The expression levels of the translational factors eEF1A 1/2 correlate with cell growth but not apoptosis in hepatocellular carcinoma cell lines with different differentiation grade

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.

In Vitro and In Vivo Evaluation of the Effects of Drug 2c and Derivatives on Ovarian Cancer Cells

BACKGROUND

The identification of novel therapeutic strategies for ovarian cancer (OC), the most lethal gynecological neoplasm, is of utmost urgency. Here, we have tested the effectiveness of the compound 2c (4-hydroxy-2,6-bis(4-nitrobenzylidene)cyclohexanone 2). 2c interferes with the cysteine-dependent deubiquitinating enzyme (DUB) UCHL5, thus affecting the ubiquitin-proteasome-dependent degradation of proteins.

METHODS

2c phenotypic/molecular effects were studied in two OC 2D/3D culture models and in a mouse xenograft model. Furthermore, we propose an in silico model of 2c interaction with DUB-UCHL5. Finally, we have tested the effect of 2c conjugated to several linkers to generate 2c/derivatives usable for improved drug delivery.

RESULTS

2c effectively impairs the OC cell line and primary tumor cell viability in both 2D and 3D conditions. The effectiveness is confirmed in a xenograft mouse model of OC. We show that 2c impairs proteasome activity and triggers apoptosis, most likely by interacting with DUB-UCHL5. We also propose a mechanism for the interaction with DUB-UCHL5 via an in silico evaluation of the enzyme-inhibitor complex. 2c also reduces cell growth by down-regulating the level of the transcription factor E2F1. Eventually, 2c activity is often retained after the conjugation with linkers.

CONCLUSION

Our data strongly support the potential therapeutic value of 2c/derivatives in OC.

Oncogenic activation of EEF1A2 expression: a journey from a putative to an established oncogene

Protein synthesis via translation is a central process involving several essential proteins called translation factors. Although traditionally described as cellular "housekeepers," multiple studies have now supported that protein initiation and elongation factors regulate cell growth, apoptosis, and tumorigenesis. One such translation factor is eukaryotic elongation factor 1 alpha 2 (EEF1A2), a member of the eukaryotic elongation factor family, which has a canonical role in the delivery of aminoacyl-tRNA to the A-site of the ribosome in a guanosine 5'-triphosphate (GTP)-dependent manner. EEF1A2 differs from its closely related isoform, EEF1A1, in tissue distribution. While EEF1A1 is present ubiquitously, EEF1A2 replaces it in specialized tissues. The reason why certain specialized tissues need to essentially switch EEF1A1 expression altogether with EEF1A2 remains to be answered. Abnormal "switch on" of the EEF1A2 gene in normal tissues is witnessed and is seen as a cause of oncogenic transformation in a wide variety of solid tumors. This review presents the journey of finding increased expression of EEF1A2 in multiple cancers, establishing molecular mechanism, and exploring it as a target for cancer therapy. More precisely, we have compiled studies in seven types of cancers that have reported EEF1A2 overexpression. We have discussed the effect of aberrant EEF1A2 expression on the oncogenic properties of cells, signaling pathways, and interacting partners of EEF1A2. More importantly, in the last part, we have discussed the unique potential of EEF1A2 as a therapeutic target. This review article gives an up-to-date account of EEF1A2 as an oncogene and can draw the attention of the scientific community, attracting more research.

The Anticancer Efficacy of Thiourea-Mediated Reduced Graphene Oxide Nanosheets against Human Colon Cancer Cells (HT-29)

The current research focuses on the fabrication of water-soluble, reduced graphene oxide (rGO) employing thiourea (T) using a simple cost-effective method, and subsequently examining its anticancer characteristics. The cytotoxicity caused by graphene oxide (GO) and T-rGO is investigated in detail. Biological results reveal a concentration-dependent toxicity of GO and T-rGO in human colon cancer cells HT-29. A decrease in cell viability alongside DNA fragmentation is observed. Flow cytometry analysis confirms the cytotoxic effects. The novelty in this work is the use of raw graphite powder, and oxidants such as KMNO₄, NaNO₃, and 98 percent H₂SO₄ to produce graphene oxide by a modified Hummers method. This study demonstrates a simple and affordable procedure for utilising thiourea to fabricate a water-soluble reduced graphene oxide, which will be useful in a variety of biomedical applications.

5-Azacytidine Downregulates the Proliferation and Migration of Hepatocellular Carcinoma Cells In Vitro and In Vivo by Targeting miR-139-5p/ROCK2 Pathway

Simple Summary

For hepatocellular carcinoma (HCC), the second most common cause of cancer-related death, effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to the development of HCC, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. However, despite the potential efficacy of 5-Aza in HCC, most of its mechanisms of action are still unknown. Here, we investigate the phenotypic/molecular effects of 5-Aza with a focus on miR-139-5p. Using multiple in vitro and in vivo models of HCC, we show for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn downregulates the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. These observations elucidate the mechanisms of action of 5-Aza in HCC, strengthen its therapeutic potential, and provide novel information about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/MMP-2 in HCC.

Abstract

Background: For hepatocellular carcinoma (HCC), effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to HCC development, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. As most 5-Aza mechanisms of action are unknown, we investigated its phenotypic/molecular effects. Methods: 5-Aza effects were examined in the human HCC cell lines JHH-6/HuH-7 and in the rat cell-line N1-S1. We also employed a xenograft mouse model (HuH-7), a zebrafish model (JHH-6), and an orthotopic syngeneic rat model (N1-S1) of HCC. Results: 5-Aza downregulated cell viability/growth/migration/adhesion by upregulating miR-139-5p, which in turn downregulated ROCK2/cyclin D1/E2F1 and increased p27^kip1, resulting in G1/G0 cell accumulation. Moreover, a decrease in cyclin B1 and an increase in p27^kip1 led to G2/M accumulation. Finally, we observed a decrease in MMP-2 levels, a stimulator of HCC cell migration. Aza effects were confirmed in the mouse model; in the zebrafish model, we also demonstrated the downregulation of tumor neo-angiogenesis, and in the orthotopic rat model, we observed impaired N1-S1 grafting in a healthy liver. Conclusion: We demonstrate for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn impairs the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. Thus, we provide novel information about 5-Aza mechanisms of action and deepen the knowledge about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/p27^kip1/MMP-2 in HCC.

[EEFSEC knockdown inhibits proliferation, migration and invasion of prostate cancer cells in vitro]

OBJECTIVE

To investigate the role of selenocysteine-tRNA specific eukaryotic elongation factor (EEFSEC) in regulating the proliferation, migration, and invasion of human prostate cancer 22Rv1 cells.

METHODS

We detected EEFSEC mRNA expression levels in human normal prostate cell line RWPE1 and human prostate cancer cell lines 22Rv1, LNCaP, Vcap and PC-3 using qRT-PCR and EEFSEC protein expression in surgical specimens of prostate cancer and adjacent tissues using Western blotting. 22Rv1 cells were infected with a lentiviral vector carrying EEFSEC shRNA or a control lentivirus and the interference efficiency was determined using Western blotting. XTT assay was used to assess the changes in the viability of the infected cells, and Transwell chamber assay was used to examine the changes in cell migration and invasion. The effect of EEFSEC knockdown on cell cycle progression was determined with flow cytometry and by detecting the expressions of cell cycle proteins using qRT-PCR.

RESULTS

EEFSEC was significantly upregulated in prostate cancer cells (P < 0.05), and a high expression of EEFSEC was associated with a poor prognosis of the patients with prostate cancer. In 22Rv1 cells, EEFSEC knockdown significantly suppressed the proliferation (P < 0.001), migration (P < 0.001) and invasion (P < 0.001) of the cells, resulted in cell cycle arrest in G₀/G₁ phase, obviously inhibited the expression of C-myc and CCNB1, and significantly increased the expression of p15.

CONCLUSION

EEFSEC knockdown can inhibit the proliferation, migration, and invasion of prostate cancer cells in vitro possibly by down-regulating the expression of C-myc.

Expression and Clinical Value of Eukaryotic Translation Elongation Factor 1A1 (EEF1A1) in Diffuse Large B Cell Lymphoma

Background

The eukaryotic translation elongation factor 1A1 (EEF1A1) participates in protein translation and has been reported to be involved in tumor progression such as hepatocellular carcinoma. Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy in adults. In the present study, we aimed to detect the expression of EEF1A1 in DLBCL and to analyze its relationship with prognosis.

