Clinical implication of 14-3-3 epsilon expression in gastric cancer

Negative Charges, Not Necessary Phosphorylation, are Required for Ligand Recognition by 14-3-3 Proteins

Protein-protein interactions involving 14-3-3 proteins regulate various cellular activities in normal and pathological conditions. These interactions have mostly been reported to be phosphorylation-dependent, but the 14-3-3 proteins also interact with unphosphorylated proteins. In this work, we investigated whether phosphorylation is required, or, alternatively, whether negative charges are sufficient for 14-3-3ε binding. We substituted the pThr residue of pT(502-510) peptide by residues with varying number of negative charges, and investigated binding of the peptides to 14-3-3ε using MD simulations and biophysical methods. We demonstrated that at least one negative charge is required for the peptides to bind 14-3-3ε while phosphorylation is not necessary, and that two negative charges are preferable for high affinity binding.

Evidence and Metabolic Implications for a New Non-Canonical Role of Cu-Zn Superoxide Dismutase

Copper-zinc superoxide dismutase 1 (SOD1) has long been recognized as a major redox enzyme in scavenging superoxide radicals. However, there is little information on its non-canonical role and metabolic implications. Using a protein complementation assay (PCA) and pull-down assay, we revealed novel protein-protein interactions (PPIs) between SOD1 and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ) or epsilon (YWHAE) in this research. Through site-directed mutagenesis of SOD1, we studied the binding conditions of the two PPIs. Forming the SOD1 and YWHAE or YWHAZ protein complex enhanced enzyme activity of purified SOD1 in vitro by 40% (p < 0.05) and protein stability of over-expressed intracellular YWHAE (18%, p < 0.01) and YWHAZ (14%, p < 0.05). Functionally, these PPIs were associated with lipolysis, cell growth, and cell survival in HEK293T or HepG2 cells. In conclusion, our findings reveal two new PPIs between SOD1 and YWHAE or YWHAZ and their structural dependences, responses to redox status, mutual impacts on the enzyme function and protein degradation, and metabolic implications. Overall, our finding revealed a new unorthodox role of SOD1 and will provide novel perspectives and insights for diagnosing and treating diseases related to the protein.

CDC25B Inhibition by menadione: a potential new therapeutical approach

Gastric cancer (GC) is the fifth most common type of tumor and the third leading cause of cancer death worldwide. The evolution of gastric carcinogenesis is still poorly understood and, for this reason, preclinical research protocols were established that included the development of gastric cancer cell lines and the establishment of models of gastric carcinogenesis in non-human primate Sapajus apella. A comprehensive literature search was performed in relevant databases such as PubMed, ResearchGate and Google Scholar to identify studies related to the topic. After an in-depth study of these reports, significant data/data were collected and compiled under appropriate headings. The main result of the studies carried out by the group on GC is the demonstration of the MYC gene overexpression as a common phenomenon in stomach carcinogenesis. Furthermore, we revealed that reducing the expression of the CDC25B gene, regulated by the MYC protein, is a therapeutic strategy against stomach tumors. This review article reveals preclinical evidence that treatment with menadione in experimental models of gastric tumorigenesis, in vivo and in vitro, inhibits the action of the phosphatase CDC25B and, consequently, prevents cell proliferation, invasion and migration.

ZIP9 Is a Druggable Determinant of Sex Differences in Melanoma

Melanoma and most other cancers occur more frequently and have worse prognosis in males compared with females. Although sex steroids are thought to be involved, classical androgen and estrogen receptors are not detectable in most melanomas. Here we show that testosterone promotes melanoma proliferation by activating ZIP9 (SLC39A9), a zinc transporter that is widely expressed in human melanoma but not intentionally targeted by available therapeutics. This testosterone activity required an influx of zinc, activation of MAPK, and nuclear translocation of YAP. FDA-approved inhibitors of the classical androgen receptor also inhibited ZIP9, thereby antagonizing the protumorigenic effects of testosterone in melanoma. In male mice, androgen receptor inhibitors suppressed growth of ZIP9-expressing melanomas but had no effect on isogenic melanomas lacking ZIP9 or on melanomas in females. These data suggest that ZIP9 might be effectively targeted in melanoma and other cancers by repurposing androgen receptor inhibitors that are currently approved only for prostate cancer. SIGNIFICANCE: Testosterone signaling through ZIP9 mediates some of the sex differences in melanoma, and drugs that target AR can be repurposed to block ZIP9 and inhibit melanoma in males.

