Isoform-specific expression of 14-3-3 proteins in human astrocytoma

Inducible Knockout of 14-3-3β Attenuates Proliferation and Spheroid Formation in a Human Glioblastoma Cell Line U87MG

Glioblastomas (GBs) are the most common and malignant brain tumors in adults. A protein encoded by the gene YWHAB, 14-3-3β, is commonly found to be upregulated throughout the initiation and progression of GB. The 14-3-3β has oncogenic roles in several different types of cancer cells through interactions with proteins such as Bad, FBI1, Raf-1, Cdc25b, and others. Previous RNA interference studies have shown that 14-3-3β promotes proliferation, cell cycle progression, and migration and invasion of GB cells. However, despite the many oncogenic functions of 14-3-3β, a CRISPR/Cas9 knockout model of 14-3-3β has not been investigated. This study confirmed previous findings and showed that siRNA inhibition of 14-3-3β results in reduced cellular proliferation in a human glioblastoma cell line, U87MG. We also used a YWHAB Tet-On CRISPR/Cas9 U87MG cell line that, upon doxycycline induction, leads to robust Cas9 expression and subsequent knockout of 14-3-3β. Using this model, we show that loss of 14-3-3β significantly reduces cellular proliferation and spheroid formation of U87MG cells.

A Data Science Approach for the Identification of Molecular Signatures of Aggressive Cancers

The main hallmarks of cancer include sustaining proliferative signaling and resisting cell death. We analyzed the genes of the WNT pathway and seven cross-linked pathways that may explain the differences in aggressiveness among cancer types. We divided six cancer types (liver, lung, stomach, kidney, prostate, and thyroid) into classes of high (H) and low (L) aggressiveness considering the TCGA data, and their correlations between Shannon entropy and 5-year overall survival (OS). Then, we used principal component analysis (PCA), a random forest classifier (RFC), and protein-protein interactions (PPI) to find the genes that correlated with aggressiveness. Using PCA, we found GRB2, CTNNB1, SKP1, CSNK2A1, PRKDC, HDAC1, YWHAZ, YWHAB, and PSMD2. Except for PSMD2, the RFC analysis showed a different list, which was CAD, PSMD14, APH1A, PSMD2, SHC1, TMEFF2, PSMD11, H2AFZ, PSMB5, and NOTCH1. Both methods use different algorithmic approaches and have different purposes, which explains the discrepancy between the two gene lists. The key genes of aggressiveness found by PCA were those that maximized the separation of H and L classes according to its third component, which represented 19% of the total variance. By contrast, RFC classified whether the RNA-seq of a tumor sample was of the H or L type. Interestingly, PPIs showed that the genes of PCA and RFC lists were connected neighbors in the PPI signaling network of WNT and cross-linked pathways.

PhAc-ALGP-Dox, a Novel Anticancer Prodrug with Targeted Activation and Improved Therapeutic Index

Clinical use of doxorubicin (Dox) is limited by cumulative myelo- and cardiotoxicity. This research focuses on the detailed characterization of PhAc-ALGP-Dox, a targeted tetrapeptide prodrug with a unique dual-step activation mechanism, designed to circumvent Dox-related toxicities and is ready for upcoming clinical investigation. Coupling Dox to a phosphonoacetyl (PhAc)-capped tetrapeptide forms the cell-impermeable, inactive compound, PhAc-ALGP-Dox. After extracellular cleavage by tumor-enriched thimet oligopeptidase-1 (THOP1), a cell-permeable but still biologically inactive dipeptide-conjugate is formed (GP-Dox), which is further processed intracellularly to Dox by fibroblast activation protein-alpha (FAPα) and/or dipeptidyl peptidase-4 (DPP4). In vitro, PhAc-ALGP-Dox is effective in various 2D- and 3D-cancer models, while showing improved safety toward normal epithelium, hematopoietic progenitors, and cardiomyocytes. In vivo, these results translate into a 10-fold higher tolerability and 5-fold greater retention of Dox in the tumor microenvironment compared with the parental drug. PhAc-ALGP-Dox demonstrates 63% to 96% tumor growth inhibition in preclinical models, an 8-fold improvement in efficacy in patient-derived xenograft (PDX) models, and reduced metastatic burden in a murine model of experimental lung metastasis, improving survival by 30%. The current findings highlight the potential clinical benefit of PhAc-ALGP-Dox, a targeted drug-conjugate with broad applicability, favorable tissue biodistribution, significantly improved tolerability, and tumor growth inhibition at primary and metastatic sites in numerous solid tumor models.

14-3-3 Proteins are Potential Regulators of Liquid-Liquid Phase Separation

The 14-3-3 family proteins are vital scaffold proteins that ubiquitously expressed in various tissues. They interact with numerous protein targets and mediate many cellular signaling pathways. The 14-3-3 binding motifs are often embedded in intrinsically disordered regions which are closely associated with liquid-liquid phase separation (LLPS). In the past ten years, LLPS has been observed for a variety of proteins and biological processes, indicating that LLPS plays a fundamental role in the formation of membraneless organelles and cellular condensates. While extensive investigations have been performed on 14-3-3 proteins, its involvement in LLPS is overlooked. To date, 14-3-3 proteins have not been reported to undergo LLPS alone or regulate LLPS of their binding partners. To reveal the potential involvement of 14-3-3 proteins in LLPS, in this review, we summarized the LLPS propensity of 14-3-3 binding partners and found that about one half of them may undergo LLPS spontaneously. We further analyzed the phase separation behavior of representative 14-3-3 binders and discussed how 14-3-3 proteins may be involved. By modulating the conformation and valence of interactions and recruiting other molecules, we speculate that 14-3-3 proteins can efficiently regulate the functions of their targets in the context of LLPS. Considering the critical roles of 14-3-3 proteins, there is an urgent need for investigating the involvement of 14-3-3 proteins in the phase separation process of their targets and the underling mechanisms.

The mechanobiome: a goldmine for cancer therapeutics

Cancer progression is dependent on heightened mechanical adaptation, both for the cells' ability to change shape and to interact with varying mechanical environments. This type of adaptation is dependent on mechanoresponsive proteins that sense and respond to mechanical stress, as well as their regulators. Mechanoresponsive proteins are part of the mechanobiome, which is the larger network that constitutes the cell's mechanical systems that are also highly integrated with many other cellular systems, such as gene expression, metabolism, and signaling. Despite the altered expression patterns of key mechanobiome proteins across many different cancer types, pharmaceutical targeting of these proteins has been overlooked. Here, we review the biochemistry of key mechanoresponsive proteins, specifically nonmuscle myosin II, α-actinins, and filamins, as well as the partnering proteins 14-3-3 and CLP36. We also examined a wide range of data sets to assess how gene and protein expression levels of these proteins are altered across many different cancer types. Finally, we determined the potential of targeting these proteins to mitigate invasion or metastasis and suggest that the mechanobiome is a goldmine of opportunity for anticancer drug discovery and development.