Methods

We reviewed medical records of DLBCL patients in our hospital and evaluated their expression level of EEF1A1 in tumor tissues using immunohistochemical (IHC) assay. The Chi-square method was used for correlation analysis. The Kaplan–Meier method with Log rank test was used for univariate analysis. Cox proportional hazards model was used for multivariate analysis. Cellular and mice models were introduced to validate its oncogenic role.

Results

EEF1A1 expression in tumor cells was higher in certain DLBCL cases. Patients with higher EEF1A1 expression were more likely to have advanced tumor stage and poorer 5-year overall survival (OS) rates. EEF1A1 expression in tumor cells was an independent risk predictor for OS (P < 0.05). Cellular assays demonstrated that EEF1A1-shRNA significantly inhibited lymphoma cell proliferation. The study of xenografts further verified the effect of EEF1A1-shRNA on suppressing tumor growth in vivo.

Conclusion

EEF1A1 positivity predicts short survival in DLBCL patients. For patients with higher EEF1A1 expression, more strategy such as anti-EEF1A1 antibody treatment should be developed.

Translational Regulation in Hepatocellular Carcinogenesis

The mortality of hepatocellular carcinoma (HCC) is distributed unevenly worldwide. One of the major causes is hepatitis B or hepatitis C virus infection and the development and progression of liver cirrhosis. The carcinogenesis of HCC is among others regulated via the mTOR (mechanistic target of rapamycin) signaling pathway and represents a possible method of targeted treatment. The aim of our article was to address the most recent clinical advances and findings of basic studies on the mTOR signaling pathway and the involved factors. Risk factors play a key role in dysregulation of the signaling pathway, where both mTORCs are upregulated and protein synthesis is altered. eIFs and, to a lesser extent, eEFs play an essential role in this process. Whether the factor will be upregulated or downregulated, among others, depends on hepatitis B/C virus infection. The amount of a particular factor in a patient sample lets us know whether HCC recurrence will occur, what is the likelihood of chemoresistance, and what outcome is predicted for patients with an increased value. Our analysis shows that in addition to mTOR, eIF3, eIF4, and eIF5 play an important role, as they can serve as biomarkers for non- and virus-related HCC.

FAT10: Function and Relationship with Cancer

Posttranslational protein modifications are known to be extensively involved in cancer, and a growing number of studies have revealed that the ubiquitin-like modifier FAT10 is directly involved in cancer development. FAT10 was found to be highly upregulated in various cancer types, such as glioma, hepatocellular carcinoma, breast cancer and gastrointestinal cancer. Protein FAT10ylation and interactions with FAT10 lead to the functional change of proteins, including proteasomal degradation, subcellular delocalization and stabilization, eventually having significant effects on cancer cell proliferation, invasion, metastasis and even tumorigenesis. In this review, we summarized the current knowledge on FAT10 and discussed its biological functions in cancer, as well as potential therapeutic strategies based on the FAT10 pathway.

A novel melanin complex displayed the affinity to HepG2 cell membrane and nucleus

Chitosan-melanin complex from Catharsius molossus L. has proven to possess superior pharmaceutical excipient performance and may be the new source of water-soluble protein-free natural melanin. Herein, it was enzymatically hydrolyzed into the chitooligosaccharide-melanin complex (CMC) whose main chemical units were composed of eumelanin and chitooligosaccharides and showed three-layer structures. Additionally, this biomacromolecule could self-assemble into 40 nm nanoparticles (CMC Nps) in a weakly acidic aqueous solution. Interestingly, CMC displayed strong affinity for cell membrane by binding the phosphatidylserine, glycoprotein, glycolipids and glycosaminoglycans accumulated on the surface of tumor cells, notably, CMC Nps could enter cells and mainly target the nucleus by interacting with DNA and/or RNA substrates located around the nucleus to disrupt the proliferation and apoptosis processes. The findings suggest CMC may be the novel material for subcellular organelle targeting of cancer cells.

Targeted delivery of siRNAs against hepatocellular carcinoma-related genes by a galactosylated polyaspartamide copolymer

Given the lack of effective treatments for Hepatocellular carcinoma (HCC), the development of novel therapeutic approaches is very urgent. Here, siRNAs were delivered to HCC cells by a synthetic polymer containing α,β-poly-(N-2-hydroxyethyl)-D,L-aspartamide-(PHEA) derivatized with diethylene triamine (DETA) and bearing in the side chain galactose (GAL) linked via a polyethylene glycol (PEG) to obtain (PHEA-DETA-PEG-GAL, PDPG). The GAL residue allows the targeting to the asialo-glycoprotein receptor (ASGPR), overexpressed in HCC cells compared to normal hepatocytes. Uptake studies performed using a model siRNA or a siRNA targeted against the enhanced green fluorescence protein, demonstrated the PDPG specific delivery of siRNA to HuH7 cells, a human cellular model of HCC. GAL-free copolymer (PHEA-DETA-PEG-NH₂, PDP) or the chemical block of ASGPR, impaired PDPG targeting effectiveness in vitro. The specificity of PDPG delivery was confirmed in vivo in a mouse dorsal skinfold window chamber assay. Functional studies using siRNAs targeting the mRNAs of HCC-related genes (eEF1A1, eEF1A2 and E2F1) delivered by PDPG, significantly decreased HuH7 vitality/number and down regulated the expression of the target genes. Only minor effectiveness was in contrast observed for PDP. In IHH, a human model of normal hepatocytes with reduced ASGPR expression, PDPG barely reduced cell vitality. In a subcutaneous xenograft mouse model of HCC, PDPG-siRNAs reduced HCC tumor growth compared to controls without significant toxic effects. In conclusion, our study demonstrates the valuable potentials of PDPG for the specific delivery of siRNAs targeting HCC-related genes.

Hepatitis B Virus DNA Polymerase Displays an Anti-Apoptotic Effect by Interacting with Elongation Factor-1 Alpha-2 in Hepatoma Cells

Hepatitis B virus (HBV) genome P-encoded protein HBV DNA polymerase (Pol) has long been known as a reverse transcriptase during HBV replication. In this study, we investigated the impact of HBV Pol on host cellular processes, mainly apoptosis, and the underlying mechanisms. We showed a marked reduction in apoptotic rates in the HBV Pol-expressed HepG2 cells compared to controls. Moreover, a series of assays, i.e., yeast two-hybrid, GST pull-down, co-immunoprecipitation, and confocal laser scanning microscopy, identified the host factor eEF1A2 to be associated with HBV Pol. Furthermore, knockdown of eEF1A2 gene by siRNA abrogated the HBV Pol-mediated anti-apoptotic effect with apoptosis induced by endoplasmatic reticulum (ER) stress-inducer thapsigargin (TG), thus suggesting that the host factor eEF1A2 is essential for HBV Pol's anti-apoptosis properties. Our findings have revealed a novel role for HBV Pol in its modulation of apoptosis through integrating with eEF1A2.

EEF1A2 triggers stronger ERK mediated metastatic program in ER negative breast cancer cells than in ER positive cells

AIMS

Ever since EEF1A2's identification as a putative oncogene in breast cancer, it has stimulated curiosity due to its contrasting role in predicting the prognostic values in breast cancer patients. Contradicting reports suggest it to be playing a pro-survival as well as a negative role in the survival of patients. This prompted us to find the association of this protein with molecular subtypes in breast cancer and its effect on EMT in representative cell lines.

MAIN METHODS

Data-mining was carried out to ascertain the correlation of EEF1A2 with molecular subtypes in breast cancer patients. Scratch wound healing and transwell invasion assays were carried out to assess its role in migration and invasion. Western blot, qRT-PCR, and ELISA were carried out to determine key signalling pathways, cytokines, and EMT factors responsible for the observed phenotype.

KEY FINDINGS

EEF1A2 was associated with ER receptor positivity in breast cancer and was involved in its transcriptional regulation. It induced a robust metastatic program in MDA-MB-231 (a triple-negative cell line), and induced significant changes in its invasive and migratory properties via activation of the ERK pathway. This was not the case in MCF7 which is an ER-positive cell line.