Comparative Proteomic Study Shows the Expression of Hint-1 in Pituitary Adenomas

Pituitary adenomas (PAs) can be unpredictable and aggressive tumors. No reliable markers of their biological behavior have been found. Here, a proteomic analysis was applied to identify proteins in the expression profile between invasive and non-invasive PAs to search for possible biomarkers. A histopathological and immunohistochemical (adenohypophyseal hormones, Ki-67, p53, CD34, VEGF, Flk1 antibodies) analysis was done; a proteomic map was evaluated in 64 out of 128 tumors. There were 107 (84%) invasive and 21 (16%) non-invasive PAs; 80.5% belonged to III and IV grades of the Hardy–Vezina classification. Invasive PAs (n = 56) showed 105 ± 43 spots; 86 ± 32 spots in non-invasive PAs (n = 8) were observed. The 13 most prominent spots were selected and 11 proteins related to neoplastic process in different types of tumors were identified. Hint1 (Histidine triad nucleotide-binding protein 1) high expression in invasive PA was found (11.8 ± 1.4, p = 0.005), especially at high index (>10; p = 0.0002). High Hint1 expression was found in invasive VEGF positive PA (13.8 ± 2.3, p = 0.005) and in Flk1 positive PA (14.04 ± 2.28, p = 0.006). Hint1 is related to human tumorigenesis by its interaction with signaling pathways and transcription factors. It could be related to invasive behavior in PAs. This is the first report on Hint expression in PAs. More analysis is needed to find out the possible role of Hint in these tumors.

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.

miR-31-5p Regulates 14-3-3 ɛ to Inhibit Prostate Cancer 22RV1 Cell Survival and Proliferation via PI3K/AKT/Bcl-2 Signaling Pathway

Introduction

Prostate cancer (PCa) is one of the most common malignancies, and almost all patients with advanced PCa will develop castration-resistant prostate cancer (CRPC) after receiving endocrine therapy. Effective treatment for patients with CRPC has not been established. Novel approaches are needed to identify therapeutic targets for CRPC.

Purpose

Recent research studies have found that members of the 14-3-3 family play an important role in the development and progression of PCa. Previous results have shown that 14-3-3 ɛ is significantly upregulated in several cancers. This study aimed to identify novel miRNAs that regulate 14-3-3 ɛ expression and therapeutic targets for CRPC.

Methods

In this study, we used computation and experimental approaches for the prediction and verification of the miRNAs targeting 14-3-3 ɛ, and investigated the potential roles of 14-3-3 ɛ in the survival and proliferation of 22RV1 cells.

Results

We confirm that mir-31-5p is downregulated in 22RV1 cells and acts as a tumor suppressor by regulating 14-3-3 ɛ. Ectopic expression of miR-31-5p or 14-3-3 ɛ interference significantly inhibits cell proliferation, invasion, and migration in 22RV1 cells, as well as promotes cell apoptosis via the PI3K/AKT/Bcl-2 signaling pathway. Moreover, 14-3-3 ɛ is required for the miR-31-5p-mediated upregulation of the PI3K/AKT/Bcl-2 signaling pathway.

Conclusion

Our findings provide information on the underlying mechanisms of miR-31-5p/14-3-3 ɛ in 22RV1 cell proliferation and apoptosis through the PI3K/AKT/Bcl-2 signaling pathway. These results suggest that miR-31-5p and 14-3-3 ɛ may potentially be utilized as novel prognostic markers and therapeutic targets for PCa treatment.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

Identification of molecular targets for the targeted treatment of gastric cancer using dasatinib

Gastric cancer (GC) remains the third leading cause of cancer-related death despite several improvements in targeted therapy. There is therefore an urgent need to investigate new treatment strategies, including the identification of novel biomarkers for patient stratification. In this study, we evaluated the effect of FDA-approved kinase inhibitors on GC. Through a combination of cell growth, migration and invasion assays, we identified dasatinib as an efficient inhibitor of GC proliferation. Mass-spectrometry-based selectivity profiling and subsequent knockdown experiments identified members of the SRC family of kinases including SRC, FRK, LYN and YES, as well as other kinases such as DDR1, ABL2, SIK2, RIPK2, EPHA2, and EPHB2 as dasatinib targets. The expression levels of the identified kinases were investigated on RNA and protein level in 200 classified tumor samples from patients, who had undergone gastrectomy, but had received no treatment. Levels of FRK, DDR1 and SRC expression on both mRNA and protein level were significantly higher in metastatic patient samples regardless of the tumor stage, while expression levels of SIK2 correlated with tumor size. Collectively, our data suggest dasatinib for treatment of GC based on its unique property, inhibiting a small number of key kinases (SRC, FRK, DDR1 and SIK2), highly expressed in GC patients.

