14-3-3ζ as a prognostic marker and therapeutic target for cancer

Diet-induced Obesity: Pathophysiology, Consequences and Target Specific Therapeutic Strategies

Diet has emerged as a pivotal factor in the current time for diet-induced obesity (DIO). A diet overloaded with fats and carbohydrates and unhealthy dietary habits contribute to the development of DIO through several mechanisms. The prominent ones include the transition of normal gut microbiota to obese microbiota, under-expression of AMPK, and abnormally high levels of adipogenesis. DIO is the root of many diseases. The present review deals with various aspects of DIO and its target proteins that can be specifically used for its treatment. Also, the currently available treatment strategies have been explored. It was found that the expression of five proteins, namely, PPARγ, FTO, CDK4, 14-3-3 ζ protein, and Galectin-1, is upregulated in DIO. They can be used as potential targets for drug-designing studies. Thus, with these targets, the treatment strategy for DIO using natural bioactive compounds can be a safer alternative to medications and bariatric surgeries.

Targeting a chemo-induced adaptive signaling circuit confers therapeutic vulnerabilities in pancreatic cancer

Advanced pancreatic ductal adenocarcinomas (PDACs) respond poorly to all therapies, including the first-line treatment, chemotherapy, the latest immunotherapies, and KRAS-targeting therapies. Despite an enormous effort to improve therapeutic efficacy in late-stage PDAC patients, effective treatment modalities remain an unmet medical challenge. To change the status quo, we explored the key signaling networks underlying the universally poor response of PDAC to therapy. Here, we report a previously unknown chemo-induced symbiotic signaling circuit that adaptively confers chemoresistance in patients and mice with advanced PDAC. By integrating single-cell transcriptomic data from PDAC mouse models and clinical pathological information from PDAC patients, we identified Yap1 in cancer cells and Cox2 in stromal fibroblasts as two key nodes in this signaling circuit. Co-targeting Yap1 in cancer cells and Cox2 in stroma sensitized PDAC to Gemcitabine treatment and dramatically prolonged survival of mice bearing late-stage PDAC, whereas simultaneously inhibiting Yap1 and Cox2 only in cancer cells was ineffective. Mechanistically, chemotherapy triggers non-canonical Yap1 activation by nemo-like kinase in 14-3-3ζ-overexpressing PDAC cells and increases secretion of CXCL2/5, which bind to CXCR2 on fibroblasts to induce Cox2 and PGE2 expression, which reciprocally facilitate PDAC cell survival. Finally, analyses of PDAC patient data revealed that patients who received Statins, which inhibit Yap1 signaling, and Cox2 inhibitors (including Aspirin) while receiving Gemcitabine displayed markedly prolonged survival compared to others. The robust anti-tumor efficacy of Statins and Aspirin, which co-target the chemo-induced adaptive circuit in the tumor cells and stroma, signifies a unique therapeutic strategy for PDAC.

14-3-3 Family of Proteins: Biological Implications, Molecular Interactions, and Potential Intervention in Cancer, Virus and Neurodegeneration Disorders

The 14-3-3 family of proteins are highly conserved acidic eukaryotic proteins (25-32 kDa) abundantly present in the body. Through numerous binding partners, the 14-3-3 is responsible for many essential cellular pathways, such as cell cycle regulation and gene transcription control. Hence, its dysregulation has been linked to the onset of critical illnesses such as cancers, neurodegenerative diseases and viral infections. Interestingly, explorative studies have revealed an inverse correlation of 14-3-3 protein in cancer and neurodegenerative diseases, and the direct manipulation of 14-3-3 by virus to enhance infection capacity has dramatically extended its significance. Of these, COVID-19 has been linked to the 14-3-3 proteins by the interference of the SARS-CoV-2 nucleocapsid (N) protein during virion assembly. Given its predisposition towards multiple essential host signalling pathways, it is vital to understand the holistic interactions between the 14-3-3 protein to unravel its potential therapeutic unit in the future. As such, the general structure and properties of the 14-3-3 family of proteins, as well as their known biological functions and implications in cancer, neurodegeneration, and viruses, were covered in this review. Furthermore, the potential therapeutic target of 14-3-3 proteins in the associated diseases was discussed.

A high-throughput screening approach to discover potential colorectal cancer chemotherapeutics: Repurposing drugs to disrupt 14-3-3 protein-BAD interactions

Inducing apoptosis in different types of cancer cells is an effective therapeutic strategy. However, the success of existing chemotherapeutics can be compromised by tumor cell resistance and systemic off-target effects. Therefore, the discovery of pro-apoptotic compounds with minimal systemic side-effects is crucial. 14-3-3 proteins are molecular scaffolds that serve as important regulators of cell survival. Our previous study demonstrated that 14-3-3ζ can sequester BAD, a pro-apoptotic member of the BCL-2 protein family, in the cytoplasm and prevent its translocation to mitochondria to inhibit the induction of apoptosis. Despite being a critical mechanism of cell survival, it is unclear whether disrupting 14-3-3 protein:BAD interactions could be harnessed as a chemotherapeutic approach. Herein, we established a BRET-based high-throughput drug screening approach (Z'-score= 0.52) capable of identifying molecules that can disrupt 14-3-3ζ:BAD interactions. An FDA-approved drug library containing 1971 compounds was used for screening, and the capacity of identified hits to induce cell death was examined in NIH3T3-fibroblasts and colorectal cancer cell lines, HT-29 and Caco-2. Our in vitro results suggest that terfenadine, penfluridol, and lomitapide could be potentially repurposed for treating colorectal cancer. Moreover, our screening method demonstrates the feasibility of identifying pro-apoptotic agents that can be applied towards conditions where aberrant cell growth or function are key determinants of disease pathogenesis.

The adaptor protein 14-3-3zeta modulates intestinal immunity and aging in Drosophila

The proteins that coordinate the complex transcriptional networks of aging have not been completely documented. Protein 14-3-3zeta is an adaptor protein that coordinates signaling and transcription factor networks, but its function in aging is not fully understood. Here, we showed that the protein expression of 14-3-3zeta gradually increased during aging. High levels of 14-3-3zeta led to shortened lifespan and imbalance of intestinal immune homeostasis in Drosophila, but the decrease in 14-3-3zeta protein levels by RNAi was able to significantly promote the longevity and intestinal immune homeostasis of fruit flies. Importantly, we demonstrate that adult-onset administration of TIC10, a compound that reduces the aging-related AKT and extracellular signal-regulated kinase (ERK) signaling pathways, rescues the shortened lifespan of 14-3-3zeta-overexpressing flies. This finding suggests that 14-3-3zeta plays a critical role in regulating the aging process. Our study elucidates the role of 14-3-3zeta in natural aging and provides the rationale for subsequent 14-3-3zeta-based antiaging research.

Stratifin Promotes Hepatocellular Carcinoma Progression by Modulating the Wnt/β-Catenin Pathway

Abnormal stratifin (SFN) expression is closely related to the progression of several human cancers, but the potential roles of SFN in hepatocellular carcinoma (HCC) remain largely unknown. In this study, we found that SFN was upregulated in HCC cell lines and tissues and was positively associated with tumor size, poor differentiation, Tumor Node Metastasis (TNM) stage, and vascular invasion. In addition, high expression levels of SFN were associated with poor overall survival and disease-free survival. Biologically, downregulation of SFN suppressed tumor cell proliferation, epithelial-mesenchymal transition (EMT), invasion, and migration in vitro and tumor growth in vivo. However, overexpression of SFN promoted cell proliferation, EMT, invasion, and migration in vitro and tumor growth in vivo. Mechanistically, overexpression of SFN activated the Wnt/β-catenin pathway by promoting Glycogen synthase kinase-3 beta (GSK-3β) phosphorylation, decreasing β-catenin phosphorylation, promoting β-catenin transport into the nucleus, and enhancing the expression of c-Myc, whereas depletion of SFN inhibited the Wnt/β-catenin pathway. In addition, TOPFlash/FOPFlash reporter assays showed that overexpression or downregulation of SFN obviously increased or decreased, respectively, the activity of the Wnt/β-catenin pathway. Our results indicated that SFN plays an important role in HCC, possibly providing a prognostic factor and therapeutic target for HCC.

Co-Expression of Chromatin Assembly Factor 1 Subunit A and Proliferating Cell Nuclear Antigen Is a Prognostic Biomarker of Esophageal Cancer

(1) Background: Esophageal cancer (EC) is an important global health challenge. Due to the lack of necessary biomarkers and therapeutic targets, the survival of EC patients is poor. The EC proteomic data of 124 patients recently published by our group provides a database for research in this field. (2) Methods: Bioinformatics analysis was used to identify DNA replication and repair-related proteins in EC. Proximity ligation assay, colony formation assay, DNA fiber assay, and flow cytometry were used to study the effects of related proteins on EC cells. Kaplan-Meier survival analysis was used to evaluate the relationship between gene expression and the survival time of EC patients. (3) Results: Chromatin assembly factor 1 subunit A (CHAF1A) was highly correlated with proliferating cell nuclear antigen (PCNA) expression in EC. CHAF1A and PCNA colocalized in the nucleus of EC cells. Compared with the knockdown of CHAF1A or PCNA alone, the double knockdown of CHAF1A and PCNA could significantly inhibit EC cell proliferation. Mechanistically, CHAF1A and PCNA synergistically accelerated DNA replication and promoted S-phase progression. EC patients with high expression of both CHAF1A and PCNA had a worse survival rate. (4) Conclusion: we identify CHAF1A and PCNA as key cell cycle-related proteins leading to the malignant progression of EC, and these proteins could serve as important prognostic biomarkers and targets for EC.

