p66Shc--a longevity redox protein in human prostate cancer progression and metastasis : p66Shc in cancer progression and metastasis

Integrins and Actions of Androgen in Breast Cancer

Androgen has been shown to regulate male physiological activities and cancer proliferation. It is used to antagonize estrogen-induced proliferative effects in breast cancer cells. However, evidence indicates that androgen can stimulate cancer cell growth in estrogen receptor (ER)-positive and ER-negative breast cancer cells via different types of receptors and different mechanisms. Androgen-induced cancer growth and metastasis link with different types of integrins. Integrin αvβ3 is predominantly expressed and activated in cancer cells and rapidly dividing endothelial cells. Programmed death-ligand 1 (PD-L1) also plays a vital role in cancer growth. The part of integrins in action with androgen in cancer cells is not fully mechanically understood. To clarify the interactions between androgen and integrin αvβ3, we carried out molecular modeling to explain the potential interactions of androgen with integrin αvβ3. The androgen-regulated mechanisms on PD-L1 and its effects were also addressed.

Dynamics of antioxidant heme oxygenase-1 and pro-oxidant p66Shc in promoting advanced prostate cancer progression

The castration-resistant (CR) prostate cancer (PCa) is lethal and is the second leading cause of cancer-related deaths in U.S. males. To develop effective treatments toward CR PCa, we investigated reactive oxygen species (ROS) signaling pathway for its role involving in CR PCa progression. ROS can regulate both cell growth and apoptosis: a moderate increase of ROS promotes proliferation; its substantial rise results in cell death. p66Shc protein can increase oxidant species production and its elevated level is associated with the androgen-independent (AI) phenotype of CR PCa cells; while heme oxygenase-1 (HO-1) is an antioxidant enzyme and elevated in a sub-group of metastatic PCa cells. In this study, our data revealed that HO-1 and p66Shc protein levels are co-elevated in various AI PCa cell lines as well as p66Shc cDNA-transfected cells. Knockdown and/or inhibition of either p66Shc or HO-1 protein leads to reduced tumorigenicity as well as a reduction of counterpart protein. Knockdown of HO-1 alone results in increased ROS levels, nucleotide and protein oxidation and induction of cell death. Together, our data indicate that elevated HO-1 protein levels protect PCa cells from otherwise apoptotic conditions induced by aberrant p66Shc/ROS production, which thereby promotes PCa progression to the CR phenotype. p66Shc and HO-1 can serve as functional targets for treating CR PCa.

Emerging Proteins in CRPC: Functional Roles and Clinical Implications

Prostate cancer (PCa) is the most common cancer in men in the western world, but the lack of specific and sensitive markers often leads to overtreatment of prostate cancer which eventually develops into castration-resistant prostate cancer (CRPC). Novel protein markers for diagnosis and management of CRPC will be promising. In this review, we systematically summarize and discuss the expression pattern of emerging proteins in tissue, cell lines, and serum when castration-sensitive prostate cancer (CSPC) progresses to CRPC; focus on the proteins involved in CRPC growth, invasion, metastasis, metabolism, and immune microenvironment; summarize the current understanding of the regulatory mechanisms of emerging proteins in CSPC progressed to CRPC at the molecular level; and finally summarize the clinical applications of emerging proteins as diagnostic marker, prognostic marker, predictive marker, and therapeutic marker.

Epidermal growth factor receptor and integrins meet redox signaling through P66shc and Rac1

This review examines the concerted role of Epidermal Growth Factor Receptor (EGFR) and integrins in regulating Reactive oxygen species (ROS) production through different signaling pathways. ROS as such are not always deleterious to the cells but they also act as signaling molecules, that regulates numerous indespensible physiological fuctions of life. Many adaptor proteins, particularly Shc and Grb2, are involved in mediating the downstream signaling pathways stimulated by EGFR and integrins. Integrin-induced activation of EGFR and subsequent tyrosine phosphorylation of a class of acceptor sites on EGFR leads to alignment and tyrosine phosphorylation of Shc, PLCγ, the p85 subunit of PI-3 K, and Cbl, followed by activation of the downstream targets Erk and Akt/PKB. Functional interactions between these receptors result in the activation of Rac1 via these adaptor proteins, thereby leading to Reactive Oxygen Species. Both GF and integrin activation can produce oxidants independently, however synergistically there is increased ROS generation, suggesting a mutual cooperation between integrins and GFRs for redox signalling. The ROS produced further promotes feed-forward stimulation of redox signaling events such as MAPK activation and gene expression. This relationship has not been reviewed previously. The literature presented here can have multiple implications, ranging from looking at synergistic effects of integrin and EGFR mediated signaling mechanisms of different proteins to possible therapeutic interventions operated by these two receptors. Furthermore, such mutual redox regulation of crosstalk between EGFR and integrins not only add to the established models of pathological oxidative stress, but also can impart new avenues and opportunities for targeted antioxidant based therapeutics.

Ras, TrkB, and ShcA Protein Expression Patterns in Pediatric Brain Tumors

Numerous papers have reported altered expression patterns of Ras and/or ShcA proteins in different types of cancers. Their level can be potentially associated with oncogenic processes. We analyzed samples of pediatric brain tumors reflecting different groups such as choroid plexus tumors, diffuse astrocytic and oligodendroglial tumors, embryonal tumors, ependymal tumors, and other astrocytic tumors as well as tumor malignancy grade, in order to characterize the expression profile of Ras, TrkB, and three isoforms of ShcA, namely, p66Shc, p52Shc, and p46Shc proteins. The main aim of our study was to evaluate the potential correlation between the type of pediatric brain tumors, tumor malignancy grade, and the expression patterns of the investigated proteins.