SIGNIFICANCE

We highlight the specific tendency of EEF1A2 to enhance invasive properties of cell lines in particular molecular subtype only. This sheds light on its selective role in regulating oncogenic processes in breast cancer and could explain its contradicting association with good survival, despite being an oncogene in a certain cohort of breast cancer patients.

Expression pattern of EEF1A2 in brain tumors: Histological analysis and functional role as a promoter of EMT

AIMS

Glioblastomas are highly aggressive brain tumors with a very poor survival rate. EEF1A2, the proto-oncogenic isoform of the EEF1A translation factor family, has been found to be overexpressed and promoting tumorigenesis in multiple cancers. Interestingly, recent studies reported reduced expression of this protein in brain tumors, drawing our attention to find the functional role and mechanism of this protein in brain tumor progression.

MAIN METHODS

Using representative cell line as models, the role of EEF1A2 in cell proliferation, migration and invasion were assessed using MTS assay, scratch wound-healing assay, transwell migration and invasion assay, respectively. Activation of key signaling pathways was assessed using western blots and real-time PCR. Finally, using immunohistochemistry we checked the protein levels of EEF1A2 in CNS tumors.

KEY FINDINGS

EEF1A2 was found to increase the proliferative, migratory and invasive properties of cell lines of both glial and neuronal origin. PI3K activation directly correlated with EEF1A2 levels. Protein levels of key EMT markers viz. Twist, Snail, and Slug were increased upon ectopic EEF1A2 expression. Furthermore, EEF1A2 was found to affect the expression levels of key inflammatory cytokines, growth factors and matrix metalloproteases. IHC analysis showed that EEF1A2 is upregulated in tumor tissues compared to normal tissue.

SIGNIFICANCE

EEF1A2 acts as an oncogene in both neuronal and glial cells and triggers an EMT program via PI3K pathway. However, it shows enhanced expression in neuronal cells of the brain than the glial cells, which could explain the previously reported anomaly.

Opposing roles of C/EBPα and eEF1A1 in Sp1-regulated miR-122 transcription

We previously showed that miR-122 was frequently downregulated in hepatocellular carcinoma (HCC) and C/EBPα transactivated miR-122 expression. In this study, we found that Sp1 bound to the miR-122 promoter at two different sites. Interestingly, either inhibition or overexpression of Sp1 could decrease the miR-122 promoter activity and the cellular miR-122 level in hepatoma cells. Further investigations disclosed that Sp1 cooperated with C/EBPα to induce miR-122 transcription by binding to the positive regulatory site D in the miR-122 promoter, whereas eEF1A1 interacted with Sp1 to bind to the negative regulatory site E and inhibit miR-122 transcription. Significantly, both Sp1 and eEF1A1 levels were enhanced, but C/EBPα and miR-122 expression were reduced in HCC tissues. Knockdown of eEF1A1 enhanced miR-122 level and inhibited cell growth, and these effects were abrogated when Sp1 was silenced. Consistently, the promoter activity enhanced by site E deletion was attenuated by silencing Sp1. Moreover, reduction of miR-122 resulted from Sp1 overexpression was rescued by coexpressing C/EBPα. These data suggest that C/EBPα and eEF1A1 may play opposing roles in Sp1-regulating miR-122 transcription, and the eEF1A1 upregulation accompanied by C/EBPα downregulation in HCC may switch the regulatory functions of Sp1 and led to reduced miR-122 transcription. These findings highlight the complex regulatory network of miR-122 expression and its significance in hepatocarcinogenesis.Abbreviations: MiRNA: microRNA; HCC, hepatocellular carcinoma; eEF1A1: eukaryote translation elongation factor 1A1; siRNA: small interfering RNA; qPCR: real-time quantitative RT-PCR; EMSA: electrophoretic mobility shift assay; ChIP: chromatin immunoprecipitation; TSS: transcription start site.

Effects of eEF1A1 targeting by aptamer/siRNA in chronic lymphocytic leukaemia cells

BACKGROUND

The effectiveness of therapies for chronic lymphocytic leukemia (CLL), the most common leukemia in Western countries adults, can be improved via a deeper understanding of its molecular abnormalities. Whereas the isoforms of the eukaryotic elongation factor 1A (eEF1A1 and eEF1A2) are implicated in different tumors, no information are available in CLL.

METHODS

eEF1A1/eEF1A2 amounts were quantitated in the lymphocytes of 46 CLL patients vs normal control (real time PCR, western blotting). eEF1A1 role in CLL was investigated in a cellular (MEC-1) and animal model of CLL via its targeting by an aptamer (GT75) or a siRNA (siA1) delivered by electroporation (in vitro) or lipofection (in vivo).

RESULTS

eEF1A1/eEF1A2 were elevated in CLL lymphocytes vs control. eEF1A1 but not eEF1A2 levels were higher in patients which died during the study compared to those surviving. eEF1A1 targeting (GT75/siA1) resulted in MEC-1 viability reduction/autophagy stimulation and in vivo tumor growth down-regulation.

CONCLUSIONS

The increase of eEF1A1 in dead vs surviving patients may confer to eEF1A1 the role of a prognostic marker for CLL and possibly of a therapeutic target, given its involvement in MEC-1 survival. Specific aptamer/siRNA released by optimized delivery systems may allow the development of novel therapeutic options.

A rapid and specific method to simultaneously quantify eukaryotic elongation factor 1A1 and A2 protein levels in cancer cells

BACKGROUND

The two isoforms of the eukaryotic Elongation Factor 1A (eEF1A1 and eEF1A2), sustain the progression/aggressiveness of cancer cells. Thus, they are considered promising therapeutic targets and prognostic markers. It follows that their precise quantification is of utmost relevance in research and development. The simultaneous quantification of A1 and A2 proteins in the cells helps the comprehension of cancer biology mechanisms and response to drug treatments. However, the high homology at the amino-acidic level (92%) can cause antibodies cross-reaction. Moreover, the commonly employed western blotting just gives semi-quantitative data and does not allow the detection of both protein targets within the same cell. Thus, we developed an in cell western (ICW) technique to bypass the above limitations.

METHODS

Firstly, relevant antibodies cross-reaction was excluded by immunohistochemistry on normal pancreatic tissue; then eEF1A1-A2 protein levels were quantitated by ICW in prostate and colorectal cancer cell lines in 96 well plates under different conditions, which include: 1) drug treatment, 2) siRNA silencing, 3) cell seeding density.

RESULTS

We show that: 1) eEF1A1-A2 levels vary depending on the cell type following drug treatment, 2) ICW can accurately detect eEF1A1-A2 protein levels following siRNA silencing, 3) cell seeding density influences eEF1A1-A2 levels, depending on cell type.

CONCLUSIONS

ICW is a valuable tool to specifically determine the intracellular level of eEF1A1-A2 proteins thus contributing to better define their role as potential therapeutic targets and prognostic markers in human tumors as well as for drug effects screening.

Elevated levels of eEF1A2 protein expression in triple negative breast cancer relate with poor prognosis

Eukaryotic elongation factor 1 alpha 2 (eEF1A2) is a translation factor selectively expressed by heart, skeletal muscle, nervous system and some specialized cells. Its ectopic expression relates with tumorigenesis in several types of human cancer. No data are available about the role of eEF1A2 in Triple Negative Breast Cancers (TNBC). This study investigated the relation between eEF1A2 protein levels and the prognosis of TNBC. A total of 84 TNBC diagnosed in the period 2002-2011 were included in the study. eEF1A2 protein level was measured in formalin-fixed paraffin-embedded tissues by immunohistochemistry in a semi-quantitative manner (sum of the percentage of positive cells x staining intensity) on a scale from 0 to 300. Cox regression assessed the association between eEF1A2 levels and disease-free survival (DFS) and breast cancer-specific survival (BCSS). Elevated values of eEF1A2 were associated with older age at diagnosis (p = 0.003), and androgen receptors positivity (p = 0.002). At univariate Cox analysis, eEF1A2 levels were not significantly associated with DFS and BCSS (p = 0.11 and p = 0.08, respectively) whereas adjusting for stage of disease, elevated levels of eEF1A2 protein resulted associated with poor prognosis (HR = 1.05, 95% CI: 1.01-1.11, p = 0.04 and HR = 1.07, 95% CI: 1.01-1.14, p = 0.03 for DFS and BCSS, respectively). This trend was confirmed analyzing negative versus positive samples by using categorized scores. Our data showed a negative prognostic role of eEF1A2 protein in TNBC, sustaining further investigations to confirm this result by wider and independent cohorts of patients.

