EIF3i promotes colon oncogenesis by regulating COX-2 protein synthesis and β-catenin activation

METTL3-mediated m6A modification of lncRNA TSPAN12 promotes metastasis of hepatocellular carcinoma through SENP1-depentent deSUMOylation of EIF3I

In a previous study, we discovered that the level of lnc-TSPAN12 was significantly elevated in hepatocellular carcinoma (HCC) and correlated with a low survival rate. However, the function and mechanism of lnc-TSPAN12 in modulating epithelial-mesenchymal transition (EMT) and metastasis in HCC remains poorly understood. This study demonstrates that lnc-TSPAN12 positively influences migration, invasion, and EMT of HCC cells in vitro and promotes hepatic metastasis in vivo. The modification of N6-methyladenosine, driven by METTL3, is essential for the stability of lnc-TSPAN12, which may partially contribute to the upregulation of lnc-TSPAN12. Mechanistically, lnc-TSPAN12 exhibits direct interactions with EIF3I and SENP1, acting as a scaffold to enhance the SENP1-EIF3I interaction. As a result, the SUMOylation of EIF3I is inhibited, preventing its ubiquitin-mediated degradation. Ultimately, this activates the Wnt/β-catenin signaling pathway, stimulating EMT and metastasis in HCC. Our findings shed light on the regulatory mechanism of lnc-TSPAN12 in HCC metastasis and identify the lnc-TSPAN12-EIF3I/SENP1 axis as a novel therapeutic target for HCC.

eIF3i promotes colorectal cancer cell survival via augmenting PHGDH translation

Translational regulation is one of the decisive steps in gene expression, and its dysregulation is closely related to tumorigenesis. Eukaryotic translation initiation factor 3 subunit i (eIF3i) promotes tumor growth by selectively regulating gene translation, but the underlying mechanisms are largely unknown. Here, we show that eIF3i is significantly increased in colorectal cancer (CRC) and reinforces the proliferation of CRC cells. Using ribosome profiling and proteomics analysis, several genes regulated by eIF3i at the translation level were identified, including D-3-phosphoglycerate dehydrogenase (PHGDH), a rate-limiting enzyme in the de novo serine synthesis pathway that participates in metabolic reprogramming of tumor cells. PHGDH knockdown significantly represses CRC cell proliferation and partially attenuates the excessive growth induced by eIF3i overexpression. Mechanistically, METTL3-mediated N6-methyladenosine modification on PHGDH mRNA promotes its binding with eIF3i, ultimately leading to a higher translational rate. In addition, knocking down eIF3i and PHGDH impedes tumor growth in vivo. Collectively, this study not only uncovered a novel regulatory mechanism for PHGDH translation but also demonstrated that eIF3i is a critical metabolic regulator in human cancer.

Insights into the Structure and Function of TRIP-1, a Newly Identified Member in Calcified Tissues

Eukaryotic initiation factor subunit I (EIF3i), also called as p36 or TRIP-1, is a component of the translation initiation complex and acts as a modulator of TGF-β signaling. We demonstrated earlier that this intracellular protein is not only exported to the extracellular matrix via exosomes but also binds calcium phosphate and promotes hydroxyapatite nucleation. To assess other functional roles of TRIP-1, we first examined their phylogeny and showed that it is highly conserved in eukaryotes. Comparing human EIF3i sequence with that of 63 other eukaryotic species showed that more than 50% of its sequence is conserved, suggesting the preservation of its important functional role (translation initiation) during evolution. TRIP-1 contains WD40 domains and predicting its function based on this structural motif is difficult as it is present in a vast array of proteins with a wide variety of functions. Therefore, bioinformatics analysis was performed to identify putative regulatory functions for TRIP-1 by examining the structural domains and post-translational modifications and establishing an interactive network using known interacting partners such as type I collagen. Insight into the function of TRIP-1 was also determined by examining structurally similar proteins such as Wdr5 and GPSß, which contain a ß-propeller structure which has been implicated in the calcification process. Further, proteomic analysis of matrix vesicles isolated from TRIP-1-overexpressing preosteoblastic MC3T3-E1 cells demonstrated the expression of several key biomineralization-related proteins, thereby confirming its role in the calcification process. Finally, we demonstrated that the proteomic signature in TRIP1-OE MVs facilitated osteogenic differentiation of stem cells. Overall, we demonstrated by bioinformatics that TRIP-1 has a unique structure and proteomic analysis suggested that the unique osteogenic cargo within the matrix vesicles facilitates matrix mineralization.

Translational Regulation by eIFs and RNA Modifications in Cancer

Translation is a fundamental process in all living organisms that involves the decoding of genetic information in mRNA by ribosomes and translation factors. The dysregulation of mRNA translation is a common feature of tumorigenesis. Protein expression reflects the total outcome of multiple regulatory mechanisms that change the metabolism of mRNA pathways from synthesis to degradation. Accumulated evidence has clarified the role of an increasing amount of mRNA modifications at each phase of the pathway, resulting in translational output. Translation machinery is directly affected by mRNA modifications, influencing translation initiation, elongation, and termination or altering mRNA abundance and subcellular localization. In this review, we focus on the translation initiation factors associated with cancer as well as several important RNA modifications, for which we describe their association with cancer.