Structure-functional implications of longevity protein p66Shc in health and disease

ShcA (Src homologous- collagen homologue), family of adapter proteins, consists of three isoforms which integrate and transduce external stimuli to different signaling networks. ShcA family consists of p46Shc, p52Shc and p66Shc isoforms, characterized by having multiple protein-lipid and protein-protein interaction domains implying their functional diversity. Among the three isoforms p66Shc is structurally different containing an additional CH2 domain which attributes to its dual functionality in cell growth, mediating both cell proliferation and apoptosis. Besides, p66Shc is also involved in different biological processes including reactive oxygen species (ROS) production, cell migration, ageing, cytoskeletal reorganization and cell adhesion. Moreover, the interplay between p66Shc and ROS is implicated in the pathology of various dreadful diseases. Accordingly, here we discuss the recent structural aspects of all ShcA adaptor proteins but are highlighting the case of p66Shc as model isoform. Furthermore, this review insights the role of p66Shc in progression of chronic age-related diseases like neuro diseases, metabolic disorders (non-alcoholic fatty liver, obesity, diabetes, cardiovascular diseases, vascular endothelial dysfunction) and cancer in relation to ROS. We finally conclude that p66Shc might act as a valuable biomarker for the prognosis of these diseases and could be used as a potential therapeutic target.

Integrin αvβ3 in the Mediating Effects of Dihydrotestosterone and Resveratrol on Breast Cancer Cell Proliferation

Hormones and their receptors play an important role in the development and progression of breast cancer. Hormones regulate the proliferation of breast cancer cells through binding between estrogen or progestins and steroid receptors that may reside in the cytoplasm or be transcriptionally activated as steroid–protein nuclear receptor complexes. However, receptors for nonpeptide hormones also exist in the plasma membrane. Via those receptors, hormones are able to stimulate breast cancer cell proliferation when activated. Integrins are heterodimeric structural proteins of the plasma membrane. Their primary functions are to interact with extracellular matrix proteins and growth factors. Recently, integrin αvβ3 has been identified as a receptor for nonpeptide hormones, such as thyroid hormone and dihydrotestosterone (DHT). DHT promotes the proliferation of human breast cancer cells through binding to integrin αvβ3. A receptor for resveratrol, a polyphenol stilbene, also exists on this integrin in breast cancer cells, mediating the anti-proliferative, pro-apoptotic action of the compound in these cells. Unrelated activities of DHT and resveratrol that originate at integrin depend upon downstream stimulation of mitogen-activated protein kinase (MAPK, ERK1/2) activity, suggesting the existence of distinct, function-specific pools of ERK1/2 within the cell. This review will discuss the features of these receptors in breast cancer cells, in turn suggesting clinical applications that are based on the interactions of resveratrol/DHT with integrin αvβ3 and other androgen receptors.

Prognostic value and prospective molecular mechanism of miR-100-5p in hepatocellular carcinoma: A comprehensive study based on 1,258 samples

The prognostic value and molecular mechanism of microRNA-100-5p (miR-100-5p) in hepatocellular carcinoma (HCC) are still unclear. To explore the prognostic value and the mechanism of miR-100-5p in HCC, the present study analyzed the results of 18 previous studies and bioinformatic datasets. The clinical significance of miR-100-5p and its targets in HCC were investigated using The Cancer Genome Atlas and the Gene Expression Omnibus, as well as relevant literature. In total, 12 online tools were used to predict the target genes of miR-100-5p. Bioinformatics analysis and Spearman correlation analysis were performed, and genomic alterations of the hub genes were evaluated. A meta-analysis with 1,258 samples revealed that miR-100-5p was significantly downregulated in HCC [standard mean difference (SMD), -0.94; 95% confidence interval (CI), -1.14 to -0.74; I2, 35.2%]. Lower miR-100-5p expression was associated with poorer clinical characteristics and a poorer prognosis for patients with HCC. Additionally, bioinformatics analysis revealed that the 'regulation of transcription', 'chromatin remodeling complex', 'transcription regulator activity', 'pathways in cancer' and 'heparan sulfate biosynthesis' were the most enriched terms. Furthermore, expression of histone deacetylase (HDAC)2, HDAC3, SHC-transforming protein 1 (SHC1), Ras-related protein Rac1 (RAC1) and E3 ubiquitin-protein ligase CBL (CBL) was negatively correlated with miR-100-5p expression. Among these, upregulated HDAC2 [hazard ratio (HR), 1.910; 95% CI, 1.309-2.787; P=0.0007], HDAC3 (HR, 1.474; 95% CI, 1.012-2.146; P=0.0435), SHC1 (HR, 1.52; 95% CI, 1.043-2.215; P=0.0281) and RAC1 (HR, 1.817; 95% CI, 1.248-2.645; P=0.0022) were associated with shorter survival. Alterations in HDAC2, SHC1, RAC1 and IGF1R were linked with a poorer outcome for HCC, and alternative splicing of SHC and RAC1 were significantly decreased and increased in HCC, respectively. In summary, the downregulation of miR-100-5p may be involved in the progression and prognosis of HCC. The upregulation of HDAC2, HDAC3, SHC1 and RAC1 may indicate a poorer survival rate for patients with HCC. Thus, miR-100-5p and these 4 potential target genes may provide novel therapeutic targets and prognostic predictors for patients with HCC.

Targeting the Shc-EGFR interaction with indomethacin inhibits MAP kinase pathway signalling

Receptor tyrosine kinase (RTK)-mediated hyperactivation of the MAPK/Erk pathway is responsible for a large number of pathogenic outcomes including many cancers. Considerable effort has been directed at targeting this pathway with varying degrees of long term therapeutic success. Under non-stimulated conditions Erk is bound to the adaptor protein Shc preventing aberrant signalling by sequestering Erk from activation by Mek. Activated RTK recruits Shc, via its phosphotyrosine binding (PTB) domain (ShcPTB), precipitating the release of Erk to engage in a signalling response. Here we describe a novel approach to inhibition of MAP kinase signal transduction through attempting to preserve the Shc-Erk complex under conditions of activated receptor. A library of existing drug molecules was computationally screened for hits that would bind to the ShcPTB and block its interaction with the RTKs EGFR and ErbB2. The primary hit from the screen was indomethacin, a non-steroidal anti-inflammatory drug. Validation of this molecule in vitro and in cellular efficacy studies in cancer cells provides proof of principle of the approach to pathway down-regulation and a potential optimizable lead compound.

