Expression and amplification of eIF-5A2 in human epithelial ovarian tumors and overexpression of EIF-5A2 is a new independent predictor of outcome in patients with ovarian carcinoma

Unveiling EIF5A2: A multifaceted player in cellular regulation, tumorigenesis and drug resistance

The eukaryotic initiation factor 5A2 gene (EIF5A2) is a highly conserved and multifunctional gene that significantly influences various cellular processes, including translation elongation, RNA binding, ribosome binding, protein binding and post-translational modifications. Overexpression of EIF5A2 is frequently observed in multiple cancers, where it functions as an oncoprotein. Additionally, EIF5A2 is implicated in drug resistance through the regulation of various molecular pathways. In the review, we describe the structure and functions of EIF5A2 in normal cells and its role in tumorigenesis. We also elucidate the molecular mechanisms associated with EIF5A2 in the context of tumorigenesis and drug resistance. We propose that the biological roles of EIF5A2 in regulating diverse cellular processes and tumorigenesis are clinically significant and warrant further investigation.

Knockout or inhibition of DHPS suppresses ovarian tumor growth and metastasis by attenuating the TGFβ pathway

Deoxyhypusine synthase (DHPS) is an enzyme encoded by the DHPS gene, with high expression in various cancers, including ovarian cancer (OC). DHPS regulates the translation initiation factor EIF5A, and EIF5A2 knockout inhibits OC tumor growth and metastasis by blocking the epithelial-to-mesenchymal transition (EMT) and the TGFβ pathway. In this study, we show that DHPS is amplified in OC patients, and its elevated expression correlates with poor survival. Using lentiviral CRISPR/Cas9 vectors for DHPS knockout, we observed EMT inhibition in SKOV3 and OVCAR8 cells through suppressed hypusination and reduced EIF5A2 expression. Inhibition of DHPS activity with GC7 similarly blocked hypusination and EMT. Disrupting DHPS expression, either genetically or pharmacologically, inhibited primary tumor growth and metastasis in OC mouse models. These findings suggest that targeting DHPS and inhibiting hypusination could be promising strategies for OC treatment.

Ribosomal rodeo: wrangling translational machinery in gynecologic tumors

Gynecologic cancers are a significant cause of morbidity and mortality among women worldwide. Despite advancements in diagnosis and treatment, the molecular mechanisms underlying the development and progression of these cancers remain poorly understood. Recent studies have implicated translational machinery (ribosomal proteins (RPs) and translation factors (TFs)) as potential drivers of oncogenic processes in various cancer types, including gynecologic cancers. RPs are essential components of the ribosome, which is responsible for protein synthesis. In this review paper, we aim to explore the role of translational machinery in gynecologic cancers. Specifically, we will investigate the potential mechanisms by which these components contribute to the oncogenic processes in these cancers and evaluate the feasibility of targeting RPs as a potential therapeutic strategy. By doing so, we hope to provide a broader view of the molecular pathogenesis of gynecologic cancers and highlight their potential as novel therapeutic targets for the management of these challenging diseases.

Insights into eukaryotic translation initiation factor 5A: Its role and mechanisms in protein synthesis

The protein synthesis within eukaryotic cells is a complex process involving various translation factors. Among these factors, eukaryotic translation initiation factor 5 A (eIF5A) emerges as a crucial translation factor with high evolutionary conservation. eIF5A is unique as it is the only protein in eukaryotic cells containing the hypusine modification. Initially presumed to be a translation initiation factor, eIF5A was subsequently discovered to act mainly during the translation elongation phase. Notably, eIF5A facilitates the translation of peptide sequences containing polyproline stretches and exerts a universal regulatory effect on the elongation and termination phases of protein synthesis. Additionally, eIF5A indirectly affects various physiological processes within the cell by modulating the translation of specific proteins. This review provides a comprehensive overview of the structure, physiological functions, various post-translational modifications of eIF5A, and its association with various human diseases. The comparison between eIF5A and its bacterial homolog, EF-P, extends the discussion to the evolutionary conservation of eIF5A. This highlights its significance across different domains of life.

Prognostic value of EIF5A2 in solid tumors: A meta-analysis and bioinformatics analysis

Aims

In cancer biology, the aberrant overexpression of eukaryotic translation initiation factor 5A2 (EIF5A2) has been correlative with an ominous prognosis, thereby underscoring its pivotal role in fostering metastatic progression. Consequently, EIF5A2 has garnered significant attention as a compelling prognostic biomarker for various malignancies. Our research endeavors were thus aimed at elucidating the utility and significance of EIF5A2 as a robust indicator of cancer outcome prediction.

Method

An exhaustive search of the PubMed, EMBASE, and Web of Science databases found relevant studies. The link between EIF5A2 and survival prognosis was examined using hazard ratios and 95% confidence intervals. Subsequently, The Cancer Genome Atlas (TCGA) and the Gene Expression Profiling Interactive Analysis (GEPIA) databases were employed to validate EIF5A2 expression across various cancer types.

Results

Through pooled analysis, we found that increased EIF5A2 expression was significantly associated with decreased overall survival (OS) and disease-free survival/progression-free survival/relapse-free survival (DFS/PFS/RFS). Moreover, TCGA analysis revealed that EIF5A2 was significantly upregulated in 27 types of cancer, with overexpression being linked to shorter OS in three, worse DFS in two, and worse PFS in six types of cancer. GEPIA showed that patients with EIF5A2 overexpression had reduced OS and DFS.

Conclusions

In solid tumors, EIF5A2 emerges as a reliable prognostic marker. Our meta-analysis comprehensively analyzed the prognostic value of EIF5A2 in solid tumors and assessed its efficacy as a predictive marker.

Long non-coding RNA RAD51-AS1 promotes the tumorigenesis of ovarian cancer by elevating EIF5A2 expression

PURPOSE

The present study aims to determine the molecular mechanism mediated by RAD51 antisense RNA 1 (RAD51-AS1) in ovarian cancer (OvCA).

METHODS

The data associated with RAD51-AS1 in OvCA were obtained from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) database. Relative expression of RAD51-AS1 was detected. Determination of cell proliferation, metastasis, and invasion was performed by cell counting, colony formation, would-healing, and transwell invasion assays. Protein levels were detected by western blotting. The molecular mechanism mediated by RAD51-AS1 was predicted by bioinformatics analysis and verified by dual-luciferase reporter assays. Subcutaneous tumorigenesis models were used to confirm the function of RAD51-AS1 in vivo.

RESULTS

Data from TCGA and GEO showed that RAD51-AS1 was associated with poor prognosis in OvCA patients and DNA repair, cell cycle, focal adhesion, and apoptosis in SKOV3.ip cells. High levels of RAD51-AS1 were detected in OvCA cells. Overexpressing RAD51-AS1 enhanced the proliferative, invading, and migratory capabilities of OvCA cells in vitro while silencing RAD51-AS1 exhibited the opposite effects. Mechanically, RAD51-AS1 elevated eukaryotic initiation factor 5A2 (EIF5A2) expression as a sponge for microRNA (miR)-140-3p. Finally, the role of RAD51-AS1 was verified by subcutaneous tumorigenesis models.

CONCLUSION

RAD51-AS1 promoted OvCA progression by the regulation of the miR-140-3p/EIF5A2 axis, which illustrated the potential therapeutic target for OvCA.

Hypusination-induced DHPS/eIF5A pathway as a new therapeutic strategy for human diseases: A mechanistic review and structural classification of DHPS inhibitors

The discovery of new therapeutic strategies for diseases is essential for drug research. Deoxyhypusine synthase (DHPS) is a critical enzyme that modifies the conversion of the eukaryotic translation initiation factor 5A (eIF5A) precursor into physiologically active eIF5A (eIF5A-Hyp). Recent studies have revealed that the hypusine modifying of DHPS on eIF5A has an essential regulatory role in human diseases. The hypusination-induced DHPS/eIF5A pathway has been shown to play an essential role in various cancers, and it could regulate immune-related diseases, glucose metabolism-related diseases, neurological-related diseases, and aging. In addition, DHPS has a more defined substrate and a well-defined structure within the active pocket than eIF5A. More and more researchers are focusing on the prospect of advanced development of DHPS inhibitors. This review summarizes the regulatory mechanisms of the hypusination-induced DHPS/eIF5A pathway in a variety of diseases in addition to the inhibitors related to this pathway; it highlights and analyzes the structural features and mechanisms of action of DHPS inhibitors and expands the prospects of future drug development using DHPS as an anticancer target.

