Overexpression of eukaryotic initiation factor 4E (eIF4E) and its clinical significance in lung adenocarcinoma

Effect of aza-BODIPY-photodynamic therapy on the expression of carcinoma-associated genes and cell death mode

BACKGROUND

Breast cancer is the most common cancer affecting women worldwide.Photodynamic therapy(PDT) has now proven to be a promising form of cancer therapy due to its targeted and low cytotoxicity to healthy cells and tissues.PDT is a technique used to create cell death localized by light after application of a light-sensitive agent.Aza-BODIPY is a promising photosensitizer for use in PDT. Our results showed that aza-BODIPY-PDT induced apoptosis, probably through p53 and caspase3 in MCF-7 cells. Future studies should delineate the molecular mechanisms underlying aza-BODIPY-PDT-induced cell death for a better understanding of the signaling pathways modulated by the therapy so that this novel technology could be implemented in the clinic for treating breast cancer.

AIM

In this study,we aimed to determine the change in the expression levels of 88 carcinoma-associated genes induced by aza-BODIPY-PDT were analyzed so as to understand the specific pathways that are modulated by aza-BODIPY-PDT.

MATERIAL METHOD

In this study,the molecular basis of the anti-cancer activity of aza-BODIPY-PDT was investigated.Induction of apoptosis and necrosis in MCF-7 breast cancer cells after treatment with aza- BODIPY derivative with phthalonitrile substituents (aza-BODIPY) followed by light exposure was evaluated by Annexin V 7- Aminoactinomycin D (7-AAD) flow cytometry.

RESULTS

Aza-BODIPY-PDT induced cell death in MCF-7 cells treated with aza-BODIPY-PDT; flow cytometry revealed that 28 % of the cells died by apoptosis. Seven of the 88 carcinoma-associated genes that were assayed were differentially expressed -EGF, LEF1, WNT1, TCF7, and TGFBR2 were downregulated, and CASP3 and TP53 were upregulated - in cells subjected to aza-BODIPY-PDT.This made us think that the aza-BODIPY-PDT induced caspase 3 and p53-mediated apoptosis in MCF7 cells.

CONCLUSION

In our study,it was determined that the application of aza-BODIPY-PDT to MCF7 cells had a negative effect on cell connectivity and cell cycle.The fact that the same effect was not observed in control cells and MCF7 cells in the dark field of aza-BODIPY indicates that aza-BODIPY has a strong phodynamic anticancer effect.

Medicinal chemistry approaches to target the MNK-eIF4E axis in cancer

Aberrant translation of proteins that promote cell proliferation is an essential factor that defines oncogenic processes and cancer. The process for ribosomal translation of proteins from mRNA requires an essential initiation step which is controlled by the protein eIF4E, which binds the RNA 5'-cap and forms the eIF4F complex that subsequently translates protein. Typically, eIF4E is activated by phosphorylation on Ser209 by MNK1 and MNK2 kinases. Substantial work has shown that eIF4E and MNK1/2 are dysregulated in many cancers and this axis has therefore become an active area of interest for developing new cancer therapeutics. This review summarizes and discusses recent work to develop small molecules that target different steps in the MNK-eIF4E axis as potential cancer therapeutics. The aim of this review is to cover the breadth of different molecular approaches being taken and the medicinal chemistry basis for their optimization and testing as new cancer therapeutics.

Identification of a First-in-Class Small-Molecule Inhibitor of the EIF4E-RBM38 Complex That Enhances Wild-type TP53 Protein Translation for Tumor Growth Suppression

EIF4E, an mRNA cap-binding protein, is necessary for cap-dependent translation. Overexpression of EIF4E is known to promote cancer development by preferentially translating a group of oncogenic mRNAs. Thus, 4EGI-1, a disruptor of EIF4E-EIF4G1 interaction, was developed to inhibit oncoprotein expression for cancer therapy. Interestingly, RBM38, an RNA-binding protein, interacts with EIF4E on TP53 mRNA, prevents EIF4E from binding to TP53 mRNA cap, and inhibits TP53 expression. Thus, Pep8, an eight amino acid peptide derived from RBM38, was developed to disrupt the EIF4E-RBM38 complex, leading to increased TP53 expression and decreased tumor cell growth. Herein, we have developed a first-in-class small-molecule compound 094, which interacts with EIF4E via the same pocket as does Pep8, dissociates RBM38 from EIF4E, and enhances TP53 translation in RBM38- and EIF4E-dependent manners. Structure-activity relationship studies identified that both the fluorobenzene and ethyl benzamide are necessary for compound 094 to interact with EIF4E. Furthermore, we showed that compound 094 is capable of suppressing three-dimensional tumor spheroid growth in RBM38- and TP53-dependent manners. In addition, we found that compound 094 cooperates with the chemotherapeutic agent doxorubicin and EIF4E inhibitor 4EGI-1 to suppress tumor cell growth. Collectively, we showed that two distinct approaches can be used together to target EIF4E for cancer therapy by enhancing wild-type TP53 expression (094) and by suppressing oncoprotein expression (4EGI-1).

