Shc3 facilitates breast cancer drug resistance by interacting with ErbB2 to initiate ErbB2/COX2/MDR1 axis.

Multidrug resistance (MDR) is a primary limitation of breast cancer chemotherapy. The common mechanism of MDR is various anticancer drugs can be effluxed by the cell membrane protein P-glycoprotein (P-gp). Here, we found that ectopic overexpression of Shc3 was detected specifically in drug-resistant breast cancer cells, consequently reducing sensitivity to chemotherapy and promoting cell migration by mediating P-gp expression. However, the molecular mechanism underlying the interplay between P-gp and Shc3 in breast cancer is unknown. We reported an additional resistance mechanism involving an increase in the active form of P-gp after Shc3 upregulation. MCF-7/ADR and SK-BR-3 cells can be sensitive to doxorubicin after knockdown of Shc3. Our results indicated that the interaction between ErbB2 and EphA2 is indirect and regulated by Shc3, and also, this complex is essential for activation of the MAPK and AKT pathways. Meanwhile, Shc3 promotes ErbB2 nuclear translocation, followed by a subsequent increase of the COX2 expression through ErbB2 binding to the COX2 promoter. We further demonstrated that COX2 expression was positively correlated with P-gp expression and the Shc3/ErbB2/COX2 axis upregulates P-gp activity in vivo. Our results show the crucial roles of Shc3 and ErbB2 in modulating P-gp efficacy in breast cancer cells and suggest that Shc3 inhibition may enhance the sensitivity to chemotherapeutic drugs that target oncogene addiction pathways.

Can the hyperthermia-mediated heat shock factor/heat shock protein 70 pathway dampen the cytokine storm during SARS-CoV-2 infection?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major global public health problem. Infection by this virus involves many pathophysiological processes, such as a "cytokine storm," that is, very aggressive inflammatory response that offers new perspectives for the management and treatment of patients. Here, we analyse relevant mechanism involved in the hyperthermia-mediated heat shock factors (HSFs)/heat shock proteins (HSP)70 pathway which may provide a possible treatment tool. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Differential Proteomic Analysis of Astrocytes and Astrocytes-Derived Extracellular Vesicles from Control and Rai Knockout Mice: Insights into the Mechanisms of Neuroprotection.

Reactive astrocytes are a hallmark of neurodegenerative disease including multiple sclerosis. It is widely accepted that astrocytes may adopt alternative phenotypes depending on a combination of environmental cues and intrinsic features in a highly plastic and heterogeneous manner. However, we still lack a full understanding of signals and associated signaling pathways driving astrocyte reaction and of the mechanisms by which they drive disease. We have previously shown in the experimental autoimmune encephalomyelitis mouse model that deficiency of the molecular adaptor Rai reduces disease severity and demyelination. Moreover, using primary mouse astrocytes, we showed that Rai contributes to the generation of a pro-inflammatory central nervous system (CNS) microenvironment through the production of nitric oxide and IL-6 and by impairing CD39 activity in response to soluble factors released by encephalitogenic T cells. Here, we investigated the impact of Rai expression on astrocyte function both under basal conditions and in response to IL-17 treatment using a proteomic approach. We found that astrocytes and astrocyte-derived extracellular vesicles contain a set of proteins, to which Rai contributes, that are involved in the regulation of oligodendrocyte differentiation and myelination, nitrogen metabolism, and oxidative stress. The HIF-1α pathway and cellular energetic metabolism were the most statistically relevant molecular pathways and were related to ENOA and HSP70 dysregulation.

Shc3 promotes hepatocellular carcinoma stemness and drug resistance by interacting with ß-catenin to inhibit its ubiquitin degradation pathway.

