Inhibition of proliferation, invasion, and migration of prostate cancer cells by downregulating elongation factor-1alpha expression

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.

Translational regulation of cell invasion through extracellular matrix-an emerging role for ribosomes

Many developmental and physiological processes require cells to invade and migrate through extracellular matrix barriers. This specialized cellular behavior is also misregulated in many diseases, such as immune disorders and cancer. Cell invasive activity is driven by pro-invasive transcriptional networks that activate the expression of genes encoding numerous different proteins that expand and regulate the cytoskeleton, endomembrane system, cell adhesion, signaling pathways, and metabolic networks. While detailed mechanistic studies have uncovered crucial insights into pro-invasive transcriptional networks and the distinct cell biological attributes of invasive cells, less is known about how invasive cells modulate mRNA translation to meet the robust, dynamic, and unique protein production needs of cell invasion. In this review we outline known modes of translation regulation promoting cell invasion and focus on recent studies revealing elegant mechanisms that expand ribosome biogenesis within invasive cells to meet the increased protein production requirements to invade and migrate through extracellular matrix barriers.

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.

Simvastatin delays castration‑resistant prostate cancer metastasis and androgen receptor antagonist resistance by regulating the expression of caveolin‑1

The failure of androgen deprivation therapy in prostate cancer treatment mainly results from drug resistance to androgen receptor antagonists. Although an aberrant caveolin‑1 (Cav‑1) expression has been reported in multiple tumor cell lines, it is unknown whether it is responsible for the progression of castration‑resistant prostate cancer (CRPC). Thus, the aim of the present study was to determine whether Cav‑1 can be used as a key molecule for the prevention and treatment of CRPC, and to explore its mechanism of action in CRPC. For this purpose, tissue and serum samples from patients with primary prostate cancer and CRPC were analyzed using immunohistochemistry and enzyme‑linked immunosorbent assay, which revealed that Cav‑1 was overexpressed in CRPC. Furthermore, Kaplan‑Meier survival analysis and univariate Cox proportional hazards regression analysis demonstrated that Cav‑1 expression in tumors was an independent risk factor for the occurrence of CRPC and was associated with a shorter recurrence‑free survival time in patients with CRPC. Receiver operating characteristic curves suggested that serum Cav‑1 could be used as a diagnostic biomarker for CRPC (area under the curve, 0.876) using a cut‑off value of 0.68 ng/ml (with a sensitivity of 82.1% and specificity of 80%). In addition, it was determined that Cav‑1 induced the invasion and migration of CRPC cells by the activation of the H‑Ras/phosphoinositide‑specific phospholipase Cε signaling cascade in the cell membrane caveolae. Importantly, simvastatin was able to augment the anticancer effects of androgen receptor antagonists by downregulating the expression of Cav‑1. Collectively, the findings of this study provide evidence that Cav‑1 is a promising predictive biomarker for CRPC and that lowering cholesterol levels with simvastatin or interfering with the expression of Cav‑1 may prove to be a useful strategy with which to prevent and/or treat CRPC.

[Eukaryotic translation elongation factor 1A1 positively regulates NOB1 expression to promote invasion and metastasis of hepatocellular carcinoma cells in vitro]

OBJECTIVE

To explore the role of eukaryotic translation elongation factor 1A1 (eEF1A1) in regulating the invasion and metastasis of hepatocellular carcinoma (HCC) cells and the possible mechanism.

METHODS

qRT-PCR and Western blotting were used to detect the mRNA and protein expression of eEF1A1 and NOB1 in different HCC cell lines and normal liver cells. The invasion and migration abilities of HCC cells with eEF1A1 knockdown or overexpression were examined using Transwell chamber assay and RTCA assay, and the changes in NOB1 mRNA and protein expressions in the cells were detected. The effects of increasing NOB1 expression in HCCLM3-sheEF1A1 cells and decreasing NOB1 expression in eEF1A1-overexpressing MHCC97h cells on eEF1A1 expression and cell invasion and migration abilities were analyzed using Western blotting, Transwell chamber assay and RTCA assay.

RESULTS

The expressions of eEF1A1 and NOB1 were significantly increased in positive correlation in HCC cells as compared with normal hepatocytes. Knockdown of eEF1A1 significantly decreased the invasion and migration of HCC cells and reduced the mRNA and protein expression of NOB1 (P < 0.01). Overexpression of eEF1A1 significantly enhanced invasion and migration of HCC cells and increased NOB1 mRNA and protein expressions (P < 0.01). Increasing NOB1 expression in HCCLM3-sheEF1A1 cells led to the restoration of NOB1 expression and cell invasion and migration abilities (P < 0.01), whereas decreasing NOB1 in MHCC97h-eEF1A1 cells resulted in inhibition of NOB1 expression and cell invasion and migration (P < 0.01).