Emerging roles of 14-3-3γ in the brain disorder

14-3-3 proteins are mostly expressed in the brain and are closely involved in numerous brain functions and various brain disorders. Among the isotypes of the 14-3-3 proteins, 14-3-3γ is mainly expressed in neurons and is highly produced during brain development, which could indicate that it has a significance in neural development. Furthermore, the distinctive levels of temporally and locally regulated 14-3-3γ expression in various brain disorders suggest that it could play a substantial role in brain plasticity of the diseased states. In this review, we introduce the various brain disorders reported to be involved with 14-3-3γ, and summarize the changes of 14-3-3γ expression in each brain disease. We also discuss the potential of 14-3-3γ for treatment and the importance of research on specific 14-3-3 isotypes for an effective therapeutic approach.

Low Expression of 14-3-3beta Is Associated With Adverse Survival of Diffuse Large B-Cell Lymphoma Patients

Diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin's lymphoma in the world, is highly heterogeneous. Although current therapies have improved the clinical outcome, 30-40% of the patients are still not cured. Thus, novel treatment options such as targeted therapy is urgently needed. Accumulating evidence suggests that 14-3-3beta protein plays an important role in tumorigenesis and tumor progression. However, the specific roles of 14-3-3beta in DLBCL are still poorly understood. In this study, we retrospectively analyzed 120 archived wax blocks obtained from patients with DLBCL (n = 70) and non-neoplastic lymph nodes (n = 50). Immunohistochemical staining showed that 14-3-3beta gene expression was significantly decreased in DLBCL tissues (P < 0.001) compared to that in non-neoplastic lymph nodes. Low 14-3-3beta expression was significantly correlated with extra-nodal status (P = 0.026), serum LDH level (P = 0.023) and adverse survival of DLBCL patients. In survival analyses, low 14-3-3beta expression was significantly associated with adverse overall survival of the DLBCL patients (P = 0.003). Using the Kaplan-Meier analysis module of the R2 microarray analysis and visualization platform (http://r2.amc.nl), we also confirmed that low expression of 14-3-3beta gene had inferior overall survival in DLBCL patients. Based on our results, we conclude that low expression of 14-3-3beta is associated with adverse survival of diffuse large B-cell lymphoma patients, suggesting a novel prognostic marker and potential therapeutic target.

Down-regulation of 14-3-3 zeta sensitizes human glioblastoma cells to apoptosis induction

Strong 14-3-3 zeta protein expression plays an important role in tumorigenesis, including in the maintenance of cell growth, resistance increase, and the prevention of apoptosis. In this study, we focus on two targets: (1) the expression of 14-3-3 zeta in the different grades of human astrocytoma (II-IV), (2) suppression of 14-3-3 zeta protein expression in glioblastoma derived astrocytes by 14-3-3 zeta shRNA lentiviral particles. The tissues of human astrocytoma were provided from 30 patients (ten of each grade of astrocytoma). Control tissues were obtained from the peritumoral brain zone of those patients with glioblastoma. The protein and mRNA expression levels of each astrocytoma grade were assessed via western blotting and RT-PCR, respectively. Results indicated that 14-3-3 zeta was significantly expressed in glioblastoma multiforme (grade IV) and 14-3-3 zeta expression levels enhanced according to the increase of astrocytoma malignancy. In the cellular study for knock down of the 14-3-3 zeta protein, surgical biopsy of glioblastoma was used to isolate primary astrocyte. Astrocytes were transduced with 14-3-3 zeta shRNA or non-targeted shRNA lentiviral particles. Furthermore, reduction of the 14-3-3 zeta protein expression in the astrocytes evaluated through qRT-PCR and western blot after transduction of 14-3-3 zeta shRNA lentiviral particles. Moreover, apoptosis properties, including DNA fragmentation and ratio increase of Bax/Bcl-2 were observed in astrocytes following reduction of 14-3-3 zeta protein expression. Further observation indicated that the mitochondrial pathway through release of cytochorome c and caspase-3 activity was involved in the apoptosis induction. Hence, this study demonstrates a key role of the 14-3-3 zeta protein in tumorigenesis but also indicates that 14-3-3 zeta can be considered as a target for the astrocytoma treatment specially glioblastoma.

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.

Shuttling SLC2A4RG is regulated by 14-3-3θ to modulate cell survival via caspase-3 and caspase-6 in human glioma

Background

Glioma is the most common and aggressive primary brain tumor with polygenic susceptibility. The cytoplasmic/nuclear shuttling protein, SLC2A4RG (SLC2A4 regulator), has been identified in the 20q13.33 region influencing glioma susceptibility by genome-wide association studies (GWAS) and fine mapping analyses.

Methods

To discover the expression of SLC2A4RG and its relationship with patient prognosis, tissue microarray containing glioma samples and normal brains was constructed followed by immunohistochemical staining. The role of SLC2A4RG on cell proliferation, cell cycle, and apoptosis was evaluated by gain- and loss-of-function assays in vivo, and subcutaneous and intracranial xenografts were performed to assess its functional effects. The mechanism underlying SLC2A4RG was further investigated via luciferase reporter analyses, ChIP, mass spectrometry, Co-IP, immunofluorescence, etc.

Findings

The potential tumor suppressor role of SLC2A4RG was further validated by in vitro and in vivo experiments that SLC2A4RG could attenuate cell proliferation via G2/M phase arrest and induce glioma cell apoptosis by direct transactivation of caspase-3 and caspase-6. Moreover, its function displaying showed to depend on the nuclear transportation of SLC2A4RG, however, bound with 14-3-3θ, it would be sequestered in the cytoplasm followed by reversal effect.

Interpretation

We identify a new pro-oncogenic mechanism whereby 14-3-3θ negatively regulates the nuclear function of the tumor suppressor SLC2A4RG, with significant therapeutic implications for the intervention of human glioma.

Fund

This work was supported by the National Natural Science Foundation of China (81372706, 81572501, and 81372235).

The Importance of the Right Framework: Mitogen-Activated Protein Kinase Pathway and the Scaffolding Protein PTPIP51

The protein tyrosine phosphatase interacting protein 51 (PTPIP51) regulates and interconnects signaling pathways, such as the mitogen-activated protein kinase (MAPK) pathway and an abundance of different others, e.g., Akt signaling, NF-κB signaling, and the communication between different cell organelles. PTPIP51 acts as a scaffold protein for signaling proteins, e.g., Raf-1, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (Her2), as well as for other scaffold proteins, e.g., 14-3-3 proteins. These interactions are governed by the phosphorylation of serine and tyrosine residues of PTPIP51. The phosphorylation status is finely tuned by receptor tyrosine kinases (EGFR, Her2), non-receptor tyrosine kinases (c-Src) and the phosphatase protein tyrosine phosphatase 1B (PTP1B). This review addresses various diseases which display at least one alteration in these enzymes regulating PTPIP51-interactions. The objective of this review is to summarize the knowledge of the MAPK-related interactome of PTPIP51 for several tumor entities and metabolic disorders.