ErbB-2 signaling in advanced prostate cancer progression and potential therapy

Currently, prostate cancer (PCa) remains the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in US men. Most of these deaths are attributed to the development of castration-resistant (CR) PCa. ErbB-2 and ErbB family members have been demonstrated to contribute to the progression of this lethal disease. In this review, we focus on updating the role of ErbB-2 in advanced PCa progression and its regulation, including its regulation via ligand activation, miRNAs and protein phosphorylation. We also discuss its downstream signaling pathways, including AKT, ERK1/2 and STATs, involved in advanced PCa progression. Additionally, we evaluate the potential of ErbB-2, focusing on its protein hyper-phosphorylation status, as a biomarker for aggressive PCa as well as the effectiveness of ErbB-2 as a target for the treatment of CR PCa via a multitude of approaches, including orally available inhibitors, intratumoral expression of cPAcP, vaccination and immunotherapy.

The oxidoreductase p66Shc acts as tumor suppressor in BRAFV600E-transformed cells

Metabolic reprogramming, as exemplified by the shift from oxidative phosphorylation to glycolysis, is a common feature of transformed cells. In many tumors, altered metabolism is also reflected in increased reactive oxygen species (ROS) levels, which contribute to proliferation and survival signaling. However, despite high ROS levels, cancer cells can be efficiently killed by further increasing ROS production. We have shown previously that both wild‐type and oncogenic CRAF and BRAF prevent excessive mitochondrial ROS production. Subsequently, it has been demonstrated that raising ROS levels in BRAFV600E‐transformed melanoma cells by inhibiting BRAF or MEK rendered them susceptible to cell death induction. To understand how oncogenic BRAF affects mitochondrial ROS production in melanoma, we studied the mitochondrial ROS‐producing oxidoreductase p66Shc, which is frequently overexpressed in tumors. Using NIH 3T3 BRAFV600E fibroblasts and the melanoma cell lines A375 and M238 carrying the same BRAF mutation, we show that under treatment with the ROS‐inducing agent phenethyl isothiocyanate (PEITC), oncogenic BRAF renders cells refractory to p66ShcS36 phosphorylation, which is essential for p66Shc activation and mitochondrial ROS production. Consistent with this, the activation of JNK1/2, which phosphorylate S36, was blunted, while other mitogen‐activated protein kinases were not affected. Inhibition of JNK1/2 efficiently prevented ROS production, while BRAF and MEK inhibitors increased ROS levels. Vemurafenib‐resistant M238R melanoma cells were impaired in S36 phosphorylation and ROS production following PEITC treatment. Moreover, they failed to increase ROS levels after MEK/BRAF inhibition. Finally, shRNA‐mediated knockdown of p66Shc led to increased growth of BRAFV600E‐transformed NIH 3T3 cells in soft agar assay. Taken together, these data suggest that phosphorylation‐activated p66Shc functions as a tumor suppressor in melanoma cells.

p66Shc Mediates Mitochondrial Dysfunction Dependent on PKC Activation in Airway Epithelial Cells Induced by Cigarette Smoke

Airway epithelial mitochondrial injury plays a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). The p66Shc adaptor protein is a newly recognized mediator of mitochondrial dysfunction. However, little is known about the effect of p66Shc on airway epithelial damage in the development of COPD. The aim of the present study is to investigate the roles of p66Shc and its upstream regulators in the mitochondrial injury of airway epithelial cells (Beas-2b) induced by cigarette smoke extract (CSE). Our present study revealed that CSE increased p66Shc expression and its mitochondrial translocation in concentration and time-dependent manners in airway epithelial cells. And p66Shc siRNA significantly attenuated mitochondrial dysfunction and cell injury when airway epithelial cells were stimulated with 7.5% CSE. The total and phosphorylated expression of PKCβ and PKCδ was significantly increased associated with mitochondrial dysfunction and cell injury when airway epithelial cells were exposed to 7.5% CSE. The pretreatments with pharmacological inhibitors of PKCβ and PKCδ could notably suppress p66Shc phosphorylation and its mitochondrial translocation and protect the mitochondria and cells against oxidative damage when airway epithelial cells were incubated with 7.5% CSE. These data suggest that a novel PKCβ/δ-p66Shc signaling pathway may be involved in the pathogenesis of COPD and other oxidative stress-associated pulmonary diseases and provide a potential therapeutic target for these diseases.

p66Shc regulates migration of castration-resistant prostate cancer cells

Metastatic castration-resistant (CR) prostate cancer (PCa) is a lethal disease for which no effective treatment is currently available. p66Shc is an oxidase previously shown to promote androgen-independent cell growth through generation of reactive oxygen species (ROS) and is elevated in clinical PCa and multiple CR PCa cell lines. We hypothesize p66Shc also increases the migratory activity of PCa cells through ROS and investigate the associated mechanism. Using the transwell assay, our study reveals that the level of p66Shc protein correlates with cell migratory ability across several PCa cell lines. Furthermore, we show hydrogen peroxide treatment induces migration of PCa cells that express low levels of p66Shc in a dose-dependent manner, while antioxidants inhibit migration. Conversely, PCa cells that express high levels of endogenous p66Shc or by cDNA transfection possess increased cell migration which is mitigated upon p66Shc shRNA transfection or expression of oxidase-deficient dominant-negative p66Shc W134F mutant. Protein microarray and immunoblot analyses reveal multiple proteins, including ErbB-2, AKT, mTOR, ERK, FOXM1, PYK2 and Rac1, are activated in p66Shc-elevated cells. Their involvement in PCa migration was examined using respective small-molecule inhibitors. The role of Rac1 was further validated using cDNA transfection and, significantly, p66Shc is found to promote lamellipodia formation through Rac1 activation. In summary, the results of our current studies clearly indicate p66Shc also regulates PCa cell migration through ROS-mediated activation of migration-associated proteins, notably Rac1.

