upregulation of TEAD1/AREG in human endometrial cancer

Lipolysis-stimulated lipoprotein receptor (LSR) is a unique molecule of tricellular contacts of normal and cancer cells. We investigated how the loss of LSR induced cell migration, invasion and proliferation in endometrial cancer cell line Sawano. mRNAs of amphiregulin (AREG) and TEA domain family member 1 (TEAD1) were markedly upregulated by siRNA-LSR. In endometrial cancer tissues, downregulation of LSR and upregulation of AREG were observed together with malignancy, and Yes-associated protein (YAP) was present in the nuclei. siRNA-AREG prevented the cell migration and invasion induced by siRNA-LSR, whereas treatment with AREG induced cell migration and invasion. LSR was colocalized with TRIC, angiomotin (AMOT), Merlin and phosphorylated YAP (pYAP). siRNA-LSR increased expression of pYAP and decreased that of AMOT and Merlin. siRNA-YAP prevented expression of the mRNAs of AREG and TEAD1, and the cell migration and invasion induced by siRNA-LSR. Treatment with dobutamine and 2-deoxy-D-glucose and glucose starvation induced the pYAP expression and prevented the cell migration and invasion induced by siRNA-LSR. siRNA-AMOT decreased the Merlin expression and prevented the cell migration and invasion induced by siRNA-LSR. The loss of LSR promoted cell invasion and migration via upregulation of TEAD1/AREG dependent on YAP/pYAP and AMOT/Merlin in human endometrial cancer cells.