Characterization of a Putative Ovarian Oncogene, Elongation Factor 1α, Isolated by Panning a Synthetic Phage Display Single-Chain Variable Fragment Library with Cultured Human Ovarian Cancer Cells

The eEF1A protein in cancer: Clinical significance, oncogenic mechanisms, and targeted therapeutic strategies

Eukaryotic elongation factor 1A (eEF1A) is among the most abundant proteins in eukaryotic cells. Evolutionarily conserved across species, eEF1A is in charge of translation elongation for protein biosynthesis as well as a plethora of non-translational moonlighting functions for cellular homeostasis. In malignant cells, however, eEF1A becomes a pleiotropic driver of cancer progression via a broad diversity of pathways, which are not limited to hyperactive translational output. In the past decades, mounting studies have demonstrated the causal link between eEF1A and carcinogenesis, gaining deeper insights into its multifaceted mechanisms and corroborating its value as a prognostic marker in various cancers. On the other hand, an increasing number of natural and synthetic compounds were discovered as anticancer eEF1A-targeting inhibitors. Among them, plitidepsin was approved for the treatment of multiple myeloma whereas metarrestin was currently under clinical development. Despite significant achievements in these two interrelated fields, hitherto there lacks a systematic examination of the eEF1A protein in the context of cancer research. Therefore, the present work aims to delineate its clinical implications, molecular oncogenic mechanisms, and targeted therapeutic strategies as reflected in the ever expanding body of literature, so as to deepen mechanistic understanding of eEF1A-involved tumorigenesis and inspire the development of eEF1A-targeted chemotherapeutics and biologics.

DIA-based proteomics analysis of serum-derived exosomal proteins as potential candidate biomarkers for intrahepatic cholestasis in pregnancy

BACKGROUND

Data-independent acquisition (DIA) is one of the most powerful and reproducible proteomic technologies for large-scale digital qualitative and quantitative research. The aim of this study was to use proteomic methodologies for the identification of biomarkers that are over or underexpressed in women with intrahepatic cholestasis of pregnancy (ICP) compared with controls and discover a potential biomarker panel for ICP detection.

METHODS

The participants included 11 ICP patients and 11 healthy pregnant women as controls. The clinical characteristic data and the laboratory biochemical data were collected at the time of recruitment. Then, a data-independent acquisition (DIA)-based proteomics approach was used to identify differentially expressed proteins (DEPs) in serum exosomes between ICP patients and controls. Finally, bioinformatics analysis was used to identify the relevant processes in which these DEPs were involved.

RESULTS

The proteomics results showed that there were 162 DEPs in serum exosomes between pregnant women with ICP and healthy pregnant women, of which 106 were upregulated and 56 were downregulated in ICP. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the identified proteins were functionally related to specific cell processes including apoptosis, lipid metabolism, immune response and cell proliferation, and metabolic disorders, suggesting that these may be primary causative factors in ICP pathogenesis. Meanwhile, complement and coagulation cascades may be closely related to the development of ICP. Receiver operating characteristic curve (ROC) analysis showed that the area under the curve values of Elongation factor 1-alpha 1, Beta-2-glycoprotein I, Zinc finger protein 238, CP protein and Ficolin-3 were all approximately 0.9, indicating the promising diagnostic value of these proteins.

CONCLUSIONS

This preliminary work provides a better understanding of the proteomic alterations in the serum exosomes of pregnant women with ICP.

Initiation and elongation factor co-expression correlates with recurrence and survival in epithelial ovarian cancer

High grade epithelial ovarian cancer (EOC) represents a diagnostic and therapeutic challenge due to its aggressive features and short recurrence free survival (RFS) after primary treatment. Novel targets to inform our understanding of the EOC carcinogenesis in the translational machinery can provide us with independent prognostic markers and provide drugable targets. We have identified candidate eukaryotic initiation factors (eIF) and eukaryotic elongation factors (eEF) in the translational machinery for differential expression in EOC through in-silico analysis. We present the analysis of 150 ovarian tissue microarray (TMA) samples on the expression of the translational markers eIF2α, eIF2G, eIF5 (eIF5A and eIF5B), eIF6 and eEF1A1. All translational markers were differentially expressed among non-neoplastic ovarian samples and tumour samples (borderline tumours and EOC). In EOC, expression of eIF5A was found to be significantly correlated with recurrence free survival (RFS) and expression of eIF2G and eEF1A1 with overall survival (OS). Expression correlation among factor subunits showed that the correlation of eEF1A1, eIF2G, EIF2α and eIF5A were significantly interconnected. eIF5A was also correlated with eIF5B and eIF6. Our study demonstrates that EOCs have different translational profile compared to benign ovarian tissue and that eIF5A is a central dysregulated factor of the translation machinery.