Phosphorylation of threonine residues on Shc promotes ligand binding and mediates crosstalk between MAPK and Akt pathways in breast cancer cells

Scaffold proteins play important roles in regulating signalling network fidelity, the absence of which is often the basis for diseases such as cancer. In the present work, we show that the prototypical scaffold protein Shc is phosphorylated by the extracellular signal-regulated kinase, Erk. In addition, Shc threonine phosphorylation is specifically up-regulated in two selected triple-negative breast cancer (TNBC) cell lines. To explore how Erk-mediated threonine phosphorylation on Shc might play a role in the dysregulation of signalling events, we investigated how Shc affects pathways downstream of EGF receptor. Using an in vitro model and biophysical analysis, we show that Shc threonine phosphorylation is responsible for elevated Akt and Erk signalling, potentially through the recruitment of the 14-3-3 ζ and Pin-1 proteins.

Interaction of Mitochondria with the Endoplasmic Reticulum and Plasma Membrane in Calcium Homeostasis, Lipid Trafficking and Mitochondrial Structure

Studying organelles in isolation has been proven to be indispensable for deciphering the underlying mechanisms of molecular cell biology. However, observing organelles in intact cells with the use of microscopic techniques reveals a new set of different junctions and contact sites between them that contribute to the control and regulation of various cellular processes, such as calcium and lipid exchange or structural reorganization of the mitochondrial network. In recent years, many studies focused their attention on the structure and function of contacts between mitochondria and other organelles. From these studies, findings emerged showing that these contacts are involved in various processes, such as lipid synthesis and trafficking, modulation of mitochondrial morphology, endoplasmic reticulum (ER) stress, apoptosis, autophagy, inflammation and Ca2+ handling. In this review, we focused on the physical interactions of mitochondria with the endoplasmic reticulum and plasma membrane and summarized present knowledge regarding the role of mitochondria-associated membranes in calcium homeostasis and lipid metabolism.

The Landscape of Isoform Switches in Human Cancers

Alternative usage of transcript isoforms from the same gene has been hypothesized as an important feature in cancers. However, differential usage of gene transcripts between conditions (isoform switching) has not been comprehensively characterized in and across cancer types. To this end, we developed methods for identification and visualization of isoform switches with predicted functional consequences. Using these methods, we characterized isoform switching in RNA-seq data from >5,500 cancer patients covering 12 solid cancer types. Isoform switches with potential functional consequences were common, affecting approximately 19% of multiple transcript genes. Among these, isoform switches leading to loss of DNA sequence encoding protein domains were more frequent than expected, particularly in pancancer switches. We identified several isoform switches as powerful biomarkers: 31 switches were highly predictive of patient survival independent of cancer types. Our data constitute an important resource for cancer researchers, available through interactive web tools. Moreover, our methods, available as an R package, enable systematic analysis of isoform switches from other RNA-seq datasets.Implications: This study indicates that isoform switches with predicted functional consequences are common and important in dysfunctional cells, which in turn means that gene expression should be analyzed at the isoform level. Visual Overview: http://mcr.aacrjournals.org/content/molcanres/15/9/1206/F1.large.jpg.Mol Cancer Res; 15(9); 1206-20. ©2017 AACR.

Calcium regulates cell death in cancer: Roles of the mitochondria and mitochondria-associated membranes (MAMs)

Until 1972, the term 'apoptosis' was used to differentiate the programmed cell death that naturally occurs in organismal development from the acute tissue death referred to as necrosis. Many studies on cell death and programmed cell death have been published and most are, at least to some degree, related to cancer. Some key proteins and molecular pathways implicated in cell death have been analyzed, whereas others are still being actively researched; therefore, an increasing number of cellular compartments and organelles are being implicated in cell death and cancer. Here, we discuss the mitochondria and subdomains of the endoplasmic reticulum (ER) that interact with mitochondria, the mitochondria-associated membranes (MAMs), which have been identified as critical hubs in the regulation of cell death and tumor growth. MAMs-dependent calcium (Ca²⁺) release from the ER allows selective Ca²⁺ uptake by the mitochondria. The perturbation of Ca²⁺ homeostasis in cancer cells is correlated with sustained cell proliferation and the inhibition of cell death through the modulation of Ca²⁺ signaling. This article is part of a Special Issue entitled Mitochondria in Cancer, edited by Giuseppe Gasparre, Rodrigue Rossignol and Pierre Sonveaux.

Effects of Resveratrol on p66Shc phosphorylation in cultured prostate cells

There is increasing evidence that diet plays a crucial role in age-related diseases and cancer. Oxidative stress is a conceivable link between diet and diseases, thus food antioxidants, counteracting the damage caused by oxidation, are potential tools for fight age-related diseases and cancer. Resveratrol (RSV), a polyphenolic antioxidant from grapes, has gained enormous attention particularly because of its ability to induce growth arrest and apoptosis in cancer cells, and it has been proposed as both chemopreventive and therapeutic agent for cancer and other diseases. Even though the effects of RSV have been studied in prostate cancer cells and animal models, little is known about its effects on normal cells and tissues. To address this issue, we have investigated the effects of RSV on EPN cells, a human non-transformed prostate cell line, focusing on the relationship between RSV and p66Shc, a redox enzyme whose activities strikingly intersect those of RSV. p66Shc activity is regulated by phosphorylation of serine 36 (Ser36) and has been related to mitochondrial oxidative stress, apoptosis induction, regulation of cell proliferation and migration. Here we show that RSV inhibits adhesion, proliferation and migration of EPN cells, and that these effects are associated to induction of dose- and time-dependent p66Shc-Ser36 phosphorylation and ERK1/2 de-phosphorylation. Moreover, we found that RSV is able to activate also p52Shc, another member of the Shc protein family. These data show that RSV affects non-transformed prostate epithelial cells and suggest that Shc proteins may be key contributors of RSV effects on prostate cells.