14-3-3β exerts glioma-promoting effects and is associated with malignant progression and poor prognosis in patients with glioma

Glioma is a type of tumor that affects the central nervous system. It has been demonstrated that 14-3-3β, a protein that is mainly concentrated in the brain, serves an important role in tumor regulation. However, the mechanism of action of 14-3-3β that underlies the pathogenesis of glioma remains to be elucidated. In the present study, 14-3-3β was silenced by RNA interference in the human glioma cell line U373-MG. Following knockdown of 14-3-3β, the proliferation, colony formation, cell cycle progression, migration and invasion of U373-MG cells were significantly decreased (P<0.01), whereas cell apoptosis was increased (P<0.01). Furthermore, in a tumor xenograft experiment, silencing 14-3-3β significantly inhibited the in vivo tumor growth of U373-MG cells (P<0.01). The results demonstrated that 14-3-3β levels were significantly higher in human glioma tissues compared with normal brain tissues (P<0.01) and high 14-3-3β expression was significantly associated with advanced pathological grade (P<0.03) and low Karnofsky performance scale (P<0.003). Patients with glioma who had high 14-3-3β levels had a significantly shorter survival time compared with those with low expression of 14-3-3β (P=0.031), suggesting that 14-3-3β may be an effective predictor of the prognosis of patients with glioma. The results of the present study indicate that 14-3-3β serves an oncogenic role in glioma, suggesting that 14-3-3β may have potential as a promising therapeutic target for glioma.

Downregulation of 14-3-3β inhibits proliferation and migration in osteosarcoma cells

The 14-3-3 protein isoform β (14‑3‑3β), which is an intracellular adaptor protein that exists in all eukaryotic organisms, is highly expressed in many cancer tissues, including glioma, lung carcinoma and breast cancer. However, 14‑3‑3β expression and function in osteosarcoma progression remain unknown. In the present study, the endogenous expression of 14‑3‑3β was assessed in osteosarcoma samples and the effect of 14‑3‑3β knockdown was examined in human osteosarcoma MG63 cells using small interfering RNA (siRNA). mRNA and protein expression levels for 14‑3‑3β were detected by reverse transcription‑quantitative polymerase reaction and western blotting, respectively. The results demonstrated that endogenous 14‑3‑3β mRNA and protein were highly expressed in human osteosarcoma tissues and osteosarcoma cell lines (U2OS, MG63 and SaOs‑2), but not in normal bone tissues or normal osteoblast hFOB1.19 cells. These data suggested that increased expression of 14‑3‑3β may be significantly associated with the development and progression of osteosarcoma. Therefore, the effect of 14‑3‑3β knockdown in MG63 cells was further examined in vitro. Knockdown of 14‑3‑3β by siRNA significantly decreased cell viability, and inhibited cell proliferation and invasion. In addition, 14‑3‑3β knockdown significantly decreased the protein expression levels of β‑catenin, cyclin D1, v‑myc avian myelocytomatosis viral oncogene homolog and matrix metallopeptidase 9 in osteosarcoma MG63 cells. These results suggested that the anticancer effects of 14‑3‑3β knockdown in MG63 cells might be mediated by the inhibition of the Wnt/β‑catenin signaling pathway. In summary, 14‑3‑3β knockdown decreased proliferation and invasion in MG63 cells, which suggests a potential therapeutic application for 14‑3‑3β as a novel target for the treatment of osteosarcoma patients.

Combination Treatment with PPARγ Ligand and Its Specific Inhibitor GW9662 Downregulates BIS and 14-3-3 Gamma, Inhibiting Stem-Like Properties in Glioblastoma Cells

PPARγ is a nuclear receptor that regulates differentiation and proliferation and is highly expressed in many cancer cells. Its synthetic ligands, such as rosiglitazone and ciglitazone, and its inhibitor GW9662, were shown to induce cellular differentiation, inhibit proliferation, and lead to apoptosis. Glioblastoma is a common brain tumor with poor survival prospects. Recently, glioblastoma stem cells (GSCs) have been examined as a potential target for anticancer therapy; however, little is known about the combined effect of various agents on GSCs. In this study, we found that cotreatment with PPARγ ligands and GW9662 inhibited stem-like properties in GSC-like spheres, which significantly express SOX2. In addition, this treatment decreased the activation of STAT3 and AKT and decreased the amounts of 14-3-3 gamma and BIS proteins. Moreover, combined administration of small-interfering RNA (siRNA) transfection with PPARγ ligands induced downregulation of SOX2 and MMP2 activity together with inhibition of sphere-forming activity regardless of poly(ADP-ribose) polymerase (PARP) cleavage. Taken together, our findings suggest that a combination therapy using PPARγ ligands and its inhibitor could be a potential therapeutic strategy targeting GSCs.

Incremental Expression of 14-3-3 Protein Beta/Alpha in Urine Correlates with Advanced Stage and Poor Survival in Patients with Clear Cell Renal Cell Carcinoma

We investigated the urinary levels of 14-3-3 protein beta/alpha to evaluate their diagnostic significance with regard to clear cell renal cell carcinoma (ccRCC) and angiomyolipoma (AML). Urine samples from 91 patients with ccRCC, 16 patients with AML and 24 healthy volunteers were assessed. We used an enzyme-linked immunosorbent assay (ELISA) to quantify 14-3-3 protein beta/alpha levels in urine. Values were higher in patients with ccRCC than in those with AML and in healthy volunteers. High levels were associated with pathologic stage, lymph node status, distant metastasis and poor survival. Urinary levels of 14-3-3 protein beta/alpha were significantly increased in patients with small-sized carcinoma, irrespective of being less than 4.0 cm and 2.0 cm, compared with levels in patients with AML. This study is the first to report that increased expression of 14-3- 3 protein beta/alpha in urine is associated with advanced stage and poor survival in patients with ccRCC. In addition, urinary 14-3-3 protein beta/alpha may differentiate AML from RCC, even when small sized. These results suggest that examination of urinary 14-3-3 protein beta/alpha could serve as a diagnostic and prognostic marker in patients with ccRCC.

14-3-3β Depletion Drives a Senescence Program in Glioblastoma Cells Through the ERK/SKP2/p27 Pathway

The induction of senescence in cancer cells has recently been implicated as a mechanism of tumor regression in response to various modes of stress. 14-3-3 proteins are conserved scaffolding molecules that are involved in various cellular functions. Among the seven isoforms, 14-3-3β is specifically expressed in astrocytoma in correlation with the malignancy grade. We investigated the possible role of 14-3-3β in the regulation of senescence induction in A172 glioblastoma cells. The knockdown of 14-3-3β by specific small interfering RNA resulted in a significant change in cellular phenotypes and an increase in cells staining positive for senescence-associated β-galactosidase. Western blotting of the 14-3-3β-depleted A172 cells revealed increased p27 expression and decreased SKP2 expression, while the expression of p53 and p21 was not altered. Subsequently, we demonstrated that ERK is a key modulator of SKP2/p27 axis activity in 14-3-3β-mediated senescence based on the following: (1) 14-3-3β knockdown decreased p-ERK levels; (2) treatment with U0126, an MEK inhibitor, completely reproduced the senescence morphology as well as the expression profiles of p27 and SKP2; and (3) the senescence phenotypes induced by 14-3-3β depletion were considerably recovered by constitutively active ERK expression. Our results indicate that 14-3-3β negatively regulates senescence in glioblastoma cells via the ERK/SKP2/p27 pathway. Furthermore, 14-3-3β depletion also resulted in senescence phenotypes in U87 glioblastoma cells, suggesting that 14-3-3β could be targeted to induce premature senescence as a therapeutic strategy against glioblastoma progression.