---Successful Application of Whole Cell Panning for Isolation of Phage Antibody Fragments Specific to Differentiated Gastric Cancer Cells

Purpose: Generation of antibodies which potentially discriminate between malignant and healthy cells is an important prerequisite for early diagnosis and treatment of gastric cancer (GC). Comparative analysis of cell surface protein landscape will provide an experimental basis for biomarker discovery, which is essential for targeted molecular therapies. This study aimed to isolate phage-displayed antibody fragments recognizing cell surface proteins, which were differently expressed between two closely related GC cell lines, namely AGS and MKN-45.

Methods: We selected and screened a semisynthetic phage-scFv library on AGS, MKN-45, and NIH-3T3 cell lines by utilizing a tailored selection scheme that was designed to isolate phagescFvs that not only recognize the differentiated AGS cells but also distinguish them from NIH3T3 fibroblasts and the poorly differentiated MKN-45 cells.

Results: After four rounds of subtractive whole cell panning, 14 unique clones were identified by ELISA screening and nucleotide sequencing. For further characterization, we focused on four phage-scFvs with strong signals in screening, and their specificity was confirmed by cell-based ELISA. Furthermore, the selected phage-scFvs were able to specifically stain AGS cells with 38.74% (H1), 11.04% (D11), 76.93% (G11), and 69.03% (D1) in flow cytometry analysis which supported the ability of these phage scFvs in distinguishing AGS from MKN-45 and NIH-3T3 cells.

Conclusion: Combined with other proteomic techniques, these phage-scFvs can be applied to membrane proteome analysis and, subsequently, identification of novel tumor-related antigens mediating proliferation and differentiation of cells. Furthermore, such antibody fragments can be exploited for diagnostic purposes as well as targeted drug delivery of GC.

[Directed evolution in drug and antibody development : From the Nobel Prize to broad clinical application]

Combinatorial procedures have become established in recent years as alternatives to rational design in drug research, particularly when no structural information is available. This article presents the principle that was originally developed by three scientists and was honored with the Nobel Prize for Chemistry in 2018. Furthermore, the application in the field of monclonal antibodies is discussed.

Nanoscale Extracellular Vesicle Analysis in Alzheimer's Disease Diagnosis and Therapy

Diagnostic assays that leverage bloodborne neuron-derived (neuronal) nanoscale extracellular vesicles (nsEVs) as “windows into the brain” can predict incidence of Alzheimer's Disease (AD) many years prior to onset. Beyond diagnostics, bloodborne neuronal nsEVs analysis may have substantial translational impact by revealing mechanisms of AD pathology; such knowledge could enlighten new drug targets and lead to new therapeutic approaches. The potential to establish three-dimensional nsEV analysis methods that characterize highly purified bloodborne nsEV populations in method of enrichment, cell type origin, and protein or RNA abundance dimensions could bring this promise to bear by yielding nsEV “omics” datasets that uncover new AD biomarkers and enable AD therapeutic development. In this review we provide a survey of both the current status of and new developments on the horizon in the field of neuronal nsEV analysis. This survey is supplemented by a discussion of the potential to translate such neuronal nsEV analyses to AD clinical diagnostic applications and drug development.