The progress of protein synthesis factors eIFs, eEFs and eRFs in inflammatory bowel disease and colorectal cancer pathogenesis

Colorectal diseases are threatening human health, especially inflammatory bowel disease (IBD) and colorectal cancer (CRC). IBD is a group of chronic, recurrent and incurable disease, which may affect the entire gastrointestinal tract, increasing the risk of CRC. Eukaryotic gene expression is a complicated process, which is mainly regulated at the level of gene transcription and mRNA translation. Protein translation in tissue is associated with a sequence of steps, including initiation, elongation, termination and recycling. Abnormal regulation of gene expression is the key to the pathogenesis of CRC. In the early stages of cancer, it is vital to identify new diagnostic and therapeutic targets and biomarkers. This review presented current knowledge on aberrant expression of eIFs, eEFs and eRFs in colorectal diseases. The current findings of protein synthesis on colorectal pathogenesis showed that eIFs, eEFs and eRFs may be potential targets for CRC treatment.

Effects of N6-Methyladenosine Regulators on LAG3 and Immune Infiltrates in Lung Adenocarcinoma

Background. Lung adenocarcinoma (LUAD) is the most common histological subtype of lung cancer, which is one of the most commonly diagnosed tumors and the leading causes of death from cancer around the world. Since RNA methylation is a posttranscriptional modification and affects so much biological progress, it is urged to explore the role of N6-methyladenosine (m6A) methylation in LUAD. Methods. We explored the expression of 24 m6A methylation genes, as well as their correlations with LAG3 in 561 LUAD samples from TCGA. Consensus clustering was applied to m6A methylation genes, and two LUAD subgroups were identified. The expression of m6A genes was analyzed by the Wilcoxon test. KEGG and GO enrichment analyses were performed to indicate the pathway affected by differentially expressed genes in the two groups. A prognostic model based on LASSO regression using an eleven-m6A gene signature was constructed according to the expression of these genes. Receiver operating characteristic (ROC) curve was used to confirm the accuracy of the model in the TCGA cohort, as well as in the test cohort from the Gene Expression Omnibus (GEO) database. Results. Compared to cluster 1, cluster 2 showed poorer overall survival (OS) and higher LAG3 expression. In addition, KEGG and GO enrichment analyses indicated that differentially expressed genes are enriched in the immune response. We also observed that the expression of LAG3 is positively correlated with IGF2BP2, CBLL1, and HNRNPA2B1 and negatively correlated with YTHDF2, YTHDF3, and FTO. For patients in the TCGA cohort, the AUC score is 0.7, and the AUC score for the GSE50081 cohort is 0.675. Patients with lower risk scores exhibited better overall survival and lower expression of LAG3 than patients with higher risk scores. Conclusions. In brief, our results indicated the important role of m6 methylation in affecting the tumor immune microenvironment and the survival of patients with LUAD. The m6A methylation gene signatures might serve as promising therapeutic targets and help the immunotherapy of LUAD in the future.

Liver cancer cells with nuclear MET overexpression release translation regulatory protein-enriched extracellular vesicles exhibit metastasis promoting activity

MET receptor tyrosine kinase is a cell surface receptor that plays important role in embryonic development and tissue regeneration. Aberrant MET activation has been widely reported in different human cancers, making MET an attractive therapeutic target. The presence of truncated MET within the nucleus (nMET) with potential novel functions poses a great challenge to the current therapeutic strategies against MET surface receptor. Previous work has demonstrated the promoting effect of nMET in aggressive properties of hepatocellular carcinoma (HCC) cells by activating TAK1/NF-κB signalling pathway. Herein, we report the role of nMET in modulating tumour microenvironment and tumour metastasis mediated by extracellular vesicles (EVs). EVs released by nMET overexpressing cells enhanced cell motility and provoked metastasis. Proteomic profiling revealed the enrichment of translational regulatory proteins in EVs derived from nMET overexpressing cells. These proteins include eukaryotic initiation factor (EIF), ribosomal protein small subunit (RPS) and ribosomal protein larger subunit (RPL) gene families. Knockdown of EIF3I, RPS3A and RPL10 diminished the promoting effect of EVs in cell migration invasiveness and metastasis. In conclusion, the findings reveal an unrecognized capacity of nMET to augment HCC through the release of EVs with oncogenic effect. Targeting these translation-related proteins may serve as an alternative treatment for patients with nMET overexpression.

eIF3a regulation of mTOR signaling and translational control via HuR in cellular response to DNA damage

eIF3a (eukaryotic translation initiation factor 3a), a subunit of the eIF3 complex, has been suggested to play a regulatory role in protein synthesis and in cellular response to DNA-damaging treatments. S6K1 is an effector and a mediator of mTOR complex 1 (mTORC1) in regulating protein synthesis and integrating diverse signals into control of cell growth and response to stress. Here, we show that eIF3a regulates S6K1 activity by inhibiting mTORC1 kinase via regulating Raptor synthesis. The regulation of Raptor synthesis is via eIF3a interaction with HuR (human antigen R) and binding of the eIF3a-HuR complex to the 5'-UTR of Raptor mRNA. Furthermore, mTORC1 may mediate eIF3a function in cellular response to cisplatin by regulating synthesis of NER proteins and NER activity. Taken together, we conclude that the mTOR signaling pathway may also be regulated by translational control and mediate eIF3a regulation of cancer cell response to cisplatin by regulating NER protein synthesis.