Regulation of aldo-keto-reductase family 1 B10 by 14-3-3ε and their prognostic impact of hepatocellular carcinoma

14-3-3ε is overexpressed in hepatocellular carcinoma (HCC) and its expression significantly associates with a poor prognostic outcome. To uncover how 14-3-3ε contributes to the tumor progression of HCC, we investigated the potential downstream targets regulated by 14-3-3ε. We found that 14-3-3ε increases expression and nuclear translocation of β-catenin and that 14-3-3ε-induced cell proliferation is attenuated by β-catenin silencing in HCC cells. Moreover, 14-3-3ε induces aldo-keto reductase family 1 member B10 (AKR1B10) expression through the activation of β-catenin signaling. Knockdown of AKR1B10 by siRNAs abolished 14-3-3ε-induced in vitro cell proliferation, anchorage-independent growth as well as in vivo tumor growth. Furthermore, AKR1B10 silencing increased retinoic acid (RA) levels in the serum of tumor-bearing mice and RA treatment attenuated 14-3-3ε-induced HCC cell proliferation. We further examined 14-3-3ε and AKR1B10 expression and clinicopathological characteristics of HCC tumors. Although the expression of AKR1B10 was significantly correlated with 14-3-3ε, an increase of AKR1B10 expression in 14-3-3ε positive patients paradoxically had better overall survival and disease-free survival rates as well as lower metastatic incidence than those without an AKR1B10 increase. Finally, we found a loss of AKR1B10 expression in cells exhibiting a high capacity of invasiveness. Silencing of AKR1B10 resulted in inducing snail and vimentin expression in HCC cells. These results indicate that AKR1B10 may play a dual role during HCC tumor progression. Our results also indicate that 14-3-3ε regulates AKR1B10 expression by activating β-catenin signaling. A combination of 14-3-3ε with AKR1B10 is a potential therapeutic target and novel prognostic biomarker of HCC.

Molecular mechanisms of the effect of TGF-β1 on U87 human glioblastoma cells

Glioblastoma multiforme (GBM) is the most widespread and aggressive type of primary brain tumor. The prognosis following diagnosis with GBM is poor, with a median survival time of 14 months. Tumor cell invasion, metastasis and proliferation are the major causes of mortality in patients with GBM. In order to develop effective GBM treatment methods it is necessary to identify novel targets involved in these processes. Recently, there has been increasing interest in investigating the signaling pathways involved in GBM development, and the transforming growth factor-β (TGF-β) signaling pathway is understood to be significant for regulating the behavior of GBM, as well as stimulating its invasion and metastatic development. Particular interest has been given to investigating the modulation of TGF-β-induced epithelial-to-mesenchymal transition (EMT); during this process, epithelial cells transdifferentiate into mobile cells with a mesenchymal phenotype. The induction of EMT increases the invasiveness of various types of carcinoma; however, the role of TGF-β in this process remains to be elucidated, particularly in the case of GBM. The current study presents a comparative proteome mapping of the U87 human glioblastoma cell line, with and without TGF-β1 treatment. Proteome analysis identified numerous proteins involved in the molecular mechanisms of GBM oncogenesis and TGF-β1 signaling in glioblastoma. The results of the present study facilitated the identification of novel potential markers of metastasis and candidates for targeted glioblastoma therapy, which may potentially be validated and used in clinical medicine to develop improved approaches for GBM diagnosis and treatment.

14-3-3 eta isoform colocalizes TDP-43 on the coarse granules in the anterior horn cells of patients with sporadic amyotrophic lateral sclerosis

The immunolocalization of the 14-3-3 eta isoform in the anterior horn cells (AHCs) of patients with sporadic amyotrophic lateral sclerosis (ALS) and controls was examined. Compared with the immunolocalization of other 14-3-3 isoforms, the immunolocalization of the 14-3-3 eta isoform was either synaptic at the periphery of AHCs, spindle-shaped in neurites, or granular in the cytoplasm. By double labeling with phosphorylated (p-)TDP-43, the transactivation response DNA binding protein of 43kDa (TDP-43) demonstrated frequent colocalization of the 14-3-3 eta isoform in granular structures (90%) and spindle-shaped structures (85.4%), but not in p-TDP-43-positive round inclusions. It is speculated that the 14-3-3 eta isoform is associated with not only a synaptic pathology of ALS but also TDP-positive small lesions in the cytoplasm and neurites. The absence of eta-like immunoreactivity in p-TDP-43-positive large inclusions suggests the restricted relevance of the 14-3-3 eta isoform during ALS pathogenesis to some phases of the p-TDP pathology.

14-3-3β Promotes Migration and Invasion of Human Hepatocellular Carcinoma Cells by Modulating Expression of MMP2 and MMP9 through PI3K/Akt/NF-κB Pathway

14-3-3β has been demonstrated to possess the oncogenic potential, and its increased expression has been detected in multiple types of carcinomas. However, majority of previous studies focused on the role of 14-3-3β in tumor cell proliferation and apoptosis, leaving much to be elucidated about its function in tumor cell invasion and metastasis. Hence, the present study aimed to investigate the role of 14-3-3β in the invasion of hepatocellular carcinoma (HCC) cells and the implications in the prognosis of HCC patients. We first examined the expression of 14-3-3β in the primary tumors of HCC patients with or without portal vein tumor thrombus (PVTT), and found that 14-3-3β expression was higher in the primary tumors with PVTT, and the level was even higher in the PVTTs. Kaplan-Meier curves and multivariate analysis revealed that high expression of 14-3-3β was associated with overall survival (OS) and time to recurrence (TTR) of HCC patients. In addition, ectopic expression of 14-3-3β in HCC cell lines led to enhanced migration ability and invasiveness, as well as up-regulation of matrix metalloproteinase 2 and 9, which could be suppressed by inhibiting the activation of Akt and nuclear factor-κB (NF-κB) signaling. Furthermore, we identified a correlated elevation of 14-3-3β and p-Akt in the primary tumors of HCC patients, and showed that a combinatory detection of 14-3-3β and p-Akt could better predict post-surgical outcome of HCC patients.

Comparative analysis of 14-3-3 isoform expression and epigenetic alterations in colorectal cancer

Background

The 14-3-3 family is a group of intracellular proteins found in all eukaryotic organisms. Humans have seven isoforms that serve as scaffolds to promote interactions of regulatory phospho-proteins involved in many vital cellular processes and previous studies have shown that disturbances in native 14-3-3 levels can contribute significantly to the development of various cancers.

Methods

DNA and RNA was extracted from frozen tissue samples collected by the Human Cooperative Tissue Network. RNA samples were reverse transcribed and subjected to qRT-PCR analysis using fluorescently labelled probes. Genomic DNA was treated with bisulfite and cloned into bacterial vectors for subsequent high-resolution sequencing. Mammalian NIH3T3 cells were transformed with 14-3-3 eta and Ras expression vectors synthesized from cDNA. Colonies were counted and transforming capability assessed after 21 days of growth. Cell lysates were analyzed by western blot to verify protein expression.