Polymer-Mediated Delivery of siRNAs to Hepatocellular Carcinoma: Variables Affecting Specificity and Effectiveness

Despite the advances in anticancer therapies, their effectiveness for many human tumors is still far from being optimal. Significant improvements in treatment efficacy can come from the enhancement of drug specificity. This goal may be achieved by combining the use of therapeutic molecules with tumor specific effects and delivery carriers with tumor targeting ability. In this regard, nucleic acid-based drug (NABD) and particularly small interfering RNAs (siRNAs), are attractive molecules due to the possibility to be engineered to target specific tumor genes. On the other hand, polymeric-based delivery systems are emerging as versatile carriers to generate tumor-targeted delivery systems. Here we will focus on the most recent findings in the selection of siRNA/polymeric targeted delivery systems for hepatocellular carcinoma (HCC), a human tumor for which currently available therapeutic approaches are poorly effective. In addition, we will discuss the most attracting and, in our opinion, promising siRNA-polymer combinations for HCC in relation to the biological features of HCC tissue. Attention will be also put on the mathematical description of the mechanisms ruling siRNA-carrier delivery, this being an important aspect to improve effectiveness reducing the experimental work.

eEF1A1 Overexpression Enhances Tumor Progression and Indicates Poor Prognosis in Hepatocellular Carcinoma

Liver is a major contributor of protein production physiologically. The aberrant state of protein synthesis leads to tumor progression. Eukaryotic elongation factor 1 alpha 1 (eEF1A1) is a major member of the eukaryotic elongation factor family that regulates protein synthesis. Although eEF1A1 plays an essential role in controlling the cell fate, its clinical significance in tumor development and progression has not been reported. Here, we aimed to uncover the expression and prognostic significance of eEF1A1 in hepatocellular carcinoma (HCC). Our data indicated that eEF1A1 expression was elevated in HCC cell lines and clinical samples at both the mRNA and protein levels. Immunohistochemistry revealed that eEF1A1 expression was upregulated in HCC samples compared with corresponding non-tumorous tissues. In 50 HCC cases with portal vein embolus, higher eEF1A1 immunoreactivity was detected in tumor metastases compared with the primary lesions. Kaplan–Meier analysis indicated that increased eEF1A1 expression was closely associated with unfavorable post-surgical overall and disease-free survival in 453 HCC patients. Moreover, multivariate analysis indicated eEF1A1 as an independent predictor for overall and disease-free survival. Collectively, our study suggests eEF1A1 as a novel prognostic biomarker and potential therapeutic target for HCC patients.

Use of HuH6 and other human-derived hepatoma lines for the detection of genotoxins: a new hope for laboratory animals?

Cell lines which are currently used in genotoxicity tests lack enzymes which activate/detoxify mutagens. Therefore, rodent-derived liver preparations are used which reflect their metabolism in humans only partly; as a consequence misleading results are often obtained. Previous findings suggest that certain liver cell lines express phase I/II enzymes and detect promutagens without activation; however, their use is hampered by different shortcomings. The aim of this study was the identification of a suitable cell line. The sensitivity of twelve hepatic cell lines was investigated in single cell gel electrophoresis assays. Furthermore, characteristics of these lines were studied which are relevant for their use in genotoxicity assays (mitotic activity, p53 status, chromosome number, and stability). Three lines (HuH6, HCC1.2, and HepG2) detected representatives of five classes of promutagens, namely, IQ and PhIP (HAAs), B(a)P (PAH), NDMA (nitrosamine), and AFB₁ (aflatoxin), and were sensitive towards reactive oxygen species (ROS). In contrast, the commercially available line HepaRG, postulated to be a surrogate for hepatocytes and an ideal tool for mutagenicity tests, did not detect IQ and was relatively insensitive towards ROS. All other lines failed to detect two or more compounds. HCC1.2 cells have a high and unstable chromosome number and mutated p53, these features distract from its use in routine screening. HepG2 was frequently employed in earlier studies, but pronounced inter-laboratory variations were observed. HuH6 was never used in genotoxicity experiments and is highly promising, it has a stable karyotype and we demonstrated that the results of genotoxicity experiments are reproducible.

Dissecting the role of the elongation factor 1A isoforms in hepatocellular carcinoma cells by liposome-mediated delivery of siRNAs

Eukaryotic elongation factor 1A (eEF1A), a protein involved in protein synthesis, has two major isoforms, eEF1A1 and eEF1A2. Despite the evidences of their involvement in hepatocellular carcinoma (HCC), the quantitative contribution of each of the two isoforms to the disease is unknown. We depleted the two isoforms by means of siRNAs and studied the effects in three different HCC cell lines. Particular care was dedicated to select siRNAs able to target each of the two isoform without affecting the other one. This is not a trivial aspect due to the high sequence homology between eEF1A1 and eEF1A2. The selected siRNAs can specifically deplete either eEF1A1 or eEF1A2. This, in turn, results in an impairment of cell vitality, growth and arrest in the G1/G0 phase of the cell cycle. Notably, these effects are quantitatively superior following eEF1A1 than eEF1A2 depletion. Moreover, functional tests revealed that the G1/G0 block induced by eEF1A1 depletion depends on the down-regulation of the transcription factor E2F1, a known player in HCC. In conclusion, our data indicate that the independent targeting of the two eEF1A isoforms is effective in reducing HCC cell growth and that eEF1A1 depletion may result in a more evident effect.

Clinical, cellular, and bioinformatic analyses reveal involvement of WRAP53 overexpression in carcinogenesis of lung adenocarcinoma

Lung cancer, of which non-small cell lung cancer accounts for 80%, remains a leading cause of cancer-related mortality and morbidity worldwide. Our study revealed that the expression of WD repeat containing antisense to P53 (WRAP53) is higher in lung-adenocarcinoma specimens than in specimens from adjacent non-tumor tissues. The prevalence of WRAP53 overexpression was significantly higher in patients with tumor larger than 3.0 cm than in patients with tumor smaller than 3.0 cm. The depletion of WRAP53 inhibits the proliferation of lung-adenocarcinoma A549 and SPC-A-1 cells via G1/S cell-cycle arrest. Several proteins interacting with WRAP53 were identified through co-immunoprecipitation and liquid chromatography/mass spectrometry. These key proteins indicated previously undiscovered functions of WRAP53. These observations strongly suggested that WRAP53 should be considered a promising target in the prevention or treatment of lung adenocarcinoma.

Rapid and cost-effective xenograft hepatocellular carcinoma model in Zebrafish for drug testing

We developed a novel, rapid and cost-effective Zebrafish xenograft model of hepatocellular carcinoma (HCC) for drug screening in the disease. Following injection into the yolk sack of Zebrafish larvae of the human HCC cell line JHH6 stained by a vital dye, tumor mass growth was followed by fluorescence microscopy and by human Ki67 quantification. Tumor induced neo-angiogenesis was evaluated by alkaline phosphatase staining of the vessels, by using the Tg(fli1:EGFP)y¹ strain of Zebrafish and by the quantification of the zebrafish vascular endothelial growth factor and of its receptor. We show that it is feasible to micro-inject JHH6 in Zebrafish larvae, that injected cells can grow for different days and that this induces a marked neo-angiogenesis. Finally, we show that our model allows testing the effects of anti-HCC drugs such as Bortezomib. Compared to more complex HCC mouse models, our model is far less expensive, faster to set up and does not need immunosuppressant treatment. Finally, the model makes use of JHH6, an aggressive form of HCC cell line never tested before in Zebrafish. In conclusion, the possibility to test anti HCC/neo-angiogenesis drugs makes our JHH6 model useful to select therapeutic molecules for a highly vascularized tumor such as HCC.

