Gliovascular transcriptional perturbations in Alzheimer's disease reveal molecular mechanisms of blood brain barrier dysfunction.

To uncover molecular changes underlying blood-brain-barrier dysfunction in Alzheimer's disease, we performed single nucleus RNA sequencing in 24 Alzheimer's disease and control brains and focused on vascular and astrocyte clusters as main cell types of blood-brain-barrier gliovascular-unit. The majority of the vascular transcriptional changes were in pericytes. Of the vascular molecular targets predicted to interact with astrocytic ligands, SMAD3, upregulated in Alzheimer's disease pericytes, has the highest number of ligands including VEGFA, downregulated in Alzheimer's disease astrocytes. We validated these findings with external datasets comprising 4,730 pericyte and 150,664 astrocyte nuclei. Blood SMAD3 levels are associated with Alzheimer's disease-related neuroimaging outcomes. We determined inverse relationships between pericytic SMAD3 and astrocytic VEGFA in human iPSC and zebrafish models. Here, we detect vast transcriptome changes in Alzheimer's disease at the gliovascular-unit, prioritize perturbed pericytic SMAD3-astrocytic VEGFA interactions, and validate these in cross-species models to provide a molecular mechanism of blood-brain-barrier disintegrity in Alzheimer's disease.

APOE deficiency impacts neural differentiation and cholesterol biosynthesis in human iPSC-derived cerebral organoids.

BACKGROUND: The apolipoprotein E (APOE) gene is the strongest genetic risk factor for Alzheimer's disease (AD); however, how it modulates brain homeostasis is not clear. The apoE protein is a major lipid carrier in the brain transporting lipids such as cholesterol among different brain cell types. METHODS: We generated three-dimensional (3-D) cerebral organoids from human parental iPSC lines and its isogenic APOE-deficient (APOE-/-) iPSC line. To elucidate the cell-type-specific effects of APOE deficiency in the cerebral organoids, we performed scRNA-seq in the parental and APOE-/- cerebral organoids at Day 90. RESULTS: We show that APOE deficiency in human iPSC-derived cerebral organoids impacts brain lipid homeostasis by modulating multiple cellular and molecular pathways. Molecular profiling through single-cell RNA sequencing revealed that APOE deficiency leads to changes in cellular composition of isogenic cerebral organoids likely by modulating the eukaryotic initiation factor 2 (EIF2) signaling pathway as these events were alleviated by the treatment of an integrated stress response inhibitor (ISRIB). APOE deletion also leads to activation of the Wnt/ß-catenin signaling pathway with concomitant decrease of secreted frizzled-related protein 1 (SFRP1) expression in glia cells. Importantly, the critical role of apoE in cell-type-specific lipid homeostasis was observed upon APOE deletion in cerebral organoids with a specific upregulation of cholesterol biosynthesis in excitatory neurons and excessive lipid accumulation in astrocytes. Relevant to human AD, APOE4 cerebral organoids show altered neurogenesis and cholesterol metabolism compared to those with APOE3. CONCLUSIONS: Our work demonstrates critical roles of apoE in brain homeostasis and offers critical insights into the APOE4-related pathogenic mechanisms.

A Syx-RhoA-Dia1 signaling axis regulates cell cycle progression, DNA damage, and therapy resistance in glioblastoma.

Glioblastomas (GBM) are aggressive tumors that lack effective treatments. Here, we show that the Rho family guanine nucleotide exchange factor Syx promotes GBM cell growth both in vitro and in orthotopic xenografts derived from patients with GBM. Growth defects upon Syx depletion are attributed to prolonged mitosis, increased DNA damage, G2/M cell cycle arrest, and cell apoptosis, mediated by altered mRNA and protein expression of various cell cycle regulators. These effects are phenocopied by depletion of the Rho downstream effector Dia1 and are due, at least in part, to increased phosphorylation, cytoplasmic retention, and reduced activity of the YAP/TAZ transcriptional coactivators. Furthermore, targeting Syx signaling cooperates with radiation treatment and temozolomide (TMZ) to decrease viability in GBM cells, irrespective of their inherent response to TMZ. The data indicate that a Syx-RhoA-Dia1-YAP/TAZ signaling axis regulates cell cycle progression, DNA damage, and therapy resistance in GBM and argue for its targeting for cancer treatment.