High levels of hypusinated eIF5A in leiomyoma and leiomyosarcoma pathologies: a possible novel therapeutic target

RESEARCH QUESTION

Is the hypusinated form of the eukaryotic translation initiation factor 5A (EIF5A) present in human myometrium, leiomyoma and leiomyosarcoma, and does it regulate cell proliferation and fibrosis?

DESIGN

The hypusination status of eIF5A in myometrial and leiomyoma patient-matched tissues was evaluated by immunohistochemistry and Western blotting as well as in leiomyosarcoma tissues by immunohistochemistry. Myometrial, leiomyoma and leiomyosarcoma cell lines were treated with N1-guanyl-1,7-diaminoheptane (GC-7), responsible for the inhibition of the first step of eIF5A hypunization, and the proliferation rate was determined by MTT assay; fibronectin expression was analysed by Western blotting. Finally, expression of fibronectin in leiomyosarcoma tissues was detected by immunohistochemistry.

RESULTS

The hypusinated form of eIF5A was present in all tissues examined, with an increasing trend of hypusinated eIF5A levels from normal myometrium to neoplastic benign leiomyoma up to neoplastic malignant leiomyosarcoma. The higher levels in leiomyoma compared with myometrium were confirmed by Western blotting (P = 0.0046). The inhibition of eIF5A hypusination, with GC-7 treatment at 100 nM, reduced the cell proliferation in myometrium (P = 0.0429), leiomyoma (P = 0.0030) and leiomyosarcoma (P = 0.0044) cell lines and reduced the expression of fibronectin in leiomyoma (P = 0.0077) and leiomyosarcoma (P = 0.0280) cells. The immunohistochemical staining of leiomyosarcoma tissue revealed that fibronectin was highly expressed in the malignant aggressive (central) part of the leiomyosarcoma lesion, where hypusinated eIF5A was also highly represented.

CONCLUSIONS

These data support the hypothesis that eIF5A may be involved in the pathogenesis of myometrial benign and malignant pathologies.

iCancer-Pred: A tool for identifying cancer and its type using DNA methylation

DNA methylation is an important epigenetics, which occurs in the early stages of tumor formation. And it also is of great significance to find the relationship between DNA methylation and cancer. This paper proposes a novel model, iCancer-Pred, to identify cancer and classify its types further. The datasets of DNA methylation information of 7 cancer types have been collected from The Cancer Genome Atlas (TCGA). The coefficient of variation firstly is used to reduce the number of features, and then the elastic network is applied to select important features. Finally, a fully connected neural network is constructed with these selected features. In predicting seven types of cancers, iCancer-Pred has achieved an overall accuracy of over 97% accuracy with 5-fold cross-validation. For the convenience of the application, a user-friendly web server: http://bioinfo.jcu.edu.cn/cancer or http://121.36.221.79/cancer/ is available. And the source codes are freely available for download at https://github.com/Huerhu/iCancer-Pred.

Extrachromosomal circular DNA: biogenesis, structure, functions and diseases

Extrachromosomal circular DNA (eccDNA), ranging in size from tens to millions of base pairs, is independent of conventional chromosomes. Recently, eccDNAs have been considered an unanticipated major source of somatic rearrangements, contributing to genomic remodeling through chimeric circularization and reintegration of circular DNA into the linear genome. In addition, the origin of eccDNA is considered to be associated with essential chromatin-related events, including the formation of super-enhancers and DNA repair machineries. Moreover, our understanding of the properties and functions of eccDNA has continuously and greatly expanded. Emerging investigations demonstrate that eccDNAs serve as multifunctional molecules in various organisms during diversified biological processes, such as epigenetic remodeling, telomere trimming, and the regulation of canonical signaling pathways. Importantly, its special distribution potentiates eccDNA as a measurable biomarker in many diseases, especially cancers. The loss of eccDNA homeostasis facilitates tumor initiation, malignant progression, and heterogeneous evolution in many cancers. An in-depth understanding of eccDNA provides novel insights for precision cancer treatment. In this review, we summarized the discovery history of eccDNA, discussed the biogenesis, characteristics, and functions of eccDNA. Moreover, we emphasized the role of eccDNA during tumor pathogenesis and malignant evolution. Therapeutically, we summarized potential clinical applications that target aberrant eccDNA in multiple diseases.

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

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

Long non-coding RNA HNF1A-AS1 induces 5-FU resistance of gastric cancer through miR-30b-5p/EIF5A2 pathway

BACKGROUND

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide and chemoresistance is a major cause for its poor prognosis. Long non-coding RNAs (lncRNAs) are associated with cancer chemoresistance. The current study sought to explore the mechanism of lncRNA HNF1A antisense RNA 1 (HNF1A-AS1) in mediating 5-fluorouracil (5-FU) resistance of GC.

METHODS

qRT-PCR was performed to detect the expression level of HNF1A-AS1 in GC tissues and cells. Abnormal expression of HNF1A-AS1 in GC cells was induced by lentivirus infection. Protein levels of EIF5A2, E-Cadherin, Vimentin and N-Cadherin were detected using western blot. Competitive endogenous RNA (ceRNA) mechanisms were explored through luciferase assays and RNA immunoprecipitation (RIP) assays. Functional experiments of chemoresistance were performed by CCK-8 assays, colony formation assays and flow cytometry with the treatment of 5-FU. Mouse tumor xenograft assays were performed to verify the findings in vivo.

RESULTS

The findings showed HNF1A-AS1 was significantly upregulated in GC tissues especially in chemoresistance group. Findings from in vitro and in vivo experiments showed HNF1A-AS1 increased cell viability and proliferation, repressed apoptosis and promoted xenograft tumors growth in the presence of 5-FU. Mechanistic studies revealed HNF1A-AS1 promoted chemoresistance by facilitating epithelial mesenchymal transition (EMT) process through upregulating EIF5A2 expression and HNF1A-AS1 acted as a sponge of miR-30b-5p.

CONCLUSIONS

The findings from the current study showed HNF1A-AS1 promoted 5-FU resistance by acting as a ceRNA of miR-30b-5p and promoting EIF5A2-induced EMT process in GC. This indicates that HNF1A-AS1 is a potential therapeutic target for alleviating GC chemoresistance.

Role of RONS and eIFs in Cancer Progression

Various research works have piled up conflicting evidence questioning the effect of oxidative stress in cancer. Reactive oxygen and nitrogen species (RONS) are the reactive radicals and nonradical derivatives of oxygen and nitrogen. RONS can act as a double-edged weapon. On the one hand, RONS can promote cancer initiation through activating certain signal transduction pathways that direct proliferation, survival, and stress resistance. On the other hand, they can mitigate cancer progression via their resultant oxidative stress that causes many cancer cells to die, as some recent studies have proposed that high RONS levels can limit the survival of cancer cells during certain phases of cancer development. Similarly, eukaryotic translation initiation factors are key players in the process of cellular transformation and tumorigenesis. Dysregulation of such translation initiation factors in the form of overexpression, downregulation, or phosphorylation is associated with cancer cell's altering capability of survival, metastasis, and angiogenesis. Nonetheless, eIFs can affect tumor age-related features. Data shows that alternating the eukaryotic translation initiation apparatus can impact many downstream cellular signaling pathways that directly affect cancer development. Hence, researchers have been conducting various experiments towards a new trajectory to find novel therapeutic molecular targets to improve the efficacy of anticancer drugs as well as reduce their side effects, with a special focus on oxidative stress and initiation of translation to harness their effect in cancer development. An increasing body of scientific evidence recently links oxidative stress and translation initiation factors to cancer-related signaling pathways. Therefore, in this review, we present and summarize the recent findings in this field linking certain signaling pathways related to tumorigeneses such as MAPK and PI3K, with either RONS or eIFs.

EIF5A expression and its role as a potential diagnostic biomarker in hepatocellular carcinoma

Introduction and objectives: Eukaryotic translation initiation factor 5A (EIF5A) is a member of the identified eIF family and played an important role in cell proliferation. There are few studies about the correlation between EIF5A and hepatocellular carcinoma (HCC).