Mebendazole induces apoptosis via C-MYC inactivation in malignant ascites cell line (AGP01)

The objective of study was to examine the role of MBZ on malignant ascites cells and the involvement of C-MYC. Comet assay was used to assess the genotoxic effects of MBZ in AGP01 cells and human lymphocytes; differential staining by ethidium bromide and acridine orange, caspase 3/7 and flow cytometry assay was done to access the mechanisms of apoptosis and cell cycle analysis of MBZ in AGP01 cells. C-MYC amplification, C-MYC mRNA and C-MYC protein expression were evaluated by FISH, RT-qPCR and Western blotting, respectively. In addition, cytotoxicity of MBZ was evaluated in AGP01 and AGP01 shRNA MYC by MTT. MBZ significantly increased the damage index and no produced in human lymphocytes. MBZ caused remarkable cell cycle arrest in G0/G1 and G2/M phases at 0.5μM and 1.0 μM, respectively and induced significantly apoptosis in higher concentrations. Additionally, MBZ (0.5 μM and 1.0 μM) increased caspase 3 and 7 activities. MBZ decreased signals, C-MYC mRNA and C-MYC protein expression in AGP01 cells. MBZ induced lower cell viability in AGP01 cells compared AGP01 shRNA MYC in the same concentration. Therefore, our results show the evidence of C-MYC gene as one of the pathways by which MBZ induces cell death in gastric cancer cells.

Serum and tissue proteomic signatures of patients with hepatocellular carcinoma using 2‑D gel electrophoresis

Hepatocellular carcinoma (HCC) accounts for ~85% of primary liver cancer cases and is a leading cause of mortality worldwide. Effective early diagnosis is difficult for HCC; however, effective biomarkers may be beneficial for diagnosis. In the current study, serum samples, and HCC and adjacent tissue samples were obtained from patients with HCC for the detection of biomarkers using 2-D gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight (TOF)/TOF mass spectrometry. The crude serum samples did not need to be prepared for removal of high abundance proteins. The mRNA expression levels of HCC-associated proteins were detected in tissues using reverse transcription-quantitative PCR. Statistical analysis and database matching were used to identify the differentially expressed proteins detected in the serum and tissue groups. Immunohistochemistry (IHC) was performed to detect the expression of significant proteins in HCC and adjacent tissues. The results revealed ~800 protein spots on a 2-DE gel that were detected in serum samples, and 1,200 spots were identified in the tissue samples. The protein and mRNA expression levels of oxysterol binding protein-like 11 (OSBPL11) in HCC serum and tissue samples were consistent. Pathway analysis demonstrated that members of the apolipoprotein family, particularly apolipoprotein E (APOE), and RAS family members were closely associated in HCC, either directly or via ferratin heavy polypeptide 1. IHC results demonstrated that the APOE protein serves an important role in liver cancer development. The lysis buffer used in the current study was effective for serum protein separation in 2-DE sample preparation. In addition, the present study revealed that downregulated OSBPL11 may be a potential indicator for HCC, and the apolipoprotein family, particularly APOE, and the RAS family may cooperatively serve an important role.

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.

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.

HPV positive, wild type TP53, and p16 overexpression correlate with the absence of residual tumors after chemoradiotherapy in anal squamous cell carcinoma

Background

Anal residual tumors are consensually identified within six months of chemoradiotherapy and represent a persistent lesion that may have prognostic value for overall survival. The aim of this study was to evaluate the association of HPV and HIV status, p16 expression level and TP53 mutations with the absence of residual tumors (local response) in Squamous Cell Carcinoma (SCC) of the anal canal after chemoradiotherapy.

Methods

We performed a study on 78 patients with SCC of the anal canal who submitted to chemoradiotherapy and were followed for a six-month period to identify the absence or presence of residual tumors. HPV DNA was identified by polymerase chain reaction and direct sequencing, HIV RNA was detected by TaqMan amplification, p16 expression was detected by western blotting, and the mutational analysis of TP53 was performed by direct sequencing; additionally, samples carrying mutations underwent fluorescent in sit hybridization. The evaluation of the tumor response to treatment was conducted six months after the conclusion of chemoradiotherapy. The following classifications were used to evaluate the outcomes: a) no response (presence of residual tumor) and b) complete response (absence of residual tumor).

Results

The significant variables associated with the absence of residual tumors were HPV positive, p16 overexpressed, wild-type TP53, female gender, and stages I and II. Only the presence of HPV was independently correlated with the clinical response; this variable increased the chances of a response within six months by 31-fold.