YBX1 regulates the survival of chronic myeloid leukemia stem cells by modulating m6A-mediated YWHAZ stability

PURPOSE

Chronic myeloid leukemia (CML) is a myeloproliferative disease derived from hematopoietic stem cells (HSCs) that harbor Philadelphia chromosome (Ph chromosome). In clinic, leukemia stem cells (LSCs) in CML are insensitive to the treatment with tyrosine kinase inhibitors, and are responsible for disease relapse. However, the molecular mechanisms for maintaining LSCs survival remain elusive.

METHODS

CML patient-derived cell lines and BCR-ABL-induced CML mouse model were used to explore the role of YBX1 in regulating the survival of CML LSCs. Bone marrow transduction and transplantation, and colony-forming unit assay were used to investigate LSC function. The underlying mechanism of how YBX1 regulates LSCs survival were assessed using flow cytometry, RNA sequencing, western blot, RNA decay assay, co-immunoprecipitation and RNA immunoprecipitation.

RESULTS

Here we show that RNA-binding protein YBX1 plays an important role in regulating survival of CML LSCs. We find that YBX1 expression is significantly increased in CML cells, and confirm that YBX1 is required for maintaining survival of LSCs. Deletion of YBX1 impairs the propagation of CML through blocking cell proliferation and inducing apoptosis of LSCs. Mechanistically, we find that YBX1 regulates expression of apoptotic associated genes. YBX1 cooperates with RNA m⁶A reader IGF2BPs to stabilize YWHAZ transcript in an m⁶A-dependent manner, and loss of YBX1 decreases YWHAZ expression by accelerating mRNA decay. Restoration of YWHAZ efficiently rescues the defects of YBX1-deficient CML cells.

CONCLUSION

Our findings reveal a critical role of YBX1 in maintaining survival of CML LSCs, which provides a rationale for targeting YBX1 in CML treatment.

High expression of 14-3-3ơ indicates poor prognosis and progression of lung adenocarcinoma

Lung adenocarcinoma (LUAD) is one of the leading causes of cancer-related death worldwide. 14-3-3ơ is an intracellular phosphoserine-binding protein that has been proposed to be involved in tumorigenesis. However, the biofunctional role of 14-3-3ơ and its clinicopathological/prognostic significance in LUAD have remained elusive. In the present study, western blot and immunohistochemical analyses of cancer tissues/cells and the corresponding normal controls were performed to verify that 14-3-3ơ was upregulated in LUAD. Univariate and multivariate logistic regression analysis indicated that high expression of 14-3-3ơ predicted poor overall survival and progression-free survival of patients with LUAD. Furthermore, in vivo and in vitro experiments demonstrated that overexpression of 14-3-3ơ markedly promoted cell proliferation, colony formation, anchorage-independent growth and tumor growth, whereas 14-3-3ơ depletion produced the opposite effects. Of note, 14-3-3ơ was identified as an independent prognostic factor for patients with LUAD. Collectively, the present results revealed that high expression of 14-3-3ơ may serve as an independent biomarker, contributing to poor prognosis and progression of LUAD.

Exosomes for Regulation of Immune Responses and Immunotherapy

Exosomes are membrane-enveloped nanosized (30–150 nm) extracellular vesicles of endosomal origin produced by almost all cell types and encompass a multitude of functioning biomolecules. Exosomes have been considered crucial players of cell-to-cell communication in physiological and pathological conditions. Accumulating evidence suggests that exosomes can modulate the immune system by delivering a plethora of signals that can either stimulate or suppress immune responses, which have potential applications as immunotherapies for cancer and autoimmune diseases. Here, we discuss the current knowledge about the active biomolecular components of exosomes that contribute to exosomal function in modulating different immune cells and also how these immune cell-derived exosomes play critical roles in immune responses. We further discuss the translational potential of engineered exosomes as immunotherapeutic agents with their advantages over conventional nanocarriers for drug delivery and ongoing clinical trials.

The 14-3-3 Protein Family and Schizophrenia

Schizophrenia is a debilitating mental disorder that affects approximately 1% of the world population, yet the disorder is not very well understood. The genetics of schizophrenia is very heterogenous, making it hard to pinpoint specific alterations that may cause the disorder. However, there is growing evidence from human studies suggesting a link between alterations in the 14-3-3 family and schizophrenia. The 14-3-3 proteins are abundantly expressed in the brain and are involved in many important cellular processes. Knockout of 14-3-3 proteins in mice has been shown to cause molecular, structural, and behavioral alterations associated with schizophrenia. Thus, 14-3-3 animal models allow for further exploration of the relationship between 14-3-3 and schizophrenia as well as the study of schizophrenia pathology. This review considers evidence from both human and animal model studies that implicate the 14-3-3 family in schizophrenia. In addition, possible mechanisms by which alterations in 14-3-3 proteins may contribute to schizophrenia-like phenotypes such as dopaminergic, glutamatergic, and cytoskeletal dysregulations are discussed.

Exploiting Interdata Relationships in Prostate Cancer Proteomes: Clinical Significance of HO-1 Interactors

Prostate cancer (PCa) cells display abnormal expression of proteins resulting in an augmented capacity to resist chemotherapy and colonize distant organs. We have previously shown the anti-tumoral role of heme oxygenase 1 (HO-1) in this disease. In this work, we undertook a mass spectrometry-based proteomics study to identify HO-1 molecular interactors that might collaborate with its modulatory function in PCa. Among the HO-1 interactors, we identified proteins with nuclear localization. Correlation analyses, using the PCa GSE70770 dataset, showed a significant and positive correlation between HMOX1 and 6 of those genes. Alternatively, HMOX1 and YWHAZ showed a negative correlation. Univariable analyses evidenced that high expression of HNRNPA2B1, HSPB1, NPM1, DDB1, HMGA1, ZC3HAV1, and HMOX1 was associated with increased relapse-free survival (RFS) in PCa patients. Further, PCa patients with high HSPB1/HMOX1, DDB1/HMOX1, and YWHAZ/HMOX1 showed a worse RFS compared with patients with lower ratios. Moreover, a decrease in RFS for patients with higher scores of this signature was observed using a prognostic risk score model. However, the only factor significantly associated with a higher risk of relapse was high YWHAZ. Multivariable analyses confirmed HSPB1, DDB1, and YWHAZ independence from PCa clinic-pathological parameters. In parallel, co-immunoprecipitation analysis in PCa cells ascertained HO-1/14-3-3ζ/δ (protein encoded by YWHAZ) interaction. Herein, we describe a novel protein interaction between HO-1 and 14-3-3ζ/δ in PCa and highlight these factors as potential therapeutic targets.

Genetic variation of YWHAE gene-"Switch" of disease control

YWHAE gene is located on chromosome 17p13.3, and its product 14-3-3epsilon protein belongs to 14-3-3 protein family. As a molecular scaffold, YWHAE participates in biological processes such as cell adhesion, cell cycle regulation, signal transduction and malignant transformation, and is closely related to many diseases. Overexpression of YWHAE in breast cancer can increase the ability of proliferation, migration and invasion of breast cancer cells. In gastric cancer, YWHAE acts as a negative regulator of MYC and CDC25B, which reduces their expression and inhibits the proliferation, migration, and invasion of gastric cancer cells, and enhances YWHAE-mediated transactivation of NF-κB through CagA. In colorectal cancer, YWHAE lncRNA, as a sponge molecule of miR-323a-3p and miR-532-5p, can compete for endogenous RNA through direct interaction with miR-323a-3p and miR-532-5p, thus up-regulating K-RAS/ERK/1/2 and PI3K-AKT signaling pathways and promoting the cell cycle progression of the colorectal cancer. YWHAE not only mediates tumorigenesis as a competitive endogenous RNA, but also affects gene expression through chromosome variation. For example, the FAM22B-YWHAE fusion gene caused by t(10; 17) (q22; p13) may be associated with the development of endometrial stromal sarcoma. At the same time, the fusion transcript of YWHAE and NUTM2B/E may also lead to the occurrence of endometrial stromal sarcoma. To understand the relationship between YWHAE, NUTM2A, and NUTM2B gene rearrangement/fusion and malignant tumor, YWHAE-FAM22 fusion gene/translocation and tumor, YWHAE gene polymorphism and mental illness, as well as the relationship between 17p13.3 region change and disease occurrence. It provides new idea and basis for understanding the effect of YWHAE gene molecular mechanism and genetic variation on the disease progression, and for the targeted for the diseases.