ShcA Protects against Epithelial-Mesenchymal Transition through Compartmentalized Inhibition of TGF-β-Induced Smad Activation

Epithelial–mesenchymal transition (EMT) is a normal cell differentiation event during development and contributes pathologically to carcinoma and fibrosis progression. EMT often associates with increased transforming growth factor-β (TGF-β) signaling, and TGF-β drives EMT, in part through Smad-mediated reprogramming of gene expression. TGF-β also activates the Erk MAPK pathway through recruitment and Tyr phosphorylation of the adaptor protein ShcA by the activated TGF-β type I receptor. We found that ShcA protects the epithelial integrity of nontransformed cells against EMT by repressing TGF-β-induced, Smad-mediated gene expression. p52ShcA competed with Smad3 for TGF-β receptor binding, and down-regulation of ShcA expression enhanced autocrine TGF-β/Smad signaling and target gene expression, whereas increased p52ShcA expression resulted in decreased Smad3 binding to the TGF-β receptor, decreased Smad3 activation, and increased Erk MAPK and Akt signaling. Furthermore, p52ShcA sequestered TGF-β receptor complexes to caveolin-associated membrane compartments, and reducing ShcA expression enhanced the receptor localization in clathrin-associated membrane compartments that enable Smad activation. Consequently, silencing ShcA expression induced EMT, with increased cell migration, invasion, and dissemination, and increased stem cell generation and mammosphere formation, dependent upon autocrine TGF-β signaling. These findings position ShcA as a determinant of the epithelial phenotype by repressing TGF-β-induced Smad activation through differential partitioning of receptor complexes at the cell surface.

The adaptor protein ShcA protects epithelial cells from transitioning toward a mesenchymal phenotype by controlling partitioning of the TGF-β receptor and repressing downstream Smad2/3 activation.

TGF-β family proteins control cell differentiation and various cell functions. Increased TGF-β signaling, acting through heteromeric receptor complexes, contributes to carcinoma progression and fibrosis. TGF-β drives epithelial–mesenchymal transdifferentiation (EMT), which enables cell migration and invasion. Upon TGF-β binding, “type I” receptors activate, through phosphorylation, Smad2 and Smad3 that control target gene transcription. In EMT, Smad complexes activate the expression of EMT “master” transcription factors and cooperate with these to repress the epithelial phenotype and activate mesenchymal gene expression. TGF-β receptors also activate Erk MAPK signaling, involving association of the adaptor protein ShcA and Tyr phosphorylation of ShcA by type I receptors. We now show that the predominant ShcA isoform, p52ShcA, competes with Smad2/3 for binding to type I TGF-β receptors, thus repressing Smad2/3 activation in response to TGF-β and localizing the receptors to caveolar compartments. Consequently, decreased ShcA expression enhanced TGF-β receptor localization in clathrin compartments and autocrine Smad2/3 signaling, repressed the epithelial phenotype, and promoted EMT. The changes following decreased ShcA expression resulted in increased cell migration and invasion, as well as increased stem cell generation, dependent upon autocrine TGF-β signaling. These findings position ShcA as a determinant of the epithelial phenotype by repressing TGF-β-induced Smad activation through differential partitioning of receptor complexes at the cell surface.

ITGA2B and ITGA8 are predictive of prognosis in clear cell renal cell carcinoma patients

Integrins play an important role in cancer growth and metastasis. This study aimed at determining the predictive ability of integrins and associated genes identified through molecular network in clear cell renal cell carcinoma. A total of 525 patients with ccRCC from The Cancer Genome Atlas (TCGA) cohorts were collected in this study. The expression profile of integrins and related genes were obtained from the TCGA RNAseq database. Clinicopathological characteristics, including age, gender, tumor size, tumor node metastasis (TNM), tumor grade, stage, laterality, and overall survival were collected. Cox proportional hazards regression model as well as Kaplan-Meier curve were used to assess the relative factors. Genes of integrin family that showed certain correlations with overall survival (OS) were further validated in the Fudan University Shanghai Cancer Center (FUSCC) cohort. In the TCGA cohort, after Cox proportional hazards analysis, ITGA2B (hazards ratio (HR) = 1.232, 95 % CI 1.097 to 1.383) and ITGA8 (HR = 0.804, 95 % CI 0.696 to 0.930) were shown predictive of ccRCC prognosis. Low ITGA8 expression was associated with poor prognosis for OS (log-rank test, p < 0.0001), while high level of ITGA2B expression was correlated with poor prognosis for OS (log-rank test, p < 0.0001). This finding was validated in FUSCC cohort (log-rank test, all p < 0.05). As a result, low ITGA8 expression was associated with poor prognosis for OS (log-rank test, p = 0.0053), while high level of ITGA2B expression was correlated with poor prognosis for OS (log-rank test, p < 0.0001). Plus, low ITGA8 expression was associated with poor prognosis for disease-free survival (DFS) in the TCGA cohort (log-rank test, p < 0.0001). In the gene cluster network analysis, GIT1 and SHC1 associated with ITGA2B and ITGA8 were identified as independent predictive factors of overall survival of ccRCC. ITGA2B, ITGA8, GIT1, and SHC1 were identified as independent prognostic factors of overall survival of ccRCC. This method may act as a tool to reveal more prognostic-associated genes in ccRCC.

Novel Imidazopyridine Derivatives Possess Anti-Tumor Effect on Human Castration-Resistant Prostate Cancer Cells

Prostate cancer (PCa) is the second leading cause of cancer-related death afflicting United States males. Most treatments to-date for metastatic PCa include androgen-deprivation therapy and second-generation anti-androgens such as abiraterone acetate and enzalutamide. However, a majority of patients eventually develop resistance to these therapies and relapse into the lethal, castration-resistant form of PCa to which no adequate treatment option remains. Hence, there is an immediate need to develop effective therapeutic agents toward this patient population. Imidazopyridines have recently been shown to possess Akt kinase inhibitory activity; thus in this study, we investigated the inhibitory effect of novel imidazopyridine derivatives HIMP, M-MeI, OMP, and EtOP on different human castration-resistant PCa cells. Among these compounds, HIMP and M-MeI were found to possess selective dose- and time-dependent growth inhibition: they reduced castration-resistant PCa cell proliferation and spared benign prostate epithelial cells. Using LNCaP C-81 cells as the model system, these compounds also reduced colony formation as well as cell adhesion and migration, and M-MeI was the most potent in all studies. Further investigation revealed that while HIMP primarily inhibits PCa cell growth via suppression of PI3K/Akt signaling pathway, M-MeI can inhibit both PI3K/Akt and androgen receptor pathways and arrest cell growth in the G2 phase. Thus, our results indicate the novel compound M-MeI to be a promising candidate for castration-resistant PCa therapy, and future studies investigating the mechanism of imidazopyridine inhibition may aid to the development of effective anti-PCa agents.