CONCLUSIONS

eEF1A1 positively regulates the expression of NOB1 to promote the invasion and migration of HCC cells in vitro.

Proteomic Identification of eEF1A1 as a Molecular Target of Curcumol for Suppressing Metastasis of MDA-MB-231 Cells

Curcumol, a major volatile component in Rhizoma Curcumae, exhibits a potent antimetastatic effect on breast cancer cells. However, its molecular mechanism remains poorly understood. In this study, we employed two-dimensional gel electrophoresis-based proteomics to investigate the cellular targets of curcumol in MDA-MB-231 cells and identified 10 differentially expressed proteins. Moreover, Gene Ontology analysis revealed that these proteins are mainly involved in nine types of cellular components, seven different biological processes, and nine kinds of molecular functions, and 35 pathways (p < 0.05) were enriched by KEGG pathway analysis. Specially, eEF1A1, a well-characterized actin binding protein, draws our attention. Curcumol decreased eEF1A1 expression at both mRNA and protein levels. EEF1A1 expression was shown to be correlated with the invasiveness of cancer cells. Importantly, overexpression of eEF1A1 significantly reversed the inhibition of curcumol regarding the invasion and adhesion of MDA-MB-231 cells (p < 0.05). Together, our data suggest that eEF1A1 may be a potential molecular target underlying the antimetastatic effect of curcumol.

The Ubiquitin-like Protein FAT10 Stabilizes eEF1A1 Expression to Promote Tumor Proliferation in a Complex Manner

Human HLA-F adjacent transcript 10 (FAT10) is the only ubiquitin-like protein that can directly target substrates for degradation by proteasomes, but it can also stabilize the expression of certain substrates by antagonizing ubiquitination, through mechanisms as yet uncharacterized. In this study, we show how FAT10 stabilizes the translation elongation factor eEF1A1, which contributes to cancer cell proliferation. FAT10 overexpression increased expression of eEF1A1, which was sufficient to promote proliferation of cancer cells. Mechanistic investigations revealed that FAT10 competed with ubiquitin (Ub) for binding to the same lysines on eEF1A1 to form either FAT10-eEF1A1 or Ub-eEF1A1 complexes, respectively, such that FAT10 overexpression decreased Ub-eEF1A1 levels and increased FAT10-eEF1A1 levels. Overall, our work establishes a novel mechanism through which FAT10 stabilizes its substrates, advancing understanding of the biological function of FAT10 and its role in cancer. Cancer Res; 76(16); 4897-907. ©2016 AACR.

EEF1D modulates proliferation and epithelial-mesenchymal transition in oral squamous cell carcinoma

EEF1D (eukaryotic translation elongation factor 1δ) is a subunit of the elongation factor 1 complex of proteins that mediates the elongation process during protein synthesis via enzymatic delivery of aminoacyl-tRNAs to the ribosome. Although the functions of EEF1D in the translation process are recognized, EEF1D expression was found to be unbalanced in tumours. In the present study, we demonstrate the overexpression of EEF1D in OSCC (oral squamous cell carcinoma), and revealed that EEF1D and protein interaction partners promote the activation of cyclin D1 and vimentin proteins. EEF1D knockdown in OSCC reduced cell proliferation and induced EMT (epithelial-mesenchymal transition) phenotypes, including cell invasion. Taken together, these results define EEF1D as a critical inducer of OSCC proliferation and EMT.

Proteomic study of HPV-positive head and neck cancers: preliminary results

Human papillomavirus (HPV) was recently recognized as a new risk factor for head and neck squamous cell carcinoma. For oropharyngeal cancers, an HPV+ status is associated with better prognosis in a subgroup of nonsmokers and nondrinkers. However, HPV infection is also involved in the biology of head and neck carcinoma (HNC) in patients with a history of tobacco use and/or alcohol consumption. Thus, the involvement of HPV infection in HN carcinogenesis remains unclear, and further studies are needed to identify and analyze HPV-specific pathways that are involved in this process. Using a quantitative proteomics-based approach, we compared the protein expression profiles of two HPV+ HNC cell lines and one HPV- HNC cell line. We identified 155 proteins that are differentially expressed (P < 0.01) in these three lines. Among the identified proteins, prostate stem cell antigen (PSCA) was upregulated and eukaryotic elongation factor 1 alpha (EEF1α) was downregulated in the HPV+ cell lines. Immunofluorescence and western blotting analyses confirmed these results. Moreover, PSCA and EEF1 α were differentially expressed in two clinical series of 50 HPV+ and 50 HPV- oral cavity carcinomas. Thus, our study reveals for the first time that PSCA and EEF1 α are associated with the HPV-status, suggesting that these proteins could be involved in HPV-associated carcinogenesis.