Conclusions

The presence of HPV in tumor cells was correlated with the absence of a residual tumor. This correlation is valuable and can direct future therapeutic approaches in the anal canal.

YWHAE silencing induces cell proliferation, invasion and migration through the up-regulation of CDC25B and MYC in gastric cancer cells: new insights about YWHAE role in the tumor development and metastasis process

We previously observed reduced YWHAE (14-3-3ε) protein expression in a small set of gastric cancer samples. YWHAE may act as a negative regulator of the cyclin CDC25B, which is a transcriptional target of MYC oncogene. The understanding of YWHAE role and its targets is important for the better knowledge of gastric carcinogenesis. Thus, we aimed to evaluate the relationship among YWHAE, CDC25B, and MYC in vitro and in vivo. For this, we analyzed the YWHAE, CDC25B, and MYC expression in YWHA-silenced, CDC25B-silenced, and MYC-silenced gastric cancer cell lines, as well as in gastric cancer and non-neoplastic gastric samples. In gastric cancer cell lines, YWHAE was able to inhibit the cell proliferation, invasion and migration through the reduction of MYC and CDC25B expression. Conversely, MYC induced the cell proliferation, invasion and migration through the induction of CDC25B and the reduction of YWHAE. Most of the tumors presented reduced YWHAE and increased CDC25B expression, which seems to be important for tumor development. Increased MYC expression was a common finding in gastric cancer and has a role in poor prognosis. In the tumor initiation, the opposite role of YWHAE and CDC25B in gastric carcinogenesis seems to be independent of MYC expression. However, the inversely correlation between YWHAE and MYC expression seems to be important for gastric cancer cells invasion and migration. The interaction between YWHAE and MYC and the activation of the pathways related to this interaction play a role in the metastasis process.

14-3-3ε is a nuclear matrix protein, and its altered expression and localization are associated with curcumin-induced apoptosis of MG-63 cells

The 14-3-3 protein family may regulates protein interaction, transportation and cellular localization. The regulatory role of 14-3-3ε is influenced by its altered localization. In the present study, human osteosarcoma MG-63 cells were treated with curcumin to induce apoptosis. Subsequently, the altered expression and localization of 14-3-3ε and its co-localization with other apoptosis-associated proteins during apoptosis was investigated. Analysis of nuclear matrix proteins (NMPs), using two-dimensional gel electrophoresis with matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry, revealed that 14-3-3ε existed on the nuclear matrix of MG-63 cells, and its expression was decreased compared with that in control cells following curcumin treatment. In addition, western blot analysis validated that the expression level of 14-3-3ε was downregulated during curcumin-induced apoptosis of MG-63 cells compared with that in control cells. Using immunofluorescence labeling, it was observed that 14-3-3ε was located on the nuclear matrix of MG-63 cells and the distribution of 14-3-3ε on the nuclear matrix was decreased following treatment with curcumin, compared with that in control cells. Double immunofluorescence staining and laser-scanning confocal microscopy demonstrated that 14-3-3ε was co-localized with B-cell lymphoma-2 (Bcl-2), Bcl-2-associated-X protein, p53 and c-FOS transcription factor in MG-63 cells. Furthermore, following treatment with curcumin, these co-localization regions were decreased. The results of the present study revealed that 14-3-3ε is an NMP in MG-63 cells, and its altered expression and co-localization with apoptosis-associated proteins indicated an important function of 14-3-3ε in apoptosis of MG-63 cells. Additional studies are required to investigate the results of the present study.

Comparing intestinal versus diffuse gastric cancer using a PEFF-oriented proteomic pipeline

Gastric cancer is the fifth most common malignant neoplasia and the third leading cause of cancer death worldwide. Mac-Cormick et al. recently showed the importance of considering the anatomical region of the tumor in proteomic gastric cancer studies; more differences were found between distinct anatomical regions than when comparing healthy versus diseased tissue. Thus, failing to consider the anatomical region could lead to differential proteins that are not disease specific. With this as motivation, we compared the proteomic profiles of intestinal and diffuse adenocarcinoma from the same anatomical region, the corpus. To achieve this, we used isobaric labeling (iTRAQ) of peptides, a 10-step HILIC fractionation, and reversed-phase nano-chromatography coupled online with a Q-Exactive Plus mass spectrometer. We updated PatternLab to take advantage of the new Comet-PEFF search engine that enables identifying post-translational modifications and mutations included in neXtProt's PSI Extended FASTA Format (PEFF) metadata. Our pipeline then uses a text-mining tool that automatically extracts PubMed IDs from the proteomic result metadata and drills down keywords from manuscripts related with the biological processes at hand. Our results disclose important proteins such as apolipoprotein B-100, S100 and 14-3-3 proteins, among many others, highlighting the different pathways enriched by each cancer type.