Expression of eIF4E Gene in Glioma and Its Sensitivity to Oxidative Stress

Objective

Increased expression of eIF4E has been observed in various cancers, which makes eIF4E an attractive target of anticancer drugs. This study mainly discussed eIF4E gene expression in glioma and its sensitivity to oxidative stress (OS).

Methods

Relevant data from The Cancer Genome Atlas (TCGA) database regarding eIF4E gene expression and its prognostic significance in glioma samples were analyzed. Additionally, we measured eIF4E at mRNA and protein levels in clinical samples collected between July 2019 and September 2021, as well as glioma cell strains. U251 cells cultured in vitro were treated with OS injury induced by hydrogen peroxide (H₂O₂) and then transfected with si-eIF4E to determine changes in cell multiplication, invasiveness, and migration capacities as well as apoptosis rate. ELISA quantified cell malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) concentrations, and flow cytometry measured reactive oxygen species (ROS) level.

Results

In glioma samples from the TCGA database, eIF4E showed obviously elevated levels in LGG and GBM patients, which was usually associated with adverse patient prognosis (P < 0.05). eIF4E was also upregulated in glioma cell strains than in HBE cells. In comparison with the blank control group, transfection of si-eIF4E statistically suppressed the capacity of U251 cells to proliferate, invade and migrate, and enhance apoptosis rate, while reducing SOD and GSH-Px and increasing MDA and ROS. In addition, H₂O₂ induced the upregulation of eIF4E in U251 cells. H₂O₂ + si-eIF4E exhibited reduced multiplication and number of clone cell formation, invasion, and migration of U251 cells, as well as increased apoptosis rate than H₂O₂ + si-NC group.

Conclusions

eIF4E is highly expressed in glioma. Knocking down eIF4E can effectively inhibit the capacity of U251 to proliferate, invade and migrate, and significantly increase apoptosis. In addition, eIF4E knock-down is able to lower OS reaction under H₂O₂ inducement and enhance U251 cells' sensitivity to OS.

Outcome of Patients With Head and Neck Squamous Cell Carcinoma Can be Predicted by Expression of eIF4E and Osteopontin in Free Surgical Margins

Squamous cell carcinoma of the head and neck (HNSCC) is recognized as the third most common cause of death. Incomplete resection of the primary tumor is the main cause of local recurrence and poor prognosis in HNSCC. Histologic assessment in order to determine "tumor-free" margins could be inadequate because of malignant transformation occurs at the molecular level earlier than the morphologic level. The present study aimed to evaluate the prognostic significance of eukaryotic initiation factor 4E (eIF4E) and Osteopontin in the tumor cells and histologically tumor free surgical margins of HNSCC. This cohort study was performed on 60 cases of HNSCC diagnosed at the Department of Pathology and treated at the Clinical Oncology Department, Faculty of Medicine, Zagazig University. Our enrolled formalin fixed paraffin embedded biopsy specimens with their matched tumor free surgical margins from resected head and neck squamous cell carcinoma were immunostaind for eIF4E and Osteopontin markers. 65% of our HNSCC patients had eIF4 E positive cytoplasmic immunostaining and 70% of them exhibited Osteopontin staining. Two-thirds of the dead patients exhibited high Osteopontin positive staining, whereas the surviving group did not exhibit this high expression. Concerning eIF4E, 85% and 5% of the dead patients showed high and low eIF4E expression, respectively. Disease-free survival (DFS) and overall survival were significantly (P=0.000) different between high and negative expression of Osteopontin, high and negative expression of eIF4E. 84% of patients with eIF4E positive margins and 75% with Osteopontin positive margins had local recurrence. In addition, negative expression of eIF4E is associated with highly significant better DFS and overall survival (P=0.000 and 0.001), respectively, in the margin negative expression status, while negative expression of Osteopontin was significantly associated with better DFS but of no significance in overall survival outcome. Our findings suggest that tumor-free surgical margins in HNSCC may be redefined as histologically Osteopontin and eIF4E negative resection margins. However, multicenter prospective studies are required to further evaluate their clinical utility in the surgical management of primary HNSCC.

Identification of significant genes as prognostic markers and potential tumor suppressors in lung adenocarcinoma via bioinformatical analysis

Background

Lung adenocarcinoma (LAC) is the predominant histologic subtype of lung cancer and has a complicated pathogenesis with high mortality. The purpose of this study was to identify differentially expressed genes (DEGs) with prognostic value and determine their underlying mechanisms.