Integrative Analyses of Circulating mRNA and lncRNA Expression Profile in Plasma of Lung Cancer Patients

Circulating-free RNAs (cfRNAs) have been regarded as potential biomarkers for “liquid biopsy” in cancers. However, the circulating messenger RNA (mRNA) and long noncoding RNA (lncRNA) profiles of lung cancer have not been fully characterized. In this study, we profiled circulating mRNA and lncRNA profiles of 16 lung cancer patients and 4 patients with benign pulmonary nodules. Compared with benign pulmonary nodules, 806 mRNAs and 1,762 lncRNAs were differentially expressed in plasma of lung adenocarcinoma patients. For lung squamous cell carcinomas, 256 mRNAs and 946 lncRNAs were differentially expressed. A total of 231 mRNAs and 298 lncRNAs were differentially expressed in small cell lung cancer. Eleven mRNAs, 51 lncRNAs, and 207 canonical pathways were differentially expressed in lung cancer in total. Forty-five blood samples were collected to verify our findings via performing qPCR. There are plenty of meaningful mRNAs and lncRNAs that were found. MYC, a transcription regulator associated with the stemness of cancer cells, is overexpressed in lung adenocarcinoma. Transforming growth factor beta (TGFB1), which plays pleiotropic roles in cancer progression, was found to be upregulated in lung squamous carcinoma. MALAT1, a well-known oncogenic lncRNA, was also found to be upregulated in lung squamous carcinoma. Thus, this study provided a systematic resource of mRNA and lncRNA expression profiles in lung cancer plasma.

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Circular RNA hsa_circ_0011385 contributes to cervical cancer progression through sequestering miR-149-5p and increasing PRDX6 expression

Cervical cancer (CC) is a common tumor in the female reproductive tract. Circular RNA hsa_circ_0011385 has been reported to be up-regulated in CC tissues. Nevertheless, the role and regulatory mechanism of hsa_circ_0011385 in CC are still being further verified. The levels of hsa_circ_0011385, microRNA (miR)- 149-5p, and peroxiredoxin 6 (PRDX6) mRNA in CC samples and cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Loss-of-function experiments were performed to survey the impacts of hsa_circ_0011385 inhibition on CC cell proliferation, colony formation, cycle progression, apoptosis, metastasis, invasion, and angiogenesis. Protein levels were detected by western blotting. The relationship between hsa_circ_0011385 or PRDX6 and miR-149-5p was verified by dual-luciferase reporter, RNA immunoprecipitation (RIP), and/or RNA pull-down assays. The tumorigenesis role of hsa_circ_0011385 in CC was confirmed by xenograft assay. We observed that hsa_circ_0011385 and PRDX6 were up-regulated while miR-149-5p was down-regulated in CC samples and cell lines. CC patients with high hsa_circ_0011385 expression possessed a shorter overall survival. Hsa_circ_0011385 knockdown reduced tumor growth in vivo and facilitated apoptosis, cell cycle arrest, impeded proliferation, metastasis, invasion, and angiogenesis of CC cells in vitro. Hsa_circ_0011385 could mediate PRDX6 expression through binding to miR-149-5p. MiR-149-5p silencing reversed hsa_circ_0011385 knockdown-mediated effects on CC cell angiogenesis and malignancy. PRDX6 overexpression overturned the inhibitory effects of miR-149-5p overexpression on angiogenesis and malignant behaviors of CC cells. In conclusion, hsa_circ_0011385 accelerated angiogenesis and malignant behaviors of CC cells by regulating the miR-149-5p/PRDX6 axis, manifesting that hsa_circ_0011385 might be a therapeutic target for CC.

Eukaryotic translation initiation factor 3 subunit B could serve as a potential prognostic predictor for breast cancer

The EIF3 gene family is essential in controlling translation initiation during the cell cycle. The significance of the EIF3 subunits as prognostic markers and therapeutic targets in breast cancer is not yet clear. We analyzed the expression of EIF3 subunits in breast cancer on the GEPIA and Oncomine databases and compared their expression in breast cancer and normal tissues using BRCA data downloaded from TCGA. Then we performed clinical survival analysis on the Kaplan–Meier Plotter database and clinicopathologic analysis on the bc-genexMiner v4.1 database. And EIF3B was chosen for mutation analysis via the Cancer SEA online tool. Meanwhile, we performed the immunohistochemical assay, real-time RT-PCR, and Western blotting to analyze EIF3B expression levels in breast cancer. An EIF3B knockdown and a negative control cell line were conducted for MTT assay and cell cycle analysis to assess cell growth. Specifically, the results of TCGA and online databases demonstrated that upregulated EIF3B was associated with poorer overall and advanced tumor progression. We also confirmed that EIF3B was more highly expressed in breast cancer cells and tissues than normal and correlated with a worse outcome. And knockdown of EIF3B expression inhibited the cell cycle and proliferation. Furthermore, EIF3B was highly mutated in breast cancer. Collectively, our results suggested EIF3B as a potential prognostic marker and therapeutic target for breast cancer.

EIF3m promotes the malignant phenotype of lung adenocarcinoma by the up-regulation of oncogene CAPRIN1

EIF3m is the latest identified subunit of the eukaryotic translation initiation factor 3 (eIF3), however, its function in malignant tumor is rarely reported. In the current work, we observed that EIF3m was aberrant over-expressed in lung adenocarcinoma (LADC) tissues and cell lines, and the increased EIF3m level was closely related to the poor clinical outcomes of the LADC patients. The gain- and loss-of-function assays demonstrated the proto-oncogenetic potential of EIF3m in vitro and in vivo. EIF3m induced-malignant phenotype was partly mediated by the up-regulation of CAPRIN1. The biochemical analysis showed that EIF3m could bind to the 5'UTR of CAPRIN1 and positively modulate its expression at the post-transcription level. Furthermore, we identified the interaction between EIF3m and the deubiquitinase UCHL5, which stabilized and promoted the accumulation of EIF3m in LADC cells. In summary, our findings extended the knowledge about the EIF3m function and highlight the roles of the UCHL5/EIF3m/CAPRIN1 axis during the progression of LADC.