SIGNIFICANCE

Gastric cancer is a heterogeneous and multifactorial disease responsible for a significant number of deaths every year. Despite the constant improvement of surgical techniques and multimodal treatments, survival rates are low, mostly due to limited diagnostic techniques and late symptoms. Intestinal and diffuse types of gastric cancer have distinct clinical and pathological characteristics; yet little is known about the molecular mechanisms regulating these two types of gastric tumors. Here we compared the proteomic profile of diffuse and intestinal types of gastric cancer from the same anatomical location, the corpus, from four male patients. This methodological design aimed to eliminate proteomic variations resulting from comparison of tumors from distinct anatomical regions. Our PEFF-tailored proteomic pipeline significantly increased the identifications as when compared to previous versions of PatternLab.

Mebendazole, an antiparasitic drug, inhibits drug transporters expression in preclinical model of gastric peritoneal carcinomatosis

The present study aimed to investigate whether MBZ down-regulates drug transporter expression (ABCB1, ABCC1, SLC47A1). mRNA expression level of ABCB1, ABCC1 and SLC47A1 was evaluated by qPCR and protein expression levels MDR-1 was performed by western blotting in malignant ascites cells (AGP-01) treated with MBZ for 24h. The mRNA expression level of ABCB1 and ABCC1 significantly decreased at a 1.0μM of MBZ compared to negative control, while SLC47A1 extremely decreased at all tested concentrations of MBZ. Protein expression levels MDR-1 significantly decreased at a 1.0μM of MBZ compared to negative control. Therefore, our results showed MBZ may play an important role in inhibiting MDR gene expression in malignant ascites cells.

Progress and prospects for the discovery of biomarkers for gastric cancer: a focus on proteomics

INTRODUCTION

Patient outcomes from gastric cancer vary due to the complexity of stomach carcinogenesis. Recent research using proteomic technologies has targeted components of all of these systems in order to develop biomarkers to aid the early diagnosis of gastric cancer and to assist in prognostic stratification. Areas covered: This review is comprised of evidence obtained from literature searches from PubMed. It covers the evidence of diagnostic, prognostic, and predictive biomarkers for gastric cancer using proteomic technologies, and provides up-to-date references. Expert commentary: The proteomic technologies have not only enabled the screening of a large number of samples, but also enabled the identification of diagnostic, prognostic and predictive biomarkers for gastric cancer. While major challenges still remain, to date, proteomic studies in gastric cancer have provided a wealth of information in revealing proteome alterations associated with the disease.

Proteomic analysis of selective cytotoxic anticancer properties of flavonoids isolated from Citrus platymamma on A549 human lung cancer cells

Citrus platymamma Hort. ex Tanaka (Byungkyul in Korean) has been used in Korean folk medicine for the treatment of inflammatory disorders and cancer. However, the molecular mechanism underlying the anticancer properties of flavonoids isolated from C. platymamma (FCP) remains to be elucidated. Therefore, the present study attempted to identify the key proteins, which may be important in the anticancer effects of FCP on A549 cells using a proteomic approach. FCP showed a potent cytotoxic effect on the A549 human lung cancer cells, however, it had no effect on WI‑38 human fetal lung fibroblasts at the same concentrations. Furthermore, 15 differentially expressed protein spots (spot intensities ≥2‑fold change; P<0.05) were obtained from comparative proteome analysis of two‑dimensional gel electrophoresis maps of the control (untreated) and FCP‑treated A549 cells. Finally, eight differentially expressed proteins, one of which was upregulated and seven of which were downregulated, were successfully identified using matrix‑assisted laser desorption/ionization time‑of‑flight/time‑of‑flight tandem mass spectrometry and peptide mass fingerprinting analysis. Specifically, proteins involved in signal transduction were significantly downregulated, including annexin A1 (ANXA1) and ANXA4, whereas 14‑3‑3ε was upregulated. Cytoskeletal proteins, including cofilin‑1 (CFL1), cytokeratin 8 (KRT8) and KRT79, and molecular chaperones/heat shock proteins, including endoplasmin, were downregulated. Proteins involved in protein metabolism, namely elongation factor Ts were also downregulated. Consistent with results of the proteome analysis, the immunoblotting results showed that 14‑3‑3ε was upregulated, whereas CFL1, ANXA4 and KRT8 were downregulated in the FCP‑treated A549 cells. The majority of the proteins were involved in tumor growth, cell cycle, apoptosis, migration and signal transduction. These findings provide novel insights into the molecular mechanisms underlying FCP-induced anticancer effects on A549 cells.