Aptamer targeting of the elongation factor 1A impairs hepatocarcinoma cells viability and potentiates bortezomib and idarubicin effects

The high morbidity and mortality of hepatocellular carcinoma (HCC) is mostly due to the limited efficacy of the available therapeutic approaches. Here we explore the anti-HCC potential of an aptamer targeting the elongation factor 1A (eEF1A), a protein implicated in the promotion of HCC. As delivery methods, we have compared the effectiveness of cationic liposome and cholesterol-mediated approaches. A75 nucleotide long aptamer containing GT repetition (GT75) was tested in three HCC cell lines, HepG2, HuH7 and JHH6. When delivered by liposomes, GT75 was able to effectively reducing HCC cells viability in a dose and time dependent fashion. Particular sensitive were JHH6 where increased apoptosis with no effects on cell cycle were observed. GT75 effect was likely due to the interference with eEF1A activity as neither the mRNA nor the protein levels were significantly affected. Notably, cholesterol-mediated delivery of GT75 abrogated its efficacy due to cellular mis-localization as proven by fluorescence and confocal microscopic analysis. Finally, liposome-mediated delivery of GT75 improved the therapeutic index of the anticancer drugs bortezomib and idarubicin. In conclusion, liposome but not cholesterol-mediated delivery of GT75 resulted in an effective delivery of GT75, causing the impairment of the vitality of a panel of HCC derived cells.

eEF1A1 binds and enriches protoporphyrin IX in cancer cells in 5-aminolevulinic acid based photodynamic therapy

Photodynamic therapy (PDT) with protoporphyrin IX (PpIX), which is endogenously derived from 5-aminolevulinic acid (5-ALA) or its derivatives, is a promising modality for the treatment of both pre-malignant and malignant lesions. However, the mechanisms of how ALA-induced PpIX selectively accumulated in the tumors are not fully elucidated. Here we discovered that eukaryotic translation elongation factor 1 alpha 1 (eEF1A1) interacted with PpIX (with an affinity constant of 2.96 × 10(6) M(-1)). Microscopy imaging showed that ALA-induced PpIX was co-localized with eEF1A1 in cancer cells. eEF1A1 was found to enrich ALA-induced PpIX in cells by competitively blocking the downstream bioavailability of PpIX. Taken together, our study discovered eEF1A1 as a novel photosensitizer binding protein, which may play an essential role in the enrichment of ALA-induced PpIX in cancer cells during PDT. These suggested eEF1A1 as a molecular marker to predict the selectivity and efficiency of 5-ALA based PDT in cancer therapy.

Eukaryotic elongation factor-1α 2 knockdown inhibits hepatocarcinogenesis by suppressing PI3K/Akt/NF-κB signaling

AIM: To assess the impact of eukaryotic elongation factor 1 alpha 2 (eEF1A2) on hepatocellular carcinoma (HCC) cell proliferation, apoptosis, migration and invasion, and determine the underlying mechanisms.

METHODS: eEF1A2 levels were detected in 62 HCC tissue samples and paired pericarcinomatous specimens, and the human HCC cell lines SK-HEP-1, HepG2 and BEF-7402, by real-time PCR and immunohistochemistry. Experimental groups included eEF1A2 silencing in BEL-7402 cells with lentivirus eEF1A2-shRNA (KD group) and eEF1A2 overexpression in SK-HEP-1 cells with eEF1A2 plasmid (OE group). Non-transfected cells (control group) and lentivirus-based empty vector transfected cells (NC group) were considered control groups. Cell proliferation (MTT and colony formation assays), apoptosis (Annexin V-APC assay), cell cycle (DNA ploidy assay), and migration and invasion (Transwell assays) were assessed. Protein levels of PI3K/Akt/NF-κB signaling effectors were evaluated by Western blot.

RESULTS: eEF1A2 mRNA and protein levels were significantly higher in HCC cancer tissue samples than in paired pericarcinomatous and normal specimens. SK-HEP-1 cells showed lower eEF1A2 mRNA levels; HepG2 and BEL-7402 cells showed higher eEF1A2 mRNA levels, with BEL-7402 cells displaying the highest amount. Efficient eEF1A2 silencing resulted in reduced cell proliferation, migration and invasion, increased apoptosis, and induced cell cycle arrest. The PI3K/Akt/NF-κB signaling pathway was notably inhibited. Inversely, eEF1A2 overexpression resulted in promoted cell proliferation, migration and invasion.

CONCLUSION: eEF1A2, highly expressed in HCC, is a potential oncogene. Its silencing significantly decreases HCC tumorigenesis, likely by inhibiting PI3K/Akt/NF-κB signaling.

Elongation Factor 1A-1 Is a Mediator of Hepatocyte Lipotoxicity Partly through Its Canonical Function in Protein Synthesis

Elongation factor 1A-1 (eEF1A-1) has non-canonical functions in regulation of the actin cytoskeleton and apoptosis. It was previously identified through a promoter-trap screen as a mediator of fatty acid-induced cell death (lipotoxicity), and was found to participate in this process downstream of ER stress. Since ER stress is implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), we investigated the mechanism of action of eEF1A-1 in hepatocyte lipotoxicity. HepG2 cells were exposed to excess fatty acids, followed by assessments of ER stress, subcellular localization of eEF1A-1, and cell death. A specific inhibitor of eEF1A-1 elongation activity, didemnin B, was used to determine whether its function in protein synthesis is involved in lipotoxicity. Within 6 h, eEF1A-1 protein was modestly induced by high palmitate, and partially re-localized from its predominant location at the ER to polymerized actin at the cell periphery. This early induction and subcellular redistribution of eEF1A-1 coincided with the onset of ER stress, and was later followed by cell death. Didemnin B did not prevent the initiation of ER stress by high palmitate, as indicated by eIF2α phosphorylation. However, consistent with sustained inhibition of eEF1A-1-dependent elongation activity, didemnin B prevented the recovery of protein synthesis and increase in GRP78 protein that are normally associated with later phases of the response to ongoing ER stress. This resulted in decreased palmitate-induced cell death. Our data implicate eEF1A-1, and its function in protein synthesis, in hepatocyte lipotoxicity.

The eEF1A Proteins: At the Crossroads of Oncogenesis, Apoptosis, and Viral Infections

Eukaryotic translation elongation factors 1 alpha, eEF1A1 and eEF1A2, are not only translation factors but also pleiotropic proteins that are highly expressed in human tumors, including breast cancer, ovarian cancer, and lung cancer. eEF1A1 modulates cytoskeleton, exhibits chaperone-like activity and also controls cell proliferation and cell death. In contrast, eEF1A2 protein favors oncogenesis as shown by the fact that overexpression of eEF1A2 leads to cellular transformation and gives rise to tumors in nude mice. The eEF1A2 protein stimulates the phospholipid signaling and activates the Akt-dependent cell migration and actin remodeling that ultimately favors tumorigenesis. In contrast, inactivation of eEF1A proteins leads to immunodeficiency, neural and muscular defects, and favors apoptosis. Finally, eEF1A proteins interact with several viral proteins resulting in enhanced viral replication, decreased apoptosis, and increased cellular transformation. This review summarizes the recent findings on eEF1A proteins indicating that eEF1A proteins play a critical role in numerous human diseases through enhancement of oncogenesis, blockade of apoptosis, and increased viral pathogenesis.

Impairment of the Pin1/E2F1 axis in the anti-proliferative effect of bortezomib in hepatocellular carcinoma cells

BACKGROUND

The modest efficacy of available therapies for Hepatocellular carcinoma (HCC) indicates the need to develop novel therapeutic approaches. For the proteasome inhibitor Bortezomib (BZB), potentially attractive for HCC treatment, the mechanism of action is largely unknown. The BZB effect on E2Fs and the E2Fs control on the peptidylproline cis-trans isomerase (Pin1), prompted us to explore the BZB effect on the Pin1-E2F1 axis.

METHODS

The tumorigenic cell line HuH7 together with the non-tumorigenic cells IHH and the human pluripotent stem cell derived hepatocytes (hPSC-H), were used as cellular models of HCC and normal liver cells, respectively.

RESULTS

BZB reduces HuH7 growth as shown by cell counting, cell vitality test and cell cycle analysis; this is paralleled by the decrease of Pin1, E2F1, cyclin A2 and of the hyper-phosphorylated pRB. Pin1-E2F1 axis impairment justifies the anti-proliferative effect since Pin-E2F1 depletion decreases HuH7 growth while the over-expression rescues BZB-induced inhibition of proliferation. Moreover, Pin1-E2F1 promote HuH7 growth via the up-regulation of cyclin D1, cyclin E, cyclin A2, E2F2 and in part E2F3. Finally, in the control cells IHH and hPSC-H, BZB effect on cell vitality is not irrelevant, a fact correlated to the cellular proliferation rate. Thus, BZB effect on healthy liver tissue may not be entirely negligible hence caution should be exercised in its use in liver regeneration processes.