Materials and methods: We evaluated the expression of the EIF5A in human HCC cell lines and tissues by western blot analysis. Immunohistochemistry analysis of EIF5A was performed on a tissue microarray including 10 normal liver samples and 90 pathological section of HCC. Receiver operating characteristic (ROC) was introduced to obtain an optimal cut-off score for EIF5A positive expression.

Results: Western blot results showed that EIF5A was highly expressed in HCC cell lines and tissues. Based on ROC curve analysis, 1/10 (10.0%) of normal hepatic tissues and 67/90 (74.4%) of HCC tissues were tested positive for EIF5A expression, which indicated that EIF5A were significantly up-regulated in HCC tissues compared with normal liver tissues (χ²=17.177, P<0.001). Furthermore, expression of EIF5A was significantly correlated with histological grade (P=0.048), clinical stage (P=0.003) and pT stage (P=0.003) but not correlated with sex (P=0.617) and age (P=0.831).

Conclusions: In our study, we demonstrated the expression of EIF5A is closely correlated with HCC. In consideration of its relationship with clinicopathological parameters including histological grade, clinical stage and pT stage of HCC, EIF5A could be a potential biomarker.

Multifaceted control of mRNA translation machinery in cancer

The mRNA translation machinery is tightly regulated through several, at times overlapping, mechanisms that modulate its efficiency and accuracy. Due to their fast rate of growth and metabolism, cancer cells require an excessive amount of mRNA translation and protein synthesis. However, unfavorable conditions, such as hypoxia, amino acid starvation, and oxidative stress, which are abundant in cancer, as well as many anti-cancer treatments inhibit mRNA translation. Cancer cells adapt to the various internal and environmental stresses by employing specialised transcript-specific translation to survive and gain a proliferative advantage. We will highlight the major signaling pathways and mechanisms of translation that regulate the global or mRNA-specific translation in response to the intra- or extra-cellular signals and stresses that are key components in the process of tumourigenesis.

EIF5A2 enhances stemness of epithelial ovarian cancer cells via a E2F1/KLF4 axis

BACKGROUND

Ovarian cancer stem cells (OCSC), endowed with tumor-initiating and self-renewal capacity, would account not only for the tumor growth, the peritoneal metastasis, and the relapse, but also for the acquisition of chemotherapy resistance. Nevertheless, figuring out their phenotypical and functional traits has proven quite challenging, mainly because of the heterogeneity of ovarian cancer. A deeper understanding of OCSC mechanisms will shed light on the development of the disease. Therefore, we aim to explore it for the design of innovative treatment regimens which aim at the eradication of ovarian cancer through the elimination of the CSC component.

METHODS

In this study, immunohistochemistry assay and western blot assay were used to detect protein expression in the primary tumor and peritoneal multi-cellular aggregates/spheroids (MCAs/MCSs). OCSCs induced from cell line SKOV3 and HO-8910 were enriched in a serum-free medium (SFM). The effect of EIF5A2 on CSC-like properties was detected by sphere-forming assays, re-differentiation assays, quantitative real-time polymerase chain reaction, western blotting, flow cytometry, cell viability assays, immunofluorescence staining, and in vivo xenograft experiments. RNA-sequencing (RNA-seq) was used to reveal the mechanism by which EIF5A2 positively modulates the stem-like properties of ovarian cancer cells.

RESULTS

Expression of EIF5A2 was significantly higher in peritoneal MCAs/MCSs compared to matched primary tumors, and EIF5A2 was also unregulated in ovarian cancer cell line-derived spheroids. Knockdown of EIF5A2 reduced the expression of the stem-related markers (ALDH1A1 and OCT-4), inhibited self-renewal ability, improved the sensitivity to chemotherapeutic drugs, and inhibited tumorigenesis in vivo. Mechanistic studies revealed that EIF5A2 knockdown reduced the expression of KLF4, which could partially rescue stem-like properties abolished by EIF5A2 knockdown or strengthened by EIF5A2 overexpression, through the transcription factor E2F1, which directly bind to KLF4 promoter.

CONCLUSION

Our results imply that EIF5A2 positively regulates stemness in ovarian cancer cells via E2F1/KLF4 pathway and may serve as a potential target in CSCs-targeted therapy for ovarian cancer.

Eukaryotic translation initiation factor 5A in the pathogenesis of cancers

Cancer is the leading cause of death worldwide. The absence of obvious symptoms and insufficiently sensitive biomarkers in early stages of carcinoma limits early diagnosis. Cancer therapy agents and targeted therapy have been used extensively against tissues or organs of specific cancers. However, the intrinsic and/or acquired resistance to the agents or targeted drugs as well as the serious toxic side effects of the drugs would limit their use. Therefore, identifying biomarkers involved in tumorigenesis and progression represents a challenge for cancer diagnosis and therapeutic strategy development. The eukaryotic translation factor 5A (eIF5A), originally identified as an initiation factor, was later shown to promote translation elongation of iterated proline sequences. There are two eIF5A isoforms (eIF5A1 and eIF5A2). eIF5A2 protein consists of 153 residues, and shares 84% amino acid identity with eIF5A1. However, the biological functions of these two isoforms may be significantly different. Recently, it was demonstrated that eIF5Ais widely involved in the pathogenesis of a number of diseases, including cancers. In particular, eIF5A plays an important role in regulating tumor growth, invasion, metastasis and tumor microenvironment. It was also shown to serve as a potential biomarker and target for the diagnosis and treatment of cancers. The present review briefly discusses the latest findings of eIF5A in the pathogenesis of certain malignant cancers and evolving clinical applications.

Overexpression of EIF5A2 Predicts Poor Prognosis in Patients with Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common epithelial malignancy affecting the oral cavity, and it is especially significant in Asian countries. Patients diagnosed with OSCC have an unfavorable prognosis and additional prognostic markers would help improve therapeutic strategies. We sought to investigate the association between eukaryotic translation initiation factor 5A2 (EIF5A2) and epithelial-mesenchymal transition (EMT) markers as well as the prognostic significance of EIF5A2 in OSCC. The expression of EIF5A2 and EMT markers was measured through the immunohistochemical staining of specimens from 272 patients with OSCC. In addition, the correlation between different clinicopathological factors and EIF5A2 expression was analyzed. The prognostic role of EIF5A2 was then analyzed via Kaplan-Meier analysis and Cox proportional hazard models. Among the 272 patients, high EIF5A2 expression was significantly associated with an advanced N value (p = 0.008). High tumor expression of EIF5A2 was prone to the expression of low E-cadherin and high beta-catenin (p = 0.046 and p = 0.020, respectively). Patients with high EIF5A2 expression had unfavorable five-year survival rates as compared with those with low expression (49.7% and 67.3%, respectively). The prognostic role of EIF5A2 was further confirmed through multivariate analysis (hazard ratio = 1.714, 95% confidence interval: 1.134-2.590, p = 0.011). High EIF5A2 expression is associated with an advanced N value and EMT markers and may serve as a marker for an unfavorable prognosis in patients with OSCC.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial-mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell-cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.

Overexpression of EIF5A2 is associated with poor survival and aggressive tumor biology in gallbladder cancer

Gallbladder cancer (GBC) is a malignant tumor of the biliary tract. The main problem affecting the treatment of gallbladder cancer is late diagnosis and poor prognosis. EIF5A2 is one of two isoforms of the EIF5A family and is reported to be a new oncogenic protein in many human cancers. In this study, our results showed for the first time that EIF5A2 was overexpressed in GBC samples compared with non-tumor tissue. Overexpression of EIF5A2 was associated with lymph node metastasis, tumor differentiation, UICC (Union for International Cancer Control) staging, histological type, metastasis, and tumor size. Overexpression of EIF5A2 in gallbladder carcinoma tissues is also associated with poor prognosis in patients. The interference of EIF5A2 significantly inhibited the proliferation, cell cycle, migration and colony formation of GBC-SD cells in vitro. Our results suggest that EIF5A2 is a target oncogene and may be an important prognostic biomarker in the pathogenesis of gallbladder cancer.