14-3-3ζ negatively regulates mitochondrial biogenesis in GBM residual cells

Glioblastoma (GBM) is the most lethal primary brain tumour with a median survival of only 15 months. We have previously demonstrated the generation of an in vitro therapy resistance model that captures the residual resistant (RR) disease cells of GBM post-radiation. We also reported the proteomic landscape of parent, residual, and relapse cells using iTRAQ based quantitative proteomics of glioma cells. The proteomics data revealed significant up-regulation (fold change >1.5) of 14-3-3ζ, specifically in GBM RR cells. This was further confirmed by western blots in residual cells generated from GBM cell lines and patient sample-derived short-term primary culture. ShRNA-mediated knockdown of 14-3-3ζ radio-sensitized GBM cells and further stimulated therapy-induced senescence (TIS) and multinucleated giant cells (MNGCs) phenotype in RR cells. Intriguingly, 14-3-3ζ knockdown residual cells also showed a significantly higher number of mitochondria and increased mtDNA content. Indeed, in vitro GST pull-down mass spectrometry analysis of GST tagged 14-3-3ζ from RR cells identified novel interacting partners of 14-3-3ζ involved in cellular metabolism. Taken together, here we identified novel interacting partners of 14-3-3ζ and proposed an unconventional function of 14-3-3ζ as a negative regulator of TIS and mitochondrial biogenesis in residual resistant cells and loss of which also radio-sensitize GBM cells.

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14-3-3ζ is up-regulated in residual disease cells of GBM.

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14-3-3ζ knockdown radiosensitizes GBM cells.

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14-3-3ζ knockdown increases MNGCs formation and senescence in residual cells.

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14-3-3ζ negatively regulates mitochondrial biogenesis of residual disease cells.

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Novel interacting partners of 14-3-3ζ from residual cells are involved in cellular metabolism.

14-3-3ζ promoted invasion and lymph node metastasis of breast invasive ductal carcinoma with HER2 overexpression

BACKGROUND

HER2 was a recognized oncogene that promoted the development and metastasis of breast cancer, but its positive expression rate in invasive ductal carcinoma (IDC) was much lower than that in ductal carcinoma in situ (DCIS). The correlation between the occurrence and development of breast cancer and the amplification and overexpression of HER2 gene alone was still controversial. 14-3-3ζ had a strong protein binding ability and a variety of functions, mainly through the interaction with other proteins to exert its unique biological activities. However, influence and interaction relationship of the two proteins on the development of IDC was not clear. Furthermore, the mutual effect mechanism of synergy effect on lymph node metastasis of IDC was not known well too.

METHODS

Immunohistochemistry experiment was performed to detect expression status of 14-3-3ζ, HER2, TGF-β, p53 and Gli2 in paraffin-embedded samples respectively, including 30 cases of normal breast tissue, 30 cases of usual ductal hyperplasia (UDH), 30 cases of atypical ductal hyperplasia (ADH), 30 cases of DCIS and 120 cases of IDC.

RESULTS

The positive expression rates of 14-3-3ζ/HER2 in Normal group, UDH group, ADH group, DCIS group and IDC group were 30%/0.00%, 26.7%/0.00%, 53.3%/33.3%, 46.7%/53.3% and 50%/24.2%, respectively. Compared with Normal group or UDH group, the expression of 14-3-3ζ was significantly increased in ADH, DCIS and IDC groups. 14-3-3ζ was overexpressed in only 4 of the 16 DCIS cases with HER2 overexpression (25.0%, 4/16), but it was overexpressed in 7 of the 9 IDC cases with DCIS (77.8%, 7/9). Among HER2 overexpression cases, 14-3-3ζ overexpression was significantly different between DCIS group and IDC with DCIS group (P = 0.017). In 18 IDC cases with lymph node metastasis and HER2 overexpression, 14-3-3ζ was overexpressed in 15 cases (83.3%, 15/18), while in the 11 IDC cases without lymph node metastasis, 14-3-3ζ and HER2 were overexpressed in only 5 cases (45.5%, 5/11). Co-overexpression of 14-3-3ζ and HER2 was positively correlated with occurrence of lymph node metastasis (P = 0.048). TGF-β was overexpressed in both precancerous lesion group and IDC group compared with normal group. Compared with the IDC group without lymph node metastasis, TGF-β expression was significantly increased in the IDC group with lymph node metastasis (P = 0.015). In IDC cases with 14-3-3ζ and HER2 co-overexpression, the expression of p53 in IDC with lymph node metastasis was significantly decreased (P = 0.010), while the expression of Gli2 was significantly increased compared with IDC cases without lymph node metastasis (P = 0.038). The co-overexpression of 14-3-3ζ and HER2 was positively correlated with ER negative expression (P < 0.001) and PR negative expression (P = 0.038), respectively.

CONCLUSION

14-3-3ζ synergistic with HER2 could promote the occurrence and development of breast IDC and induce the lymph node metastasis of IDC, suggesting that combined overexpression of 14-3-3ζ and HER2 would lead to higher invasion and metastasis risk of breast cancer. It was speculated that the combined detection of 14-3-3ζ and HER2 would be one of the key factors affecting the clinical treatment decision and prognosis.

Compensatory Protection of Thioredoxin-Deficient Cells from Etoposide-Induced Cell Death by Selenoprotein W via Interaction with 14-3-3

Selenoprotein W (SELENOW) is a 9.6 kDa protein containing selenocysteine (Sec, U) in a conserved Cys-X-X-Sec (CXXU) motif. Previously, we reported that SELENOW regulates various cellular processes by interacting with 14-3-3β at the U of the CXXU motif. Thioredoxin (Trx) is a small protein that plays a key role in the cellular redox regulatory system. The CXXC motif of Trx is critical for redox regulation. Recently, an interaction between Trx1 and 14-3-3 has been predicted. However, the binding mechanism and its biological effects remain unknown. In this study, we found that Trx1 interacted with 14-3-3β at the Cys32 residue in the CXXC motif, and SELENOW and Trx1 were bound at Cys191 residue of 14-3-3β. In vitro binding assays showed that SELENOW and Trx1 competed for interaction with 14-3-3β. Compared to control cells, Trx1-deficient cells and SELENOW-deficient cells showed increased levels of both the subG1 population and poly (ADP-ribose) polymerase (PARP) cleavage by etoposide treatment. Moreover, Akt phosphorylation of Ser473 was reduced in Trx1-deficient cells and was recovered by overexpression of SELENOW. These results indicate that SELENOW can protect Trx1-deficient cells from etoposide-induced cell death through its interaction with 14-3-3β.

14-3-3ζ: A suppressor of inflammatory arthritis

Inflammatory arthritis (IA) is a common disease that affects millions of individuals worldwide. Proinflammatory events during IA pathogenesis are well studied; however, loss of protective immunity remains underexplored. Earlier, we reported that 14-3-3zeta (ζ) has a role in T-cell polarization and interleukin (IL)-17A signal transduction. Here, we demonstrate that 14-3-3ζ knockout (KO) rats develop early-onset severe arthritis in two independent models of IA, pristane-induced arthritis and collagen-induced arthritis. Arthritic 14-3-3ζ KO animals showed an increase in bone loss and immune cell infiltration in synovial joints. Induction of arthritis coincided with the loss of anti-14-3-3ζ antibodies; however, rescue experiments to supplement the 14-3-3ζ antibody by passive immunization did not suppress arthritis. Instead, 14-3-3ζ immunization during the presymptomatic phase resulted in significant suppression of arthritis in both wild-type and 14-3-3ζ KO animals. Mechanistically, 14-3-3ζ KO rats exhibited elevated inflammatory gene signatures at the messenger RNA and protein levels, particularly for IL-1β. Furthermore, the immunization with recombinant 14-3-3ζ protein suppressed IL-1β levels, significantly increased anti-14-3-3ζ antibody levels and collagen production, and preserved bone quality. The 14-3-3ζ protein increased collagen expression in primary rat mesenchymal cells. Together, our findings indicate that 14-3-3ζ causes immune suppression and extracellular remodeling, which lead to a previously unrecognized IA-suppressive function.

Human papillomavirus oncoproteins and post-translational modifications: generating multifunctional hubs for overriding cellular homeostasis

Human papillomaviruses (HPVs) are major human carcinogens, causing around 5% of all human cancers, with cervical cancer being the most important. These tumors are all driven by the two HPV oncoproteins E6 and E7. Whilst their mechanisms of action are becoming increasingly clear through their abilities to target essential cellular tumor suppressor and growth control pathways, the roles that post-translational modifications (PTMs) of E6 and E7 play in the regulation of these activities remain unclear. Here, we discuss the direct consequences of some of the most common PTMs of E6 and E7, and how this impacts upon the multi-functionality of these viral proteins, and thereby contribute to the viral life cycle and to the induction of malignancy. Furthermore, it is becoming increasingly clear that these modifications, may, in some cases, offer novel routes for therapeutic intervention in HPV-induced disease.

MDM2 induces EMT via the B‑Raf signaling pathway through 14‑3‑3

MDM2 proto-oncogene, E3 ubiquitin protein ligase (MDM2) is a well-known oncogene and has been reported to be closely associated with epithelial-to-mesenchymal transition (EMT). The present study first demonstrated that the expression levels of MDM2 were markedly increased in TGF-β-induced EMT using quantitative PCR and western blotting. In addition, MDM2 was demonstrated to be associated with pathological grade in clinical glioma samples by immunohistochemical staining. Furthermore, overexpression of MDM2 promoted EMT in glioma, lung cancer and breast cancer cell lines using a scratch wound migration assay. Subsequently, the present study explored the mechanism by which MDM2 promoted EMT and revealed that MDM2 induced EMT by upregulating EMT-related transcription factors via activation of the B-Raf signaling pathway through tyrosine 3-monooxygenase activation protein ε using RNA sequencing and western blotting. This mechanism depended on the p53 gene. Furthermore, in vivo experiments and the colony formation experiment demonstrated that MDM2 could promote tumor progression and induce EMT via the B-Raf signaling pathway. Since EMT contributes to increased drug resistance in tumor cells, the present study also explored the relationship between MDM2 and drug sensitivity using an MTT assay, and identified that MDM2 promoted cell insensitivity to silibinin treatment in an EMT-dependent manner. This finding is crucial for the development of cancer therapies and can also provide novel research avenues for future biological and clinical studies.