Results

Here we examined normal and cancerous 14-3-3 expression levels of all seven isoforms in a cohort of sporadic colorectal adenocarcinomas and in a group of tumors and their matched normals using qRT-PCR analysis. We found a statistically significant decrease in the levels of 14-3-3 sigma, eta, and zeta observed among adenocarcinomas compared to normal tissue. A parallel analysis of microarray data from the TCGA dataset confirmed that expression of sigma and eta were down-regulated in colon tumors. To explore the mechanisms behind 14-3-3 expression changes, we examined the methylation status of the sigma, eta, and zeta gene promoters in selected samples. Our data identified novel CpG methylation sites in the eta promoter consistent with epigenetic silencing of both 14-3-3 sigma and eta isoforms during colon tumorigenesis. Because epigenetic silencing is the hallmark of a tumor suppressor we tested eta in focus formation assays and found that it is capable of suppressing ras-induced transformation of NIH3T3 cells.

Conclusion

To our knowledge, this is the first study to identify the 14-3-3 eta gene as a tumor suppressor and that its expression is suppressed in colon tumors by DNA hypermethylation. These data suggest a link between 14-3-3 expression levels and the development of colon cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1856-y) contains supplementary material, which is available to authorized users.

Integrate Omics Data and Molecular Dynamics Simulations toward Better Understanding of Human 14-3-3 Interactomes and Better Drugs for Cancer Therapy

The 14-3-3 protein family is among the most extensively studied, yet still largely mysterious protein families in mammals to date. As they are well recognized for their roles in apoptosis, cell cycle regulation, and proliferation in healthy cells, aberrant 14-3-3 expression has unsurprisingly emerged as instrumental in the development of many cancers and in prognosis. Interestingly, while the seven known 14-3-3 isoforms in humans have many similar functions across cell types, evidence of isoform-specific functions and localization has been observed in both healthy and diseased cells. The strikingly high similarity among 14-3-3 isoforms has made it difficult to delineate isoform-specific functions and for isoform-specific targeting. Here, we review our knowledge of 14-3-3 interactome(s) generated by high-throughput techniques, bioinformatics, structural genomics and chemical genomics and point out that integrating the information with molecular dynamics (MD) simulations may bring us new opportunity to the design of isoform-specific inhibitors, which can not only be used as powerful research tools for delineating distinct interactomes of individual 14-3-3 isoforms, but also can serve as potential new anti-cancer drugs that selectively target aberrant 14-3-3 isoform.

Involvement of 14-3-3 Proteins in Regulating Tumor Progression of Hepatocellular Carcinoma

There are seven mammalian isoforms of the 14-3-3 protein, which regulate multiple cellular functions via interactions with phosphorylated partners. Increased expression of 14-3-3 proteins contributes to tumor progression of various malignancies. Several isoforms of 14-3-3 are overexpressed and associate with higher metastatic risks and poorer survival rates of hepatocellular carcinoma (HCC). 14-3-3β and 14-3-3ζ regulate HCC cell proliferation, tumor growth and chemosensitivity via modulating mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK) and p38 signal pathways. Moreover, 14-3-3ε suppresses E-cadherin and induces focal adhesion kinase (FAK) expression, thereby enhancing epithelial-mesenchymal transition (EMT) and HCC cell migration. 14-3-3ζ forms complexes with αB-crystallin, which induces EMT and is the cause of sorafenib resistance in HCC. Finally, a recent study has indicated that 14-3-3σ induces heat shock protein 70 (HSP70) expression, which increases HCC cell migration. These results suggest that selective 14-3-3 isoforms contribute to cell proliferation, EMT and cell migration of HCC by regulating distinct targets and signal pathways. Targeting 14-3-3 proteins together with specific downstream effectors therefore has potential to be therapeutic and prognostic factors of HCC. In this article, we will overview 14-3-3’s regulation of its downstream factors and contributions to HCC EMT, cell migration and proliferation.

Down-regulation of 14-3-3β exerts anti-cancer effects through inducing ER stress in human glioma U87 cells: Involvement of CHOP-Wnt pathway

We previously identified 14-3-3β as a tumor-specific isoform of 14-3-3 protein in astrocytoma, but its functional role in glioma cells and underlying mechanisms are poorly understood. In the present study, we investigated the effects of 14-3-3β inhibition in human glioma U87 cells using specific targeted small interfering RNA (siRNA). The results showed that 14-3-3β is highly expressed in U87 cells but not in normal astrocyte SVGp12 cells. Knockdown of 14-3-3β by Si-14-3-3β transfection significantly decreased the cell viability but increased the LDH release in a time-dependent fashion in U87 cells, and these effects were accompanied with G0/G1 cell cycle arrest and apoptosis. In addition, 14-3-3β knockdown induced ER stress in U87 cells, as evidenced by ER calcium release, increased expression of XBP1S mRNA and induction of ER related pro-apoptotic factors. Down-regulation of 14-3-3β significantly decreased the nuclear localization of β-catenin and inhibited Topflash activity, which was shown to be reversely correlated with CHOP. Furthermore, Si-CHOP and sFRP were used to inhibit CHOP and Wnt, respectively. The results showed that the anti-cancer effects of 14-3-3β knockdown in U87 cells were mediated by increased expression of CHOP and followed inhibition of Wnt/β-catenin pathway. In summary, the remarkable efficiency of 14-3-3β knockdown to induce apoptotic cell death in U87 cells may find therapeutic application for the treatment of glioma patients.

Short-term type-1 diabetes differentially modulates 14-3-3 proteins in rat brain and liver

BACKGROUND

The 14-3-3 proteins family consists of seven proteins that are highly conserved molecular chaperones with roles in the regulation of metabolism, signal transduction, cell cycle control, protein trafficking and apoptosis. Their role in several pathologies has been reported. In this study, we investigated the mRNA and protein expression of the 14-3-3s in rat brain and liver in the early stage of Type-1 diabetes (T1D).

MATERIAL AND METHODS

Diabetes was induced by a single intraperitoneal injection (70 mg/kg bw) of freshly prepared streptozotocin (STZ), and, after 3 weeks of treatment, brain and liver nuclei and cytosolic extracts were prepared. Quantitative real-time PCR and Western blotting analyses were performed to evaluate mRNA and protein expression for each of the seven 14-3-3s.

RESULTS

In nondiabetic control rats, the expression profile of 14-3-3s revealed a tissue-specific distribution, and the expression level of each isoform was found higher in the brain than in the liver. In the diabetic brain, mRNA and protein levels of the 14-3-3β, ε, ζ, η and θ were lower; 14-3-3σ mRNA significantly increased while its protein level decreased. In the diabetic liver, the mRNA of 14-3-3γ, 14-3-3θ and 14-3-3σ significantly increased, but only the 14-3-3γ protein level increased. Overall, in diabetic animals, the changes in the expression levels of brain 14-3-3s were much more pronounced than in the liver.

CONCLUSION

Our results indicate that during the early phase of STZ-induced T1D, the 14-3-3 proteins are affected in an isoform- and tissue-specific way.