Recent insights into eukaryotic translation initiation factors 5A1 and 5A2 and their roles in human health and disease

The eukaryotic translation initiation factor 5A1 (eIF5A1) and its homolog eIF5A2 are the only two human proteins containing the unique post-translational modification-hypusination, which is essential for the function of these two proteins. eIF5A1 was initially identified as a translation initiation factor by promoting the first peptide bond formation of protein during translation; however, recent results suggest that eIF5A1 also functions as a translation elongation factor. It has been shown that eIF5A1 is implicated in certain human diseases, including diabetes, several human cancer types, viral infections and diseases of neural system. Meanwhile, eIF5A2 is overexpressed in many cancers, and plays an important role in the development and progression of cancers. As multiple roles of these two factors were observed among these studies, therefore, it remains unclear whether they act as oncogene or tumor suppressor. In this review, the recent literature of eIF5As and their roles in human diseases, especially in human cancers, will be discussed.

Thermo-chemotherapy inhibits the proliferation and metastasis of gastric cancer cells via suppression of EIF5A2 expression

Purpose

Thermo-chemotherapy (TCT) is a new approach for the treatment of cancer that combines chemotherapy with thermotherapy. In the present study, we investigated the relationship between eukaryotic translation initiation factor 5A2 (EIF5A2) and TCT sensitivity in gastric cancer (GC) to further illuminate the molecular mechanism underlying the effect of TCT on GC.

Methods

A TCT cell model was constructed, and EIF5A2 was silenced or overexpressed by infection with a lentivirus expressing either EIF5A2 or EIF5A2 shRNA. Then, RT-qPCR, Western blotting, and immunohistochemistry assays were performed to evaluate the changes in the expression levels of EIF5A2, c-myc, vimentin, and E-cadherin. Cell proliferation and xenograft assays were conducted to evaluate the effect on cell proliferation. Finally, wound-healing and Transwell invasion assays were performed to evaluate the effects on migration and invasion.

Results

TCT reduced EIF5A2 expression at both the mRNA and protein levels. It also inhibited cell proliferation, migration, and invasion, downregulated the expression of c-myc and vimentin, and increased the expression of E-cadherin in both MKN28 and MKN45 cells. Silencing of EIF5A2 enhanced the above effects of TCT on MKN28 and MKN45 cells, while overexpression of EIF5A2 had the opposite effects. In addition, EIF5A2 overexpression weakened the inhibitory effect of TCT on tumor growth in vivo as well as the effects on c-myc, vimentin, and E-cadherin.

Conclusion

TCT inhibits GC cell proliferation and metastasis by suppressing EIF5A2 expression. Our results provide new insights into our understanding of the molecular mechanism underlying the effects of TCT in GC.

Eukaryotic initiation factor 5A2 and human digestive system neoplasms

Eukaryotic initiation factor 5A2 (eIF5A2), as one of the two isoforms in the family, is reported to be a novel oncogenic protein that is involved in multiple aspects of many types of human cancer. Overexpression or gene amplification of EIF5A2 has been demonstrated in many cancers. Accumulated evidence shows that eIF5A2 initiates tumor formation, enhances cancer cell growth, increases cancer cell metastasis, and promotes treatment resistance through multiple means, including inducing epithelial–mesenchymal transition, cytoskeletal rearrangement, angiogenesis, and metabolic reprogramming. Expression of eIF5A2 in cancer correlates with poor survival, advanced disease stage, as well as metastasis, suggesting that eIF5A2 function is crucial for tumor development and maintenance but not for normal tissue homeostasis. All these studies suggest that eIF5A2 is a useful biomarker in the prediction of cancer prognosis and serves as an anticancer molecular target. This review focuses on the expression, subcellular localization, post-translational modifications, and regulatory networks of eIF5A2, as well as its biochemical functions and evolving clinical applications in cancer, especially in human digestive system neoplasms.

Overexpression of EIF5A2 in upper urinary tract urothelial carcinoma is a new independent prognostic marker of survival

Aim: To study the expression of EIF5A2 in urinary tract urothelial carcinoma and its clinicopathological features and prognosis. Methods: EIF5A2 expression was detected via immunohistochemistry in 101 patients. Results: Kaplan-Meier analysis showed that the EIF5A2 low expression group had significantly longer overall survival (OS; p < 0.001) and progression-free survival (PFS; p < 0.001) than the EIF5A2 high expression group. The high expression of EIF5A2 significantly predict poor OS and PFS in the subset patients (p < 0.05). EIF5A2 was an independent prognostic factor for OS and PFS (p = 0.003 and p = 0.001). The established nomogram model and its calibration curve predicted the probability of survival accurately. Conclusion: EIF5A2 is a potential molecular marker of poor prognosis in urinary tract urothelial carcinoma.

Eukaryotic translation initiation factor 5A2 is highly expressed in prostate cancer and predicts poor prognosis

Eukaryotic translation initiation factor (EIF) 5A2 exerts important functions that regulate the development and progression of cancers. The present study aimed to investigate the expression of EIF5A2 in prostate cancer (PCa) and its association with biological and prognostic significance. EIF5A2 mRNA and protein levels were analyzed in three paired samples of freshly resected PCa and adjacent non-tumor tissues. Immunohistochemical staining was used to detect the expression of EIF5A2 protein levels in 72 paraffin-embedded PCa tumor specimens. Subsequently, the association between EIF5A2 protein expression and clinicopathological parameters was assessed. Semi-quantitative reverse transcription-polymerase chain reaction and western blot analyses showed both EIF5A2 mRNA and protein levels were elevated in PCa compared with adjacent non-tumor tissues. Elevated EIF5A2 protein levels were observed in 73.6% (53/72) of the clinical PCa tissues using immunohistochemical staining. EIF5A2 expression was significantly associated with tumor stage (P=0.011) and biochemical recurrence status (P=0.032). Additionally, high levels of EIF5A2 predicted worse progression-free survival (P=0.007). Multivariate Cox regression analysis indicated that high expression of EIF5A2 was an independent prognostic factor for poor progression-free survival (hazard ratios, 0.366; 95% confidence interval, 0.349-0.460; P=0.021). The present study demonstrated that EIF5A2 is overexpressed in prostate cancer and may be a potential predictor and therapeutic target in PCa patients.

Prognostic value of AIB1 and EIF5A2 in intravesical recurrence after surgery for upper tract urothelial carcinoma

Objectives

The aim of this study was to investigate the prognostic effect of amplified in AIB1 and EIF5A2 expression on postoperative intravesical recurrence for upper urinary tract urothelial carcinoma (UTUC) and improve postoperative risk stratification and prediction of intravesical chemotherapy benefit.

Materials and methods

We evaluated immunohistochemical expression of AIB1 and EIF5A2 in 109 UTUC patients to determine the predictive significance in intravesical recurrence. A prognostic model was developed based on univariate and multivariate analyses.

Results

Intravesical recurrence occurred in 18 out of the 109 (16.5%) patients during the follow-up period. Significant associations of high expression of AIB1 and EIF5A2 with shortened bladder recurrence interval (median: 24 months vs 46 months, P=0.021; 28 months vs 39 months, P=0.002) were demonstrated. In different subsets of UTUC patients, high expression of AIB1 was a prognostic indicator in high grade (P=0.006) and pT2–4 (P=0.007), and high expression of EIF5A2 for high grade (P=0.014), pT2–4 (P=0.002) and pN0 (P=0.009). Moreover, in multivariate analysis, AIB1 and EIF5A2 expression (P=0.034 and 0.022, respectively) together with pN stage (P=0.009) provided significant independent predictors for intravesical recurrence after surgery for UTUC. Surgical approach with radical nephroureterectomy (RNU) was an informative factor toward good oncologic outcomes for intravesical recurrence (P=0.056). Based on a prognostic model with these factors, patients with UTUC were classified into the low-risk group and the high-risk group. In a subset analysis, the patients in the high-risk group were found to have a favorable response to intravesical chemotherapy (P=0.047). A nomogram based on the multivariate analysis was developed to predict intravesical recurrence accurately and guide postoperative intravesical instillations. The concordance index (c-index) of this model was 0.806.

Conclusion

High expression of AIB1 and EIF5A2 were independent predictors for intravesical recurrence after RNU and might be able to predict which patients benefit from postoperative intravesical chemotherapy.