Translation initiation in cancer at a glance

Cell division, differentiation and function are largely dependent on accurate proteome composition and regulated gene expression. To control this, protein synthesis is an intricate process governed by upstream signalling pathways. Eukaryotic translation is a multistep process and can be separated into four distinct phases: initiation, elongation, termination and recycling of ribosomal subunits. Translation initiation, the focus of this article, is highly regulated to control the activity and/or function of eukaryotic initiation factors (eIFs) and permit recruitment of mRNAs to the ribosomes. In this Cell Science at a Glance and accompanying poster, we outline the mechanisms by which tumour cells alter the process of translation initiation and discuss how this benefits tumour formation, proliferation and metastasis.

eIF3i regulation of protein synthesis, cell proliferation, cell cycle progression, and tumorigenesis

eIF3i, a 36-kDa protein, is a putative subunit of the eIF3 complex important for translation initiation of mRNAs. It is a WD40 domain-containing protein with seven WD40 repeats that forms a β-propeller structure with an important function in pre-initiation complex formation and mRNA translation initiation. In addition to participating in the eIF3 complex formation for global translational control, eIF3i may bind to specific mRNAs and regulate their translation individually. Furthermore, eIF3i has been shown to bind to TGF-β type II receptor and participate in TGF-β signaling. It may also participate in and regulate other signaling pathways including Wnt/β-catenin pathway via translational regulation of COX-2 synthesis. These multiple canonical and noncanonical functions of eIF3i in translational control and in regulating signal transduction pathways may be responsible for its role in cell differentiation, cell cycle regulation, proliferation, and tumorigenesis. In this review, we will critically evaluate recent progresses and assess future prospects in studying eIF3i.

eIF3a Regulation of NHEJ Repair Protein Synthesis and Cellular Response to Ionizing Radiation

Translation initiation in protein synthesis regulated by eukaryotic initiation factors (eIFs) is a crucial step in controlling gene expression. eIF3a has been shown to regulate protein synthesis and cellular response to treatments by anticancer agents including cisplatin by regulating nucleotide excision repair. In this study, we tested the hypothesis that eIF3a regulates the synthesis of proteins important for the repair of double-strand DNA breaks induced by ionizing radiation (IR). We found that eIF3a upregulation sensitized cellular response to IR while its downregulation caused resistance to IR. eIF3a increases IR-induced DNA damages and decreases non-homologous end joining (NHEJ) activity by suppressing the synthesis of NHEJ repair proteins. Furthermore, analysis of existing patient database shows that eIF3a expression associates with better overall survival of breast, gastric, lung, and ovarian cancer patients. These findings together suggest that eIF3a plays an important role in cellular response to DNA-damaging treatments by regulating the synthesis of DNA repair proteins and, thus, eIIF3a likely contributes to the outcome of cancer patients treated with DNA-damaging strategies including IR.

Cancer Targeted Gene Therapy for Inhibition of Melanoma Lung Metastasis with eIF3i shRNA Loaded Liposomes

Eukaryotic translation initiation factors 3i (eIF3i) is a proto-oncogene that is overexpressed in various tumors, reducing its expression by eIF3i shRNA is a promising strategy to inhibit tumor growth or metastasis. Tumor cell is the target of eIF3i shRNA so that tumor-site accumulation could be important for fulfilling its therapeutic effect. Thus, the iRGD modified liposome (R-LP) was rationally synthesized to enhance the antitumor effect by active targeted delivery of eIF3i shRNA to B16F10 melanoma cells. R-LP encapsulating eIF3i shRNA gene (R-LP/sheIF3i) were prepared by a film dispersion method. The transfection experiment proves that R-LP could effectively transfect B16F10 cells. R-LP/sheIF3i notably restrained the migration, invasion, and adhesion of melanoma cells in vitro. In a mouse model of lung metastasis, R-LP/sheIF3i administered by intravenous injection suppressed pulmonary metastasis of melanoma by dramatically downregulated eIF3i expression and subsequently inhibiting tumor neovascularization and tumor cells proliferation in vivo. Our results provide a basis for tumor cells targeting strategies to reduce the expression of eIF3i by RNAi in the treatment of tumor metastasis.

High expression of eukaryotic initiation factor 3M predicts poor prognosis in colon adenocarcinoma patients