Substitution of PINK1 Gly411 modulates substrate receptivity and turnover.

The ubiquitin (Ub) kinase-ligase pair PINK1-PRKN mediates the degradation of damaged mitochondria by macroautophagy/autophagy (mitophagy). PINK1 surveils mitochondria and upon stress accumulates on the mitochondrial surface where it phosphorylates serine 65 of Ub to activate PRKN and to drive mitochondrial turnover. While loss of either PINK1 or PRKN is genetically linked to Parkinson disease (PD) and activating the pathway seems to have great therapeutic potential, there is no formal proof that stimulation of mitophagy is always beneficial. Here we used biochemical and cell biological methods to study single nucleotide variants in the activation loop of PINK1 to modulate the enzymatic function of this kinase. Structural modeling and in vitro kinase assays were used to investigate the molecular mechanism of the PINK1 variants. In contrast to the PD-linked PINK1G411S mutation that diminishes Ub kinase activity, we found that the PINK1G411A variant significantly boosted Ub phosphorylation beyond levels of PINK1 wild type. This resulted in augmented PRKN activation, mitophagy rates and increased viability after mitochondrial stress in midbrain-derived, gene-edited neurons. Mechanistically, the G411A variant stabilizes the kinase fold of PINK1 and transforms Ub to adopt the preferred, C-terminally retracted conformation for improved substrate turnover. In summary, we identify a critical role of residue 411 for substrate receptivity that may now be exploited for drug discovery to increase the enzymatic function of PINK1. The genetic substitution of Gly411 to Ala increases mitophagy and may be useful to confirm neuroprotection in vivo and might serve as a critical positive control during therapeutic development.Abbreviations: ATP: adenosine triphosphate; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; Ub-CR: ubiquitin with C-terminally retracted tail; CTD: C-terminal domain (of PINK1); ELISA: enzyme-linked immunosorbent assay; HCI: high-content imaging; IB: immunoblot; IF: immunofluorescence; NPC: neuronal precursor cells; MDS: molecular dynamics simulation; PD: Parkinson disease; p-S65-Ub: ubiquitin phosphorylated at Ser65; RMSF: root mean scare fluctuation; TOMM: translocase of outer mitochondrial membrane; TVLN: ubiquitin with T66V and L67N mutation, mimics Ub-CR; Ub: ubiquitin; WT: wild-type.

Transcriptional landscape of human microglia implicates age, sex, and APOE-related immunometabolic pathway perturbations.

Microglia have fundamental roles in health and disease; however, effects of age, sex, and genetic factors on human microglia have not been fully explored. We applied bulk and single-cell approaches to comprehensively characterize human microglia transcriptomes and their associations with age, sex, and APOE. We identified a novel microglial signature, characterized its expression in bulk tissue and single-cell microglia transcriptomes. We discovered microglial co-expression network modules associated with age, sex, and APOE-ε4 that are enriched for lipid and carbohydrate metabolism genes. Integrated analyses of modules with single-cell transcriptomes revealed significant overlap between age-associated module genes and both pro-inflammatory and disease-associated microglial clusters. These modules and clusters harbor known neurodegenerative disease genes including APOE, PLCG2, and BIN1. Meta-analyses with published bulk and single-cell microglial datasets further supported our findings. Thus, these data represent a well-characterized human microglial transcriptome resource and highlight age, sex, and APOE-related microglial immunometabolism perturbations with potential relevance in neurodegeneration.

The AD tau core spontaneously self-assembles and recruits full-length tau to filaments.

Tau accumulation is a major pathological hallmark of Alzheimer's disease (AD) and other tauopathies, but the mechanism(s) of tau aggregation remains unclear. Taking advantage of the identification of tau filament cores by cryoelectron microscopy, we demonstrate that the AD tau core possesses the intrinsic ability to spontaneously aggregate in the absence of an inducer, with antibodies generated against AD tau core filaments detecting AD tau pathology. The AD tau core also drives aggregation of full-length wild-type tau, increases seeding potential, and templates abnormal forms of tau present in brain homogenates and antemortem cerebrospinal fluid (CSF) from patients with AD in an ultrasensitive real-time quaking-induced conversion (QuIC) assay. Finally, we show that the filament cores in corticobasal degeneration (CBD) and Pick's disease (PiD) similarly assemble into filaments under physiological conditions. These results document an approach to modeling tau aggregation and have significant implications for in vivo investigation of tau transmission and biomarker development.