Hepatocellular carcinoma (HCC) is one of the most common cancers with an insidious onset, strong invasiveness, insensitivity to chemotherapy, and poor prognosis, thus makes clinical treatment challenging. The mechanisms require further elucidation for developing novel therapies and targeting drug resistance. Here, we observed high Shc3 expression in patients with chemoresistant and recurrent HCCs. Shc3 overexpression induced a significant increase in MDR1/P-glycoprotein expression, whereas Shc3 knockdown impaired this expression. Further, Shc3 inhibition significantly restored HCC cell sensitivity to doxorubicin and sorafenib. Mechanistically, Shc3 interacted with ß-catenin, inhibited destruction complex stability, promoted ß-catenin release, and dampened ß-catenin ubiquitination. Shc3 bound ß-catenin and facilitated its nuclear translocation, prompting the ß-catenin/TCF pathway to elevate MDR1 transcription. ß-catenin blockage abolished the discrepancy in drug resistance between Shc3-depleted HCC cells and control cells, which further validating that ß-catenin is required for Shc3-mediated liver chemotherapy. We also determined the effect of Shc3 on the sensitivity of HCC to chemotherapy in vivo. Collectively, this study provides a potential strategy to target these pathways concurrently with systemic chemotherapy that can improve the clinical treatment of HCC.

A New Pathway Promotes Adaptation of Human Glioblastoma Cells to Glucose Starvation.

Adaptation of glioblastoma to caloric restriction induces compensatory changes in tumor metabolism that are incompletely known. Here we show that in human glioblastoma cells maintained in exhausted medium, SHC adaptor protein 3 (SHC3) increases due to down-regulation of SHC3 protein degradation. This effect is reversed by glucose addition and is not present in normal astrocytes. Increased SHC3 levels are associated to increased glucose uptake mediated by changes in membrane trafficking of glucose transporters of the solute carrier 2A superfamily (GLUT/SLC2A). We found that the effects on vesicle trafficking are mediated by SHC3 interactions with adaptor protein complex 1 and 2 (AP), BMP-2-inducible protein kinase and a fraction of poly ADP-ribose polymerase 1 (PARP1) associated to vesicles containing GLUT/SLC2As. In glioblastoma cells, PARP1 inhibitor veliparib mimics glucose starvation in enhancing glucose uptake. Furthermore, cytosol extracted from glioblastoma cells inhibits PARP1 enzymatic activity in vitro while immunodepletion of SHC3 from the cytosol significantly relieves this inhibition. The identification of a new pathway controlling glucose uptake in high grade gliomas represents an opportunity for repositioning existing drugs and designing new ones.

hNGF Peptides Elicit the NGF-TrkA Signalling Pathway in Cholinergic Neurons and Retain Full Neurotrophic Activity in the DRG Assay.

In the last decade, Nerve Growth Factor (NGF)-based clinical approaches have lacked specific and efficient Tyrosine Kinase A (TrkA) agonists for brain delivery. Nowadays, the characterization of novel small peptidomimetic is taking centre stage in preclinical studies, in order to overcome the main size-related limitation in brain delivery of NGF holoprotein for Central Nervous System (CNS) pathologies. Here we investigated the NGF mimetic properties of the human NGF 1-14 sequence (hNGF1-14) and its derivatives, by resorting to primary cholinergic and dorsal root ganglia (DRG) neurons. Briefly, we observed that: 1) hNGF1-14 peptides engage the NGF pathway through TrkA phosphorylation at tyrosine 490 (Y490), and activation of ShcC/PI3K and Plc-γ/MAPK signalling, promoting AKT-dependent survival and CREB-driven neuronal activity, as seen by levels of the immediate early gene c-Fos, of the cholinergic marker Choline Acetyltransferase (ChAT), and of Brain Derived Neurotrophic Factor (BDNF); 2) their NGF mimetic activity is lost upon selective TrkA inhibition by means of GW441756; 3) hNGF1-14 peptides are able to sustain DRG survival and differentiation in absence of NGF. Furthermore, the acetylated derivative Ac-hNGF1-14 demonstrated an optimal NGF mimetic activity in both neuronal paradigms and an electrophysiological profile similar to NGF in cholinergic neurons. Cumulatively, the findings here reported pinpoint the hNGF1-14 peptide, and in particular its acetylated derivative, as novel, specific and low molecular weight TrkA specific agonists in both CNS and PNS primary neurons.

Hypermethylation of NRG1 gene correlates with the presence of heart defects in Down's syndrome.