Eukaryotic initiation factor 3 subunit M (EIF3M) is required for key steps in the initiation of protein synthesis, and dysregulation of EIF3M is associated with tumorigenesis. This study aimed to explore the clinicopathological and prognostic role of EIF3M in patients with colon adenocarcinoma. A total of 82 pathology specimens, 20 freeze-thawed tumors and 80 healthy controls were used to investigate the expression of EIF3M in colon adenocarcinoma through immunohistochemistry, western blotting, RT-qPCR and ELISA. In addition, Kaplan-Meier curves and Cox regression analysis were used to analyze overall survival (OS) and disease-free survival (DFS). Furthermore, the Oncomine database was used for analyzing EIF3M expression. The positive rate of EIF3M in colon adenocarcinoma was higher compared with that in normal colon tissues (62.20% vs. 29.27%; P<0.001). The mean score of EIF3M was also higher in colon adenocarcinoma compared with normal colon tissue (17.28±10.05 vs. 6.53±4.87; P<0.001). The levels of EIF3M expression in freeze-thawed tumors and serum from 20 patients with colon adenocarcinoma were higher than those in normal tissues and serum from healthy controls, respectively (P<0.001). In addition, positive expression of EIF3M was associated with tumor size (P=0.002) and Dukes' stage (P<0.001). In multivariate Cox regression analysis, EIF3M expression was an independent prognostic factor for OS (P=0.003) and DFS (P=0.001). Oncomine database analysis showed a higher expression of EIF3M expression in colon adenocarcinoma compared with normal colon tissues, colon squamous cell carcinomas or gastrointestinal stromal tumors. In conclusion, EIF3M expression was associated with tumor size and Dukes' stage in colon adenocarcinoma. Hence, EIF3M is a potential prognostic indicator for colon adenocarcinoma.

A yeast phenomic model for the influence of Warburg metabolism on genetic buffering of doxorubicin

BACKGROUND

The influence of the Warburg phenomenon on chemotherapy response is unknown. Saccharomyces cerevisiae mimics the Warburg effect, repressing respiration in the presence of adequate glucose. Yeast phenomic experiments were conducted to assess potential influences of Warburg metabolism on gene-drug interaction underlying the cellular response to doxorubicin. Homologous genes from yeast phenomic and cancer pharmacogenomics data were analyzed to infer evolutionary conservation of gene-drug interaction and predict therapeutic relevance.

METHODS

Cell proliferation phenotypes (CPPs) of the yeast gene knockout/knockdown library were measured by quantitative high-throughput cell array phenotyping (Q-HTCP), treating with escalating doxorubicin concentrations under conditions of respiratory or glycolytic metabolism. Doxorubicin-gene interaction was quantified by departure of CPPs observed for the doxorubicin-treated mutant strain from that expected based on an interaction model. Recursive expectation-maximization clustering (REMc) and Gene Ontology (GO)-based analyses of interactions identified functional biological modules that differentially buffer or promote doxorubicin cytotoxicity with respect to Warburg metabolism. Yeast phenomic and cancer pharmacogenomics data were integrated to predict differential gene expression causally influencing doxorubicin anti-tumor efficacy.

RESULTS

Yeast compromised for genes functioning in chromatin organization, and several other cellular processes are more resistant to doxorubicin under glycolytic conditions. Thus, the Warburg transition appears to alleviate requirements for cellular functions that buffer doxorubicin cytotoxicity in a respiratory context. We analyzed human homologs of yeast genes exhibiting gene-doxorubicin interaction in cancer pharmacogenomics data to predict causality for differential gene expression associated with doxorubicin cytotoxicity in cancer cells. This analysis suggested conserved cellular responses to doxorubicin due to influences of homologous recombination, sphingolipid homeostasis, telomere tethering at nuclear periphery, actin cortical patch localization, and other gene functions.

CONCLUSIONS

Warburg status alters the genetic network required for yeast to buffer doxorubicin toxicity. Integration of yeast phenomic and cancer pharmacogenomics data suggests evolutionary conservation of gene-drug interaction networks and provides a new experimental approach to model their influence on chemotherapy response. Thus, yeast phenomic models could aid the development of precision oncology algorithms to predict efficacious cytotoxic drugs for cancer, based on genetic and metabolic profiles of individual tumors.

Upregulated expression of eIF3C is associated with malignant behavior in renal cell carcinoma

Eukaryotic initiation factor 3c (eIF3C) is involved in the initiation of protein translation. Aberrant eIF3C expression has been reported in different types of human cancer. The present study aimed to assess the role of eIF3C in the malignant behavior of renal cell carcinoma in vitro and in vivo. eIF3C expression was assessed in 16 pairs of renal cell carcinoma (RCC) and matched distant normal tissues, and in RCC cell lines using immunohistochemistry. Subsequently, eIF3C was depleted using lentiviral short hairpin RNA and cell proliferation, cell cycle distribution and apoptosis of these eIF3C‑depleted cells were examined. Additionally, tumor cell xenograft assays in nude mice, Affymetrix microarrays and ingenuity pathway analyses were performed. eIF3C expression was upregulated in RCC tissues and cell lines. Depletion of eIF3C reduced tumor cell proliferation and arrested them at the G1 stage, thus promoting their apoptosis in vitro. Depletion of eIF3C also inhibited the formation and growth of tumor cell xenografts in nude mice. In addition, depletion of eIF3C altered the expression levels of 994 differentially expressed genes in RCC cells (516 genes were upregulated and 478 genes were downregulated). The expression levels of phosphorylated‑AKT, c‑JUN and NFKB inhibitor α were lower in the shorth hairpin RNA eIF3C‑transfected RCC cells compared with in the control group. In conclusion, the present study demonstrated that upregulated eIF3C expression contributed to the development and progression of RCC. Future studies should further evaluate whether eIF3C could be used as a potential strategy for RCC targeting therapy.