What gastric cancer proteomic studies show about gastric carcinogenesis?

Gastric cancer is a complex, heterogeneous, and multistep disease. Over the past decades, several studies have aimed to determine the molecular factors that lead to gastric cancer development and progression. After completing the human genome sequencing, proteomic technologies have presented rapid progress. Differently from the relative static state of genome, the cell proteome is dynamic and changes in pathologic conditions. Proteomic approaches have been used to determine proteome profiles and identify differentially expressed proteins between groups of samples, such as neoplastic and nonneoplastic samples or between samples of different cancer subtypes or stages. Therefore, proteomic technologies are a useful tool toward improving the knowledge of gastric cancer molecular pathogenesis and the understanding of tumor heterogeneity. This review aimed to summarize the proteins or protein families that are frequently identified by using high-throughput screening methods and which thus may have a key role in gastric carcinogenesis. The increased knowledge of gastric carcinogenesis will clearly help in the development of new anticancer treatments. Although the studies are still in their infancy, the reviewed proteins may be useful for gastric cancer diagnosis, prognosis, and patient management.

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.

RNA interference based silencing of YWHAE suppresses proliferation of colon cancer cells

AIM: To investigate the correlation between YWHAE overexpression and colon cancer proliferation.

METHODS: We conducted immunohistochemical analysis of YWHAE overexpression in 87 colon carcinoma specimens and analyzed its relationship with clinical and pathological parameters. YWHAE expression was then silenced by RNA interference in colon cancer cell line HT-29, and the expression levels of YWHAE protein and mRNA were assayed by Western blot and reverse transcription-PCR, respectively. Cell proliferation was evaluated using the MTT method, and cell cycle and apoptosis were examined by flow cytometry. Colony formation assay was used to determine the growth properties of transfected cells.

RESULTS: YWHAE was highly expressed in colon carcinoma, and negative or low expression was observed in colon mucosal epithelial cells (P < 0.001). The expression intensity of YWHAE was significantly higher in colon cancer with metastasis than in colon cancer without metastasis (P < 0.05). The proliferation and colony formation ability of colon cancer cells were significantly reduced after silencing of YWHAE expression. Additional results showed that reduced YWHAE expression in colon cells led to an increased cell apoptosis rate and cell cycle G₁ arrest.

CONCLUSION: YWHAE is overexpressed in colon cancer, which may be related to metastasis in colon carcinoma. Silencing of YWHAE inhibited the proliferation ability of colon cancer cells, which may be associated with cell apoptosis and cell cycle arrest.

Deregulated Expression of SRC, LYN and CKB Kinases by DNA Methylation and Its Potential Role in Gastric Cancer Invasiveness and Metastasis

Kinases are downstream modulators and effectors of several cellular signaling cascades and play key roles in the development of neoplastic disease. In this study, we aimed to evaluate SRC, LYN and CKB protein and mRNA expression, as well as their promoter methylation, in gastric cancer. We found elevated expression of SRC and LYN kinase mRNA and protein but decreased levels of CKB kinase, alterations that may have a role in the invasiveness and metastasis of gastric tumors. Expression of the three studied kinases was also associated with MYC oncogene expression, a possible biomarker for gastric cancer. To understand the mechanisms that regulate the expression of these genes, we evaluated the DNA promoter methylation of the three kinases. We found that reduced SRC and LYN methylation and increased CKB methylation was associated with gastric cancer. The reduced SRC and LYN methylation was associated with increased levels of mRNA and protein expression, suggesting that DNA methylation is involved in regulating the expression of these kinases. Conversely, reduced CKB methylation was observed in samples with reduced mRNA and protein expression, suggesting CKB expression was found to be only partly regulated by DNA methylation. Additionally, we found that alterations in the DNA methylation pattern of the three studied kinases were also associated with the gastric cancer onset, advanced gastric cancer, deeper tumor invasion and the presence of metastasis. Therefore, SRC, LYN and CKB expression or DNA methylation could be useful markers for predicting tumor progression and targeting in anti-cancer strategies.