CONCLUSION

For the first time we prove the functional involvement of the Pin1-E2F1 axis in the anti-proliferative effect of BZB indicating Pin1-E2F as an attractive target to control HCC cell growth.

Translational connection of TGFβ signaling: Phosphorylation of eEF1A1 by TβR-I inhibits protein synthesis

Transforming growth factor-β (TGFβ) signaling pathways regulate a wide array of cellular activities that are crucial for cell proliferation, apoptosis, migration and differentiation. TGFβ signaling pathways are initiated by ligand-activated TGFβ receptors, with type I TGFβ receptors (TβR-I) kinase being essential for phosphorylation of downstream targets. Until now, a prevalent view was that the TGFβ intracellular signaling targets would regulate transcription. Recently, we uncovered a novel TGFβ signaling pathway that exerts a direct regulatory effect on mRNA translation and protein synthesis. Eukaryotic elongation factor eEF1A1 is a GTP-binding protein that plays a central role in protein synthesis. By using a screening method for kinase substrate that was developed in our laboratory, we identified eEF1A1 as a novel substrate of TβR-I. This shed a new light on the convergence of TGFβ signaling and protein synthesis. We also showed phosphorylation of eEF1A1 at Ser300 by TβR-I prevents aa-tRNA binding to eEF1A1. As a consequence, TGFβ-dependent phosphorylation of eEF1A1 has an inhibitory effect on protein synthesis and cell proliferation. Therefore, we unveiled a novel regulatory mechanism of cellular proliferation by TGFβ at the translational level. Here we discuss this finding in the context of its potential role in the multiplicity of TGFβ signaling, and in the regulation of fundamental cellular functions, such as proliferation.

Increased expression of stathmin and elongation factor 1α in precancerous nodules with telomere dysfunction in hepatitis B viral cirrhotic patients

Background

Telomere dysfunction is important in carcinogenesis, and recently, stathmin and elongation factor 1α (EF1α) were reported to be up-regulated in telomere dysfunctional mice.

Methods

In the present study, the expression levels of stathmin and EF1α in relation to telomere length, telomere dysfunction-induced foci (TIF), γ-H2AX, and p21^WAF1/CIP1 expression were assessed in specimens of hepatitis B virus (HBV)-related multistep hepatocarcinogenesis, including 13 liver cirrhosis specimens, 14 low-grade dysplastic nodules (DN), 17 high-grade DNs, and 14 hepatocellular carcinomas (HCC). Five normal liver specimens were used as controls. TIF were analyzed by telomere fluorescent in situ hybridization (FISH) combined with immunostaining, while the protein expressions of stathmin, EF1α, γ-H2AX, and p21^WAF1/CIP1 were detected by immunohistochemistry.

Result

The expressions of stathmin and EF1α gradually increased as multistep hepatocarcinogenesis progressed, showing the highest levels in HCC. Stathmin mRNA levels were higher in high-grade DNs than normal liver and liver cirrhosis, whereas EF1α mRNA expression did not show such a difference. The protein expressions of stathmin and EF1α were found in DNs of precancerous lesions, whereas they were absent or present at very low levels in normal liver and liver cirrhosis. Stathmin histoscores were higher in high-grade DNs and low-grade DNs than in normal liver (all, P < 0.05). EF1α histoscores were higher in high-grade DNs than in normal liver and liver cirrhosis (all, P < 0.05). Stathmin mRNA levels and histoscores, as well as EF1α histoscores (but not mRNA levels), were positively correlated with telomere shortening and γ-H2AX labeling index (all, P < 0.05). EF1α histoscores were also positively correlated with TIF (P < 0.001). Significantly greater inactivation of p21^WAF1/CIP1 was observed in low-grade DNs, high-grade DNs, and HCC, compared to liver cirrhosis (all, P < 0.05). p21^WAF1/CIP1 labeling index was inversely correlated with TIF, stathmin mRNA level, and EF1α histoscore (all, P < 0.05).

Conclusion

Stathmin and EF1α are suggested to be closely related to telomere dysfunction, DNA damage, and inactivation of p21^WAF1/CIP1 in HBV-related multistep hepatocarcinogenesis. Accordingly, assessment of stathmin and EF1α levels as a reflection of telomere dysfunction may be helpful in evaluating the biological characteristics of precancerous hepatic nodules in hepatitis B viral cirrhotic patients.

Novel hepatocellular carcinoma molecules with prognostic and therapeutic potentials

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, is the sixth most common cancer worldwide and the third leading cause of cancer-related death. The difficulty to diagnose early cancer stages, the aggressive behaviors of HCC, and the poor effectiveness of therapeutic treatments, represent the reasons for the quite similar deaths per year and incidence number. Considering the fact that the diagnosis of HCC typically occurs in the advanced stages of the disease when the therapeutic options have only modest efficacy, the possibility to identify early diagnostic markers could be of significant benefit. So far, a large number of biomarkers have been associated to HCC progression and aggressiveness, but many of them turned out not to be of practical utility. This is the reason why active investigations are ongoing in this field. Given the huge amount of published works aimed at the identification of HCC biomarkers, in this review we mainly focused on the data published in the last year, with particular attention to the role of (1) molecular and biochemical cellular markers; (2) micro-interfering RNAs; (3) epigenetic variations; and (4) tumor stroma. It is worth mentioning that a significant number of the HCC markers described in the present review may be utilized also as targets for novel therapeutic approaches, indicating the tight relation between diagnosis and therapy. In conclusion, we believe that integrated researches among the different lines of investigation indicated above should represent the winning strategies to identify effective HCC markers and therapeutic targets.

eEF1A2 promotes cell migration, invasion and metastasis in pancreatic cancer by upregulating MMP-9 expression through Akt activation

eEF1A2 is a protein translation factor involved in protein synthesis that is overexpressed in various cancers, with important functions in tumor genesis and progression. We have previously showed that the ectopic expression of eEF1A2 is correlated with lymph node metastasis and perineural invasion in pancreatic cancer. In this study, we investigated the functional role of eEF1A2 in the regulation of cell migration, invasion, and metastasis in pancreatic cancer. Furthermore, we investigated the potential molecular mechanisms involved. By evaluating the invasive ability of a panel of pancreatic cancer cell lines with different metastatic potentials, eEF1A2 expression in cells was positively associated with their invasive ability. The knockdown of eEF1A2 by siRNA decreased the migration and invasion of PANC-1 cells. By contrast, the ectopic expression of exogenous eEF1A2 significantly promoted the migration and invasion of SW1990 cells. Stable eEF1A2 overexpression in a nude mouse model of peritoneal metastasis likewise dramatically enhanced the intraperitoneal metastatic ability of SW1990 cells. In addition, eEF1A2 overexpression could upregulate MMP-9 expression and activity. A significant positive correlation between the overexpression of both eEF1A2 and MMP-9 was observed in pancreatic cancer tissues. The inhibition of MMP-9 activity reduced the promoting effect of eEF1A2 on cell migration and invasion. Furthermore, eEF1A2-mediated cell migration and invasion, as well as MMP-9 expression and upregulation, were largely dependent on the eEF1A2-induced Akt activation. The findings suggested the potentially important role of eEF1A2 in pancreatic cancer migration, invasion, and metastasis. Thus, the results provide evidence of eEF1A2 as a potential therapeutic target in the treatment of aggressive pancreatic cancer.