Impact of Heat Shock Protein 90 Inhibition on the Proteomic Profile of Lung Adenocarcinoma as Measured by Two-Dimensional Electrophoresis Coupled with Mass Spectrometry

Heat shock protein 90 (HSP90) is an important chaperone in lung adenocarcinoma, with relevant protein drivers such as EGFR (epidermal growth factor receptor) and EML4-ALK (echinoderm microtubule-associated protein-like protein4 fused to anaplastic lymphoma kinase) depending on it for their correct function, therefore HSP90 inhibitors show promise as potential treatments for lung adenocarcinoma. To study responses to its inhibition, HSP90 was pharmacologically interrupted by geldanamycin and resorcinol derivatives or with combined inhibition of HSP90 plus HSP70 in lung adenocarcinoma cell lines. Two-dimensional electrophoresis was performed to identify proteomic profiles associated with inhibition which will help to understand the biological basis for the responses. HSP90 inhibition resulted in altered protein profiles that differed according the treatment condition studied. Results revealed 254 differentially expressed proteins after treatments, among which, eukaryotic translation initiation factor3 subunit I (eIF3i) and citrate synthase demonstrated their potential role as response biomarkers. The differentially expressed proteins also enabled signalling pathways involved in responses to be identified; these included apoptosis, serine-glycine biosynthesis and tricarboxylic acid cycle. The proteomic profiles identified here contribute to an improved understanding of HSP90 inhibition and open possibilities for the detection of potential response biomarkers which will be essential to maximize treatment efficacy in lung adenocarcinoma.

Systematically profiling the expression of eIF3 subunits in glioma reveals the expression of eIF3i has prognostic value in IDH-mutant lower grade glioma

Background

Abnormal expression of the eukaryotic initiation factor 3 (eIF3) subunits plays critical roles in tumorigenesis and progression, and also has potential prognostic value in cancers. However, the expression and clinical implications of eIF3 subunits in glioma remain unknown.

Methods

Expression data of eIF3 for patients with gliomas were obtained from the Chinese Glioma Genome Atlas (CGGA) (n = 272) and The Cancer Genome Atlas (TCGA) (n = 595). Cox regression, the receiver operating characteristic (ROC) curves and Kaplan–Meier analysis were used to study the prognostic value. Gene oncology (GO) and gene set enrichment analysis (GSEA) were utilized for functional prediction.

Results

In both the CGGA and TCGA datasets, the expression levels of eIF3d, eIF3e, eIF3f, eIF3h and eIF3l highly were associated with the IDH mutant status of gliomas. The expression of eIF3b, eIF3i, eIF3k and eIF3m was increased with the tumor grade, and was associated with poorer overall survival [All Hazard ratio (HR) > 1 and P < 0.05]. By contrast, the expression of eIF3a and eIF3l was decreased in higher grade gliomas and was associated with better overall survival (Both HR < 1 and P < 0.05). Importantly, the expression of eIF3i (located on chromosome 1p) and eIF3k (Located on chromosome 19q) were the two highest risk factors in both the CGGA [eIF3i HR = 2.068 (1.425–3.000); eIF3k HR = 1.737 (1.166–2.588)] and TCGA [eIF3i HR = 1.841 (1.642–2.064); eIF3k HR = 1.521 (1.340–1.726)] databases. Among eIF3i, eIF3k alone or in combination, the expression of eIF3i was the more robust in stratifying the survival of glioma in various pathological subgroups. The expression of eIF3i was an independent prognostic factor in IDH-mutant lower grade glioma (LGG) and could also predict the 1p/19q codeletion status of IDH-mutant LGG. Finally, GO and GSEA analysis showed that the elevated expression of eIF3i was significantly correlated with the biological processes of cell proliferation, mRNA processing, translation, T cell receptor signaling, NF-κB signaling and others.

Conclusions

Our study reveals the expression alterations during glioma progression, and highlights the prognostic value of eIF3i in IDH-mutant LGG.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0867-1) contains supplementary material, which is available to authorized users.

The function and clinical significance of eIF3 in cancer

Abnormal regulation of gene expression is essential for tumorigenesis. Several studies indicate that regulation of oncogene expression and neoplastic transformation are controlled by subunits of eukaryotic translation initiation factors (eIFs). Eukaryotic translation initiation factor 3 (eIF3) is the largest (800 kDa) and the most complex mammalian initiation factor. It is composed of 13 non-identical polypeptides designated as eIF3a-m and plays a pivotal role in protein synthesis that bridges the 43S pre-initiation complex and eIF4F-bound mRNA. However, the functional roles of individual subunits are not yet very clear. This review presents on several of aberrant expressed eIF3 subunits which are detected in various human cancers and the associated mechanisms have been acknowledged or are still not sure. Finally, identifying novel targets and biomarkers for caner is of great importance in early diagnosis and treatment of cancer. eIF3 may be a novel target molecule in drug development for cancer treatment and prevention.

Up-regulation Of EIF3e Is Associated with The Progression of Esophageal Squamous Cell Carcinoma and Poor Prognosis in Patients

Introduction: Esophageal cancer is one of the most common malignant tumors in the world. Eukaryotic translation initiation factors 3e (eIF3e) makes a notable difference in the initiation of protein synthesis and tumor progression. However, the role of eIF3e in ESCC has not been revealed yet. This study aims to investigate the bio-functional and prognostic role of eIF3e in human ESCC tissues and cells. Methods: Immunohistochemical staining and Western blot were performed to detect the eIF3e expression in ESCC patients' tissues. The Kaplan-Meier product limit method and Cox regression were conducted to analyze the association between eIF3e expression, together with other related clinical/pathological features, and patients' prognosis. In the analysis of bio-functional role of eIF3e, CCK-8 and Transwell assay were performed to compare the proliferative and migrative ability after knockdown of eIF3e. Results: Up-regulation of eIF3e were demonstrated in ESCC tissues compared with the corresponding para-cancerous tissues. Overexpression of eIF3e was associated with deep tumor depth, lymph nodes metastasis, and advanced TNM stage. Importantly, the patients with high eIF3e expression suffered shorter overall and disease-free survival. Lymph node metastasis and histological grade served as independent prognostic predictors in patients' prognosis. Knockdown of eIF3e could inhibit cell proliferation and migration, in vitro. Conclusions: The eIF3e expression, or combined with other members of eIF3 complex, might predict poor prognosis of ESCC and serve as a potential breakthrough in the multimodality therapy of ESCC.