Brain metastases-derived extracellular vesicles induce binding and aggregation of low-density lipoprotein.

BACKGROUND: Cancer cell-derived extracellular vesicles (EVs) have previously been shown to contribute to pre-metastatic niche formation. Specifically, aggressive tumors secrete pro-metastatic EVs that travel in the circulation to distant organs to modulate the microenvironment for future metastatic spread. Previous studies have focused on the interface between pro-metastatic EVs and epithelial/endothelial cells in the pre-metastatic niche. However, EV interactions with circulating components such as low-density lipoprotein (LDL) have been overlooked. RESULTS: This study demonstrates that EVs derived from brain metastases cells (Br-EVs) and corresponding regular cancer cells (Reg-EVs) display different interactions with LDL. Specifically, Br-EVs trigger LDL aggregation, and the presence of LDL accelerates Br-EV uptake by monocytes, which are key components in the brain metastatic niche. CONCLUSIONS: Collectively, these data are the first to demonstrate that pro-metastatic EVs display distinct interactions with LDL, which impacts monocyte internalization of EVs.

Targeting CD38 is lethal to Breg-like chronic lymphocytic leukemia cells and Tregs, but restores CD8+ T-cell responses.

Patients with chronic lymphocytic leukemia (CLL) are characterized by monoclonal expansion of CD5+CD23+CD27+CD19+κ/λ+ B lymphocytes and are clinically noted to have profound immune suppression. In these patients, it has been recently shown that a subset of B cells possesses regulatory functions and secretes high levels of interleukin 10 (IL-10). Our investigation identified that CLL cells with a CD19+CD24+CD38hi immunophenotype (B regulatory cell [Breg]-like CLL cells) produce high amounts of IL-10 and transforming growth factor ß (TGF-ß) and are capable of transforming naive T helper cells into CD4+CD25+FoxP3+ T regulatory cells (Tregs) in an IL-10/TGF-ß-dependent manner. A strong correlation between the percentage of CD38+ CLL cells and Tregs was observed. CD38hi Tregs comprised more than 50% of Tregs in peripheral blood mononuclear cells (PBMCs) in patients with CLL. Anti-CD38 targeting agents resulted in lethality of both Breg-like CLL and Treg cells via apoptosis. Ex vivo, use of anti-CD38 monoclonal antibody (mAb) therapy was associated with a reduction in IL-10 and CLL patient-derived Tregs, but an increase in interferon-γ and proliferation of cytotoxic CD8+ T cells with an activated phenotype, which showed an improved ability to lyse patient-autologous CLL cells. Finally, effects of anti-CD38 mAb therapy were validated in a CLL-patient-derived xenograft model in vivo, which showed decreased percentage of Bregs, Tregs, and PD1+CD38hiCD8+ T cells, but increased Th17 and CD8+ T cells (vs vehicle). Altogether, our results demonstrate that targeting CD38 in CLL can modulate the tumor microenvironment; skewing T-cell populations from an immunosuppressive to immune-reactive milieu, thus promoting immune reconstitution for enhanced anti-CLL response.

Adipose-Derived Biogenic Nanoparticles for Suppression of Inflammation.

Extracellular vesicles secreted from adipose-derived mesenchymal stem cells (ADSCs) have therapeutic effects in inflammatory diseases. However, production of extracellular vesicles (EVs) from ADSCs is costly, inefficient, and time consuming. The anti-inflammatory properties of adipose tissue-derived EVs and other biogenic nanoparticles have not been explored. In this study, biogenic nanoparticles are obtained directly from lipoaspirate, an easily accessible and abundant source of biological material. Compared to ADSC-EVs, lipoaspirate nanoparticles (Lipo-NPs) take less time to process (hours compared to months) and cost less to produce (clinical-grade cell culture facilities are not required). The physicochemical characteristics and anti-inflammatory properties of Lipo-NPs are evaluated and compared to those of patient-matched ADSC-EVs. Moreover, guanabenz loading in Lipo-NPs is evaluated for enhanced anti-inflammatory effects. Apolipoprotein E and glycerolipids are enriched in Lipo-NPs compared to ADSC-EVs. Additionally, the uptake of Lipo-NPs in hepatocytes and macrophages is higher. Lipo-NPs and ADSC-EVs have comparable protective and anti-inflammatory effects. Specifically, Lipo-NPs reduce toll-like receptor 4-induced secretion of inflammatory cytokines in macrophages. Guanabenz-loaded Lipo-NPs further suppress inflammatory pathways, suggesting that this combination therapy can have promising applications for inflammatory diseases.