Sam68 promotes cellular proliferation and predicts poor prognosis in esophageal squamous cell carcinoma

Sam68 (Src-associated in mitosis of 68 kD) is a KH domain RNA-binding protein. The expression of Sam68 was correlated with kinds of tumors. Yet, the expression mechanisms and physiological significance of Sam68 in ESCC remains unclear. In this study, we clarified a potential role of Sam68 in the treatment of ESCC. Western blot and immunohistochemistry (IHC) analysis revealed that the protein level of Sam68 was higher in ESCC tumor tissues and cell lines. In addition, IHC stain revealed that Sam68 was positively correlated with clinical pathologic variables such as tumor grade and tumor invasion. In addition, Sam68 could be an independent prognostic indicator for patients' overall survival. In vitro studies such as starvation and refeeding assay along with Sam68-shRNA transfection assay demonstrated that Sam68 expression promoted proliferation of ESCC cells. And Sam68 downregulation caused decreased rate of cell growth and colony formation. Reasons are associated with growth arrest of cell cycle at G1/S phase. Moreover, our results clarified that Sam68 could promote ESCC cell proliferation via the activation of Akt/GSK-3β pathway. This research indicated that Sam68 might accelerate the cell cycle progression and be considered as a new therapy target in ESCC.

Utility of SAM68 in the progression and prognosis for bladder cancer

Background

Muscle invasive bladder cancer (MIBC) is often lethal and non-MIBC (NMIBC) can recur and progress, yet prognostic markers are currently inadequate. SAM68, a member of RNA-binding proteins, has been reported to contribute to progression of other cancers. The aim of this study is to investigate the potential utility of SAM68 in the progression and prognosis of bladder cancer.

Methods

Quantitative PCR and immunohistochemistry were utilized to examine the expression of SAM68 in ten pairs of MIBC and adjacent normal bladder urothelium, and eight pairs of MIBC and non-MIBC (NMIBC) tissues from the same patient. Moreover, SAM68 protein expression level and localization were examined by immunohistochemistry in 129 clinicopathologically characterized MIBC samples. Prognostic associations were determined by multivariable analysis incorporating standard prognostic factors.

Results

SAM68 expression was elevated in MIBC tissues compared with adjacent normal bladder urothelium, and was increased at both transcriptional and translational levels in MIBC tissues compared with NMIBC tissues of the same patient. For MIBC, high expression and nucleus-cytoplasm co-expression of SAM68 were associated with higher T-stage, higher N-stage and worse recurrence-free survival. Five-year recurrence-free survival was 80% and 52.9% for MIBC patients with low and high SAM68 expression, respectively (p = 0.001). SAM68 nucleus-cytoplasm co-expression associated with worse 5-year recurrence-free survival rate (49.2%) than SAM68 expression confined to the nucleus (82.5%) or cytoplasm (75.5%) alone. On multivariable analysis SAM68 expression level, SAM68 nucleus-cytoplasm co-expression, T-stage, and N-stage were all independent prognostic factors for recurrence-free survival of MIBC patients.

Conclusions

SAM68 expression is increased in MIBC when compared to normal urothelium and NMIBC, and appears to be a potentially useful prognostic marker for MIBC.

Selection strategies for anticancer antibody discovery: searching off the beaten path

Antibody-based drugs represent one of the most successful and promising therapeutic approaches in oncology. Large combinatorial phage antibody libraries are available for the identification of therapeutic antibodies and various technologies exist for their further conversion into multivalent and multispecific formats optimized for the desired pharmacokinetics and the pathological context. However, there is no technology for antigen profiling of intact tumors to identify tumor markers targetable with antibodies. Such constraints have led to a relative paucity of tumor-associated antigens for antibody targeting in oncology. Here we review novel approaches aimed at the identification of antibody-targetable, accessible antigens in intact tumors. We hope that such advanced selection approaches will be useful in the development of next-generation antibody therapies for cancer.

Up-regulation of eEF1A2 promotes proliferation and inhibits apoptosis in prostate cancer

BACKGROUND

eEF1A2 is a protein translation factor involved in protein synthesis, which possesses important function roles in cancer development. This study aims at investigating the expression pattern of eEF1A2 in prostate cancer and its potential role in prostate cancer development.

METHODS

We examined the expression level of eEF1A2 in 30 pairs of prostate cancer tissues by using RT-PCR and immunohistochemical staining (IHC). Then we applied siRNA specifically targeting eEF1A2 to down-regulate its expression in DU-145 and PC-3 cells. Flow cytometer was used to explore apoptosis and Western-blot was used to detect the pathway proteins of apoptosis.