Circ-VPS13C enhances cisplatin resistance in ovarian cancer via modulating the miR-106b-5p/YWHAZ axis

Introduction

Ovarian cancer (OC) is the malignant tumor with the highest mortality among gynecological cancers. Chemotherapy resistance is a major obstacle to OC therapy. Circular RNAs (circRNAs) play crucial roles in cancer development and chemoresistance. However, the role and potential mechanism of has-circ-001567 (circ-VPS13C) in chemoresistance of OC remain unknown.

Material and methods

The levels of circ-VPS13C, miR-106b-5p and 14-3-3 zeta (YWHAZ) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell Counting Kit-8 (CCK-8) assay was used to assess cell viability and calculate the half inhibition concentration (IC50) of cisplatin (DDP). The levels of autophagy-related markers were measured by western blot assay. Cell apoptosis and migration were evaluated by flow cytometry and transwell assay, respectively. The binding relationship between miR-106b-5p and circ-VPS13C or YWHAZ was confirmed by dual-luciferase reporter assay. Xenograft assay was performed to explore the role of circ-VPS13C in vivo.

Results

Circ-VPS13C and YWHAZ were up-regulated, while miR-106b-5p was down-regulated in DDP-resistant OC tissues and cells. Knockdown of circ-VPS13C enhanced DDP sensitivity by repressing autophagy in DDP-resistant cells. Circ-VPS13C increased DDP resistance via sponging miR-106b-5p. Moreover, miR-106b-5p directly targeted YWHAZ. Up-regulation of YWHAZ alleviated the decrease in DDP resistance caused by circ-VPS13C depletion. In addition, circ-VPS13C silencing decreased DDP resistance in vivo.

Conclusions

Circ-VPS13C knockdown enhanced DDP sensitivity of OC through modulation of autophagy via the miR-106b-5p/YWHAZ axis, providing a new biomarker for improving the efficacy of OC chemotherapy.

The 14-3-3σ protein promotes HCC anoikis resistance by inhibiting EGFR degradation and thereby activating the EGFR-dependent ERK1/2 signaling pathway

Resistance to anoikis, cell death due to matrix detachment, is acquired during tumor progression. The 14-3-3σ protein is implicated in the development of chemo- and radiation resistance, indicating a poor prognosis in multiple human cancers. However, its function in anoikis resistance and metastasis in hepatocellular carcinoma (HCC) is currently unknown.

Methods: Protein expression levels of 14-3-3σ were measured in paired HCC and normal tissue samples using western blot and immunohistochemical (IHC) staining. Statistical analysis was performed to evaluate the clinical correlation between 14-3-3σ expression, clinicopathological features, and overall survival. Artificial modulation of 14-3-3σ (downregulation and overexpression) was performed to explore the role of 14-3-3σ in HCC anoikis resistance and tumor metastasis in vitro and in vivo. Association of 14-3-3σ with epidermal growth factor receptor (EGFR) was assayed by co-immunoprecipitation. Effects of ectopic 14-3-3σ expression or knockdown on EGFR signaling, ligand-induced EGFR degradation and ubiquitination were examined using immunoblotting and co-immunoprecipitation, immunofluorescence staining, and flow cytometry analysis. The levels of EGFR ubiquitination, the interaction between EGFR and 14-3-3σ, and the association of EGFR with c-Cbl after EGF stimulation, in 14-3-3σ overexpressing or knockdown cells were examined to elucidate the mechanism by which 14-3-3σ inhibits EGFR degradation. Using gain-of-function or loss-of-function strategies, we further investigated the role of the EGFR signaling pathway and its downstream target machinery in 14-3-3σ-mediated anoikis resistance of HCC cells.

Results: We demonstrated that 14-3-3σ was upregulated in HCC tissues, whereby its overexpression was correlated with aggressive clinicopathological features and a poor prognosis. In vitro and in vivo experiments indicated that 14-3-3σ promoted anoikis resistance and metastasis of HCC cells. Mechanistically, we show that 14-3-3σ can interact with EGFR and significantly inhibit EGF-induced degradation of EGFR, stabilizing the activated receptor, and therefore prolong the activation of EGFR signaling. We demonstrated that 14-3-3σ downregulated ligand-induced EGFR degradation by inhibiting EGFR-c-Cbl association and subsequent c-Cbl-mediated EGFR ubiquitination. We further verified that activation of the ERK1/2 pathway was responsible for 14-3-3σ-mediated anoikis resistance of HCC cells. Moreover, EGFR inactivation could reverse the 14-3-3σ-mediated effects on ERK1/2 phosphorylation and anoikis resistance. Expression of 14-3-3σ and EGFR were found to be positively correlated in human HCC tissues.

Conclusions: Our results indicate that 14-3-3σ plays a pivotal role in the anoikis resistance and metastasis of HCC cells, presumably by inhibiting EGFR degradation and regulating the activation of the EGFR-dependent ERK1/2 pathway. To our best knowledge, this is the first report of the role of 14-3-3σ in the anoikis resistance of HCC cells, offering new research directions for the treatment of metastatic cancer by targeting 14-3-3σ.

A Novel Nanoproteomic Approach for the Identification of Molecular Targets Associated with Thyroid Tumors

A thyroid nodule is the most common presentation of thyroid cancer; thus, it is extremely important to differentiate benign from malignant nodules. Within malignant lesions, classification of a thyroid tumor is the primary step in the assessment of the prognosis and selection of treatment. Currently, fine-needle aspiration biopsy (FNAB) is the preoperative test most commonly used for the initial thyroid nodule diagnosis. However, due to some limitations of FNAB, different high-throughput “omics” approaches have emerged that could further support diagnosis based on histopathological patterns. In the present work, formalin-fixed paraffin-embedded (FFPE) tissue specimens from normal (non-neoplastic) thyroid (normal controls (NCs)), benign tumors (follicular thyroid adenomas (FTAs)), and some common types of well-differentiated thyroid carcinoma (follicular thyroid carcinomas (FTCs), conventional or classical papillary thyroid carcinomas (CV-PTCs), and the follicular variant of papillary thyroid carcinomas (FV-PTCs)) were analyzed. For the first time, FFPE thyroid samples were deparaffinized using an easy, fast, and non-toxic method. Protein extracts from thyroid tissue samples were analyzed using a nanoparticle-assisted proteomics approach combined with shotgun LC-MS/MS. The differentially regulated proteins found to be specific for the FTA, FTC, CV-PTC, and FV-PTC subtypes were analyzed with the bioinformatic tools STRING and PANTHER showing a profile of proteins implicated in the thyroid cancer metabolic reprogramming, cancer progression, and metastasis. These proteins represent a new source of potential molecular targets related to thyroid tumors.

Targeting 14-3-3ζ Overcomes Resistance to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in Lung Adenocarcinoma via BMP2/Smad/ID1 Signaling

Background: The 14-3-3ζ protein, which acts as a putative oncoprotein, has been found to promote the proliferation, metastasis, and chemoresistance of cancer cells in several cancers including lung adenocarcinoma (LUAD); however, its significance in epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) resistance remains unknown.

Methods: The Cancer Genome Atlas (TCGA) database was used to determine 14-3-3ζ expression in pancancer and LUAD. 14-3-3ζ and ID1 expression was then examined in clinical LUAD samples by immunohistochemistry (IHC). Lentiviral transfection with 14-3-3ζ-specific small hairpin RNA (shRNA) was used to establish stable 14-3-3ζ knockdown gefitinib-resistant PC9 (PC9/GR) and H1975 cell lines. The effect of 14-3-3ζ knockdown on reversing EGFR-TKI resistance was determined in vitro by Cell Counting Kit-8 (CCK-8), wound healing, Transwell assays, and flow cytometry. A xenograft tumor model was established to evaluate the role of 14-3-3ζ in EGFR-TKI resistance. Microarray analysis results showed multiple pathways regulated by 14-3-3ζ-shRNA.

Results: In the present study, we demonstrated that based on the TCGA, pancancer and LUAD 14-3-3ζ expression was elevated and predicted unfavorable prognosis. In addition, high 14-3-3ζ expression was associated with advanced T stage, TNM stage, presence of lymph node metastasis and, importantly, poor treatment response to EGFR-TKIs in LUAD patients with EGFR-activating mutations. 14-3-3ζ shRNA sensitized EGFR-TKI-resistant human LUAD cells to gefitinib and reversed epithelial-to-mesenchymal transition (EMT). After 14-3-3ζ depletion, bone morphogenetic protein (BMP) signaling activation was decreased in EGFR-TKI-resistant cells in microarray analysis, which was further validated by Western blot analysis. Furthermore, the expression of 14-3-3ζ positively correlates with ID1 expression in human EGFR-mutant LUAD patient samples. In vivo, there was a reduction in the tumor burden in mice treated with 14-3-3ζ shRNA and gefitinib compared to mice treated with gefitinib alone.