The more basic isoform of eEF1A relates to tumour cell phenotype and is modulated by hyper-proliferative/differentiating stimuli in normal lymphocytes and CCRF-CEM T-lymphoblasts

The elongation factor 1A proteins (eEF1A1/A2) are known to play a role in tumours. We previously found that a more basic isoform of eEF1A (MBI-eEF1A) is present in the cytoskeletal/nuclear-enriched extracts of CCRF-CEM T-lymphoblasts but not in those of normal lymphocytes. To obtain deeper knowledge about MBI-eEF1A biology, we investigate from which of the eEF1A proteins, eEF1A1 or eEF1A2, MBI-eEF1A originates and the possibility that its appearance can be modulated by the differentiated or proliferative cell status. CCRF-CEM T-lymphoblasts and normal lymphocytes were cultured with or without differentiation/pro-proliferative stimuli (Phorbol 12-Myristate 13-Acetate (PMA) alone or the combination of phytohaemagglutinin (PHA) with PMA, respectively), and the presence of MBI-eEF1A evaluated together with that of the eEF1A1/A2 mRNAs. Our data indicate that the MBI-eEF1A may derive from eEF1A1 as eEF1A2 is not expressed in CCRF-CEM and normal lymphocytes. Moreover, MBI-eEF1A is inducible in normal lymphocytes upon hyper-proliferative stimuli application; in CCRF-CEM, its presence can be abrogated by PMA-induced differentiation. Finally, MBI-eEF1A may have a functional role in hyper-proliferating/tumour cells as its disappearance reduces the growth of CCRF-CEM and that of PHA/PMA-stimulated lymphocytes. The presented data suggest that MBI-eEF1A may be related to oncogenic cell phenotype, rising the possibility to use MBI-eEF1A as target for novel therapeutic strategies.

Identification of a novel binding protein of FAT10: eukaryotic translation elongation factor 1A1

BACKGROUND

FAT10 is known to execute its functions mainly through conjugation to different substrates, and these known functions include cytokine responses, apoptosis, mitosis, and tumorigenesis. Nonetheless, the known binding proteins of FAT10 cannot explain all its known functions. As such, the aim of this study was to identify unidentified conjugation proteins of FAT10.

METHODS

The yeast two-hybrid system was employed in this study. FAT10 was used as the bait protein for screening of a cDNA library from a human hepatocellular carcinoma cell line, Hep3B. Protein interactions were confirmed based on localization studies and co-immunoprecipitation assays. The expression of mRNA and protein was determined using real-time polymerase chain reaction and western blot analyses, respectively.

RESULTS

In this study, we identified eukaryotic elongation factor 1A1 (eEF1A1) as a FAT10-specific binding protein. The binding between FAT10 and eEF1A1 was confirmed both in vivo and in vitro. We also found that, when the expression of FAT10 was reduced by siRNA knockdown, this resulted in downregulation of eEF1A1 expression at both the mRNA and protein levels in human hepatocellular carcinoma cells.

CONCLUSIONS

We propose a model in which eEF1A1 serves as a substrate of FAT10 to accomplish, in part, its functions in regulating the biological behavior of tumor cells. Since both eEF1A1 and FAT10 are important for tumorigenesis and development, comprehending the mechanisms of this interaction can provide clues for identification of novel strategic targets for drug screening and molecular typing, and possibly in the development of new effective therapeutic strategies against hepatocellular carcinoma.

The apoptotic effect of hesperetin on human cervical cancer cells is mediated through cell cycle arrest, death receptor, and mitochondrial pathways

Hesperetin, a flavonoid from citrus fruits, has several bioactivities such as anti-inflammatory, antihypertensive, antiatherogenic effects. However, studies elucidating the role and the mechanism(s) of action of hesperetin in cervical cancer are sparse. In this study, we investigated the mechanism of the antiproliferative and apoptotic actions exerted by hesperetin on human cervical cancer SiHa cells. The viability of SiHa cells was evaluated using the MTT assay, apoptosis by acridine orange/ethidium bromide, propidium iodide, TUNEL assay, and Annexin V-Cy3, cell cycle distribution and mitochondrial transmembrane potential using flow cytometry, and apoptotic marker genes using quantitative real-time PCR. The treatment of SiHa cells with hesperetin (IC50, 650 μm) showed a marked concentration- and time-dependent inhibition of proliferation and induced the G2/M phase in a dose-dependent manner after 24 h. There was an attenuation of mitochondrial membrane potential with increased expression of caspase-3, caspase-8, caspase-9, p53, Bax, and Fas death receptor and its adaptor protein Fas-associated death domain-containing protein (FADD), indicating the participation of both death receptor- and mitochondria-related mechanisms. Furthermore, hesperetin-induced apoptosis was confirmed by TUNEL and Annexin V-Cy3. This study shows that hesperetin exhibits a potential anticancer activity against human cervical cancer cell lines in vitro through the reduction in cell viability and the induction of apoptosis. Altogether, these data sustain our contention that hesperetin has anticancer properties and merits further investigation as a potential therapeutic agent.

Naringin induces death receptor and mitochondria-mediated apoptosis in human cervical cancer (SiHa) cells

Cervical cancer is the second most common female cancer worldwide, and it remains a challenge to manage preinvasive and invasive lesions. Fruit-based cancer prevention entities, such as flavonoid and their derivatives, have demonstrated a marked ability to inhibit preclinical models of epithelial cancer cell growth and tumor formation. Here, we extend the role of naringin-mediated chemoprevention to that of cervical carcinogenesis. The present study sought to investigate the therapeutic potential effect of naringin on apoptosis in human cervical SiHa cancer cells. Viability of SiHa cells was evaluated by the MTT assay, apoptosis and mitochondrial transmembrane potential by flow cytometry, and pro-apoptotic related genes by Real-time quantitative PCR. Naringin showed a 50% inhibition of SiHa human cervical cancer cells at a concentration of 750μM. SiHa cells exhibited apoptotic cell death, intranucleosomal DNA fragmentation, morphological changes and decline in the mitochondrial transmembrane potential. In addition, administration of naringin increased the expression of caspases, p53 and Bax, Fas death receptor and its adaptor protein FADD. These results suggest that the induction of apoptosis by naringin is through both death-receptor and mitochondrial pathways. Taken together, our results suggest that naringin might be an effective agent to treat human cervical cancer.

Molecular markers associated with nonepithelial ovarian cancer in formalin-fixed, paraffin-embedded specimens by genome wide expression profiling

Nonepithelial ovarian cancer (NEOC) is a rare cancer that is often misdiagnosed as other malignant tumors. Research on this cancer using fresh tissues is nearly impossible because of its limited number of samples within a limited time provided. The study is to identify potential genes and their molecular pathways related to NEOC using formalin-fixed paraffin embedded samples. Total RNA was extracted from eight archived NEOCs and seven normal ovaries. The RNA samples with RNA integrity number >2.0, purity >1.7 and cycle count value <28 cycles were hybridized to the Illumina Whole-Genome DASL assay (cDNA-mediated annealing, selection, extension, and ligation). We analyzed the results using the GeneSpring GX11.0 and FlexArray software to determine the differentially expressed genes. Microarray results were validated using an immunohistochemistry method. Statistical analysis identified 804 differentially expressed genes with 443 and 361 genes as overexpressed and underexpressed in cancer, respectively. Consistent findings were documented for the overexpression of eukaryotic translation elongation factor 1 alpha 1, E2F transcription factor 2, and fibroblast growth factor receptor 3, except for the down-regulated gene, early growth response 1 (EGR1). The immunopositivity staining for EGR1 was found in the majority of cancer tissues. This finding suggested that the mRNA level of a transcript did not always match with the protein expression in tissues. The current gene profile can be the platform for further exploration of the molecular mechanism of NEOC.

Dissecting the expression of EEF1A1/2 genes in human prostate cancer cells: the potential of EEF1A2 as a hallmark for prostate transformation and progression

BACKGROUND

In prostate adenocarcinoma, the dissection of the expression behaviour of the eukaryotic elongation factors (eEF1A1/2) has not yet fully elucidated.

METHODS

The EEF1A1/A2 expressions were investigated by real-time PCR, western blotting (cytoplasmic and cytoskeletal/nuclear-enriched fractions) and immunofluorescence in the androgen-responsive LNCaP and the non-responsive DU-145 and PC-3 cells, displaying a low, moderate and high aggressive phenotype, respectively. Targeted experiments were also conducted in the androgen-responsive 22Rv1, a cell line marking the progression towards androgen-refractory tumour. The non-tumourigenic prostate PZHPV-7 cell line was the control.

RESULTS

Compared with PZHPV-7, cancer cells showed no major variations in EEF1A1 mRNA; eEF1A1 protein increased only in cytoskeletal/nuclear fraction. On the contrary, a significant rise of EEF1A2 mRNA and protein were found, with the highest levels detected in LNCaP. Eukaryotic elongation factor 1A2 immunostaining confirmed the western blotting results. Pilot evaluation in archive prostate tissues showed the presence of EEF1A2 mRNA in near all neoplastic and perineoplastic but not in normal samples or in benign adenoma; in contrast, EEF1A1 mRNA was everywhere detectable.