RESULTS

Our results showed that the expression level of eEF1A2 in prostate cancer tissues was significantly higher compared to their corresponding normal tissues. Reduction of eEF1A2 expression in DU-145 and PC-3 cells led to a dramatic inhibition of proliferation accompanied with enhanced apoptosis rate. Western blot revealed that apoptosis pathway proteins (caspase3, BAD, BAX, PUMA) were significantly up-regulated after suppression of eEF1A2. More importantly, the levels of eEF1A2 and caspase3 were inversely correlated in prostate cancer tissues.

CONCLUSION

Our data suggests that eEF1A2 plays an important role in prostate cancer development, especially in inhibiting apoptosis. So eEF1A2 might serve as a potential therapeutic target in prostate cancer.

Phage display biopanning identifies the translation initiation and elongation factors (IF1α-3 and eIF-3) as components of Hsp70-peptide complexes in breast tumour cells

The heat shock protein, HSP70, is over-expressed in many tumours and acts at the crossroads of key intracellular processes in its role as a molecular chaperone. HSP70 associates with a vast array of peptides, some of which are antigenic and can mount adaptive immune responses against the tumour from which they are derived. The pool of peptides associated with HSP70 represents a unique barcode of protein metabolism in tumour cells. With a view to identifying unique protein targets that may be developed as tumour biomarkers, we used purified HSP70 and its associated peptide pool (HSP70-peptide complexes, HSP70-PCs) from different human breast tumour cell lines as targets for phage display biopanning. Our results show that HSP70-PCs from each cell line interact with unique sets of peptides within the phage display library. One of the peptides, termed IST, enriched in the biopanning process, was used in a 'pull-down' assay to identify the original protein from which the HSP70-associated peptides may have been derived. The eukaryotic translation initiation factor 3 (eIF-3), a member of the elongation factor EF1α family, and the HSP GRP78, were pulled down by the IST peptide. All of these proteins are known to be up-regulated in cancer cells. Immunohistochemical staining of tumour tissue microarrays showed that the peptide co-localised with HSP70 in breast tumour tissue. The data indicate that the reservoir of peptides associated with HSP70 can act as a unique indicator of cellular protein activity and a novel source of potential tumour biomarkers.

Functional characterization of an scFv-Fc antibody that immunotherapeutically targets the common cancer cell surface proteoglycan CSPG4

Cell surface chondroitin sulfate proteoglycan 4 (CSPG4) is an attractive target for antibody-based cancer immunotherapy because of its role in tumor cell biology, its high expression on malignant cells including cancer-initiating cells, and its restricted distribution in normal tissues. The clinical use of CSPG4 has been hampered by the lack of a CSPG4-specific chimeric, humanized, or fully human monoclonal antibody. To overcome this limitation, we generated a CSPG4-specific fully human single-chain antibody termed scFv-FcC21 and characterized its specificity and antitumor activity. Viable CSPG4(+) melanoma cells were used in a screen of a human scFv phage display library that included CDR3 engineered to optimize antibody binding sites. The scFv antibody isolated was then recombinantly engineered with a human immunoglobulin G1 Fc region to construct the fully human antibody scFv-FcC21, which recognized tumors of neuroectodermal origin, various types of carcinomas, mesotheliomas, and sarcomas as well as myeloid leukemias. scFv-FcC21 inhibited in vitro growth and migration of tumor cells and in vivo growth of human tumor xenografts. These effects were mediated by inhibition of the activation of extracellular signal-regulated kinase and focal adhesion kinase signaling pathways that are critical for tumor cell growth and migration, respectively. Our findings define the CSPG4-specific fully human scFv-FcC21 antibody as a candidate therapeutic agent to target the many types of tumors that express CSPG4.