Conclusion: Our work uncovers a hitherto unappreciated role of 14-3-3ζ in EGFR-TKI resistance. This study might provide a potential therapeutic approach for treating LUAD patients harboring EGFR mutations.

Potential of guggulsterone, a farnesoid X receptor antagonist, in the prevention and treatment of cancer

Cancer is one of the most dreadful diseases in the world with a mortality of 9.6 million annually. Despite the advances in diagnosis and treatment during the last couple of decades, it still remains a serious concern due to the limitations associated with currently available cancer management strategies. Therefore, alternative strategies are highly required to overcome these glitches. The importance of medicinal plants as primary healthcare has been well-known from time immemorial against various human diseases, including cancer. Commiphora wightii that belongs to Burseraceae family is one such plant which has been used to cure various ailments in traditional systems of medicine. This plant has diverse pharmacological properties such as antioxidant, antibacterial, antimutagenic, and antitumor which mostly owes to the presence of its active compound guggulsterone (GS) that exists in the form of Z- and E-isomers. Mounting evidence suggests that this compound has promising anticancer activities and was shown to suppress several cancer signaling pathways such as NF-κB/ERK/MAPK/AKT/STAT and modulate the expression of numerous signaling molecules such as the farnesoid X receptor, cyclin D1, survivin, caspases, HIF-1α, MMP-9, EMT proteins, tumor suppressor proteins, angiogenic proteins, and apoptotic proteins. The current review is an attempt to summarize the biological activities and diverse anticancer activities (both in vitro and in vivo) of the compound GS and its derivatives, along with its associated mechanism against various cancers.

Genetic Association Analysis of Cell Cycle Regulators Reveals YWHAZ Has Prognostic Significance in Prostate Cancer

BACKGROUND/AIM

This study aimed to identify the genes that cause biochemical recurrence (BCR) following radical prostatectomy (RP) in men with localized prostate cancer.

PATIENTS AND METHODS

A two-stage genetic association study of 19 single-nucleotide polymorphisms in 11 key cell cycle regulation genes was carried out. BCR-free survival after RP was evaluated in a discovery cohort of 458 patients with prostate cancer, and replication was investigated in another cohort of 185 patients.

RESULTS

A consistent association was found between BCR and rs2290291 (discovery: p=0.008; replication: p=0.029). rs2290291 is located in the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ), and was predicted to possess a regulatory function that affected YWHAZ expression. Furthermore, YWHAZ expression was frequently up-regulated in advanced tumours, and associated with poorer survival in patients with prostate cancer.

CONCLUSION

YWHAZ rs2290291 was found to be associated with BCR. YWHAZ may function as a putative oncogene during prostate cancer progression.

Overexpression of 14-3-3δ Predicts Poor Prognosis in Extrahepatic Cholangiocarcinoma Patients

The protein 14-3-3δ interacts with Trp53 to maintain G2 arrest and thus regulates the cell cycle. Though dysfunction of 14-3-3δ caused by hyper-methylation of CpG islands was reported in several carcinomas, the exact role of this protein in the development of extrahepatic cholangiocarcinoma has not been fully elucidated. Here, we aim at investigating the clinical relevance between 14-3-3δ and human extrahepatic cholangiocarcinoma. We collected extrahepatic cholangiocarcinoma specimens of 65 patients in Beijing Chao Yang Hospital and evaluated their 14-3-3δ expression using immunohistochemistry. We categorized the patients into different subgroups according to clinic pathological factors, such as sex, age, tumor size, pathological classification, lymph node metastasis status, tumor stage, and serum markers including CEA, CA-242, or CA19-9, and further evaluated the correlation between 14-3-3δ expression and these potential prognostic factors. As a result, we detected 14-3-3δ expression in 53 out of 65 specimens (81.5%), and the expression was positively correlated with TNM stage, lymph node metastasis, and overall survival. Our results suggest that 14-3-3δ serves as an oncogenic driver in extrahepatic cholangiocarcinoma tumorigenesis rather than a cell cycle regulator; the overexpression of 14-3-3δ might be frequently acquired by tumor cells to escape appropriate cell cycle regulation. Thus, 14-3-3δ could be a potential target for extrahepatic cholangiocarcinoma diagnosis and therapy.

Expression of yhwaz and gene regulation network in hepatocellular carcinoma

The adaptor protein 14-3-3ζ is encoded by the yhwaz gene and implicated in a wide range of biological processes. In tumorigenesis, 14-3-3ζ recognizes specific phosphorylation motifs and interacts with hundreds of target proteins and is, thus, involved in the regulation of tumor proliferation, migration and differentiation. In the present study, bioinformatics tools were used to analyze data from The Cancer Genome Atlas and Gene Expression Omnibus databases and the expression of yhwaz, and gene regulation networks were identified as potentially relevant in hepatocellular carcinoma (HCC). In HCC, yhwaz expression was demonstrated to be upregulated and significantly associated with poor prognosis. Expression levels of microRNAs targeting yhwaz were associated with improved prognosis in patients with liver cancer. Gene networks that are regulated by yhwaz were found to be involved in cell cycle regulation and tumorigenesis, indicating the potential use of the expression levels of yhwaz in liver tissue as predictive biomarkers in patients with liver cancer. In the present study, yhwaz was identified as a gene of interest through data mining gene expression databases and its involvement in regulatory networks in HCC was indicated. Therefore, further in vitro and in vivo studies on the role of yhwaz in the carcinogenesis of HCC would be greatly beneficial.

Differential Subcellular Distribution and Translocation of Seven 14-3-3 Isoforms in Response to EGF and During the Cell Cycle

Multiple isoforms of 14-3-3 proteins exist in different organisms. In mammalian cells, 14-3-3 protein has seven isoforms (α/β, ε, η, γ, σ, θ/τ, and δ/ζ), with α and δ representing the phosphorylated versions of β and ζ, respectively. While the existence of multiple isoforms may represent one more level of regulation in 14-3-3 signaling, our knowledge regarding the isoform-specific functions of 14-3-3 proteins is very limited. Determination of the subcellular localization of the different 14-3-3 isoforms could give us important clues of their specific functions. In this study, by using indirect immunofluorescence, subcellular fractionation, and immunoblotting, we studied the subcellular localization of the total 14-3-3 protein and each of the seven 14-3-3 isoforms; their redistribution throughout the cell cycle; and their translocation in response to EGF in Cos-7 cells. We showed that 14-3-3 proteins are broadly distributed throughout the cell and associated with many subcellular structures/organelles, including the plasma membrane (PM), mitochondria, ER, nucleus, microtubules, and actin fibers. This broad distribution underlines the multiple functions identified for 14-3-3 proteins. The different isoforms of 14-3-3 proteins have distinctive subcellular localizations, which suggest their distinctive cellular functions. Most notably, 14-3-3ƞ is almost exclusively localized to the mitochondria, 14-3-3γ is only localized to the nucleus, and 14-3-3σ strongly and specifically associated with the centrosome during mitosis. We also examined the subcellular localization of the seven 14-3-3 isoforms in other cells, including HEK-293, MDA-MB-231, and MCF-7 cells, which largely confirmed our findings with Cos-7 cells.

[14-3-3ζ protein mediates gemcitabine resistance in NK/T-cell lymphoma]

Objective: To explore the molecular mechanisms of 14-3-3ζ in gemcitabine resistance in extranodal NK/T-cell lymphoma, nasal type (ENKTL) . Methods: The effects of cell proliferation and invasion were detected by cell counting kit-8 (CCK-8) assay and transwell assay. YTS cells were exposed to gradually increased concentrations of gemcitabine to establish gemcitabine-resistant YTS cells (YTS-gem) in vitro. 14-3-3ζ specific siRNA lentiviral vector was transfected into YTS and YTS-gem cells to downregulate 14-3-3ζ expression, and stable transfected cell clones were screened. The protein expression was determined by Western blot. Results: ①14-3-3ζ expression was significantly up-regulated in gemcitabine resistant YTS-gem cells, comparing with that of YTS cells (P<0.05) . ②The results of CCK-8 and transwell assay showed that downregulation of 14-3-3ζ significantly reduced the cell proliferation and invasion abilities (P<0.05) . ③Downregulation of 14-3-3ζ could restore gemcitabine sensitivity in gemcitabine resistant YTS-gem cells (P<0.05) . ④Western blotting results showed that knockdown of 14-3-3ζ significantly upregulated pro-apoptotic Bax, and downregulated anti-apoptotic Bcl-2, Caspase-3, cleaved caspase-3, Cyclin D1 in gemcitabine-resistant YTS-gem cells (P<0.05) . There was no significant difference in p53 ang P-gp expression levels. Conclusions: 14-3-3ζ was upregulated in gemcitabine resistant YTS cells. Overexpression of 14-3-3ζ promoted cell proliferation and enhanced cell migration. 14-3-3ζ contributed to gemcitabine resistance to ENKTL through anti-apoptosis.

trans, trans-2,4-Decadienal, a lipid peroxidation product, induces inflammatory responses via Hsp90- or 14-3-3ζ-dependent mechanisms