Targeting Liver Cancer Stem Cells Using Engineered Biological Nanoparticles for the Treatment of Hepatocellular Cancer.

By exploiting their biological functions, the use of biological nanoparticles such as extracellular vesicles can provide an efficient and effective approach for hepatic delivery of RNA-based therapeutics for the treatment of liver cancers such as hepatocellular cancer (HCC). Targeting liver cancer stem cells (LCSC) within HCC provide an untapped opportunity to improve outcomes by enhancing therapeutic responses. Cells with tumor-initiating capabilities such as LCSC can be identified by expression of markers such as epithelial cell adhesion molecule (EpCAM) on their cell surface. EpCAM is a target of Wnt/ß-catenin signaling, a fundamental pathway in stem-cell growth. Moreover, mutations in the ß-catenin gene are frequently observed in HCC and can be associated with constitutive activation of the Wnt/ß-catenin pathway. However, targeting these pathways for the treatment of HCC has been challenging. Using RNA nanotechnology, we developed engineered biological nanoparticles capable of specific and effective delivery of RNA therapeutics targeting ß-catenin to LCSC. Extracellular vesicles isolated from milk were loaded with small interfering RNA to ß-catenin and decorated with RNA scaffolds to incorporate RNA aptamers capable of binding to EpCAM. Cellular uptake of these EpCAM-targeting therapeutic milk-derived nanovesicles in vitro resulted in loss of ß-catenin expression and decreased proliferation. The uptake and therapeutic efficacy of these engineered biological nanotherapeutics was demonstrated in vivo using tumor xenograft mouse models. Conclusion: ß-catenin can be targeted directly to control the proliferation of hepatic cancer stem cells using small interfering RNA delivered using target-specific biological nanoparticles. Application of this RNA nanotechnology-based approach to engineer biological nanotherapeutics provides a platform for developing cell-surface molecule-directed targeted therapeutics.

Tau exhibits unique seeding properties in globular glial tauopathy.

Tauopathies are neurodegenerative disorders characterized by aggregation of microtubule associated tau protein in neurons and glia. They are clinically and pathologically heterogeneous depending on the isoform of tau protein that accumulates (three or four 31-to-32-amino-acid repeats [3R or 4R] in the microtubule binding domain), as well as the cellular and neuroanatomical distribution of tau pathology. Growing evidence suggests that distinct tau conformers may contribute to the characteristic features of various tauopathies. Globular glial tauopathy (GGT) is a rare 4R tauopathy with globular cytoplasmic inclusions within neurons and glial cells. Given the unique cellular distribution and morphology of tau pathology in GGT, we sought to determine if tau species in GGT had distinctive biological properties. To address this question, we performed seeding analyses with postmortem brain tissues using a commercial tau biosensor cell line. We found that brain lysates from GGT cases had significantly higher seeding competency than other tauopathies, including corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and Alzheimer's disease (AD). The robust seeding activity of GGT brain lysates was independent of phosphorylated tau burden and diminished upon removal of tau from samples, suggesting that seeding properties were indeed mediated by tau in the lysates. In addition, cellular inclusions in the tau biosensor cell line induced by GGT had a distinct, globular morphology that was markedly different from inclusions induced by other tauopathies, further highlighting the unique nature of tau species in GGT. Characterization of different tau species in GGT showed that detergent-insoluble, fibril-like tau contained the highest seeding activity, as reflected in its ability to increase tau aggregation in primary glial cultures. Taken together, our data suggest that unique seeding properties differentiate GGT-tau from other tauopathies, which provides new insight into pathogenic heterogeneity of primary neurodegenerative tauopathies.

Src family kinases differentially influence glioma growth and motility.