iTRAQ identification of candidate serum biomarkers associated with metastatic progression of human prostate cancer

A major challenge in the management of patients with prostate cancer is identifying those individuals at risk of developing metastatic disease, as in most cases the disease will remain indolent. We analyzed pooled serum samples from 4 groups of patients (n = 5 samples/group), collected prospectively and actively monitored for a minimum of 5 yrs. Patients groups were (i) histological diagnosis of benign prostatic hyperplasia with no evidence of cancer 'BPH', (ii) localised cancer with no evidence of progression, 'non-progressing' (iii) localised cancer with evidence of biochemical progression, 'progressing', and (iv) bone metastasis at presentation 'metastatic'. Pooled samples were immuno-depleted of the 14 most highly abundant proteins and analysed using a 4-plex iTRAQ approach. Overall 122 proteins were identified and relatively quantified. Comparisons of progressing versus non-progressing groups identified the significant differential expression of 25 proteins (p<0.001). Comparisons of metastatic versus progressing groups identified the significant differential expression of 23 proteins. Mapping the differentially expressed proteins onto the prostate cancer progression pathway revealed the dysregulated expression of individual proteins, pairs of proteins and 'panels' of proteins to be associated with particular stages of disease development and progression. The median immunostaining intensity of eukaryotic translation elongation factor 1 alpha 1 (eEF1A1), one of the candidates identified, was significantly higher in osteoblasts in close proximity to metastatic tumour cells compared with osteoblasts in control bone (p = 0.0353, Mann Whitney U). Our proteomic approach has identified leads for potentially useful serum biomarkers associated with the metastatic progression of prostate cancer. The panels identified, including eEF1A1 warrant further investigation and validation.

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.

The role of nutraceuticals in chemoprevention and chemotherapy and their clinical outcomes

The genesis of cancer is often a slow process and the risk of developing cancer increases with age. Altering a diet that includes consumption of beneficial phytochemicals can influence the balance and availability of dietary chemopreventive agents. In chemopreventive approaches, foods containing chemicals that have anticancer properties can be supplemented in diets to prevent precancerous lesions from occurring. This necessitates further understanding of how phytochemicals can potently maintain healthy cells. Fortunately there is a plethora of plant-based phytochemicals although few of them are well studied in terms of their application as cancer chemopreventive and therapeutic agents. In this analysis we will examine phytochemicals that have strong chemopreventive and therapeutic properties in vitro as well as the design and modification of these bioactive compounds for preclinical and clinical applications. The increasing potential of combinational approaches using more than one bioactive dietary compound in chemoprevention or cancer therapy will also be evaluated. Many novel approaches to cancer prevention are on the horizon, several of which are showing great promise in saving lives in a cost-effective manner.

Periostin identified as a potential biomarker of prostate cancer by iTRAQ-proteomics analysis of prostate biopsy

BACKGROUND

Proteomics may help us better understand the changes of multiple proteins involved in oncogenesis and progression of prostate cancer(PCa) and identify more diagnostic and prognostic biomarkers. The aim of this study was to screen biomarkers of PCa by the proteomics analysis using isobaric tags for relative and absolute quantification(iTRAQ).

METHODS

The patients undergoing prostate biopsies were classified into 3 groups according to pathological results: benign prostate hyperplasia (BPH, n = 20), PCa(n = 20) and BPH with local prostatic intraepithelial neoplasm(PIN, n = 10). Then, all the specimens from these patients were analyzed by iTRAQ and two-dimensional liquid chromatography-tandem mass spectrometry (2DLC-MS/MS). The Gene Ontology(GO) function and the transcription regulation networks of the differentially expressed were analyzed by MetaCore software. Western blotting and Immunohistochemical staining were used to analyze the interesting proteins.

RESULT

A total of 760 proteins were identified from 13787 distinct peptides, including two common proteins that enjoy clinical application: prostate specific antigen (PSA) and prostatic acid phosphatase(PAP). Proteins that expressed differentially between PCa and BPH group were further analyzed. Compared with BPH, 20 proteins were significantly differentially up-regulated (>1.5-fold) while 26 were significantly down-regulated in PCa(<0.66-fold). In term of GO database, the differentially expressed proteins were divided into 3 categories: cellular component(CC), molecular function (MF) and biological process(BP). The top 5 transcription regulation networks of the differentially expressed proteins were initiated through activation of SP1, p53, YY1, androgen receptor(AR) and c-Myc The overexpression of periostin in PCa was verified by western blotting and immunohistochemical staining.

CONCLUSION

Our study indicates that the iTRAQ technology is a new strategy for global proteomics analysis of the tissues of PCa. A significant up-regulation of periostin in PCa compared to BPH may provide clues for not only a promising biomarker for the prognosis of PCa but also a potential target for therapeutical intervention.