Fungal metabolites with anticancer activity

Covering: 1964 to 2013. Natural products from bacteria and plants have played a leading role in cancer drug discovery resulting in a large number of clinically useful agents. In contrast, the investigations of fungal metabolites and their derivatives have not led to a clinical cancer drug in spite of significant research efforts revealing a large number of fungi-derived natural products with promising anticancer activity. Many of these natural products have displayed notable in vitro growth-inhibitory properties in human cancer cell lines and select compounds have been demonstrated to provide therapeutic benefits in mouse models of human cancer. Many of these compounds are expected to enter human clinical trials in the near future. The present review discusses the reported sources, structures and biochemical studies aimed at the elucidation of the anticancer potential of these promising fungal metabolites.

Phytotoxic Terpenes Produced by Phytopathogenic Fungi and Allelopathic Plants

This review is about the isolation as well as chemical and biological characterization of simple and complex mono-, sesqui-, di-, sester- and tri-terpenes produced by fungal pathogens of agrarian and forest plants and by some allelopathic plants. In several cases, the structure activity relationships are also discussed, as well as their potential application in agriculture as natural safe herbicides, fungicides and bactericides. Furthermore, the potential application of some fungal terpenes as anticancer compounds with a new mode of action is also discussed.

14-3-3β regulates the proliferation of glioma cells through the GSK3β/β-catenin signaling pathway

We previously demonstrated that 14-3-3β is overexpressed in astrocytomas; however, the underlying mechanisms are poorly understood. Based on the reported multiple functions of 14-3-3β, we hypothesized that it interacts with glycogen synthase kinase 3 β (GSK3β), which regulates β-catenin-mediated oncogene expression and contributes to tumorigenesis and astrocytoma progression. To test these hypotheses, we used 14-3-3β overexpression vectors and small interfering RNA (siRNA) transfection in the human normal astrocyte cell line SVGp12 and the glioma cell line U87, respectively. The results showed that overexpression of 14-3-3β promoted the proliferation of SVGp12 cells, while knockdown of 14-3-3β inhibited the proliferation of U87 cells as analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and bromodeoxyuridine (BrdU) assays. In Flag-tagged 14-3-3β-overexpressing cells, GSK3β was co-immunoprecipitated with 14-3-3β using a Flag antibody. Knockdown of β-catenin by siRNA blocked cell proliferation induced by overexpression of 14-3-3β. Furthermore, overexpression of 14-3-3β suppressed the phosphorylation of β-catenin leading to its accumulation and nuclear translocation as revealed by western blot analysis. In addition, β-catenin nuclear translocation induced by overexpression of 14-3-3β activated the transcription of oncogenes including c-myc and cyclin D1. Collectively, these results revealed that 14-3-3β regulates the proliferation of astrocytes and glioma cells through the GSK3β/β-catenin signaling pathway. The delineated mechanism of 14-3-3β may be responsible for the tumorigenesis and progression of human astrocytomas. Thus, new therapeutic strategies or drugs aimed at 14-3-3β may have potential for the treatment of human astrocytomas.

Stable isotope dimethyl labeling combined with LTQ mass spectrometric detection, a quantitative proteomics technology used in liver cancer research

Liver cancer is a common malignant disease, with high incidence and mortality rates. The study on the proteomics of liver cancer has attracted particular attention. The quantitative study method of proteomics depends predominantly on two-dimensional (2D) gel electrophoresis. In the present study we reported a rapid and accurate proteomics quantitative study method of high repeatability that includes the use of stable isotope labeling for the extraction of proteins and peptides via enzymolysis to achieve new type 2D capillary liquid chromatography-mass spectrometry separation using the separation mode of cation-exchange chromatography in conjunction with reversed-phase chromatography. LTQ OrbiTrap mass spectrometry detection was also performed. A total of 188 differential proteins were analyzed, including 122 upregulating [deuterium/hydrogen ratio (D/H) >1.5)] and 66 downregulating proteins (D/H<0.67). These proteins may play an important role in the occurrence, drug resistance, metastasis and recurrence of cancer or other pathological processes. Such a proteomics technology may provide biological data as well as a new methodological basis for liver cancer research.

Fusicoccin a, a phytotoxic carbotricyclic diterpene glucoside of fungal origin, reduces proliferation and invasion of glioblastoma cells by targeting multiple tyrosine kinases

Glioblastoma multiforme (GBM) is a deadly cancer that possesses an intrinsic resistance to pro-apoptotic insults, such as conventional chemotherapy and radiotherapy, and diffusely invades the brain parenchyma, which renders it elusive to total surgical resection. We found that fusicoccin A, a fungal metabolite from Fusicoccum amygdali, decreased the proliferation and migration of human GBM cell lines in vitro, including several cell lines that exhibit varying degrees of resistance to pro-apoptotic stimuli. The data demonstrate that fusicoccin A inhibits GBM cell proliferation by decreasing growth rates and increasing the duration of cell division and also decreases two-dimensional (measured by quantitative video microscopy) and three-dimensional (measured by Boyden chamber assays) migration. These effects of fusicoccin A treatment translated into structural changes in actin cytoskeletal organization and a loss of GBM cell adhesion. Therefore, fusicoccin A exerts cytostatic effects but low cytotoxic effects (as demonstrated by flow cytometry). These cytostatic effects can partly be explained by the fact that fusicoccin inhibits the activities of a dozen kinases, including focal adhesion kinase (FAK), that have been implicated in cell proliferation and migration. Overexpression of FAK, a nonreceptor protein tyrosine kinase, directly correlates with the invasive phenotype of aggressive human gliomas because FAK promotes cell proliferation and migration. Fusicoccin A led to the down-regulation of FAK tyrosine phosphorylation, which occurred in both normoxic and hypoxic GBM cell culture conditions. In conclusion, the current study identifies a novel compound that could be used as a chemical template for generating cytostatic compounds designed to combat GBM.

14-3-3ε overexpression contributes to epithelial-mesenchymal transition of hepatocellular carcinoma

Background

14-3-3ε is implicated in regulating tumor progression, including hepatocellular carcinoma (HCC). Our earlier study indicated that elevated 14-3-3ε expression is significantly associated with higher risk of metastasis and lower survival rates of HCC patients. However, the molecular mechanisms of how 14-3-3ε regulates HCC tumor metastasis are still unclear.

Methodology and Principal Findings

In this study, we show that increased 14-3-3ε expression induces HCC cell migration and promotes epithelial-mesenchymal transition (EMT), which is determined by the reduction of E-cadherin expression and induction of N-cadherin and vimentin expression. Knockdown with specific siRNA abolished 14-3-3ε-induced cell migration and EMT. Furthermore, 14-3-3ε selectively induced Zeb-1 and Snail expression, and 14-3-3ε-induced cell migration was abrogated by Zeb-1 or Snail siRNA. In addition, the effect of 14-3-3ε-reduced E-cadherin was specifically restored by Zeb-1 siRNA. Positive 14-3-3ε expression was significantly correlated with negative E-cadherin expression, as determined by immunohistochemistry analysis in HCC tumors. Analysis of 14-3-3ε/E-cadherin expression associated with clinicopathological characteristics revealed that the combination of positive 14-3-3ε and negative E-cadherin expression is significantly correlated with higher incidence of HCC metastasis and poor 5-year overall survival. In contrast, patients with positive 14-3-3ε and positive E-cadherin expression had better prognostic outcomes than did those with negative E-cadherin expression.