Congenital heart defects can decrease the quality of life and life expectancy in affected individuals, and constitute a major burden for the health care systems. Endocardial cushion defects are among the most prevalent heart malformations in the general population, and are extremely frequent (approximately a 100-fold higher prevalence) in children with Down syndrome. Several genes have been proposed to be involved in the pathogenesis of these malformations, but no common pathogenic DNA variants have been identified so far. Here, we focussed on constitutive, epigenetic alterations of function of selected genes, potentially important for endocardial cushion development. We used two types of microarrays, dedicated for assessment of gene promoter methylation and whole genome expression. First, we compared the gene promoter methylation profiles between two groups of Down syndrome patients, with and without heart defects of endocardial cushion-type. Then, to determine the functional role of the detected methylation alterations, we assessed the expression of the genes of interest. We detected significant hypermethylation of the NRG1 gene promoter region in children with heart defects. NRG1 is a key factor in maturation of endocardial cushions. Supplementary gene expression assessment revealed significantly decreased activity of the ERBB3, SHC3 and SHC4 genes in children with heart defects. The above three genes are closely related to the NRG1 gene and are crucial elements of the NRG/ErbB pathway. The results of this pilot study show that hypermethylation of the NRG1 gene promoter can reflect the functional genome alteration contributing to development of congenital heart defects of endocardial cushion-type.

Localization of phosphotyrosine adaptor protein ShcD/SHC4 in the adult rat central nervous system.

BACKGROUND: Mammalian Shc (Src homology and collagen) proteins comprise a family of four phosphotyrosine adaptor molecules which exhibit varied spatiotemporal expression and signaling functions. ShcD is the most recently discovered homologue and it is highly expressed in the developing central nervous system (CNS) and adult brain. Presently however, its localization within specific cell types of mature neural structures has yet to be characterized. RESULTS: In the current study, we examine the expression profile of ShcD in the adult rat CNS using immunohistochemistry, and compare with those of the neuronally enriched ShcB and ShcC proteins. ShcD shows relatively widespread distribution in the adult brain and spinal cord, with prominent levels of staining throughout the olfactory bulb, as well as in sub-structures of the cerebellum and hippocampus, including the subgranular zone. Co-localization studies confirm the expression of ShcD in mature neurons and progenitor cells. ShcD immunoreactivity is primarily localized to axons and somata, consistent with the function of ShcD as a cytoplasmic adaptor. Regional differences in expression are observed among neural Shc proteins, with ShcC predominating in the hippocampus, cerebellum, and some fiber tracts. Interestingly, ShcD is uniquely expressed in the olfactory nerve layer and in glomeruli of the main olfactory bulb. CONCLUSIONS: Together our findings suggest that ShcD may provide a distinct signaling contribution within the olfactory system, and that overlapping expression of ShcD with other Shc proteins may allow compensatory functions in the brain.

A T Cell Suppressive Circuitry Mediated by CD39 and Regulated by ShcC/Rai Is Induced in Astrocytes by Encephalitogenic T Cells.

Multiple sclerosis is an autoimmune disease caused by autoreactive immune cell infiltration into the central nervous system leading to inflammation, demyelination, and neuronal loss. While myelin-reactive Th1 and Th17 are centrally implicated in multiple sclerosis pathogenesis, the local CNS microenvironment, which is shaped by both infiltrated immune cells and central nervous system resident cells, has emerged a key player in disease onset and progression. We have recently demonstrated that ShcC/Rai is as a novel astrocytic adaptor whose loss in mice protects from experimental autoimmune encephalomyelitis. Here, we have explored the mechanisms that underlie the ability of Rai-/- astrocytes to antagonize T cell-dependent neuroinflammation. We show that Rai deficiency enhances the ability of astrocytes to upregulate the expression and activity of the ectonucleotidase CD39, which catalyzes the conversion of extracellular ATP to the immunosuppressive metabolite adenosine, through both contact-dependent and-independent mechanisms. As a result, Rai-deficient astrocytes acquire an enhanced ability to suppress T-cell proliferation, which involves suppression of T cell receptor signaling and upregulation of the inhibitory receptor CTLA-4. Additionally, Rai-deficient astrocytes preferentially polarize to the neuroprotective A2 phenotype. These results identify a new mechanism, to which Rai contributes to a major extent, by which astrocytes modulate the pathogenic potential of autoreactive T cells.