Src-family kinase (SFK) signaling impacts multiple tumor-related properties, particularly in the context of the brain tumor glioblastoma. Consequently, the pan-SFK inhibitor dasatinib has emerged as a therapeutic strategy, despite physiologic limitations to its effectiveness in the brain. We investigated the importance of individual SFKs (Src, Fyn, Yes, and Lyn) to glioma tumor biology by knocking down individual SFK expression both in culture (LN229, SF767, GBM8) and orthotopic xenograft (GBM8) contexts. We evaluated the effects of these knockdowns on tumor cell proliferation, migration, and motility-related signaling in culture, as well as overall survival in the orthotopic xenograft model. The four SFKs differed significantly in their importance to these properties. In culture, Src, Fyn, and Yes knockdown generally reduced growth and migration and altered motility-related phosphorylation patterns while Lyn knockdown did so to a lesser extent. However the details of these effects varied significantly depending on the cell line: in no case were conclusions about the role of a particular SFK applicable to all of the measures or all of the cell types examined. In the orthotopic xenograft model, mice implanted with non-target or Src or Fyn knockdown cells showed no differences in survival. In contrast, mice implanted with Yes knockdown cells had longer survival, associated with reduced tumor cell proliferation. Those implanted with Lyn knockdown cells had shorter survival, associated with higher overall tumor burden. Together, our results suggest that Yes signaling directly affects tumor cell biology in a pro-tumorigenic manner, while Lyn signaling affects interactions between tumor cells and the microenvironment in an anti-tumor manner. In the context of therapeutic targeting of SFKs, these results suggest that pan-SFK inhibitors may not produce the intended therapeutic benefit when Lyn is present.

Folate receptor-α (FOLR1) expression and function in triple negative tumors.

Folate receptor alpha (FOLR1) has been identified as a potential prognostic and therapeutic target in a number of cancers. A correlation has been shown between intense overexpression of FOLR1 in breast tumors and poor prognosis, yet there is limited examination of the distribution of FOLR1 across clinically relevant breast cancer subtypes. To explore this further, we used RNA-seq data from multiple patient cohorts to analyze the distribution of FOLR1 mRNA across breast cancer subtypes comprised of estrogen receptor positive (ER+), human epidermal growth factor receptor positive (HER2+), and triple negative (TNBC) tumors. FOLR1 expression varied within breast tumor subtypes; triple negative/basal tumors were significantly associated with increased expression of FOLR1 mRNA, compared to ER+ and HER2+ tumors. However, subsets of high level FOLR1 expressing tumors were observed in all clinical subtypes. These observations were supported by immunohistochemical analysis of tissue microarrays, with the largest number of 3+ positive tumors and highest H-scores of any subtype represented by triple negatives, and lowest by ER+ tumors. FOLR1 expression did not correlate to common clinicopathological parameters such as tumor stage and nodal status. To delineate the importance of FOLR1 overexpression in triple negative cancers, RNA-interference was used to deplete FOLR1 in overexpressing triple negative cell breast lines. Loss of FOLR1 resulted in growth inhibition, whereas FOLR1 overexpression promoted folate uptake and growth advantage in low folate conditions. Taken together, our data suggests patients with triple negative cancers expressing high FOLR1 expression represent an important population of patients that may benefit from targeted anti-FOLR1 therapy. This may prove particularly helpful for a large number of patients who would typically be classified as triple negative and who to this point have been left without any targeted treatment options.

The Rho guanine nucleotide exchange factor Syx regulates the balance of dia and ROCK activities to promote polarized-cancer-cell migration.

The role of RhoA in promoting directed cell migration has been complicated by studies showing that it is activated both in the front and the rear of migrating cells. We report here that the RhoA-specific guanine nucleotide exchange factor Syx is required for the polarity of actively migrating brain and breast tumor cells. This function of Syx is mediated by the selective activation of the RhoA downstream effector Dia1, the subsequent reorganization of microtubules, and the downregulation of focal adhesions and actin stress fibers. The data argue that directed cell migration requires the precise spatiotemporal regulation of Dia1 and ROCK activities in the cell. The recruitment of Syx to the cell membrane and the subsequent selective activation of Dia1 signaling, coupled with the suppression of ROCK and activation of cofilin-mediated actin reorganization, plays a key role in establishing cell polarity during directed cell migration.

Protein kinase D1-mediated phosphorylations regulate vasodilator-stimulated phosphoprotein (VASP) localization and cell migration.