Tumor cell migration screen identifies SRPK1 as breast cancer metastasis determinant

Tumor cell migration is a key process for cancer cell dissemination and metastasis that is controlled by signal-mediated cytoskeletal and cell matrix adhesion remodeling. Using a phagokinetic track assay with migratory H1299 cells, we performed an siRNA screen of almost 1,500 genes encoding kinases/phosphatases and adhesome- and migration-related proteins to identify genes that affect tumor cell migration speed and persistence. Thirty candidate genes that altered cell migration were validated in live tumor cell migration assays. Eight were associated with metastasis-free survival in breast cancer patients, with integrin β3-binding protein (ITGB3BP), MAP3K8, NIMA-related kinase (NEK2), and SHC-transforming protein 1 (SHC1) being the most predictive. Examination of genes that modulate migration indicated that SRPK1, encoding the splicing factor kinase SRSF protein kinase 1, is relevant to breast cancer outcomes, as it was highly expressed in basal breast cancer. Furthermore, high SRPK1 expression correlated with poor breast cancer disease outcome and preferential metastasis to the lungs and brain. In 2 independent murine models of breast tumor metastasis, stable shRNA-based SRPK1 knockdown suppressed metastasis to distant organs, including lung, liver, and spleen, and inhibited focal adhesion reorganization. Our study provides comprehensive information on the molecular determinants of tumor cell migration and suggests that SRPK1 has potential as a drug target for limiting breast cancer metastasis.

The interplay between p66Shc, reactive oxygen species and cancer cell metabolism

The adaptor protein p66Shc links membrane receptors to intracellular signalling pathways and has the potential to respond to energy status changes and regulate mitogenic signalling. Initially reported to mediate growth signals in normal and cancer cells, p66Shc has also been recognized as a pro-apoptotic protein involved in the cellular response to oxidative stress. Moreover, it is a key element in processes such as cancer cell proliferation, tumor progression, metastasis and metabolic reprogramming. Recent findings on the role of p66Shc in the above-mentioned processes have been obtained through the use of various tumor cell types, including prostate, breast, ovarian, lung, colon, skin and thyroid cancer cells. Interestingly, the impact of p66Shc on the proliferation rate was mainly observed in prostate tumors, while its impact on metastasis was mainly found in breast cancers. In this review, we summarize the current knowledge about the possible roles of p66Shc in different cancers.

Antiproliferative activity of novel imidazopyridine derivatives on castration-resistant human prostate cancer cells

Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa.

Oncogenic and oncosuppressive signal transduction at mitochondria-associated endoplasmic reticulum membranes

The different mechanisms employed by proto-oncogenes and tumor suppressors to regulate cell death pathways are strictly linked to their localization. In addition to the canonical control of apoptosis at a transcriptional/nuclear level, intracellular zones are emerging as pivotal sites for the activities of several proapoptotic and antiapoptotic factors. Here, we review the function of the endoplasmic reticulum-mitochondria interface as a primary platform for decoding danger signals as well as a structural accommodation for several regulator or effector proteins.

The adaptor proteins p66Shc and Grb2 regulate the activation of the GTPases ARF1 and ARF6 in invasive breast cancer cells

Signals downstream of growth factor receptors play an important role in mammary carcinogenesis. Recently, we demonstrated that the small GTPases ARF1 and ARF6 were shown to be activated downstream of the epidermal growth factor receptor (EGFR) and act as a key regulator of growth, migration, and invasion of breast cancer cells. However, the mechanism via which the EGFR recruits and activates ARF1 and ARF6 to transmit signals has yet to be fully elucidated. Here, we identify adaptor proteins Grb2 and p66Shc as important regulators mediating ARF activation. We demonstrate that ARF1 can be found in complex with Grb2 and p66Shc upon EGF stimulation of the basal-like breast cancer MDA-MB-231 cell line. However, we report that these two adaptors regulate ARF1 activation differently, with Grb2 promoting ARF1 activation and p66Shc blocking this response. Furthermore, we show that Grb2 is essential for the recruitment of ARF1 to the EGFR, whereas p66Shc hindered ARF1 receptor recruitment. We demonstrate that the negative regulatory role of p66Shc stemmed from its ability to block the recruitment of Grb2/ARF1 to the EGFR. Conversely, p66Shc potentiates ARF6 activation as well as the recruitment of this ARF isoform to the EGFR. Interestingly, we demonstrate that Grb2 is also required for the activation and receptor recruitment of ARF6. Additionally, we show an important role for p66Shc in modulating ARF activation, cell growth, and migration in HER2-positive breast cancer cells. Together, our results highlight a central role for adaptor proteins p66Shc and Grb2 in the regulation of ARF1 and ARF6 activation in invasive breast cancer cells.

p66Shc longevity protein regulates the proliferation of human ovarian cancer cells

p66Shc functions as a longevity protein in murine and exhibits oxidase activity in regulating diverse biological activities. In this study, we investigated the role of p66Shc protein in regulating ovarian cancer (OCa) cell proliferation. Among three cell lines examined, the slowest growing OVCAR-3 cells have the lowest level of p66Shc protein. Transient transfection with p66Shc cDNA expression vector in OVCAR-3 cells increases cell proliferation. Conversely, knock-down of p66Shc by shRNA in rapidly growing SKOV-3 cells results in decreased cell growth. In estrogen (E2)-treated CaOV-3 cells, elevated p66Shc protein level correlates with ROS level, ErbB-2 and ERK/MAPK activation, and cell proliferation. Further, the E2-stimulated proliferation of CaOV-3 cells was blocked by antioxidants and ErbB-2 inhibitor. Additionally, in E2-stimulated cells, the tartrate-sensitive, but not the tartrate-resistant, phosphatase activity decreases; concurrently, the tyrosine phosphorylation of ErbB-2 increases. Conversely, inhibition of phosphatase activity by L(+)-tartrate treatment increases p66Shc protein level, ErbB-2 tyrosine phosphorylation, ERK/MAPK activation, and cell growth. Further, inhibition of the ERK/MAPK pathway by PD98059 blocks E2-induced ERK/MAPK activation and cell proliferation in CaOV-3 cells. Moreover, immunohistochemical analyses showed that the p66Shc protein level was significantly higher in cancerous cells than in noncancerous cells in archival OCa tissues (n = 76; P = 0.00037). These data collectively indicate that p66Shc protein plays a critical role in up-regulating OCa progression.