Lentiviral Vector-Mediated SHC3 Silencing Exacerbates Oxidative Stress Injury in Nigral Dopamine Neurons by Regulating the PI3K-AKT-FoxO Signaling Pathway in Rats with Parkinson's Disease.

BACKGROUND/AIMS: Parkinson's disease (PD) is a prevalent disease that leads to motor and cognitive disabilities, and oxidative stress (OS) injury was found to be related to the etiology of PD. Increasing evidence has shown that SHC3 is aberrantly expressed in neurons. The current study examines the involvement of SHC3 silencing in OS injury in the nigral dopamine neurons in rats with PD via the PI3K-AKT-FoxO signaling pathway. METHODS: To study the mechanisms and functions of SHC3 silencing in PD at the tissue level, 170 rats were selected, and a lentivirus-based packaging system was designed to silence SHC3 expression in rats. Furthermore, PC12 cells were selected for in vitro experimentation. To evaluate the effect of SHC3 silencing in nigral dopamine neuronal growth, an MTT assay, propidium iodide (PI) single staining and Annexin V-PI double staining were performed to detect cell viability, cell cycle progression and cell apoptosis, respectively. RESULTS: SHC3 shRNA led to decreased SOD and MDA levels and enhanced GSH activity, indicating that SHC3 silencing leads to motor retardation. SHC3 silencing repressed the extent of Akt and FoxO phosphorylation, thereby inhibiting the PI3K-AKT-FoxO signaling pathway. Furthermore, in cell experiments, SHC3 silencing suppressed PC12 cell proliferation and cell cycle progression, whereas it enhanced cell apoptosis. CONCLUSION: The current study provides evidence suggesting that SHC3 silencing may aggravate OS injury in nigral dopamine neurons via downregulation of the PI3K-AKT-FoxO signaling pathway in PD rats.

Demethylation-Induced Overexpression of Shc3 Drives c-Raf-Independent Activation of MEK/ERK in HCC.

Invasion and intrahepatic metastasis are major factors of poor prognosis in patients with hepatocellular carcinoma (HCC). In this study, we show that increased Src homolog and collagen homolog 3 (Shc3) expression in malignant HCC cell lines associate with HCC invasion and metastasis. Shc3 (N-Shc) was significantly upregulated in tumors of 33 HCC patient samples as compared with adjacent normal tissues. Further analysis of 52 HCC patient samples showed that Shc3 expression correlated with microvascular invasion, cancer staging, and poor prognosis. Shc3 interacted with major vault protein, resulting in activation of MEK1/2 and ERK1/2 independently of Shc1 and c-Raf; this interaction consequently induced epithelial-mesenchymal transition and promoted HCC cell proliferation and metastasis. The observed increase in Shc3 levels was due to demethylation of its upstream promoter, which allowed c-Jun binding. In turn, Shc3 expression promoted c-Jun phosphorylation in a positive feedback loop. Analysis of metastasis using a tumor xenograft mouse model further confirmed the role of Shc3 in vivo Taken together, our results indicate the importance of Shc3 in HCC progression and identify Shc3 as a novel biomarker and potential therapeutic target in HCC.Significance: Ectopic expression of Shc3 forms a complex with MVP/MEK/ERK to potentiate ERK activation and plays an important role in sorafinib resistance in HCC. Cancer Res; 78(9); 2219-32. ©2018 AACR.

MicroRNAs-103/107 coordinately regulate macropinocytosis and autophagy.

Macropinocytosis, by which cells ingest large amounts of fluid, and autophagy, the lysosome-based catabolic process, involve vesicular biogenesis (early stage) and turnover (end stage). Much is known about early-stage events; however, our understanding of how the end stages of these processes are governed is incomplete. Here we demonstrate that the microRNA-103/107(miR-103/107) family, which is preferentially expressed in the stem cell-enriched limbal epithelium, coordinately regulates aspects of both these activities. Loss of miR-103/107 causes dysregulation of macropinocytosis with the formation of large vacuoles, primarily through up-regulation of Src, Ras, and Ankfy1. Vacuole accumulation is not a malfunction of early-stage autophagy; rather, miR-103/107 ensure proper end-stage autophagy by regulating diacylglycerol/protein kinase C and cyclin-dependent kinase 5 signaling, which enables dynamin to function in vacuole clearance. Our findings unveil a key biological function for miR-103/107 in coordinately suppressing macropinocytosis and preserving end-stage autophagy, thereby contributing to maintenance of a stem cell-enriched epithelium.