Significance

Our findings show for the first time that E-cadherin is one of the downstream targets of 14-3-3ε in modulating HCC tumor progression. Thus, 14-3-3ε may act as an important regulator in modulating tumor metastasis by promoting EMT as well as cell migration, and it may serve as a novel prognostic biomarker or therapeutic target for HCC.

Relationship of 14-3-3zeta (ζ), HIF-1α, and VEGF expression in human brain gliomas

Accumulating evidence suggests that tissue hypoxia and apoptosis play important roles in the malignant progression of brain tumors. We investigated the relationship of 14-3-3zeta (an apoptosis-related protein), HIF-1α, and VEGF immunohistochemistry, and evaluated the prognostic value of their expression in human brain gliomas. A semiquantitative analysis of the immunoreactivity scores (IRSs) of the 14-3-3zeta, HIF-1α, and VEGF proteins was performed in 27 patients with various grades of gliomas. The IRS of 14-3-3zeta increased with tumor grade, with grade IV gliomas having the highest score (P < 0.05). Similar results were found for the IRSs of HIF-1α and VEGF (P < 0.05). A significant positive correlation was found between the IRSs of 14-3-3zeta and HIF-1α, 14-3-3zeta and VEGF, and HIF-1α and VEGF (P < 0.001 for all). The survival time of HIF-1α in grade III and grade IV glioma patients with low IRSs (0-6) was significantly longer than that in such glioma patients with high IRSs (8-12) (P < 0.05). These data indicate that 14-3-3zeta, HIF-1α, and VEGF are involved in the same cascade of the malignant progression of gliomas. Further studies will elucidate their detailed role in the malignant progression of glioma, and will contribute to the development of a new treatment strategy for this lethal disease.

Implication of 14-3-3ε and 14-3-3θ/τ in proteasome inhibition-induced apoptosis of glioma cells

Proteasome inhibitors represent a novel class of anticancer agents that are used in the treatment of hematologic malignancies and various solid tumors. However, mechanisms underlying their anticancer actions were not fully understood. It has been reported that strong 14-3-3 protein expression is observed and associated with tumor genesis and progression of astrocytoma. In addition, global inhibition of 14-3-3 functions with a general 14-3-3 antagonist difopein induces apoptosis of human astrocytoma cells, validating 14-3-3 as a potential molecular target for anticancer therapeutic management. In the current study, for the first time we demonstrated that proteasome inhibitors downregulated 14-3-3ε and 14-3-3θ/τ in U87 and SF295 glioma cells. Overexpression of 14-3-3ε and 14-3-3θ/τ significantly suppressed apoptosis of human glioma cells induced by proteasome inhibitors. We also demonstrated that MG132 activated ASK1 and siASK1 compromised the MG132-induced apoptosis of glioma cells. Furthermore, overexpression of 14-3-3ε and 14-3-3θ/τ markedly suppressed activation of ASK1. Collectively, the current study supported that proteasome inhibitors, at least in part, caused cytotoxicity of glioma cells via downregulation of 14-3-3ε and 14-3-3θ/τ and subsequent activation of ASK1.

Quantitative proteomic Isotope-Coded Protein Label (ICPL) analysis reveals alteration of several functional processes in the glioblastoma

Glioblastoma (GB), the most frequent primary tumor of the central nervous system, remains one of the most lethal human cancers despite intensive researches. Current paradigm in the study of GB has been focused on inter-patient variability and on trying to isolate new classification elements or prognostic factors. Here, using ICPL, a technique for protein relative quantification by mass spectrometry, we investigated protein expression between the four regions of GB on clinically relevant biopsies from 5 patients. We identified 584 non-redundant proteins and 31 proteins were found to be up-regulated in the tumor region compared to the peri-tumoral brain tissue, among which, 24 proteins belong to an interaction network linked to 4 biological processes. The core of this network is mainly constituted of interactions between beta-actin (ACTB) with heat shock proteins (HSP90AA1, HSPA8) and 14-3-3 proteins (YWHAZ, YWHAG, YWHAB). A cluster of three isoforms of the sodium pump α-subunit (ATP1A1, ATP1A2, ATP1A3) was also identified outside this network. The differential expression observed for ACTB and 14-3-3γ was further validated by western blot and/or immunohistochemistry. Our study confirms the identity of previously proposed molecular targets, highlights several functional processes altered in GB such as energy metabolism and synaptic transmission and could thus provide added value to new therapeutic trails.

14-3-3ζ positive expression is associated with a poor prognosis in patients with glioblastoma

BACKGROUND

When identifying clinical markers predicting clinical outcome, disease recurrence and resistance to therapies often determine the diagnosis and therapy of some cancer types.

OBJECTIVE

To investigate whether 14-3-3zeta positive expression is an indicator of prognosis in patients with glioblastoma.

METHODS

Forty-seven patients treated with surgery, radiotherapy, and adjuvant chemotherapy between 2005 and 2007 were divided into 2 groups according to 14-3-3zeta expression in an immunohistochemical study: the 14-3-3zeta negative group (n = 12 patients) and the 14-3-3zeta positive group (n = 35 patients). The clinicopathologic features and survival data for patients in the 14-3-3zeta positive group were compared with data from the patients in the 14-3-3zeta negative group. Kaplan-Meier survival analysis and univariate and multivariate analyses were performed to determine the prognostic factors that influenced patient survival.

RESULTS

14-3-3zeta positive expression was observed in approximately 74.5% of patients with glioblastoma. Patients in the 14-3-3zeta positive group had lower overall survival rates and median survival time than those in the 14-3-3zeta negative group (overall 2-year actuarial survival rates, 8.6% for the 14-3-3zeta positive group vs 16.7% for the 14-3-3zeta negative group; overall 2-year median survival time, 12.9 months for the 14-3-3zeta positive group vs 17.9 months for the 14-3-3zeta negative group, P = .019). 14-3-3zeta positive expression in tumor cells also was correlated with a shorter interval to tumor recurrence (median interval to recurrence, 5.9 months in the 14-3-3zeta positive group vs 8.3 months in the 14-3-3zeta negative group, P = .002). Univariate and multivariate analyses showed that 14-3-3zeta positive expression was an independent prognostic factor.

CONCLUSION

14-3-3zeta positive expression can be used as a potential molecular risk factor in patients with glioblastoma.