Enabled/Vasodilator-stimulated phosphoprotein (Ena/VASP) protein family members link actin dynamics and cellular signaling pathways. VASP localizes to regions of dynamic actin reorganization such as the focal adhesion contacts, the leading edge or filopodia, where it contributes to F-actin filament elongation. Here we identify VASP as a novel substrate for protein kinase D1 (PKD1). We show that PKD1 directly phosphorylates VASP at two serine residues, Ser-157 and Ser-322. These phosphorylations occur in response to RhoA activation and mediate VASP re-localization from focal contacts to the leading edge region. The net result of this PKD1-mediated phosphorylation switch in VASP is increased filopodia formation and length at the leading edge. However, such signaling when persistent induced membrane ruffling and decreased cell motility.

Targeting Src family kinases inhibits bevacizumab-induced glioma cell invasion.

Anti-VEGF antibody therapy with bevacizumab provides significant clinical benefit in patients with recurrent glioblastoma multiforme (GBM). Unfortunately, progression on bevacizumab therapy is often associated with a diffuse disease recurrence pattern, which limits subsequent therapeutic options. Therefore, there is an urgent need to understand bevacizumab's influence on glioma biology and block it's actions towards cell invasion. To explore the mechanism(s) of GBM cell invasion we have examined a panel of serially transplanted human GBM lines grown either in short-term culture, as xenografts in mouse flank, or injected orthotopically in mouse brain. Using an orthotopic xenograft model that exhibits increased invasiveness upon bevacizumab treatment, we also tested the effect of dasatinib, a broad spectrum SFK inhibitor, on bevacizumab-induced invasion.We show that 1) activation of Src family kinases (SFKs) is common in GBM, 2) the relative invasiveness of 17 serially transplanted GBM xenografts correlates strongly with p120 catenin phosphorylation at Y228, a Src kinase site, and 3) SFK activation assessed immunohistochemically in orthotopic xenografts, as well as the phosphorylation of downstream substrates occurs specifically at the invasive tumor edge. Further, we show that SFK signaling is markedly elevated at the invasive tumor front upon bevacizumab administration, and that dasatinib treatment effectively blocked the increased invasion induced by bevacizumab.Our data are consistent with the hypothesis that the increased invasiveness associated with anti-VEGF therapy is due to increased SFK signaling, and support testing the combination of dasatinib with bevacizumab in the clinic.

VEGF and Angiopoietin-1 exert opposing effects on cell junctions by regulating the Rho GEF Syx.

Vascular endothelial growth factor (VEGF) and Ang1 (Angiopoietin-1) have opposing effects on vascular permeability, but the molecular basis of these effects is not fully known. We report in this paper that VEGF and Ang1 regulate endothelial cell (EC) junctions by determining the localization of the RhoA-specific guanine nucleotide exchange factor Syx. Syx was recruited to junctions by members of the Crumbs polarity complex and promoted junction integrity by activating Diaphanous. VEGF caused translocation of Syx from cell junctions, promoting junction disassembly, whereas Ang1 maintained Syx at the junctions, inducing junction stabilization. The VEGF-induced translocation of Syx from EC junctions was caused by PKD1 (protein kinase D1)-mediated phosphorylation of Syx at Ser(806), which reduced Syx association to its junctional anchors. In support of the pivotal role of Syx in regulating EC junctions, syx(-/-) mice had defective junctions, resulting in vascular leakiness, edema, and impaired heart function.

E-cadherin's dark side: possible role in tumor progression.

In the context of cancer, E-cadherin has traditionally been categorized as a tumor suppressor, given its essential role in the formation of proper intercellular junctions, and its downregulation in the process of epithelial-mesenchymal transition (EMT) in epithelial tumor progression. Germline or somatic mutations in the E-cadherin gene (CDH1) or downregulation by epigenetic mechanisms have been described in a small subset of epithelial cancers. However, recent evidence also points toward a promoting role of E-cadherin in several aspects of tumor progression. This includes preserved (or increased) E-cadherin expression in microemboli of inflammatory breast carcinoma, a possible "mesenchymal to epithelial transition" (MET) in ovarian carcinoma, collective cell invasion in some epithelial cancers, a recent association of E-cadherin expression with a more aggressive brain tumor subset, as well as the intriguing possibility of E-cadherin involvement in specific signaling networks in the cytoplasm and/or nucleus. In this review we address a lesser-known, positive role for E-cadherin in cancer.