EIF5A1 promotes epithelial ovarian cancer proliferation and progression

Epithelial ovarian cancer (EOC) is one of the most common gynecological cancers and has the highest mortality rate thereof. We found abundant eukaryotic translation initiation factor 5A1 (EIF5A1) in 54 EOC tissues, and high EIF5A1 levels predicted poor survival. EIF5A1 ectopic expression enhanced EOC cell proliferative, migration, and invasive capabilities, while EIF5A1 knockdown suppressed them. Most importantly, GC7 (N1-guanyl-1,7-diaminoheptane, an EIF5A1 hypusination inhibitor) could reverse the effect of EIF5A1 upregulation on EOC cell proliferation, migration, and invasion and mutant type EIF5A1K50A plasmid [bearing a single point mutation (K50 → A50) that prevents hypusination] had no effects on these malignant behaviors. Our findings imply that EIF5A1 is a vital regulator of EOC proliferation and progression and is a potential prognostic marker and therapeutic target in EOC.

Eukaryotic Initiation Factor 5A2 Contributes to the Maintenance of CD133(+) Hepatocellular Carcinoma Cells via the c-Myc/microRNA-29b Axis

Cancer stem cells (CSCs)/cancer-initiating cells (CICs) are suggested responsible for driving cancer resistance to conventional therapies and for cancer recurrence and/or metastasis. CD133 is served as a key biomarker to identify and characterize this subpopulation of cells in hepatocellular carcinoma (HCC). Our previous study indicated that overexpression of eukaryotic initiation factor 5A2 (EIF5A2) promotes HCC cell metastasis and angiogenesis. In this study, we demonstrated that EIF5A2 might play a crucial role in CSCs regulation and investigated its potential molecular mechanisms. Using quantitative real-time polymerase chain reaction assay, we observed that the expression of EIF5A2 positively correlated with CD133 levels in a cohort of cancerous and noncancerous liver tissues and cells. Next, HCC cells with high expression of EIF5A2 have a strong capacity to form undifferentiated tumor spheres in vitro and show elevated levels of stem cell-related genes, leading to an increased ability to develop tumors when subcutaneously injected into nude mice. Furthermore, differential microRNA expression was profiling between two EIF5A2-depleted HCC cell lines and their control one identified a decreased expression of miR-29b in EIF5A2-depleted cell lines. Further functional studies illustrated that downregulated miR-29b level is responsible for EIF5A2-maintained HCC cell stemness either in vitro or in vivo. Moreover, enforced expression of EIF5A2 in HCC cells largely enhanced the binding of c-Myc on the promoter of miR-29b and downregulation of miR-29b by EIF5A2 was dependent on c-Myc. Our findings, collectively, reveal that EIF5A2 contributes to the maintenance of CD133+ HCC cells via the c-Myc/miR-29b axis. Stem Cells 2018;36:180-191.

MicroRNA-9 enhances sensitivity to cetuximab in epithelial phenotype hepatocellular carcinoma cells through regulation of the eukaryotic translation initiation factor 5A-2

Hepatocellular carcinoma (HCC) is one of the most widespread malignant human tumors worldwide. Treatment options include radiotherapy, surgical intervention and chemotherapy; however, drug resistance is an ongoing treatment concern. In the present study, the effects of a microRNA (miR/miRNA), miR-9, on the sensitivity of HCC cell lines to the epidermal growth factor receptor inhibitor, cetuximab, were examined. miR-9 has been proposed to serve a role in tumorigenesis and tumor progression. In the present study, bioinformatics analyses identified the eukaryotic translation initiation factor 5A2 (eIF-5A-2) as a target of miR-9. The expression levels of miR-9 and eIF-5A-2 were examined by reverse transcription-quantitative polymerase chain reaction and HCC cell lines were transfected with miR-9 mimics and inhibitors to determine the effects of the miRNA on cell proliferation and viability. The miR-9 mimic was revealed to significantly increase the sensitivity of epithelial phenotype HCC cells (Hep3B and Huh7) to cetuximab, while the miR-9 inhibitor triggered the opposite effect. There were no significant differences in sensitivity to cetuximab observed in mesenchymal phenotype HCC cells (SNU387 and SNU449). Cells lines displaying high expression levels of eIF-5A-2 were more resistant to cetuximab. Transfection of cells with a miR-9 mimic resulted in downregulation of the expression of eIF-5A-2 mRNA, while an miR-9 inhibitor increased expression. When expression of eIF-5A-2 was knocked down with siRNA, the effects of miR-9 on cetuximab sensitivity were no longer observed. Taken together, these data support a role for miR-9 in enhancing the sensitivity of epithelial phenotype HCC cells to cetuximab through regulation of eIF-5A-2.

Blocking Modification of Eukaryotic Initiation 5A2 Antagonizes Cervical Carcinoma via Inhibition of RhoA/ROCK Signal Transduction Pathway

Cervical carcinoma is one of the leading causes of cancer-related death for female worldwide. Eukaryotic initiation factor 5A2 belongs to the eukaryotic initiation factor 5A family and is proposed to be a key factor involved in the development of diverse cancers. In the current study, a series of in vivo and in vitro investigations were performed to characterize the role of eukaryotic initiation factor 5A2 in oncogenesis and metastasis of cervical carcinoma. The expression status of eukaryotic initiation factor 5A2 in 15 cervical carcinoma patients was quantified. Then, the effect of eukaryotic initiation factor 5A2 knockdown on in vivo tumorigenicity ability, cell proliferation, cell cycle distribution, and cell mobility of HeLa cells was measured. To uncover the mechanism driving the function of eukaryotic initiation factor 5A2 in cervical carcinoma, expression of members within RhoA/ROCK pathway was detected, and the results were further verified with an RhoA overexpression modification. The level of eukaryotic initiation factor 5A2 in cervical carcinoma samples was significantly higher than that in paired paratumor tissues ( P < .05). And the in vivo tumorigenic ability of HeLa cells was reduced by inhibition of eukaryotic initiation factor 5A2. Knockdown of eukaryotic initiation factor 5A2 in HeLa cells decreased the cell viability compared with normal cells and induced G1 phase cell cycle arrest ( P < .05). Moreover, the cell migration ability of eukaryotic initiation factor 5A2 knockdown cells was dramatically inhibited. Associated with alterations in phenotypes, RhoA, ROCK I, and ROCK II were downregulated. The above-mentioned changes in eukaryotic initiation factor 5A2 knockdown cells were alleviated by the overexpression of RhoA. The major findings outlined in the current study confirmed the potential of eukaryotic initiation factor 5A2 as a promising prognosis predictor and therapeutic target for cervical carcinoma treatment. Also, our data inferred that eukaryotic initiation factor 5A2 might function in carcinogenesis of cervical carcinoma through an RhoA/ROCK-dependent manner.

Separation of low and high grade colon and rectum carcinoma by eukaryotic translation initiation factors 1, 5 and 6

Colorectal cancer (CRC) is the third most common cause of cancer related death worldwide. Furthermore, with more than 1.2 million cases registered per year, it constitutes the third most frequent diagnosed cancer entity worldwide. Deregulation of protein synthesis has received considerable attention as a major step in cancer development and progression. Eukaryotic translation initiation factors (eIFs) are involved in the regulation of protein synthesis and are functionally linked to the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway. The identification of factors accounting for colorectal carcinoma (CRC) development is a major gap in the field. Besides the importance of eIF3 subunits and the eIF4 complex, eIF1, eIF5 and eIF6 were found to be altered in primary and metastatic CRC. We observed significant difference in the expression profile between low and high grade CRC. eIF1, eIF5 and eIF6 are involved in translational control in CRC. Our findings also indicate a probable clinical impact when separating them into low and high grade colon and rectum carcinoma. eIF and mTOR expression were analysed on protein and mRNA level in primary low and high grade colon carcinoma (CC) and rectum carcinoma (RC) samples in comparison to non-neoplastic tissue without any disease-related pathology. To assess the therapeutic potential of targeting eIF1, eIF5 and eIF6 siRNA knockdown in HCT116 and HT29 cells was performed. We evaluated the eIF knockdown efficacy on protein and mRNA level and investigated proliferation, apoptosis, invasion, as well as colony forming and polysome associated fractions. These results indicate that eIFs, in particular eIF1, eIF5 and eIF6 play a major role in translational control in colon and rectum cancer.