Peroxidation of polyunsaturated fatty acids leads to the formation of a large array of lipid-derived electrophiles (LDEs), many of which are important signaling molecules involved in the pathogenesis of human diseases. Previous research has shown that one of such LDEs, trans, trans-2,4-decadienal (tt-DDE), increases inflammation, however, the underlying mechanisms are not well understood. Here we used click chemistry-based proteomics to identify the cellular targets which are required for the pro-inflammatory effects of tt-DDE. We found that treatment with tt-DDE increased cytokine production, JNK phosphorylation, and activation of NF-κB signaling in macrophage cells, and increased severity of dextran sulfate sodium (DSS)-induced colonic inflammation in mice, demonstrating its pro-inflammatory effects in vitro and in vivo. Using click chemistry-based proteomics, we found that tt-DDE directly interacts with Hsp90 and 14-3-3ζ, which are two important proteins involved in inflammation and tumorigenesis. Furthermore, siRNA knockdown of Hsp90 or 14-3-3ζ abolished the pro-inflammatory effects of tt-DDE in macrophage cells. Together, our results support that tt-DDE increases inflammatory responses via Hsp90- and 14-3-3ζ-dependent mechanisms.

miR-140-5p mediates bevacizumab-induced cytotoxicity to cardiomyocytes by targeting the VEGFA/14-3-3γ signal pathway

Bevacizumab (BVZ) is the first recombinant humanized monoclonal antibody against vascular endothelial growth factor (VEGFA) approved by the FDA for the treatment of different kinds of cancers, especially colorectal cancer. Although the anti-tumor effects have been verified, the side effects of BVZ are also noteworthy, among which, cardiotoxicity may be the most serious side effect of BVZ. However, the exact mechanisms of cardiotoxicity induced by BVZ have been little explored. This study was conducted in vitro in a human cardiac myocyte (HCM) model. MTT assay was conducted to determine BVZ-stimulated cell viability. For testing the function and mechanism, the cells were transfected with miR-140-5p mimics, miR-140-5p inhibitor and/or VEGFA small interfering RNA (si-VEGFA). Then, apoptosis of the cells was detected via annexin V/propidium iodide (AV-PI) staining followed by flow cytometry. qRT-PCR and western blot assays were applied to measure gene expression (i.e. mRNA) and protein levels, respectively. The CK, LDH, SOD, CAT and GSH-Px activities and MDA level were determined using commercial kits. ROS levels were determined by DCFH-DA assay. Mitochondrial membrane potential was measured by JC-1 assay. Dual-luciferase reporter assay was used to detect the interaction between miR-140-5p and VEGFA. BVZ could inhibit HCM proliferation and induce apoptosis. miR-140-5p was upregulated in response to BVZ treatment and miR-140-5p restraint could alleviate HCM damage caused by BVZ treatment. In contrast, VEGFA and 14-3-3γ expressions were down-regulated by BVZ, and miR-140-5p could inhibit the expression of 14-3-3γ by directly targeting VEGFA. Moreover, VEGFA suppression enhanced HCM injury stimulated by BVZ and partially reversed the functional role of the miR-140-5p inhibitor in BVZ-treated cells. Taken together, miR-140-5p promoted BVZ-treated cardiomyocyte toxicity by targeting the VEGFA/14-3-3γ signal pathway. Collectively, miR-140-5p mediated the BVZ-induced cytotoxicity to cardiomyocytes by targeting the VEGFA/14-3-3γ signal pathway, indicating that miR-140-5p may be a novel target for treating BVZ-induced cardiotoxicity.

Extracellular Hsp90α and clusterin synergistically promote breast cancer epithelial-to-mesenchymal transition and metastasis via LRP1

Extracellular heat shock protein 90 alpha (eHsp90α, also known as HSP90AA1) has been widely reported to promote tumor cell motility and tumor metastasis in various types of cancer. Several extracellular proteins and membrane receptors have been identified as interacting proteins of eHsp90α and mediate its pro-metastasis function. However, the regulatory mechanism of eHsp90α activity remains largely unknown. Here, we report that clusterin, a protein newly demonstrated to interact with eHsp90α, modulates eHsp90α signaling. We found that clusterin potentiated the effects of eHsp90α on activation of the AKT, ERK and NF-κB protein families, epithelial-to-mesenchymal transition (EMT) and migration in breast cancer cells. Furthermore, in vivo investigations demonstrated similar synergistic effects of eHsp90α and clusterin on tumor metastasis. Notably, the effects of eHsp90α and clusterin were mediated by low-density lipoprotein receptor-related protein 1 (LRP1). Proximity ligation assay and co-immunoprecipitation experiments demonstrated that clusterin participated in eHsp90α-LRP1 complex formation, which enhanced the binding affinity of eHsp90α to LRP1. Collectively, our data establish a role of clusterin as a newly discovered modulator of eHsp90α, and unravel detailed molecular mechanisms underlying the synergistic metastasis-promoting effects of clusterin and eHsp90α.

14-3-3 Proteins Are on the Crossroads of Cancer, Aging, and Age-Related Neurodegenerative Disease

14-3-3 proteins are a family of conserved regulatory adaptor molecules which are expressed in all eukaryotic cells. These proteins participate in a variety of intracellular processes by recognizing specific phosphorylation motifs and interacting with hundreds of target proteins. Also, 14-3-3 proteins act as molecular chaperones, preventing the aggregation of unfolded proteins under conditions of cellular stress. Furthermore, 14-3-3 proteins have been shown to have similar expression patterns in tumors, aging, and neurodegenerative diseases. Therefore, we put forward the idea that the adaptor activity and chaperone-like activity of 14-3-3 proteins might play a substantial role in the above-mentioned conditions. Interestingly, 14-3-3 proteins are considered to be standing at the crossroads of cancer, aging, and age-related neurodegenerative diseases. There are great possibilities to improve the above-mentioned diseases and conditions through intervention in the activity of the 14-3-3 protein family.

A New Switch for TGFβ in Cancer

The TGFβ cytokine plays dichotomous roles during tumor progression. In normal and premalignant cancer cells, the TGFβ signaling pathway inhibits proliferation and promotes cell-cycle arrest and apoptosis. However, the activation of this pathway in late-stage cancer cells could facilitate the epithelial-to-mesenchymal transition, stemness, and mobile features to enhance tumorigenesis and metastasis. The opposite functions of TGFβ signaling during tumor progression make it a challenging target to develop anticancer interventions. Nevertheless, the recent discovery of cellular contextual determinants, especially the binding partners of the transcription modulators Smads, is critical to switch TGFβ responses from proapoptosis to prometastasis. In this review, we summarize the recently identified contextual determinants (such as PSPC1, KLF5, 14-3-3ζ, C/EBPβ, and others) and the mechanisms of how tumor cells manage the context-dependent autonomous TGFβ responses to potentiate tumor progression. With the altered expression of some contextual determinants and their effectors during tumor progression, the aberrant molecular prometastatic switch might serve as a new class of theranostic targets for developing anticancer strategies.

14-3-3/Tau Interaction and Tau Amyloidogenesis

The major function of microtubule-associated protein tau is to promote microtubule assembly in the central nervous system. However, aggregation of abnormally phosphorylated tau is a hallmark of tauopathies. Although the molecular mechanisms of conformational transitions and assembling of tau molecules into amyloid fibril remain largely unknown, several factors have been shown to promote tau aggregation, including mutations, polyanions, phosphorylation, and interactions with other proteins. 14-3-3 proteins are a family of highly conserved, multifunctional proteins that are mainly expressed in the central nervous system. Being a scaffolding protein, 14-3-3 proteins interact with tau and regulate tau phosphorylation by bridging tau with various protein kinases. 14-3-3 proteins also directly regulate tau aggregation via specific and non-specific interactions with tau. In this review, we summarize recent advances in characterization of tau conformation and tau/14-3-3 interaction. We discuss the connection between 14-3-3 binding and tau aggregation with a special emphasis on the regulatory role of 14-3-3 on tau conformation.

YWHAZ amplification/overexpression defines aggressive bladder cancer and contributes to chemo-/radio-resistance by suppressing caspase-mediated apoptosis

The objective of this study was to characterize the oncogenic actions of a recently identified cancer‐associated gene YWHAZ (also named as 14‐3‐3 ζ/δ) in urothelial carcinomas of the urinary bladder (UCUB). A genome‐wide study revealed YWHAZ to be involved in the amplicon at 8q22.3, and its genetic amplification was detected predominantly in muscle‐invasive bladder cancer (MIBC). Immunohistochemical staining confirmed the association of YWHAZ overexpression with higher tumor stages, lymph node/vascular invasion, and mitotic activity. Univariate and multivariate analyses further indicated the prognostic potential of YWHAZ for more aggressive cancer types. Both gene set enrichment analysis and STRING network studies suggested involvement of YWHAZ in regulating caspase‐mediated apoptosis. Ectopic expression of YWHAZ in bladder cells with low endogenous YWHAZ levels boosted cell resistance to doxorubicin and cisplatin, as well as to ionizing radiation. Conversely, YWHAZ‐knockdown using specific shRNA in cells with high endogenous YWHAZ levels diminished survival activity, suppressing cell growth and increasing cell death. Our findings confirm the essential role played by YWHAZ in sustaining cell proliferation during chemo/radiotherapy. Treatments based on anti‐YWHAZ strategies may thus be beneficial for UCUB patients overexpressing YWHAZ. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

YWHAE promotes proliferation, metastasis, and chemoresistance in breast cancer cells

Breast cancer is the most common female-specific malignancy in Taiwan and developed countries worldwide, and its incidence continues to grow. 14-3-3ε (YWHAE), which belong to 14-3-3 family, it has been reported up-regulated in breast cancer tissues. However, the clinical implication and function of YWHAE in breast cancer remains unclear. In this study, we investigated the prognostic value of the YWHAE in human breast cancer. Immunohistochemistry was used to analyze YWHAE expression in breast cancer tissues. Cell model was applied to examine the functions of YWHAE. The chemotherapeutic agents were used to evaluate the effect of YWHAE in breast cancer cell lines. YWHAE expression was associated with tumor size, lymph node metastasis, and poor patient survival in patients with breast cancer. YWHAE overexpression significantly increased the proliferation, migration, and invasion abilities of breast cancer cells. Knockdown of YWHAE expression reduced the expression of Snail and Twist in breast cancer cells. We also found that YWHAE was responsible for the resistance of breast cancer cells to chemotherapeutic agents, and knockdown of YWHAE enhanced sensitivity to multiple chemotherapeutic agents in breast cancer cells. Taken together, our findings indicated that YWHAE promoted cancer progression and chemoresistance in breast cancer cells and can be a potential therapeutic target for breast cancer.