Isoform-specific immunolocalization of 14-3-3 proteins in atherosclerotic lesions of human carotid and main cerebral arteries

14-3-3 proteins are now recognized to have a wide range of potential functions and pathological relevance, such as regulating the intercellular signal processes of differentiation, the development and growth of cells, or preventing or mediating cell apoptosis and survival by controlling the localization of potential signaling molecules. We investigated the immunolocalization of 14-3-3 proteins in atherosclerotic lesions of human cerebral and carotid arteries using 14-3-3 isoform-specific antibodies to distinguish 7 isoforms, and confirmed the cell type localization using double immunofluorolabeling. 14-3-3 common (COM)-like immunoreactivity (IR) was intense, mainly in the foam cells and multinucleated giant cells of the carotid artery. The beta, gamma, epsilon, tau, eta, and zeta (6/7) isoform-specific antibodies showed similar results to those with anti-14-3-3 COM antibody. However, among these isoform-specific antibodies, the anti-eta isoform antibody most intensely immunolabeled multinucleated giant cells and foam cells, and the anti-zeta isoform antibody most intensely immunolabeled infiltrating vascular smooth muscle cells (VSMCs), in carotid plaques. Zeta IR was also observed in one part of the mural thrombus and in the nuclei of foam cells. Gamma isoform-like IR was relatively limited in cell components, but extracellular lesions were partly positive for this isoform. In the main cerebral arteries, the anti-epsilon isoform antibody most intensely immunolabeled infiltrating VSMCs in the intima of thickened fibrous cap plaques. Endothelial cells were also positive for the epsilon isoform. These findings may provide a basis for understanding the isoform-specific role associated with atherosclerotic lesions of the cerebral and carotid arteries.

Increased expression of 14-3-3β promotes tumor progression and predicts extrahepatic metastasis and worse survival in hepatocellular carcinoma

14-3-3β is implicated in cell survival, proliferation, migration, and tumor growth; however, its clinical relevance in tumor progression and metastasis have never been elucidated. To evaluate the clinical significance of 14-3-3β, we analyzed the association of 14-3-3β expression and clinicopathologic characteristics in primary and subsequent metastatic tumors of hepatocellular carcinoma patients. 14-3-3β was expressed abundantly in 40 of 55 (70.7%) primary tumors. Increased 14-3-3β expression in primary tumors predicted a higher 5-year cumulative incidence of subsequent extrahepatic metastasis, and multivariate analysis revealed 14-3-3β overexpression was an independent risk factor for extrahepatic metastasis. Patients with increased 14-3-3β expression in primary tumors had worse 5-year overall survival rates, and 14-3-3β overexpression was an independent prognostic factor on Cox regression analysis. Furthermore, stably overexpressed 14-3-3β enhanced hepatocellular carcinoma cell migration and proliferation and increased anchorage-independent cell growth. In addition, in vivo study in a nude-mice model showed tumor formation significantly increased with 14-3-3β overexpression. In conclusion, this is the first report to show that increased 14-3-3β expression is associated with subsequent extrahepatic metastasis and worse survival rates, as well as cancer progression of hepatocellular carcinoma. Thus, 14-3-3β may be a novel prognostic biomarker and therapeutic target in hepatocellular carcinoma.

Stratifin expression is a novel prognostic factor in human gliomas

Stratifin (14-3-3σ or SFN) is a member of the 14-3-3 family of proteins which play critical roles in different cellular signaling processes. Stratifin as a potential tumor suppressor gene plays an important role in carcinogenesis and metastasis. The aim of this study was to investigate the expression of Stratifin in human gliomas and to analyze its expression profile with respect to tumor development. The expression pattern of Stratifin was analyzed by immunohistochemistry and/or Western blotting in tumor samples from 186 patients with different grades of gliomas. Prognostic significance was assessed using Kaplan-Meier survival estimates and Cox regression analyses. The expression pattern of Stratifin was correlated with the pathological and clinical characteristics of the patients with gliomas. Western blot analysis indicated that the average optical densitometry (OD) ratio of Stratifin in high-grade gliomas (World Health Organization [WHO] grade III/IV) was lower than in low-grade tumors (WHO grade I/II, p=0.026). In addition, statistical analysis showed that patients expressing a high level of Stratifin have favorable overall survival rates relative to those expressing a low level of this protein. Cox multi-factor analysis showed that Stratifin (p=0.02) was an independent prognosis factor for human gliomas. Our results provide convincing evidence that the expression of Stratifin is down-regulated in human gliomas. Its expression level is correlated with the clinicopathological parameters and prognosis in patients with gliomas. Pending validation targeting, Stratifin might also be a novel opportunity to improve the therapy of this tumor.

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

IMPORTANCE OF THE FIELD

The ubiquitously expressed 14-3-3ζ protein is involved in numerous important cellular pathways involved in cancer. Recent research suggests 14-3-3ζ may play a central role regulating multiple pathways responsible for cancer initiation and progression. This review will provide an overview of 14-3-3 proteins and address the role of 14-3-3ζ overexpression in cancer.

AREAS COVERED IN THIS REVIEW

The review covers the basic role of 14-3-3 in regulation of multiple pathways with a focus on 14-3-3ζ as a clinically relevant biomarker for cancer recurrence.

WHAT THE READER WILL GAIN

14-3-3ζ overexpression has been found in multiple cancers; however, the clinical implications were unclear. Recently, 14-3-3ζ has been identified as a biomarker for poor prognosis and chemoresistance in multiple tumor types, indicating a potential clinical application for using 14-3-3ζ in selecting treatment options and predicting cancer patients' outcome.

TAKE HOME MESSAGE

14-3-3ζ is a potential prognostic marker of cancer recurrence and predictive marker for therapeutic resistance. The overexpression of 14-3-3ζ in multiple cancers suggests that it may be a common target to intervene tumor progression; therefore, more efforts are needed for the development of 14-3-3 inhibitors.

mTRAQ-based quantification of potential endometrial carcinoma biomarkers from archived formalin-fixed paraffin-embedded tissues

Formalin-fixed paraffin-embedded (FFPE) tissues are the primary and preferred medium for archiving patients' samples. Here we demonstrate relative quantifications of protein biomarkers in extracts of laser microdissected epithelial cells from FFPE endometrial carcinoma tissues versus those from normal proliferative endometria by means of targeted proteomic analyses using LC-multiple reaction monitoring (MRM) MS with MRM Tags for Relative and Absolute Quantitation (mTRAQ) labeling. Comparable results of differential expressions for pyruvate kinase isoform M2 (PK-M2) and polymeric Ig receptor were observed between analyses on laser microdissected epithelial cells from FFPE tissues and corresponding homogenates from frozen tissues of the same individuals that had previously been analyzed and reported. We also identified PK-M2 in the normal proliferative phase of the endometrium. Other biomarkers in addition to PK-M2 and polymeric Ig receptor were also observed but not consistently and/or were at levels below the threshold for quantification.

The expression of seven 14-3-3 isoforms in human meningioma

14-3-3 proteins comprise a large family of highly conserved, acidic polypeptides, expressed in all eukaryotic organisms, with highest concentration found in the brain. Multiple isoforms of 14-3-3 proteins have been shown to play an essential role in regulating differentiation, proliferation and transformation. In the previous study, the expression levels of all seven 14-3-3 isoforms were examined in astrocytoma. However, the expression of seven 14-3-3 isoforms in meningioma still remains unknown. This study is the first examination of 14-3-3 isoforms in three grades of meningioma by immunohistochemistry. 14-3-3epsilon, zeta and theta were specifically expressed in meningioma, and their expression levels increased with the increase of pathological grade of meningioma. The 14-3-3 eta, beta, gamma and sigma isoforms were negatively expressed in meningioma. In conclusion, The 14-3-3 epsilon, zeta and theta may be involved in tumorigenesis of meningioma and be efficient markers for predicting the degree of malignancy in meningioma.