N1-guanyl-1, 7-diaminoheptane enhances the sensitivity of pancreatic ductal adenocarcinoma cells to gemcitabine via the inhibition of eukaryotic translation initiation factor 5A2

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy due to its broad resistance to chemotherapy. Gemcitabine is used as a standard chemotherapeutic drug for PDAC treatment, either alone or in combination with other chemotherapeutics. However, in patients with advanced disease, survival is rarely improved. This study aimed to investigate the therapeutic efficacy of N1-guanyl-1, 7-diaminoheptane (GC7) combined with gemcitabine in PDAC therapy. We measured eukaryotic translation initiation factor 5A2 (eIF5A2) expression and gemcitabine sensitivity in different PDAC cell lines (Panc-1, BxPC-3, and T3-M4). The synergistic cytotoxic effects of gemcitabine combined with GC7 were measured using Cell Counting Kit-8 assays. Western blots were performed to measure eIF5A2 and multi-drug resistance 1 (MDR1) protein expression in PDAC cells. The present findings demonstrated that combined treatment with GC7 and gemcitabine significantly inhibited PDAC cell line viability (P<0.05). EdU incorporation assays also indicated that GC7 co-treatment remarkably enhanced gemcitabine sensitivity in PDAC cells. Furthermore, downregulation of eIF5A2 diminished the regulatory role of GC7 in gemcitabine cytotoxicity. Western blotting data indicated that GC7 downregulated the expression of MDR1 while gemcitabine induced MDR1 upregulation. These findings showed that GC7 combination therapy may enhance the therapeutic efficacy of gemcitabine in PDAC by downregulating MDR1 expression.

New liver cancer biomarkers: PI3K/AKT/mTOR pathway members and eukaryotic translation initiation factors

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. The initiation of protein translation is an important rate-limiting step in eukaryotes and is crucial in many viral infections. Eukaryotic translation initiation factors (eIFs) are involved in the initiation step of protein translation and are linked to the phosphatidylinositol-3-kinases PI3K/AKT/mTOR pathway. Therefore we aimed to investigate a potential role of eIFs in HCC. We herein report on the immunohistochemical expression of the various eIF subunits in 235 cases of virus-related human HCC. Additionally, we used immunoblot analysis to investigate the expression of virus-related HCC and non-virus-related HCC in comparison to controls. Mammalian target of rapamycin (or mechanistic target of rapamycin as it is known now (mTOR) and activated mTOR were significantly increased in chronic hepatitis C (HCV)-associated HCC, in HCC without a viral background, in alcoholic liver disease and Wilson disease. pPTEN, phosphatase and tensin homologue (PTEN) and pAKT showed a significant increase in HBV- and HCV-associated HCC, chronic hepatitis B, HCC without a viral background, alcoholic steatohepatitis (ASH) and Wilson disease. Phosphorylated (p)-eIF2α, eIF2α, eiF3B, eIF3D, eIF3J, p-eIF4B, eIF4G and eIF6 were upregulated in HCV-associated HCC. eIF2α, p-eIF4B, eIF5 and various eIF3 subunits were significantly increased in chronic hepatitis B (HBV)-associated HCC. HCC without viral background displayed a significant increase for the eIF subunits p-2α, 3C, 3I, 4E and 4G. We noticed engraved differences in the expression pattern between chronic hepatitis B and C, HBV- and HCV-associated HCC and non-virus-related HCC.

Eukaryotic translation initiation factors and cancer

Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.

Eukaryotic translation initiation factor 5A2 promotes metabolic reprogramming in hepatocellular carcinoma cells

Reprogramming of intracellular metabolism is common in liver cancer cells. Understanding the mechanisms of cell metabolic reprogramming may present a new basis for liver cancer treatment. In our previous study, we reported that a novel oncogene eukaryotic translation initiation factor 5A2 (EIF5A2) promotes tumorigenesis under hypoxic condition. Here, we aim to investigate the role of EIF5A2 in cell metabolic reprogramming during hepatocellular carcinoma (HCC) development. In this study, we reported that the messenger RNA (mRNA) level of EIF5A2 was upregulated in 59 of 105 (56.2%) HCC clinical samples (P = 0.015), and EIF5A2 overexpression was significantly associated with shorter survival time of patients with HCC (P = 0.021). Ectopic expression of EIF5A2 in HCC cell lines significantly promoted cell growth and accelerated glucose utilization and lipogenesis rates. The high rates of glucose uptake and lactate secretion conferred by EIF5A2 revealed an abnormal activity of aerobic glycolysis in HCC cells. Several key enzymes involved in glycolysis including glucose transporter type 1 and 2, hexokinase 2, phosphofructokinase liver type, glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase M2 isoform, phosphoglycerate mutase 1 and lactate dehydrogenase A were upregulated by overexpression of EIF5A2. Moreover, EIF5A2 showed positive correlations with FASN and ACSS2, two key enzymes involved in the fatty acid de novo biosynthetic pathway, at both protein and mRNA levels in HCC. These results indicated that EIF5A2 may regulate fatty acid de novo biosynthesis by increasing the uptake of acetate. In conclusion, our findings demonstrate that EIF5A2 has a critical role in HCC cell metabolic reprogramming and may serve as a prominent novel therapeutic target for liver cancer treatment.

Role of Eukaryotic Initiation Factors during Cellular Stress and Cancer Progression

Protein synthesis can be segmented into distinct phases comprising mRNA translation initiation, elongation, and termination. Translation initiation is a highly regulated and rate-limiting step of protein synthesis that requires more than 12 eukaryotic initiation factors (eIFs). Extensive evidence shows that the transcriptome and corresponding proteome do not invariably correlate with each other in a variety of contexts. In particular, translation of mRNAs specific to angiogenesis, tumor development, and apoptosis is altered during physiological and pathophysiological stress conditions. In cancer cells, the expression and functions of eIFs are hampered, resulting in the inhibition of global translation and enhancement of translation of subsets of mRNAs by alternative mechanisms. A precise understanding of mechanisms involving eukaryotic initiation factors leading to differential protein expression can help us to design better strategies to diagnose and treat cancer. The high spatial and temporal resolution of translation control can have an immediate effect on the microenvironment of the cell in comparison with changes in transcription. The dysregulation of mRNA translation mechanisms is increasingly being exploited as a target to treat cancer. In this review, we will focus on this context by describing both canonical and noncanonical roles of eIFs, which alter mRNA translation.

Eukaryotic translation initiation factor 3 subunit D overexpression is associated with the occurrence and development of ovarian cancer

Ovarian cancer is the most common cause of gynaecological cancer-associated death; thus, promising biomarkers and new therapeutic targets for ovarian cancer must be explored. Here, we report that eukaryotic translation initiation factor 3 subunit D (EIF3D), a member of the EIF3 family, was overexpressed in ovarian cancer clinical tissues. Furthermore, the expression of EIF3D was correlated with the International Federation of Gynecology and Obstetrics stage and pathological differentiation stage. 3-(4,5-dimethylthylthiazol-2-yl)-2 (MTT) and colony formation assays revealed that the lentivirus-mediated knockdown of EIF3D suppresses cell proliferation in the ovarian tumour cell lines CAOV-3 and SKOV-3. Flow cytometry revealed that cells were arrested at the G2/M phase of the cell cycle and that cyclin-dependent kinase 1 was also altered after EIF3D silencing. The results presented here demonstrate that EIF3D may play an important role in the occurrence and development of ovarian cancer.

Targeting the polyamine-hypusine circuit for the prevention and treatment of cancer

The unique amino acid hypusine is present in only two proteins in eukaryotic cells, eukaryotic translation initiation factor 5A-1 (eIF5A1), and eIF5A2, where it is covalently linked to the lysine-50 residue of these proteins via a post-translational modification coined hypusination. This unique modification is directed by two highly conserved and essential enzymes, deoxyhypusine synthase (DHPS), and deoxyhypusine hydroxylase (DOHH), which selectively use the polyamine spermidine as a substrate to generate hypusinated eIF5A. Notably, elevated levels of polyamines are a hallmark of most tumor types, and increased levels of polyamines can also be detected in the urine and blood of cancer patients. Further, in-clinic agents that block the function of key biosynthetic enzymes in the polyamine pathway markedly impair tumor progression and maintenance of the malignant state. Thus, the polyamine pathway is attractive as a prognostic, prevention and therapeutic target. As we review, recent advances in our understanding of the specific functions of hypusinated eIF5A and its role in tumorigenesis suggest that the polyamine-hypusine circuit is a high priority target for cancer therapeutics.