14-3-3ε acts as a proviral factor in highly pathogenic porcine reproductive and respiratory syndrome virus infection

The highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) emerged in 2006 in China and caused great economic losses for the swine industry because of the lack of an effective vaccine. 14-3-3 proteins are generating significant interest as potential drug targets by allowing the targeting of specific pathways to elicit therapeutic effects in human diseases. In a previous study, 14-3-3s were identified to interact with non-structural protein 2 (NSP2) of PRRSV. In the present study, the specific subtype 14-3-3ε was confirmed to interact with NSP2 and play a role in the replication of the HP-PRRSV TA-12 strain. Knockdown of 14-3-3ε in Marc-145 cells and porcine alveolar macrophages (PAMs) caused a significant decrease in TA-12 replication, while stable overexpression of 14-3-3ε caused a significant increase in the replication of TA-12 and low pathogenic PRRSV (LP-PRRSV) CH-1R. The 14-3-3 inhibitor difopein also decreased TA-12 and CH-1R replication in Marc-145 cells and PAMs. These findings are consistent with 14-3-3ε acting as a proviral factor and suggest that 14-3-3ε siRNA and difopein are therapeutic candidates against PRRSV infection.

Proteomic characterization of early lung response to breast cancer metastasis in mice

INTRODUCTION

The tumor-promoting rearrangement of the lungs facilitates the process of cancer cell survival in a foreign microenvironment and enables their protection against immune defense. The study aimed to define the fingerprint of the early rearrangement of the lungs via the proteomic profiling of the lung tissue in the experimental model of tumor metastasis in a murine 4T1 mammary adenocarcinoma.

MATERIALS AND METHODS

The studies were performed on 7-8-week-old BALB/c female mice. Viable 4T1 cancer cells were orthotopically inoculated into the right mammary fat pad. The experiment was performed in the early phase of the tumor metastasis one and two weeks after cancer cell inoculation. The comparative analysis of protein profiles was carried out with the aid of the two-dimensional difference in gel electrophoresis (2D-DIGE). Proteins, of which expression differed significantly, were identified using nano-liquid chromatography coupled to a high-resolution mass spectrometry (nanoLC/hybrid ion trap- Orbitrap XL Discovery).

RESULTS

Palpable primary tumors were noted in the 2^nd week after cancer cell inoculation. The investigated period preceded the formation of numerous macrometastases in the lungs, however the metastasis-promoting changes were visible very early. Primary tumor-induced inflammation developed in the lungs as early as after the 1^st week and progressed during the 2^nd week, accompanied by increased concentration of 2-OH-E⁺, an oxidative stress marker, and imbalance in nitric oxide metabolites, pointing to endothelium dysfunction. The early proteomic changes in the lungs in the 1^st week after 4T1 cell inoculation resulted in the reorganization of lung tissue structure [actin, cytoplasmic 1 (Actb), tubulin beta chain (Tubb5), lamin-B1 (Lmnb1), serine protease inhibitor A3K (Serpina3k)] and activation of defense mechanisms [selenium-binding protein 1 (Selenbp1), endoplasmin (Hsp90b1), stress 70 protein, mitochondrial (Hspa9), heat shock protein HSP 90-beta (Hsp90ab1)], but also modifications in metabolic pathways [glucose-6-phosphate 1-dehydrogenase X (G6pdx), ATP synthase subunit beta, mitochondrial (Atp5b), L-lactate dehydrogenase B chain (Ldhb)]. Further development of the solid tumor after the 2^nd week following cancer cell inoculation, secretion of prolific tumor-derived factors as well as the presence of the increasing number of circulating cancer cells and extravasation processes further impose reorganization of the lung tissue [Actb, vimentin (Vim), clathrin light chain A (Clta)], altering additional metabolic pathways [annexin A5 (Anxa5), Rho GDP-dissociation inhibitor 2 (Arhgdib), complement 1 Q subcomponent-binding protein, mitochondrial (C1qbp), 14-3-3 protein zeta/delta (Ywhaz), peroxiredoxin-6 (Prdx6), chitinase-like protein 4 (Chi3l4), reticulocalbin-1 (Rcn1), EF-hand domain-containing protein D2 (Efhd2), calumenin (Calu)]. Interestingly, many of differentially expressed proteins were involved in calcium homeostasis (Rcn1, Efhd2, Calu, Actb, Vim, Lmnb1, Clta, Tubb5, Serpina3k, Hsp90b1, Hsp90ab1, Hspa9. G6pdx, Atp5b, Anxa5, Arhgdib, Ywhaz).

CONCLUSION

The analysis enabled revealing the importance of calcium signaling during the early phase of metastasis development, early cytoskeleton and extracellular matrix reorganization, activation of defense mechanisms and metabolic adaptations. It seems that the tissue response is an interplay between pro- and anti-metastatic mechanisms accompanied by inflammation, oxidative stress and dysfunction of the barrier endothelial cells.

Targeting liver cancer stem cells for the treatment of hepatocellular carcinoma

Liver cancer is one of the most common malignant tumors and prognosis remains poor. It has been increasingly recognized that liver cancer stem cells (LCSCs) are responsible for the carcinogenesis, recurrence, metastasis and chemoresistance of hepatocellular carcinoma (HCC). Targeting LCSCs is promising to be a new direction for the treatment of HCC. Herein, we summarize the potentially therapeutic targets in LCSCs at the level of genes, molecules and cells, such as knockout of oncogenes or oncoproteins, restoring the silent tumor suppressor genes, inhibition of the transcription factors and regulation of noncoding RNAs (including microRNAs and long noncoding RNAs) in LCSCs at the genetic level; inhibition of markers and blockade of the key signaling pathways of LCSCs at the molecular level; and inhibiting autophagy and application of oncolytic adenoviruses in LCSCs at the cellular level. Moreover, we analyze the potential targets in LCSCs to eliminate chemoresistance of HCC. Thereinto, the suppression of autophagy and Nanog by chloroquine and shRNA respectively may be the most promising targeting approaches. These targets may provide novel therapeutic strategies for the treatment of HCC by targeting LCSCs.

14-3-3ζ inhibits heme oxygenase-1 (HO-1) degradation and promotes hepatocellular carcinoma proliferation: involvement of STAT3 signaling

Background

Heme oxygenase 1 (HO-1) has been reported to be very important in the pathogenesis or progression of multiple types of cancer. Identification of novel hmox1 binding proteins may reveal undefined oncogenes, tumor suppressors, signaling pathways, and possible treatment targets.

Methods

Immunoprecipitation and mass spectrometry analyses were used to identify novel regulators of HO-1. The association of the 14–3-3ζ protein with HO-1 and modulation of the stability of HO-1 were investigated by co-immunoprecipitation, immunofluorescence, western blotting, and quantitative RT-PCR. Degradation and in vivo ubiquitination assays were utilized to examine whether 14–3-3ζ stabilizes the HO-1 protein by inhibiting its ubiquitination. The effect of 14–3-3ζ on proliferation was investigated by function assays conducted in vitro using the CCK-8 and colony formation assays and in vivo in a xenograft mouse model. The biological functions of the 14–3-3ζ/HO-1 axis were demonstrated by western blotting and rescue experiments. Using gain-of-function and loss-of-function strategies, we further clarified the impact of 14–3-3ζ/HO-1 complex on the signal transducers and activators of transcription 3 (STAT3) signaling pathway in cancer cells.

Results

We identified 14–3-3ζ as a novel HO-1 binding protein. The binding inhibited the ubiquitination and proteasome-mediated degradation of HO-1, thus facilitating its stabilization. Enforced expression of 14–3-3ζ significantly promoted cell proliferation in vitro, as well as tumorigenesis in vivo, while 14–3-3ζ knockdown had opposite effects. The data indicated that 14–3-3ζ can stabilize HO-1 expression and thus influence cancer cell proliferation. We further demonstrated the involvement of the STAT3 pathway in 14–3-3ζ/HO-1 regulation of hepatocellular carcinoma cell proliferation.