The p66Shc adapter protein regulates the morphogenesis and epithelial maturation of fetal mouse lungs

Many signaling pathways are mediated by Shc adapter proteins that, in turn, are expressed as three isoforms with distinct functions. The p66(Shc) isoform antagonizes proliferation, regulates oxidative stress, and mediates apoptosis. It is highly expressed in the canalicular but not the later stages of mouse lung development, and its expression persists in bronchopulmonary dysplasia, a chronic disease associated with premature birth. These observations suggest that p66(Shc) has a developmental function. However, constitutive p66(Shc) deletion yields no morphological phenotype, and the structure of the Shc gene precludes its inducible deletion. To elucidate its function in lung development, we transfected p66(Shc) or nonsilencing small-interfering RNA (siRNA) into the epithelia of embryonic day 11 mouse lungs that were then cultured for 3 days and analyzed morphometrically. To assess cellular proliferation and epithelial differentiation, lung explants were immunostained and immunoblotted for p66(Shc), proliferating cell nuclear antigen (PCNA), the proximal airway differentiation antigens Clara cell 10-kDa protein (CC10) and thyroid transcription factor (TTF)-1, and the alveolar surfactant proteins (SP)-A, -B, and -C. Explants transfected with nonsilencing siRNA demonstrated specific epithelial uptake and normal morphological development relative to uninjected controls. In contrast, transfection with p66(Shc) siRNA significantly increased lumenal cross-sectional areas, decreased branching, and increased epithelial proliferation (P < 0.05 for all). Relative to controls, the expression of SP-B, SP-C, CC10, and TTF-1 was decreased by p66(Shc) knockdown. SP-A was not expressed in either control or treated lungs. These data suggest that p66(Shc) attenuates epithelial proliferation while promoting both distal and proximal epithelial maturation.

Antioxidant and vitamin E transport genes and risk of high-grade prostate cancer and prostate cancer recurrence

BACKGROUND

Observational studies suggest an inverse association between vitamin E and risk of prostate cancer, particularly aggressive tumors. However, three large randomized controlled trials have reported conflicting results. Thus, we examined circulating vitamin E and vitamin E-related genes in relation to risk of high-grade prostate cancer and prostate cancer recurrence among men initially diagnosed with clinically organ-confined disease.

METHODS

We measured circulating α- and γ-tocopherol and genotyped 30 SNPs in SOD1, SOD2, SOD3, TTPA, and SEC14L2 among 573 men with organ-confined prostate cancer who underwent radical prostatectomy. We examined associations between circulating vitamin E, genotypes, and risk of high-grade prostate cancer (Gleason grade ≥ 8 or 7 with primary score ≥ 4; n = 117) using logistic regression, and risk of recurrence (56 events; 3.7 years median follow-up) using Cox proportional hazards regression.

RESULTS

Circulating γ-tocopherol was associated with an increased risk of high-grade prostate cancer (Q4 v. Q1 odds ratio [OR] = 1.87; 95% confidence intervals [CI]: 0.97-3.58; P trend =0.02). The less common allele in SOD3 rs699473 was associated with an increased risk of high-grade disease (T > C: OR = 1.40, 95% CI: 1.04-1.89). Two independent SNPs in SOD1 were inversely associated with prostate cancer recurrence in additive models (rs17884057 hazard ratio [HR] = 0.49, 95%CI: 0.25-0.96; rs9967983 HR = 0.62, 95% CI: 0.40-0.95).

CONCLUSIONS

Among men with clinically organ-confined prostate cancer, genetic variation in SOD may be associated with risk of high-grade disease at diagnosis and disease recurrence. Circulating γ-tocopherol levels may also be associated with an increased risk of high-grade disease at diagnosis.

Targeting MCT-1 oncogene inhibits Shc pathway and xenograft tumorigenicity

Overexpression of Shc adaptor proteins is associated with mitogenesis, carcinogenesis and metastasis. Multiple copies in T-cell malignancy 1 (MCT-1) oncoprotein promotes cell proliferation, survival and tumorigenic effects. Our current data show that MCT-1 is a novel regulator of Shc-Ras-MEK-ERK signaling and MCT-1 is significantly co-activated with Shc gene in human carcinomas. The knockdown of MCT-1 enhances apoptotic cell death accompanied with the activation of caspases and cleavage of caspase substrates under environmental stress. The cancer cell proliferation, chemo-resistance and tumorigenic capacity are proved to be effectively suppressed by targeting MCT-1. Accordingly, an important linkage between MCT-1 oncogenicity and Shc pathway in tumor development has now been established. Promoting MCT-1 expression by gene hyperactivation may be recognized as a tumor marker and MCT-1 may serve as a molecular target of cancer therapy.

Cancer specificity of promoters of the genes involved in cell proliferation control

Core promoters with adjacent regions of the human genes CDC6, POLD1, CKS1B, MCM2, and PLK1 were cloned into a pGL3 vector in front of the Photinus pyrails gene Luc in order to study the tumor specificity of the promoters. The cloned promoters were compared in their ability to direct luciferase expression in different human cancer cells and in normal fibroblasts. The cancer-specific promoter BIRC5 and non-specific CMV immediately early gene promoter were used for comparison. All cloned promoters were shown to be substantially more active in cancer cells than in fibroblasts, while the PLK1 promoter was the most cancer-specific and promising one. The specificity of the promoters to cancer cells descended in the series PLK1, CKS1B, POLD1, MCM2, and CDC6. The bidirectional activity of the cloned CKS1B promoter was demonstrated. It apparently directs the expression of the SHC1 gene, which is located in a "head-to-head" position to the CKS1B gene in the human genome. This feature should be taken into account in future use of the CKS1B promoter. The cloned promoters may be used in artificial genetic constructions for cancer gene therapy.