Eukaryotic translation initiation factor 3B accelerates the progression of esophageal squamous cell carcinoma by activating β-catenin signaling pathway

INTRODUCTION

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignant tumors. Eukaryotic translation initiation factors 3B (EIF3B) is considered to influence tumor proliferation, invasion, apoptosis and cell cycle, which act together to promote the progression of tumors. However, the role of EIF3B in ESCC is unknown. This study aims to explore the clinical and biological role of EIF3B in ESCC.

RESULTS

EIF3B expressions were up-regulated in both ESCC tissues and cell lines. Overexpression of EIF3B was associated with tumor depth, lymph node metastasis and advanced TNM stage. Importantly, patients with high EIF3B expression suffered shorter overall and disease-free survival. Knockdown of EIF3B could inhibit cell proliferation and invasion, promote cell apoptosis, and interfere the cell cycle in vitro. EIF3B-knockdown cells could form smaller subcutaneous tumors in vivo. Finally, we demonstrated EIF3B could activate β-catenin signaling pathway.

METHODS

Immunohistochemical staining and Western blot were performed to detect the EIF3B expression in ESCC patient tissues and cell lines. The association between EIF3B expression and patients' prognosis was analyzed by Kaplan-Meier and Cox regression. Then, CCK-8, colony-formation, Transwell and wound-healing assay were performed to compare the bio-functional change after knockdown of EIF3B. Flow cytometry was applied to analyze the change of cell apoptosis and cycle induced by EIF3B knockdown. Tumor xenograft assay was done to verify the in-vitro results.

CONCLUSIONS

EIF3B might serve as a novel marker for predicting prognosis of ESCC patients and as a potential therapeutic target, individually or together with other subunits of EIF3 complex.

eIF3: a factor for human health and disease

The eukaryotic initiation factor 3 (eIF3) is one of the most complex translation initiation factors in mammalian cells, consisting of several subunits (eIF3a to eIF3m). It is crucial in translation initiation and termination, and in ribosomal recycling. Accordingly, deregulated eIF3 expression is associated with different pathological conditions, including cancer. In this manuscript, we discuss the interactome and function of each subunit of the human eIF3 complex. Furthermore, we review how altered levels of eIF3 subunits correlate with neurodegenerative disorders and cancer onset and development; in addition, we evaluate how such misregulation may also trigger infection cascades. A deep understanding of the molecular mechanisms underlying eIF3 role in human disease is essential to develop new eIF3-targeted therapeutic approaches and thus, overcome such conditions.

eIF3i activity is critical for endothelial cells in tumor induced angiogenesis through regulating VEGFR and ERK translation

Translational control is a critical step in the regulation of gene expression. Accumulating evidence shows that translational control of a subgroup of mRNAs tends to be selective. However, our understanding of the function of selective translational control in endothelial cells is still incomplete. We found that a key translational regulator, eIF3i, is highly expressed in endothelial cells during embryonic and tumor angiogenesis. Knockdown of eIF3i restrained cell proliferation and migration in endothelial cells. In zebrafish angiogenesis model, eIF3i mutant endothelial cells could not respond to induction signals from tumor mass. Mechanistically, we showed that eIF3i knockdown reduced VEGFR/ERK signaling by down-regulating VEGFR2 and ERK protein expression. Gene therapy model suggested that the growth and metastasis of cancer cells were suppressed by eIF3i shRNA. Therefore, our work established a selective translational regulatory mechanism during tumor induced angiogenesis and suggested that targeting eIF3i may be applicable for anticancer therapy.

Eukaryotic Translation Initiation Factor 3b is both a Promising Prognostic Biomarker and a Potential Therapeutic Target for Patients with Clear Cell Renal Cell Carcinoma

Eukaryotic translation initiation factors (eIFs) constitute a new class of therapeutic cancer targets. EIF3b is the major scaffold protein of eIF3 (the largest core of eIFs). We sought to define the role played by and the mechanism of action of eIF3b in patients with clear cell renal cell carcinoma (ccRCC). We found that high-level eIF3b expression in tumors was not only associated with an aggressive tumor phenotype, but was also independently prognostic for patients with ccRCC. Knockdown of eIF3b impaired the action of the Akt pathway, thus inhibiting cell proliferation by disrupting the cell cycle and triggering apoptosis. Furthermore, the epithelial-to-mesenchymal transition was impaired after eIF3b depletion, via suppression of cell migration and invasion. Additionally, eIF3b knockdown significantly inhibited the growth of subcutaneous xenografts in mice. Together, these data show that eIF3b is both a promising prognostic biomarker and a potential therapeutic target for patients with ccRCC.

eIF3 Regulation of Protein Synthesis, Tumorigenesis, and Therapeutic Response

Translation initiation is the rate-limiting step of protein synthesis and highly regulated. Eukaryotic initiation factor 3 (eIF3) is the largest and most complex initiation factor consisting of 13 putative subunits. A growing number of studies suggest that eIF3 and its subunits may represent a new group of proto-oncogenes and associates with prognosis. They regulate translation of a subset of mRNAs involved in many cellular processes including proliferation, apoptosis, DNA repair, and cell cycle. Therefore, unveiling the mechanisms of eIF3 action in tumorigenesis may help identify attractive targets for cancer therapy. Here, we describe a series of methods used in the study of eIF3 function in regulating protein synthesis, tumorigenesis, and cellular response to therapeutic treatments.