CONCLUSION

Eukaryotic elongation factor 1A2 switch-on, observed in cultured tumour prostate cells and in human prostate tumour samples, may represent a feature of prostate cancer; in contrast, a minor involvement is assigned to EEF1A1. These observations suggest to consider EEF1A2 as a marker for prostate cell transformation and/or possibly as a hallmark of cancer progression.

Effects of E2F1-cyclin E1-E2 circuit down regulation in hepatocellular carcinoma cells

BACKGROUND

No effective therapy is available for hepatocellular carcinoma. To identify novel therapeutic strategies, we explored the effects of the depletion of E2F1, cyclin E1-E2 whose inter-relationships in hepatocellular carcinoma cell proliferation have never been defined.

METHODS

siRNA-mediated depletion of the targets was studied in the hepatocellular carcinoma cells HepG2, HuH7 and JHH6 characterized by high, medium and low hepatocyte differentiation grade, respectively; a model of normal human hepatocytes was also considered.

RESULTS

The depletion of each target mRNA reduced the levels of the other two mRNAs, thus demonstrating a close regulatory control, also confirmed by over-expression experiments. At the protein level, an exception to this trend was observed for cyclinE1 whose amount increased upon cyclin E2 (HepG2, HuH7, JHH6) and E2F1 (HepG2) depletion. In HepG2, reduced cyclinE1 proteolysis accounted for this observation. Additionally, cyclin E1-E2-E2F1 targeting decreased the levels of cyclin A2 mRNA and of the hyper-phosphorylated form of pRb thus leading to an S-phase cell decrease; migration was impaired as well. Finally, the model of human hepatocytes used was clearly less affected by target mRNAs depletion than hepatocellular carcinoma cells.

CONCLUSION

Our data provide novel mutual relationships amongst cyclin E1-E2-E2F1 and indicate their role in sustaining hepatocellular carcinoma cell proliferation/migration, validating the concept of an anti-cyclin E1-E2-E2F1 therapeutic approach for hepatocellular carcinoma.

Mitochondrial bioenergetic profile and responses to metabolic inhibition in human hepatocarcinoma cell lines with distinct differentiation characteristics

The classical view of tumour cell bioenergetics has been recently revised. Then, the definition of the mitochondrial profile is considered of fundamental importance for the development of anti-cancer therapies, but it still needs to be clarified. We investigated two human hepatocellular carcinoma cell lines: the partially differentiated HepG2 and the undifferentiated JHH-6. High resolution respirometry revealed a marked impairment/uncoupling of OXPHOS in JHH-6 compared with HepG2, with the phosphorylation system limiting the capacity for electron transport much more in JHH-6. Blocking glycolysis or mitochondrial ATP synthase we demonstrated that in JHH-6 ATP synthase functions in reverse and consumes glycolytic ATP, thereby sustaining ΔΨm. A higher expression level of ATP synthase Inhibitor Factor 1 (IF1), a higher extent of IF1 bound to ATP synthase and a lower ATPase/synthase capacity were documented in JHH-6. Thus, here IF1 appears to down-regulate the reverse mode of ATPsynthase activity, thereby playing a crucial role in controlling energy waste and ΔΨm. These results, while confirming the over-expression of IF1 in cancer cells, are the first to indicate an inverse link between cell differentiation status and IF1 (expression level and regulatory function).

Comparative in vitro bioactivities of tea extracts from six species of Ardisia and their effect on growth inhibition of HepG2 cells

AIM OF THE STUDY

Ardisia species, notably A. compressa, are used in some regions of the world as food or in traditional medicine for prevention and treatment of certain health conditions including liver disease. We investigated the chemical composition and relative anticancer potential of six Ardisia species [A. japonica (AJ), A. escallonioides (AES), A. mamillata (AM), A. compressa (AC), A. crenata (ACR), and A. elliptica (AE)].

MATERIALS AND METHODS

Antioxidant capacity, DNA human topoisomerase II catalytic inhibition, and cytotoxicity on human liver cancer cells (HepG2) were determined in vitro in tea extracts of the 6 Ardisia species evaluated. Selected pure phenolic compounds present in Ardisia species were also evaluated.

RESULTS

AC showed the highest topoisomerase II catalytic inhibition (IC(50)=12 microg/ml) and cytotoxicity (IC(50)=117 microg/ml) against HepG2 cells, followed by ACR and AJ. Total polyphenols ranged from 21 to 72 mg equivalents of gallic acid (GA)/g solid extract (SE). LC-MS analysis revealed the presence of GA, quercetin derivatives, ardisenone, ardisiaquinone, ardisianone, bergenin, norbergenin, and embelin. However, neither total polyphenol concentration nor antioxidant capacity correlated with anticancer capacity. Significant HepG2 cytotoxicity was also achieved by bergenin (IC(50)=18 microM) and embelin (IC(50)=120 microM). AC, bergenin, embelin, and quercetin showed a tendency to accumulate cells in the G1 phase and reduced G2/M leading to apoptosis.

CONCLUSIONS

Although the mechanism is not entirely clear, AC, ACR, and AJ are the Ardisia species with the greatest anticancer potential against liver cancer cells in vitro and deserve further investigation.

Targeting of eEF1A with Amaryllidaceae isocarbostyrils as a strategy to combat melanomas

Melanomas display poor response rates to adjuvant therapies because of their intrinsic resistance to proapoptotic stimuli. This study indicates that such resistance can be overcome, at least partly, through the targeting of eEF1A elongation factor with narciclasine, an Amaryllidaceae isocarbostyril controlling plant growth. Narciclasine displays IC(50) growth inhibitory values between 30-100 nM in melanoma cell lines, irrespective of their levels of resistance to proapoptotic stimuli. Normal noncancerous cell lines are much less affected. At nontoxic doses, narciclasine also significantly improves (P=0.004) the survival of mice bearing metastatic apoptosis-resistant melanoma xenografts in their brain. The eEF1A targeting with narciclasine (50 nM) leads to 1) marked actin cytoskeleton disorganization, resulting in cytokinesis impairment, and 2) protein synthesis impairment (elongation and initiation steps), whereas apoptosis is induced at higher doses only (≥200 nM). In addition to molecular docking validation and identification of potential binding sites, we biochemically confirmed that narciclasine directly binds to human recombinant and yeast-purified eEF1A in a nanomolar range, but not to actin or elongation factor 2, and that 5 nM narciclasine is sufficient to impair eEF1A-related actin bundling activity. eEF1A is thus a potential target to combat melanomas regardless of their apoptosis-sensitivity, and this finding reconciles the pleiotropic cytostatic of narciclasine. -

Eef1a2 promotes cell growth, inhibits apoptosis and activates JAK/STAT and AKT signaling in mouse plasmacytomas

Background

The canonical function of EEF1A2, normally expressed only in muscle, brain, and heart, is in translational elongation, but recent studies suggest a non-canonical function as a proto-oncogene that is overexpressed in a variety of solid tumors including breast and ovary. Transcriptional profiling of a spectrum of primary mouse B cell lineage neoplasms showed that transcripts encoding EEF1A2 were uniquely overexpressed in plasmacytomas (PCT), tumors of mature plasma cells. Cases of human multiple myeloma expressed significantly higher levels of EEF1A2 transcripts than normal bone marrow plasma cells. High-level expression was also a feature of a subset of cell lines developed from mouse PCT and from the human MM.

Methodology/Principal Findings

Heightened expression of EEF1A2 was not associated with increased copy number or coding sequence mutations. shRNA-mediated knockdown of Eef1a2 transcripts and protein was associated with growth inhibition due to delayed G1-S progression, and effects on apoptosis that were seen only under serum-starved conditions. Transcriptional profiles and western blot analyses of knockdown cells revealed impaired JAK/STAT and PI3K/AKT signaling suggesting their contributions to EEF1A2-mediated effects on PCT induction or progression.

Conclusions/Significance

EEF1A2 may play contribute to the induction or progression of some PCT and a small percentage of MM. Eef1a2 could also prove to be a useful new marker for a subset of MM and, ultimately, a possible target for therapy.