Prognostic significance of the expression of nuclear eukaryotic translation initiation factor 5A2 in human melanoma

Eukaryotic translation initiation factor 5A2 (EIF5A2) expression is upregulated in various cancers. The present authors previously demonstrated that cytoplasmic EIF5A2 expression increases with melanoma progression and inversely correlates with patient survival. Other studies have suggested that nuclear EIF5A2 may also play a role in oncogenesis. The present study used immunohistochemistry and tissue microarray with a large number of melanocytic lesions (n=459) and demonstrated that nuclear EIF5A2 expression was significantly upregulated between common acquired nevi, dysplastic nevi and primary melanomas, and between primary melanomas and metastatic melanomas. Nuclear EIF5A2 expression was inversely associated with overall and disease-specific 5-year survival rate for all (P<0.001) and primary (P=0.014 and P=0.015, respectively) melanoma patients. Nuclear EIF5A2 expression was directly associated with melanoma thickness (P=0.036) and American Joint Committee on Cancer staging (P<0.001), which suggests the possible role of nuclear EIF5A2 in melanoma cell invasion. Subsequently, the present study investigated the association between the expression of nuclear EIF5A2 and matrix metalloproteinase-2 (MMP-2), which is an important factor for promoting cancer cell invasion. Nuclear EIF5A2 and a strong MMP-2 expression were directly associated, and their concurrent expression was significantly associated with a poorer overall and disease-specific 5-year survival rate for all and primary melanoma patients. Nuclear and cytoplasmic EIF5A2 expression were also demonstrated to be significantly associated, and simultaneous expression of the two forms of EIF5A2 was significantly associated with poor overall and disease-specific 5-year survival rates for all and primary melanoma patients. Multivariate Cox regression analysis revealed that nuclear EIF5A2 expression alone and in combination with cytoplasmic EIF5A2 expression was an adverse independent prognostic factor for all and primary melanoma patients. In conclusion, the present study for the first time, to the best of our knowledge, demonstrated that nuclear EIF5A2 expression is an independent prognostic marker in melanoma, and revealed its role in melanoma progression and patient survival. Therefore, nuclear EIF5A2 may have the potential to serve as a therapeutic marker for melanoma.

Overexpression of eukaryotic initiation factor 5A2 (EIF5A2) is associated with cancer progression and poor prognosis in patients with early-stage cervical cancer

AIMS

As one of the only two isoforms of the eukaryotic initiation factor (EIF)5A family, EIF5A2 plays an important role in tumour progression and prognosis evaluation. The aim of this study was to investigate EIF5A2 expression in International Federation of Gynecology and Obstetrics (FIGO) stage I-II cervical cancer and to evaluate its clinical significance.

METHODS AND RESULTS

The mRNA and protein expression levels of EIF5A2 were analysed in 20 tissue samples of FIGO stage I-II cervical cancer and paired surrounding non-tumour cervical tissues by real-time polymerase chain reaction and western blot analysis. Immunohistochemistry was performed to examine EIF5A2 protein expression in paraffin-embedded tissues from 314 patients with cervical cancer. The mRNA and protein expression levels of EIF5A2 were significantly elevated in tumour tissues. The increased EIF5A2 expression was correlated with higher FIGO stage (P < 0.001), deep cervical stromal invasion (P = 0.026), lymphovascular space involvement (P = 0.002), pelvic lymph node metastasis (P < 0.001) and postoperative recurrence (P < 0.001) in patients with cervical cancer. Patients with tumours showing high EIF5A2 expression had a poorer survival time than those with normal EIF5A2 expression, especially the patients with negative pelvic lymph nodes and FIGO stage II. In addition, multivariate Cox analysis showed that high EIF5A2 expression was an independent prognostic factor for overall survival [hazard ratio 1.949; 95% confidence interval (CI) 1.116-3.404; P = 0.019] and disease-free survival (hazard ratio 1.980; 95% CI 1.189-3.297; P = 0.009).

CONCLUSIONS

EIF5A2 overexpression may contribute to cancer progression and poor prognosis. Therefore, EIF5A2 could be a novel potential prognostic marker for FIGO stage I-II cervical cancer.

Identification and validation of AIB1 and EIF5A2 for noninvasive detection of bladder cancer in urine samples

We previously demonstrated that amplified in breast cancer 1 (AIB1) and eukaryotic initiation factor 2 (EIF5A2) overexpression was an independent predictor of poor clinical outcomes for patients with bladder cancer (BCa). In this study, we evaluated the usefulness of AIB1 and EIF5A2 alone and in combination with nuclear matrix protein 22 (NMP22) as noninvasive diagnostic tests for BCa. Using urine samples from 135 patients (training set, controls [n = 50] and BCa [n = 85]), we detected the AIB1, EIF5A2, and NMP22 concentrations using enzyme-linked immunosorbent assay. We applied multivariate logistic regression analysis to build a model based on the three biomarkers for BCa diagnosis. The diagnostic accuracy of the three biomarkers and the model were assessed and compared by the area under the curve (AUC) of the receiver operating characteristic. We validated the diagnostic accuracy of these biomarkers and the model in an independent validation cohort of 210 patients. In the training set, urinary concentrations of AIB1, EIF5A2, and NMP22 were significantly elevated in BCa. The AUCs of AIB1, EIF5A2, NMP22, and the model were 0.846, 0.761, 0.794, and 0.919, respectively. The model had the highest diagnostic accuracy when compared with AIB1, EIF5A2, or NMP22 (p < 0.05 for all). The model had 92% sensitivity and 92% specificity. We obtained similar results in the independent validation cohort. AIB1 and EIF5A2 show promise for the noninvasive detection of BCa. The model based on AIB1, EIF5A2, and NMP22 outperformed each of the three individual biomarkers for detecting BCa.

Identification of recurrent focal copy number variations and their putative targeted driver genes in ovarian cancer

BACKGROUND

Genomic regions with recurrent DNA copy number variations (CNVs) are generally believed to encode oncogenes and tumor suppressor genes (TSGs) that drive cancer growth. However, it remains a challenge to delineate the key cancer driver genes from the regions encoding a large number of genes.

RESULTS

In this study, we developed a new approach to CNV analysis based on spectral decomposition of CNV profiles into focal CNVs and broad CNVs. We performed an analysis of CNV data of 587 serous ovarian cancer samples on multiple platforms. We identified a number of novel focal regions, such as focal gain of ESR1, focal loss of LSAMP, prognostic site at 3q26.2 and losses of sub-telomere regions in multiple chromosomes. Furthermore, we performed network modularity analysis to examine the relationships among genes encoded in the focal CNV regions. Our results also showed that the recurrent focal gains were significantly associated with the known oncogenes and recurrent losses associated with TSGs and the CNVs had a greater effect on the mRNA expression of the driver genes than that of the non-driver genes.

CONCLUSIONS

Our results demonstrate that spectral decomposition of CNV profiles offers a new way of understanding the role of CNVs in cancer.

Eukaryotic translation initiation factor 5A2 regulates the migration and invasion of hepatocellular carcinoma cells via pathways involving reactive oxygen species

Eukaryotic translation initiation factor 5A2 (eIF5A2) has been identified as a critical gene in tumor metastasis. Research has suggested that reactive oxygen species (ROS) serve as signaling molecules in cancer cell proliferation and migration. However, the mechanisms linking eIF5A2 and ROS are not fully understood. Here, we investigated the effects of ROS on the eIF5A2-induced epithelial-mesenchymal transition (EMT) and migration in six hepatocellular carcinoma (HCC) cell lines. Western hybridization, siRNA transfection, transwell migration assays, wound-healing assays, and immunofluorescence analysis were used. The protein levels of eIF5A2 in tumor and adjacent tissue samples from 90 HCC patients with detailed clinical, pathological, and clinical follow-up data were evaluated. Overexpression of eIF5A2 was found in cancerous tissues compared with adjacent tissues. We found that eIF5A2 overexpression in HCC was associated with reduced overall survival. Knockdown of eIF5A2 and intracellular reduction of ROS significantly suppressed the invasion and metastasis of HCC cells. Interestingly, N1-guanyl-1, 7-diaminoheptane (GC7) suppressed the intracellular ROS levels. After blocking the EMT, administration of GC7 or N-acetyl-L-cysteine did not reduce cell migration further. Based on the experimental data, we concluded that inhibition of eIF5A2 alters progression of the EMT to decrease the invasion and metastasis of HCC cells via ROS-related pathways.