Involvement of the neuronal phosphotyrosine signal adaptor N-Shc in kainic acid-induced epileptiform activity.

BDNF-TrkB signaling is implicated in experimental seizures and epilepsy. However, the downstream signaling involved in the epileptiform activity caused by TrkB receptor activation is still unknown. The aim of the present study was to determine whether TrkB-mediated N-Shc signal transduction was involved in kainic acid (KA)-induced epileptiform activity. We investigated KA-induced behavioral seizures, epileptiform activities and neuronal cell loss in hippocampus between N-Shc deficient and control mice. There was a significant reduction in seizure severity and the frequency of epileptiform discharges in N-Shc deficient mice, as compared with wild-type and C57BL/6 mice. KA-induced neuronal cell loss in the CA3 of hippocampus was also inhibited in N-Shc deficient mice. This study demonstrates that the activation of N-Shc signaling pathway contributes to an acute KA-induced epileptiform activity and neuronal cell loss in the hippocampus. We propose that the N-Shc-mediated signaling pathway could provide a potential target for the novel therapeutic approaches of epilepsy.

The Adaptor Protein Rai/ShcC Promotes Astrocyte-Dependent Inflammation during Experimental Autoimmune Encephalomyelitis.

Th17 cells have been casually associated to the pathogenesis of autoimmune disease. We have previously demonstrated that Rai/ShcC, a member of the Shc family of adaptor proteins, negatively regulates Th17 cell differentiation and lupus autoimmunity. In this study, we have investigated the pathogenic outcome of the Th17 bias associated with Rai deficiency on multiple sclerosis development, using the experimental autoimmune encephalomyelitis (EAE) mouse model. We found that, unexpectedly, EAE was less severe in Rai(-/-) mice compared with their wild-type counterparts despite an enhanced generation of myelin-specific Th17 cells that infiltrated into the CNS. Nevertheless, when adoptively transferred into immunodeficient Rai(+/+) mice, these cells promoted a more severe disease compared with wild-type encephalitogenic Th17 cells. This paradoxical phenotype was caused by a dampened inflammatory response of astrocytes, which were found to express Rai, to IL-17. The results provide evidence that Rai plays opposite roles in Th17 cell differentiation and astrocyte activation, with the latter dominant over the former in EAE, highlighting this adaptor as a potential novel target for the therapy of multiple sclerosis.

NGF controls APP cleavage by downregulating APP phosphorylation at Thr668: relevance for Alzheimer's disease.

NGF has been implicated in forebrain neuroprotection from amyloidogenesis and Alzheimer's disease (AD). However, the underlying molecular mechanisms are still poorly understood. Here, we investigated the role of NGF signalling in the metabolism of amyloid precursor protein (APP) in forebrain neurons using primary cultures of septal neurons and acute septo-hippocampal brain slices. In this study, we show that NGF controls the basal level of APP phosphorylation at Thr668 (T668) by downregulating the activity of the Ser/Thr kinase JNK(p54) through the Tyr kinase signalling adaptor SH2-containing sequence C (ShcC). We also found that the specific NGF receptor, Tyr kinase A (TrkA), which is known to bind to APP, fails to interact with the fraction of APP molecules phosphorylated at T668 (APP(pT668) ). Accordingly, the amount of TrkA bound to APP is significantly reduced in the hippocampus of ShcC KO mice and of patients with AD in which elevated APP(pT668) levels are detected. NGF promotes TrkA binding to APP and APP trafficking to the Golgi, where APP-BACE interaction is hindered, finally resulting in reduced generation of sAPPß, CTFß and amyloid-beta (1-42). These results demonstrate that NGF signalling directly controls basal APP phosphorylation, subcellular localization and BACE cleavage, and pave the way for novel approaches specifically targeting ShcC signalling and/or the APP-TrkA interaction in AD therapy.