Sam68 up-regulation correlates with, and its down-regulation inhibits, proliferation and tumourigenicity of breast cancer cells

The biosynthesis and metabolism of RNA play important roles in regulating gene expression. On the other hand, it has been shown that RNA expression profiling is differentially distinct between cancer and normal cells, suggesting the possibility that aberrant regulation of RNA metabolism might be associated with the development and progression of cancer. In the current study, we found that Sam68, an RNA-binding protein that links cellular signalling to RNA processing, was markedly overexpressed in breast cancer cells and tissues. Immunohistochemical analysis showed that the expression and cytoplasmic localization of Sam68 significantly correlated with clinical characteristics of patients, including clinical stage, tumour-nodule-metastasis (TNM) classification, histological grade, and ER expression. Univariate and multivariate analyses showed that the expression level and cytoplasmic localization of Sam68 were identified as independent prognostic factors. Furthermore, we found that siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of breast cancer cells in vitro, through blocking the G1 to S phase transition. Moreover, we demonstrated that the anti-proliferative effect of silencing Sam68 on breast cancer cells was associated with up-regulation of cyclin-dependent kinase inhibitor p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors, and attenuation of Akt/GSK-3β signalling. Taken together, our results suggest that Sam68 might play an important role in promoting the proliferation and carcinogenesis of human breast cancer, and thereby might be a novel and useful prognostic marker and a potential target for human breast cancer treatment.

Rosiglitazone inhibits monocyte/macrophage adhesion through de novo adiponectin production in human monocytes

Rosiglitazone (RSG) has a variety of actions on both insulin sensitization and anti-atherogenic effects. The molecular effect of RSG on monocyte/macrophage function in terms of de novo synthesis of adiponectin is not fully understood. Here, we examined the regulation of adiponectin expression in human monocytes/macrophages by RSG and its function on monocyte adhesion during initiation of atherosclerosis. Adiponectin expression in monocytes and macrophages was studied by RT-PCR, quantitative real-time PCR, Western blot, and immunocytochemistry. Signal transduction and adhesion molecules were studied in order to describe the function of de novo synthesized adiponectin in monocyte adhesion. Adiponectin was expressed and upregulated during monocyte differentiation. The expression of adiponectin was enhanced, albeit at a much lesser degree, by a peroxisome proliferator-activated receptor gamma (PPAR gamma) agonist RSG, which was similar to what was found in adipocytes. Monocyte adhesion was remarkably reduced when the cells were treated with RSG for 12 h. This inhibitory effect of RSG was abolished by specific anti-adiponectin antibodies but not by non-immune immunoglobulin G in a serum-free condition. Adiponectin-induced suppression on monocyte adhesion was inhibited by a selective AMP-activated protein kinase (AMPK) inhibitor compound C. The reduced expression and/or function of adhesion molecule integrins may underlie the mechanism contributing to reduced monocyte adhesion upon AMPK activation. Our data suggest that the inhibitory effect of RSG on monocyte adhesion might be at least in part through de novo adiponectin expression and activation of an AMPK-dependent pathway, which might play an important role in atherogenesis.

Integrated proteomic analysis of human cancer cells and plasma from tumor bearing mice for ovarian cancer biomarker discovery

Background

The complexity of the human plasma proteome represents a substantial challenge for biomarker discovery. Proteomic analysis of genetically engineered mouse models of cancer and isolated cancer cells and cell lines provide alternative methods for identification of potential cancer markers that would be detectable in human blood using sensitive assays. The goal of this work is to evaluate the utility of an integrative strategy using these two approaches for biomarker discovery.

Methodology/Principal Findings

We investigated a strategy that combined quantitative plasma proteomics of an ovarian cancer mouse model with analysis of proteins secreted or shed by human ovarian cancer cells. Of 106 plasma proteins identified with increased levels in tumor bearing mice, 58 were also secreted or shed from ovarian cancer cells. The remainder consisted primarily of host-response proteins. Of 25 proteins identified in the study that were assayed, 8 mostly secreted proteins common to mouse plasma and human cancer cells were significantly upregulated in a set of plasmas from ovarian cancer patients. Five of the eight proteins were confirmed to be upregulated in a second independent set of ovarian cancer plasmas, including in early stage disease.

Conclusions/Significance

Integrated proteomic analysis of cancer mouse models and human cancer cell populations provides an effective approach to identify potential circulating protein biomarkers.