14-3-3ε functions as an oncogene in SGC7901 gastric cancer cells through involvement of cyclin E and p27kip1

Investigation into the highly conserved 14‑3‑3ε protein has become increasingly important in cell biology due to its involvement in cell survival signaling, cell cycle control and apoptosis. The 14‑3‑3ε protein has been found to exert an impact on the development of various tumor types. However, the functional role and the possible mechanism of 14‑3‑3ε in gastric cancer remains to be elucidated. A previous study by our group indicated a negative correlation between 14‑3‑3ε expression levels and gastric cancer tissue differentiation and a positive correlation between 14‑3‑3ε expression levels and tumor infiltration, lymph node metastasis and tumor, nodes and metastasis staging. In the present study, 14‑3‑3ε suppression in the SGC7901 gastric cancer cell line was demonstrated to inhibit cell proliferation in vitro and tumor growth in vivo and the cell cycle‑associated proteins cyclin E and p27kip1 may have contributed to this antitumor effect. The present study showed for the first time that reducing the expression of 14‑3‑3ε may inhibit the proliferation and progression of gastric cancer and inhibition of this protein may provide a potential strategy for gastric cancer therapy in the future.

Small molecules modulation of 14-3-3 protein-protein interactions

14-3-3 is a family of highly conserved regulatory proteins which is attracting a significant interest due to its potential role as target for pharmacological intervention against cancer and neurodegenerative disorders. Although modulating protein-protein interactions (PPI) is still conceived as a challenging task in drug discovery, in past few years peptide inhibitors and small molecular modulators of 14-3-3 PPI have been described. Here we examine structural and biological features of 14-3-3 and propose an overview on techniques used for discovering small molecular inhibitors and stabilizers of 14-3-3 PPI.

Deregulated expression of annexin-A2 and galectin-3 is associated with metastasis in gastric cancer patients

Gastric cancer (GC) is the second highest cause of cancer mortality worldwide. However, nowadays, most of the studies aiming to understand the gastric carcinogenesis analyzed tumors of individuals from Asian population and, thus, may not reflect the distinct biological and clinical behaviors among GC processes. Since several membrane proteins have been implicated in carcinogenesis, we aimed to evaluate ANXA2 and GAL3 role in gastric tumors and GC cell lines of individuals from northern Brazil. The cellular localization of ANXA2 and GAL3 in the GC cell lines was evaluated by immunofluorescence. Gene expression was evaluated by real-time reverse-transcription PCR and protein expression by Western blot in gastric adenocarcinomas and non-neoplastic gastric samples, as well as in GC cell lines. ANXA2 and GAL3 were presented as dots in the plasma membrane and cytoplasm in ACP02 and ACP03 cell lines. ANXA2 mRNA expression was up-regulated in 32.14 % of gastric tumors compared to non-neoplastic tissues. ANXA2 up-regulation was associated with the metastasis process in vivo and with cell line invasive behavior. GAL3 protein expression was at least 1.5-fold reduced in 50 % of gastric tumors. The reduced GAL3 expression was associated with the presence of distant metastasis and with a higher invasive phenotype in vitro. Our study shows that ANXA2 and GAL3 deregulated expression was associated with an invasive phenotype in GC cell lines and may contribute to metastasis in GC patients. Therefore, these proteins may have potential prognostic relevance for GC of individuals from northern Brazil.

Overexpression of nuclear apoptosis-inducing factor 1 altered the proteomic profile of human gastric cancer cell MKN45 and induced cell cycle arrest at G1/S phase

Nuclear apoptosis-inducing factor 1 (NAIF1) was previously reported to induce apoptosis. Moreover, the expression of NAIF1 was significantly down-regulated in human gastric cancer tissues compared to adjacent normal tissues. However, the mechanism by which the NAIF1 gene induces apoptosis is not fully understood. Our results show that NAIF1 was minimally expressed in all the tested gastric cancer cell lines. Our data also demonstrates that NAIF1 is localized in the nuclei of cells as detected by monitoring the green fluorescence of NAIF1-GFP fusion protein using fluorescent confocal microscopy. Next, a comparative proteomic approach was used to identify the differential expression of proteins between gastric cancer cell lines MKN45/NAIF1 (−) and MKN45/NAIF1 (+). We found five proteins (proteasome 26S subunit 2, proteasome 26S subunit 13, NADH dehydrogenase Fe-S protein 1, chaperonin containing TCP1 subunit 3 and thioredoxin reductase 1) that were up-regulated and three proteins (ribonuclease inhibitor 1, 14-3-3 protein epsilon isoform and apolipoprotein A-I binding protein) that were down-regulated in the MKN45 cells overexpressing NAIF1. We also discovered that NAIF1 could induce cell cycle arrest at G1/S phase by altering the expression of cell cycle proteins cyclinD1, cdc2 and p21. The differentially expressed proteins identified here are related to various cellular programs involving cell cycle, apoptosis, and signal transduction regulation and suggest that NAIF1 may be a tumor suppressor in gastric cancer. Our research provides evidence that elucidates the role of how NAIF1 functions in gastric cancer.