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.

Effective Targeting of the Survivin Dimerization Interface with Small-Molecule Inhibitors

Many oncoproteins are considered undruggable because they lack enzymatic activities. In this study, we present a small-molecule-based anticancer agent that acts by inhibiting dimerization of the oncoprotein survivin, thereby promoting its degradation along with spontaneous apoptosis in cancer cells. Through a combination of computational analysis of the dimerization interface and in silico screening, we identified one compound that induced proteasome-dependent survivin degradation. Analysis of a set of structural analogues led us to identify a lead compound (LQZ-7F), which was effective in blocking the survival of multiple cancer cell lines in a low micromolar concentration range. LQZ-7F induced proteasome-dependent survivin degradation, mitotic arrest, and apoptosis, and it blocked the growth of human tumors in mouse xenograft assays. In addition to providing preclinical proof of concept for a survivin-targeting anticancer agent, our work offers novel in silico screening strategies to therapeutically target homodimeric oncogenic proteins considered undruggable.

Clusterin facilitates metastasis by EIF3I/Akt/MMP13 signaling in hepatocellular carcinoma

Clusterin (CLU) is a stress-induced chaperone that confers proliferative and survival advantages to cancer cells. However, effects and molecular mechanisms of CLU in hepatocellular carcinoma (HCC) metastasis are still unknown. In this study, HCC tissue array (n = 198) was utilized to investigate correlation between CLU expression and clinicopathological features. Overexpression of CLU in HCC tissues was correlated with shorter overall survival and higher tumor recurrence. In vitro and in vivo assays demonstrated that silencing CLU attenuated the invasion and metastasis of HCC cells, whereas ectopic overexpression of CLU resulted in the forced metastasis of HCC cells. We also revealed that CLU activated Akt signaling through complexing with eukaryotic translation initiation factor 3 subunit I (EIF3I), which in turn promoted matrix metalloproteinase 13 (MMP13) expression and HCC metastasis. Positive correlations between CLU and MMP13, p-Akt, or EIF3I were found in HCC tissues. We further observed that CLU knockdown using the CLU inhibitor OGX-011 significantly suppressed HCC metastasis in two metastatic models through inhibiting EIF3I/Akt/MMP13 signaling. These findings indicate that CLU is an independent predictive factor for prognosis of HCC and it facilitates metastasis through EIF3I/Akt/MMP13 signaling. CLU suppression using OGX-011 may represent a promising therapeutic option for suppressing HCC metastasis.

Knockdown of eIF3D inhibits breast cancer cell proliferation and invasion through suppressing the Wnt/β-catenin signaling pathway

eIF3D (eukaryotic translation initiation factor 3 subunit D) is one member of the eIF3 family and plays a critical role in translation initiation. Previous studies showed that it was involved in the development and progression of several tumors. However, the role of eIF3D in breast cancer and the underlying mechanism is still unclear. Therefore, this study set out to investigate the role of eIF3D in breast cancer. Our results demonstrated that eIF3D is up-regulated in breast cancer cells. Knockdown of eIF3D inhibited breast cancer cell proliferation and invasion. In addition, knockdown of eIF3D inhibited the expression of β-catenin, cyclin D1 and c-Myc in breast cancer cells. Taken together, our findings show that siRNA-eIF3D inhibits breast cancer cell proliferation and invasion through suppressing the Wnt/β-catenin signaling pathway. Therefore, eIF3D may be a good molecular target for the prevention and treatment of breast cancer.

Overexpression of eIF3e is correlated with colon tumor development and poor prognosis

EIF3e is a component of the eukaryotic translation initiation factor 3 (eIF-3) complexes, which is an essential factor for initiation of protein synthesis in mammalian cells. Translational control plays key roles in the complex mechanism of cancer development and progression. However, the clinical significance of eIF3e in colon cancer remains to be elucidated. We analyzed the eIF3e expression in a tissue microarray (TMA), which contained 173 colon cancer tissues paired with adjacent normal mucosa and lymph node metastasis. The expression of eIF3e was significantly elevated in colon cancer tissues in comparison with those in adjacent normal mucosa (P < 0.001) and lymph node metastasis (P < 0.001). The high expression of eIF3e in colon cancer was significantly correlated with tumor size (P < 0.001), lymph node involvement (P < 0.001), distant metastasis (P < 0.001), clinical stage (P < 0.001), histopathologic classification (P < 0.001), and vessel invasion (P = 0.036). Univariate and multivariate analysis revealed that eIF3e is an independent prognosis factor for overall survival and disease-free survival in colon cancer. Down-regulation of eIF3e in vitro inhibited colon cancer cell proliferation, clonality and promoted cell apoptosis. Taken together, high eIF3e expression may contribute to tumor progression and predict poor prognosis in colon cancer.