Increased p66Shc in the inner ear of D-galactose-induced aging mice with accumulation of mitochondrial DNA 3873-bp deletion: p66Shc and mtDNA damage in the inner ear during aging

Aging has been associated with mitochondrial DNA damage. P66Shc is an age-related adaptor protein that has a substantial impact on mitochondrial metabolism through regulation of the cellular response to oxidative stress. Our study aimed to establish a D-galactose (D-gal)-induced inner ear aging mouse model and to investigate the potential role of p66Shc and its serine 36-phosphorylated form in the inner ear during aging by using this model. Real-time PCR was performed to detect the mtDNA 3873-bp deletion and the level of p66Shc mRNA in the cochlear lateral wall. Western blot analysis was performed to analyze the total and mitochondrial protein levels of p66Shc and the level of Ser36-P-p66Shc in the cochlear lateral wall. Immunofluoresence was performed to detect the location of the Ser36-P-p66Shc expression in the cochlear lateral wall. The results showed that the accumulation of the mtDNA 3873-bp deletion, total and mitochondrial protein levels of p66Shc and level of Ser36-P-p66Shc were significantly increased in the cochlear lateral wall of the D-gal-treated group when compared to the control group and that Ser36-P-p66Shc was mainly localized in the cytoplasm of the cells in the stria vascularis. During aging, the oxidative stress-related increase of p66Shc and Ser36-P-p66Shc might be associated with the accumulation of the mtDNA 3873-bp deletion in the inner ear.

Teaching an old dogma new tricks: twenty years of Shc adaptor signalling

Shc (Src homology and collagen homology) proteins are considered prototypical signalling adaptors in mammalian cells. Consisting of four unique members, ShcA, B, C and D, and multiple splice isoforms, the family is represented in nearly every cell type in the body, where it engages in an array of fundamental processes to transduce environmental stimuli. Two decades of investigation have begun to illuminate the mechanisms of the flagship ShcA protein, whereas much remains to be learned about the newest discovery, ShcD. It is clear, however, that the distinctive modular architecture of Shc proteins, their promiscuous phosphotyrosine-based interactions with a multitude of membrane receptors, involvement in central cascades including MAPK (mitogen-activated protein kinase) and Akt, and unconventional contributions to oxidative stress and apoptosis all require intricate regulation, and underlie diverse physiological function. From early cardiovascular development and neuronal differentiation to lifespan determination and tumorigenesis, Shc adaptors have proven to be more ubiquitous, versatile and dynamic than their structures alone suggest.

Mutant p53 disrupts role of ShcA protein in balancing Smad protein-dependent and -independent signaling activity of transforming growth factor-β (TGF-β)

Biomarkers are lacking for identifying the switch of transforming growth factor-β (TGF-β) from tumor-suppressing to tumor-promoting. Mutated p53 (mp53) has been suggested to switch TGF-β to a tumor promoter. However, we found that mp53 does not always promote the oncogenic role of TGF-β. Here, we show that endogenous mp53 knockdown enhanced cell migration and phosphorylation of ERK in DU145 prostate cancer cells. Furthermore, ectopic expression of mp53 in p53-null PC-3 prostate cancer cells enhanced Smad-dependent signaling but inhibited TGF-β-induced cell migration by down-regulating activated ERK. Reactivation of ERK by the expression of its activator, MEK-1, restored TGF-β-induced cell migration. Because TGF-β is known to activate the MAPK/ERK pathway through direct phosphorylation of the adaptor protein ShcA and MAPK/ERK signaling is pivotal to tumor progression, we investigated whether ShcA contributed to mp53-induced ERK inhibition and the conversion of the role of TGF-β during carcinogenesis. We found that mp53 expression led to a decrease of phosphorylated p52ShcA/ERK levels and an increase of phosphorylated Smad levels in a panel of mp53-expressing cancer cell lines and in mammary glands and tumors from mp53 knock-in mice. By manipulating ShcA levels to regulate ERK and Smad signaling in human untransformed and cancer cell lines, we showed that the role of TGF-β in regulating anchorage-dependent and -independent growth and migration can be shifted between growth suppression and migration promotion. Thus, our results for the first time suggest that mp53 disrupts the role of ShcA in balancing the Smad-dependent and -independent signaling activity of TGF-β and that ShcA/ERK signaling is a major pathway regulating the tumor-promoting activity of TGF-β.

Resveratrol regulates p66Shc activation in HaCaT cells

Skin is exposed to both endogenous and environmental oxidant agents, leading to the harmful generation of reactive oxygen species. Particular interest has been pointed on plant antioxidants, such as resveratrol, because of their wide-ranging biological activity and clinical potential. Resveratrol exerts antioxidant, metabolism-regulating and pro-apoptotic/anti-cancer effects on a variety of experimental models and has been suggested to protect skin from ultraviolet-induced photodamaging and photoaging. In parallel, also the biological significance of p66Shc, a member of the Src Homologue and Collagene homologue family with redox activity, is getting further attention. Because of the striking intersection among the activities of resveratrol with those of p66Shc, we investigated whether resveratrol would activate p66Shc in human immortalised keratinocytes (HaCaT cells), a well known and largely used model for skin keratinocytes. HaCaT cells were treated with resveratrol (10-150 μm) for different times. The effect of resveratrol on the proliferation of HaCaT cells and the activation of ERK1/2, AKT, and p66Shc was investigated by cell counting, fluorescence-activated cell sorting, and western blot analysis of total or immunoprecipitated cell extracts. In HaCaT cells, resveratrol induces dose- and time-dependent growth arrest, p66Shc-Ser36 phosphorylation, ERK1/2 phosphorylation and AKT dephosphorylation. Finally, we showed that resveratrol-induced p66Shc-Ser36 phosphorylation is dependent on ERK1/2 activation. Interestingly, these resveratrol-induced molecular effects were associated with reduced adhesion and reversible growth arrest rather than cell death pathways. This is the first evidence linking resveratrol with p66Shc and suggests that p66Shc may contribute to the effect of resveratrol on cell proliferation and function in the outermost layer of the skin.