Proteomic analysis of cellular response induced by multi-walled carbon nanotubes exposure in A549 cells

The wide application of multi-walled carbon nanotubes (MWCNT) has raised serious concerns about their safety on human health and the environment. However, the potential harmful effects of MWCNT remain unclear and contradictory. To clarify the potentially toxic effects of MWCNT and to elucidate the associated underlying mechanisms, the effects of MWCNT on human lung adenocarcinoma A549 cells were examined at both the cellular and the protein level. Cytotoxicity and genotoxicity were examined, followed by a proteomic analysis (2-DE coupled with LC-MS/MS) of the cellular response to MWCNT. Our results demonstrate that MWCNT induces cytotoxicity in A549 cells only at relatively high concentrations and longer exposure time. Within a relatively low dosage range (30 µg/ml) and short time period (24 h), MWCNT treatment does not induce significant cytotoxicity, cell cycle changes, apoptosis, or DNA damage. However, at these low doses and times, MWCNT treatment causes significant changes in protein expression. A total of 106 proteins show altered expression at various time points and dosages, and of these, 52 proteins were further identified by MS. Identified proteins are involved in several cellular processes including proliferation, stress, and cellular skeleton organization. In particular, MWCNT treatment causes increases in actin expression. This increase has the potential to contribute to increased migration capacity and may be mediated by reactive oxygen species (ROS).

A comparative proteomic study identified calreticulin and prohibitin up-regulated in adrenocortical carcinomas

Background

Identifying novel tumor biomarkers to develop more effective diagnostic and therapeutic strategies for patients with ACC is urgently needed. The aim of the study was to compare the proteomic profiles between adrenocortical carcinomas (ACC) and normal adrenocortical tissues in order to identify novel potential biomarkers for ACC.

Methods

The protein samples from 12 ACC tissues and their paired adjacent normal adrenocortical tissues were profiled with two-dimensional electrophoresis; and differentially expressed proteins were identified by mass spectrometry. Expression patterns of three differently expressed proteins calreticulin, prohibitin and HSP60 in ACC, adrenocortical adenomas (ACA) and normal adrenocortical tissues were further validated by immunohistochemistry.

Results

In our proteomic study, we identified 20 up-regulated and 9 down-regulated proteins in ACC tissues compared with paired normal controls. Most of the up-regulated proteins were focused in protein binding and oxidoreductase activity in Gene Ontology (GO) molecular function classification. By immunohistochemistry, two biomarkers calreticulin and prohibitin were validated to be overexpressed in ACC compared with adrenocortical adenomas (ACA) and normal tissues, but also calreticulin overexpression was significantly associated with tumor stages of ACC.

Conclusion

For the first time, calreticulin and prohibitin were identified to be novel candidate biomarkers for ACC, and their roles during ACC carcinogenesis and clinical significance deserves further investigation.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1897372598927465

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.

Differential proteomic analysis of noncardia gastric cancer from individuals of northern Brazil

Gastric cancer is the second leading cause of cancer-related death worldwide. The identification of new cancer biomarkers is necessary to reduce the mortality rates through the development of new screening assays and early diagnosis, as well as new target therapies. In this study, we performed a proteomic analysis of noncardia gastric neoplasias of individuals from Northern Brazil. The proteins were analyzed by two-dimensional electrophoresis and mass spectrometry. For the identification of differentially expressed proteins, we used statistical tests with bootstrapping resampling to control the type I error in the multiple comparison analyses. We identified 111 proteins involved in gastric carcinogenesis. The computational analysis revealed several proteins involved in the energy production processes and reinforced the Warburg effect in gastric cancer. ENO1 and HSPB1 expression were further evaluated. ENO1 was selected due to its role in aerobic glycolysis that may contribute to the Warburg effect. Although we observed two up-regulated spots of ENO1 in the proteomic analysis, the mean expression of ENO1 was reduced in gastric tumors by western blot. However, mean ENO1 expression seems to increase in more invasive tumors. This lack of correlation between proteomic and western blot analyses may be due to the presence of other ENO1 spots that present a slightly reduced expression, but with a high impact in the mean protein expression. In neoplasias, HSPB1 is induced by cellular stress to protect cells against apoptosis. In the present study, HSPB1 presented an elevated protein and mRNA expression in a subset of gastric cancer samples. However, no association was observed between HSPB1 expression and clinicopathological characteristics. Here, we identified several possible biomarkers of gastric cancer in individuals from Northern Brazil. These biomarkers may be useful for the assessment of prognosis and stratification for therapy if validated in larger clinical study sets.