Different Effects of p52SHC1 and p52SHC3 on the Cell Cycle of Neurons and Neural Stem Cells.

SHC3 is exclusively expressed in postmitotic neurons, while SHC1 is found in neural stem cells and neural precursor cells but absent in mature neurons. In this study, we discovered that suppression of p52SHC1 expression by RNA interference resulted in proliferation defects in neural stem cells, along with significantly reduced protein levels of cyclin E and cyclin A. At the same time, p52SHC3 RNAi caused cell cycle re-entry (9.54% in S phase and 5.70% in G2-M phase) in primary neurons with significantly up-regulated expression of cyclin D1, cyclin E, cyclin A, CDK2, and phosphorylated CDK2. When p52SHC3 was overexpressed, the cell cycle of neural stem cells was arrested with reduced protein levels of cyclin D1, cyclin E, and cyclin A, while overexpression of p52SHC1 did not result in significant changes in postmitotic neurons. Our results indicate that p52SHC3 plays an important role in maintaining the mitotic quiescence of neurons, while p52SHC1 regulates the proliferation of neural stem cells.

The ShcA adaptor activates AKT signaling to potentiate breast tumor angiogenesis by stimulating VEGF mRNA translation in a 4E-BP-dependent manner.

The ShcA adaptor protein is engaged by numerous receptor tyrosine kinases (RTKs) in breast cancer cells. Once activated, RTKs phosphorylate three key tyrosine phosphorylation sites (Y239, Y240 and Y317) within ShcA that creates a docking site for Grb2/SOS and Grb2/Gab-containing complexes to activate the MAPK and AKT signaling pathways, respectively. We previously demonstrated that a tyrosine to phenylalanine substitution of the ShcA tyrosine phosphorylation sites (Shc3F-Y239/240/313F) significantly impairs breast tumor growth and angiogenesis in transgenic mouse models, in part, through the regulation of vascular endothelial growth factor (VEGF) production. Despite this fact, the underlying molecular mechanisms by which ShcA transduces pro-tumorigenic signals in breast cancer cells remain poorly defined. In this study, we demonstrate that ShcA-dependent activation of AKT, but not the RAS/MAPK pathway, induces VEGF production by bolstering VEGF mRNA translation. Accordingly, ShcA drives breast tumor growth and angiogenesis in vivo in a 4E-BP-dependent manner. These findings establish ShcA as a biological bridge that links AKT activation downstream of RTKs to cap-dependent VEGF mRNA translation in order to promote mammary tumorigenesis.

Cell density modulates SHC3 expression and survival of human glioblastoma cells through Fak activation.

Shc3 protein levels are high in human glioblastoma but they decrease in vitro. We found that SHC3 mRNA and protein increased when glioblastoma cells grew as multicellular tumor spheroid (MTS). Shc3 expression was also induced in adherent cultures by increasing cell density. Among the Shc family members, only Shc2 and Shc3 increased with cell density. Shc3 and focal adhesion kinase (Fak) interact as shown by co-immunoprecipitation. Inhibition of Fak activation reduced Shc3 increase and MTS formation and changed Shc3 phosphorylation pattern. Our results suggest that in gliomas cell density modulates Shc3 protein levels and its activity, at least in part, through Fak activation.

Rai is a new regulator of neural progenitor migration and glioblastoma invasion.

The invasive nature of glioblastoma (GBM) is one important reason for treatment failure. GBM stem/progenitor cells retain the migratory ability of normal neural stem/progenitor cells and infiltrate the brain parenchyma. Here, we identify Rai (ShcC/N-Shc), a member of the family of Shc-like adaptor proteins, as a new regulator of migration of normal and cancer stem/progenitor cells. Rai is expressed in neurogenic areas of the brain and its knockdown impairs progenitor migration to the olfactory bulb. Its expression is retained in GBM stem/progenitor cells where it exerts the same promigratory activity. Rai silencing in cancer stem/progenitor cells isolated from different patients causes significant decrease in cell migration and invasion, both in vitro and in vivo, providing survival benefit. Rai depletion is associated with alteration of multiple-signaling pathways, yet it always leads to reduced expression of proinvasive genes.