Expression of eukaryotic translation initiation factor 5A-2 (eIF5A-2) associated with poor survival in gastric cancer

Altered expression of eukaryotic translation initiation factor 5A-2 (eIF5A-2) was associated with human carcinogenesis and progression. This study assessed eIF5A-2 expression in gastric cancer tissues for association with clinicopathological parameters and survival of patients. A total of 436 gastric cancer tissues and 92 normal mucosal blocks were collected for construction of tissue microarrays and immunohistochemical assessment of eIF5A-2 expression. The data were statistically analyzed for association with clinicopathological factors and survival of patients. Immunohistochemical data showed that eIF5A-2 protein was highly expressed in gastric cancer tissues (p < 0.001). Upregulated expression of eIF5A-2 protein was associated with tumor Lauren classification, size, location, invasion, TNM stages, and lymph node and distant metastases. The 3- and 5-year cumulative survival rates of these 436 patients were 88.5 and 58.1 %, respectively. In contrast, the mean survival time of patients with increased tumor eIF5A-2 was 30.22 ± 1.23 vs. 51.29 ± 0.86 months for those with low tumor eIF5A-2 (p < 0.001). Multivariate analysis showed that eIF5A-2 expression and related tumor parameters were independent indicators of overall survival in gastric cancer patients. In conclusion, the current study indicates that overexpression of eIF5A-2 protein was associated with poor overall survival of gastric cancer patients.

Eukaryotic translation initiation factor 5A2 (eIF5A2) regulates chemoresistance in colorectal cancer through epithelial mesenchymal transition

BACKGROUND

Chemoresistance is a major obstacle to successful chemotherapy for colorectal cancer. Eukaryotic translation initiation factor 5A2 (eIF5A2), one of the two isoforms in the eIF5A family, has been reported to be a new oncogene in many types of human cancer. In the present study, we aimed to investigate whether eIF5A2 was involved in the chemoresistance to doxorubicin in colorectal cancer.

METHODS

Cell viability was measured by CCK-8 assay with or without doxorubicin treatment. Protein expression was detected by western blot. Tumor cells were transfected with eIF5A2 siRNA or plasmid encoding eIF5A2 to down- or up regulate the expression of eIF5A2.

RESULTS

We found that eIF5A2-negtive colon cancer cells (HCT116 and HT29) were more sensitive to doxorubicin compare with the eIF5A2-positive cells (LOVO and SW480). Downregulation of eIF5A2 in LOVO and SW480 cells enhanced the chemosensitivity to doxorubicin. On the contrary, overexpression of eIF5A2 reduced doxorubicin sensitivity in colon cancer cells. In addition, eIF5A2 knockdown increased the protein level of E-cadherin and reduced vimentin expression in LOVO and SW480 cells. Meanwhile, upregulation of eIF5A2 potentiated epithelial mesenchymal transition (EMT) in colon cancer cells. Moreover, blockade of EMT with Twist siRNA abolished eIF5A2-regulated chemoresistance in colon cancer cells.

CONCLUSION

Our present study demonstrated that eIF5A2 promoted the chemoresistance to doxorubicin via regulation of EMT in colon cancer cells. Therefore, eIF5A2 inhibition may be a new potential strategy for the reversal of drug resistance in colorectal cancer therapy.

EIF5A2 is a novel chemoresistance gene in breast cancer

BACKGROUND

The eIF5A2 gene (encoding the eukaryotic initiation factor 5A2) located at 3q26 is a putative oncogene that is overexpressed in colon and rectal carcinomas, lung cancer and hepatocellular carcinoma. EIF5A2 overexpression correlates significantly with tumor metastasis and is an adverse prognostic marker. However, eIF-5A2 overexpression in breast cancer and its effect on chemotherapy are unknown.

METHODS

We measured eIF-5A2 expression and doxorubicin sensitivity in different human breast cancer cell lines (Bcap-1937, HCC1937, and MCF-7). To investigate a role for eIF-5A2 in chemoresistance, cells were treated with eIF-5A2-siRNA, exposed to various concentrations of doxorubicin, and toxicity was assayed by CCK-8 (cell counting kit).

RESULTS

The eIF-5A2 expression levels varied among breast cancer cells. Higher expression levels correlated with decreased doxorubicin sensitivity. Silencing of eIF-5A2 significantly improved doxorubicin toxicity in all three breast cancer cell lines.

CONCLUSION

This study shows that eIF-5A2 plays an important role in doxorubicin chemoresistance in breast cancer cells.

Lentivirus-mediated shRNA interference of clusterin blocks proliferation, motility, invasion and cell cycle in the ovarian cancer cells

Background

In a previous analysis on the patients with ovarian cancers, we have found that clusterin is a biomarker associated with ovarian cancer in vivo and may be a prognostic factor associated with adverse outcome. Here, we explored the effect of lentivirus-mediated shRNA interference of clusterin, investigated whether clusterin was associated with adverse outcome of ovarian cancer cells in vitro.

Methods

OVCAR-3 and TOV-21G cell lines were infected with the lentivirus for delivering clusterin shRNA, and the stably transfected cells were selected. The effect of clusterin silencing was detected by western blotting assay. The proliferation, clonability, migration, invasion and cell cycle of two cell lines were detected separately by MTT assay, clone formation assay, scratch assay, transwell assay and fluorescence-activated cell sorting.

Results

Following clusterin silencing with shRNA, the expression of clusterin in two cell lines were decreased. And the proliferation, clonability, migration, invasion of these two cell lines were down-regulated apparently. The cell cycle of two cell lines was disturbed, cells in G1 phase was increased, but cells in G2 and S phase was decreased.

Conclusions

The expression of clusterin is significantly correlated with the biological characteristics of ovarian cancer cells, it may be a potential molecular for ovarian cancer treatment.

MiR-30b suppresses tumor migration and invasion by targeting EIF5A2 in gastric cancer

AIM

To elucidate the potential biological role of miR-30b in gastric cancer and investigate the underlying molecular mechanisms of miR-30b to inhibit metastasis of gastric cancer cells.

METHODS

The expression of miR-30b was detected in gastric cancer cell lines and samples by reverse transcription-polymerase chain reaction. CCK-8 assays were conducted to explore the impact of miR-30b overexpression on the proliferation of gastric cancer cells. Flow cytometry was used to examine the effect of miR-30b on the apoptosis. Transwell test was used for the migration and invasion assays. Luciferase reporter assays and Western blot were employed to validate regulation of putative target of miR-30b.

RESULTS

The results showed that miR-30b was downregulated in gastric cancer tissues and cancer cell lines and functioned as a tumor suppressor. Overexpression of miR-30b promoted cell apoptosis, and suppressed proliferation, migration and invasion of the gastric cancer cell lines AGS and MGC803. Bioinformatic analysis identified the 3'-untranslated region of eukaryotic translation initiation factor 5A2 (EIF5A2) as a putative binding site of miR-30b. Luciferase reporter assays and Western blot analysis confirmed the EIF5A2 gene as a target of miR-30b. Moreover, expression levels of the EIF5A2 targets E-cadherin and Vimentin were altered following transfection of miR-30b mimics.

CONCLUSION

Our findings describe a link between miR-30b and EIF5A2, which plays an important role in mediating epithelial-mesenchymal transition.

The translation factor eIF5A and human cancer

The eukaryotic initiation factor eIF5A is a translation factor that, unusually, has been assigned functions in both initiation and elongation. Additionally, it is implicated in transcription, mRNA turnover and nucleocytoplasmic transport. Two eIF5A isoforms are generated from distinct but related genes. The major isoform, eIF5A1, is considered constitutive, is abundantly expressed in most cells, and is essential for cell proliferation. The second isoform, eIF5A2, is expressed in few normal tissues but is highly expressed in many cancers and has been designated a candidate oncogene. Elevated expression of either isoform carries unfavorable prognostic implications for several cancers, and both have been advanced as cancer biomarkers. The amino acid hypusine, a presumptively unique eIF5A post-translational modification, is required for most known eIF5A functions and it renders eIF5A susceptible to inhibitors of the modification pathway as therapeutic targets. eIF5A has been shown to regulate a number of gene products specifically, termed the eIF5A regulon, and its role in translating proline-rich sequences has recently been identified. A model is advanced that accommodates eIF5A in both the initiation and elongation phases of translation. We review here the biochemical functions of eIF5A, the relationship of its isoforms with human cancer, and evolving clinical applications. This article is part of a Special Issue entitled: Translation and Cancer.