Conclusions

Collectively, these data show that 14–3-3ζ regulates the stability of HO-1 to promote cancer cell proliferation and STAT3 signaling activation. The data establish the 14–3-3ζ-HO-1-STAT3 axis as an important regulatory mechanism of cancer cell growth and implicate HO-1 and 14–3-3ζ as potential therapeutic targets in hepatocellular carcinoma.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-1007-9) contains supplementary material, which is available to authorized users.

miR-375-3p/YWHAZ/β-catenin axis regulates migration, invasion, EMT in gastric cancer cells

YWHAZ (14-3-3ζ) plays crucial roles in regulating proliferation, apoptosis, migration, and invasion of gastric cancer (GC) cells. However, its extensive roles and potential mechanisms in GC cells remain unknown, and need to be researched deeply. In this study, we focus on the role of miR-375/YWHAZ axis in migration, invasion and epithelial-to-mesenchymal transition (EMT) of GC cells. YWHAZ level was assessed by western blot and qPCR assays in GC cells. Scratch and transwell assays were used to determine the migration and invasion of GC cells. The protein levels of correlative molecules were detected by western blot. The regulation of miR-375 on the expression of its target gene YWHAZ was verified by dual-luciferase report system. According to the results, knockdown of YWHAZ inhibited the migration, invasion and EMT of GC cells. Moreover, silencing of YWHAZ restrained the activation of wnt/β-catenin signalling pathway. YWHAZ was confirmed to be a target gene of miR-375, and its expression was regulated by miR-375 in GC cells. Transfection of miR-375 inhibitor promoted the migration, invasion, EMT and activation of wnt/β-catenin pathway in GC cells, which was suppressed by inhibition of YWHAZ. Taken together, this study suggests that miR-375/YWHAZ axis may be served as a novel therapeutic target for GC patients.

Combined Short-Term Glucose Starvation and Chemotherapy in 3D Colorectal Cancer Cell Culture Decreases 14-3-3 Family Protein Expression and Phenotypic Response to Therapy

Short-term glucose starvation prior to chemotherapy has the potential to preferentially weaken cancer cells, making them more likely to succumb to treatment, while protecting normal cells. In this study, we used 3D cell cultures of colorectal cancer and assessed the effects of short-term glucose starvation and chemotherapy compared to treatment of either individually. We evaluated both phenotypic changes and protein expression levels. Our findings indicate that the combined treatment results in more significant phenotypic responses, including decreased cell viability and clonogenicity. These phenotypic responses can be explained by the decreased expression of LDHA and 14-3-3 family proteins, which were found only in the combined treatment groups. This study indicates that short-term glucose starvation has the potential to increase the efficacy of current cancer treatment regimes. Graphical Abstract ᅟ.

The dynamic and stress-adaptive signaling hub of 14-3-3: emerging mechanisms of regulation and context-dependent protein-protein interactions

14-3-3 proteins are a family of structurally similar phospho-binding proteins that regulate essentially every major cellular function. Decades of research on 14-3-3s have revealed a remarkable network of interacting proteins that demonstrate how 14-3-3s integrate and control multiple signaling pathways. In particular, these interactions place 14-3-3 at the center of the signaling hub that governs critical processes in cancer, including apoptosis, cell cycle progression, autophagy, glucose metabolism, and cell motility. Historically, the majority of 14-3-3 interactions have been identified and studied under nutrient-replete cell culture conditions, which has revealed important nutrient driven interactions. However, this underestimates the reach of 14-3-3s. Indeed, the loss of nutrients, growth factors, or changes in other environmental conditions (e.g., genotoxic stress) will not only lead to the loss of homeostatic 14-3-3 interactions, but also trigger new interactions, many of which are likely stress adaptive. This dynamic nature of the 14-3-3 interactome is beginning to come into focus as advancements in mass spectrometry are helping to probe deeper and identify context-dependent 14-3-3 interactions-providing a window into adaptive phosphorylation-driven cellular mechanisms that orchestrate the tumor cell's response to a variety of environmental conditions including hypoxia and chemotherapy. In this review, we discuss emerging 14-3-3 regulatory mechanisms with a focus on post-translational regulation of 14-3-3 and dynamic protein-protein interactions that illustrate 14-3-3's role as a stress-adaptive signaling hub in cancer.

Effect of cytokine-induced killer cells combined with dendritic cells on the survival rate and expression of 14-3-3ζ and p-Bad proteins in Lewis lung cancer cell lines

In the present study, the function and mechanism of cytokine-induced killer cells (CIK) combined with dendritic cells (DC-CIK) were examined in Lewis lung cancer (LLC) cells. Co-culture of CIK dendritic cells (DC) in vitro was used to investigate their proliferation and the antitumor effects on LLC cells. DC and CIK cells were collected from healthy human peripheral blood mononuclear cells and co-cultured as an experimental group, while LLC cells were cultured alone as a control group. Cell morphology was observed by an inverted microscope and an MTT assay was utilized to detect the proliferation of LLC cells. Expression of 14-3-3ζ and p-Bad were measured by western blot analysis. Compared with the control group, treatment of LLC cells with DC-CIK resulted in decreased cell adherence, reduced cell proliferation and abnormal morphological changes. Additionally, DC-CIK treatment of LLC cells resulted in the decreased expression of 14-3-3ζ and p-Bad protein in LLC cells, which may provide important information pertaining to the possible mechanism of DC-CIK-induced antitumor activity against LLC cells. The present study provides a theoretical and experimental basis for the clinical treatment of DC-CIK cell co-culture.

Structural basis of O-GlcNAc recognition by mammalian 14-3-3 proteins

O-GlcNAc is an intracellular posttranslational modification that governs myriad cell biological processes and is dysregulated in human diseases. Despite this broad pathophysiological significance, the biochemical effects of most O-GlcNAcylation events remain uncharacterized. One prevalent hypothesis is that O-GlcNAc moieties may be recognized by "reader" proteins to effect downstream signaling. However, no general O-GlcNAc readers have been identified, leaving a considerable gap in the field. To elucidate O-GlcNAc signaling mechanisms, we devised a biochemical screen for candidate O-GlcNAc reader proteins. We identified several human proteins, including 14-3-3 isoforms, that bind O-GlcNAc directly and selectively. We demonstrate that 14-3-3 proteins bind O-GlcNAc moieties in human cells, and we present the structures of 14-3-3β/α and γ bound to glycopeptides, providing biophysical insights into O-GlcNAc-mediated protein-protein interactions. Because 14-3-3 proteins also bind to phospho-serine and phospho-threonine, they may integrate information from O-GlcNAc and O-phosphate signaling pathways to regulate numerous physiological functions.

The ASH1-miR-375-YWHAZ Signaling Axis Regulates Tumor Properties in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a worldwide malignance, and the underlying mechanisms of this disease are not fully elucidated. In this study, the existence and function of achaete-scute homolog-1 (ASH1)-miR-375-YWHAZ signaling axis in HCC were determined. Our experiments and the Cancer Genome Atlas (TCGA) sequencing data analyses showed that ASH1 and miR-375 were significantly downregulated, whereas YWHAZ was significantly upregulated in HCC. Furthermore, we found that ASH1 positively regulates miR-375, and miR-375 directly downregulates its target YWHAZ. Gain- and loss-of-function study demonstrated ASH1 and miR-375 function as tumor suppressors, whereas YWHAZ acts as an oncogene in HCC. Animal experiment indicated that YWHAZ small interfering RNAs (siRNAs) (si-YWHAZ) delivered by nanoliposomes could suppress the growth of hepatoma xenografts and was well tolerant by nude mice. Further studies revealed that YWHAZ was involved in several protein networks, such as cell autophagy, epithelial-mesenchymal transition (EMT), apoptosis, cell cycle, invasion, and migration. In addition, the patient group with ASH1-high-expression-miR-375-high-expression-YWHAZ-low-expression was correlated with a better clinical prognosis compared with the opposite expression group. In conclusion, we proved the existence of ASH1-miR-375-YWHAZ signaling axis and interpreted its important role in driving HCC tumor progression.

Hybrid Capture-Based Tumor Sequencing and Copy Number Analysis to Confirm Origin of Metachronous Metastases in BRCA1-Mutant Cholangiocarcinoma Harboring a Novel YWHAZ-BRAF Fusion

Biliary tract cancers such as cholangiocarcinoma represent a heterogeneous group of cancers that can be difficult to diagnose. Recent comprehensive genomic analyses in large cholangiocarcinoma cohorts have defined important molecular subgroups within cholangiocarcinoma that may relate to anatomic location and etiology [1], [2], [3], [4] and may predict responsiveness to targeted therapies in development [5], [6], [7]. These emerging data highlight the potential for tumor genomics to inform diagnosis and treatment options in this challenging tumor type. We report the case of a patient with a germline BRCA1 mutation who presented with a cholangiocarcinoma driven by the novel YWHAZ-BRAF fusion. Hybrid capture-based DNA sequencing and copy number analysis performed as part of clinical care demonstrated that two later-occurring tumors were clonally derived from the primary cholangiocarcinoma rather than distinct new primaries, revealing an unusual pattern of late metachronous metastasis. We discuss the clinical significance of these genetic alterations and their relevance to therapeutic strategies.

KEY POINTS

Hybrid capture-based next-generation DNA sequencing assays can provide diagnostic clarity in patients with unusual patterns of metastasis and recurrence in which the pathologic diagnosis is ambiguous.To our knowledge, this is the first reported case of a YWHAZ-BRAF fusion in pancreaticobiliary cancer, and a very rare case of cholangiocarcinoma in the setting of a germline BRCA1 mutation.The patient's BRCA1 mutation and YWHAZ-BRAF fusion constitute potential targets for future therapy.