Methods

Gene expression data of GSE27262 and GSE118370 were acquired from the Gene Expression Omnibus database, enrolling 31 LAC and 31 normal tissues. Common DEGs between LAC and normal tissues were identified using the GEO2R tool and Venn diagram software. Next, the Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used to analyze the Gene Ontology and Kyoto Encyclopedia of Gene and Genome (KEGG) pathways. Then, protein-protein interaction (PPI) network of DEGs was visualized by Cytoscape with Search Tool for the Retrieval of Interacting Genes and central genes were identified via Molecular Complex Detection. Furthermore, the expression and prognostic information of central genes were validated via Gene Expression Profiling Interactive Analysis (GEPIA) and Kaplan-Meier analysis, respectively. Finally, DAVID, real-time PCR and immunohistochemistry were applied to re-analyze the identified genes, which were also further validated in two additional datasets from ArrayExpress database.

Results

First, 189 common DEGs were identified among the two datasets, including 162 downregulated and 27 upregulated genes. Next, Gene Ontology and KEGG pathway analysis of the DEGs were conducted through DAVID. Then, PPI network of DEGs was constructed and 17 downregulated central genes were identified. Furthermore, the 17 downregulated central genes were validated via GEPIA and datasets from ArrayExpress, and 12 of them showed a significantly better prognosis. Finally, six genes were identified significantly enriched in neuroactive ligand-receptor interactions (EDNRB, RXFP1, P2RY1, CALCRL) and Rap1 signaling pathway (TEK, P2RY1, ANGPT1) via DAVID, which were further validated to be weakly expressed in LAC tissues via RNA quantification and immunohistochemistry analysis.

Conclusions

The low expression pattern and relation to prognosis indicated that the six genes were potential tumor suppressor genes in LAC. In conclusion, we identified six significantly downregulated DEGs as prognostic markers and potential tumor suppressor genes in LAC based on integrated bioinformatics methods, which could act as potential molecular markers and therapeutic targets for LAC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08308-3.

Indole hydrazide compound ZJQ-24 inhibits angiogenesis and induces apoptosis cell death through abrogation of AKT/mTOR pathway in hepatocellular carcinoma

Angiogenesis and the activation of AKT/mTOR pathway are crucial for hepatocarcinoma development and progression, the activation of mTORC1/2 and relevant substrates have been confirmed in clinical hepatocarcinoma samples. Therefore, AKT/mTOR pathway represents the major targets for anti-cancer drugs development. Here, we investigated the anti-proliferative activity and mechanisms of ZJQ-24 in hepatocellular carcinoma, both in vivo and in vitro. A hepatocellular carcinoma xenograft model showed that ZJQ-24 significantly inhibited tumor growth with few side effects. MTT assays, flow cytometric analysis, Western blotting and immunohistochemistry identified that ZJQ-24 effectively suppressed hepatocellular carcinoma cell proliferation via G₂/M phase arrest and caspase-dependent apoptosis but had no cytotoxic on normal cells. Furthermore, ZJQ-24 significantly blocked AKT/mTOR signaling by down-regulation of mTORC1 molecules, including phospho-p70S6K (Thr³⁸⁹) and phospho-4EBP-1 (Ser65, Thr^37/46, Thr⁷⁰) and phospho-AKT (Ser⁴⁷³) in HCC cells. It is very important that the ZJQ-24 did not induce the mTORC1-depdent PI3K/Akt feedback activation through JNK excitation. Moreover, ZJQ-24 inhibited the cap-dependent translation initiation by impairing the assembly of the eIF4E/eIF4G complex. Immunohistochemistry further confirmed ZJQ-24 inhibited the tumor growth through suppression of VEGF and AKT/mTOR pathways in vivo. Thus, the present study is the first to illustrate that ZJQ-24 triggers antiangiogenic activity and apoptosis via inhibiting the AKT/mTOR pathway in hepatocellular carcinoma cells, providing basic scientific evidence that ZJQ-24 shows great potential function as inhibitor of angiogenesis and tumor growth in hepatocellular carcinoma.

Clinical Significance of Eukaryotic Initiation Factor 4E (eIF4E) Level among Cases Suffering Basal Cell Carcinoma of Skin

BACKGROUND Eukaryotic initiation factor 4E (eIF4E) has been reported to act as a prognostic biomarker in various cancers, but its actual effect on basal cell cancer (BCC) of the skin is rarely reported. Our research measured eIF4E levels and discussed its consequence in BCC of the skin. MATERIAL AND METHODS Semi-quantitative real-time polymerase chain reaction (RT-PCR) and western blotting analysis were used to detect relative expression level of eIF4E in specimens at both mRNA and protein levels. The relationship of eIF4E level with clinical profiles was analyzed via chi-square test. Additionally, prognostic value of eIF4E was analyzed via Kaplan-Meier and cox regression analysis. RESULTS We found that eIF4E was over-expressed in tumor tissues, in comparison to bordering cancer-free tissue samples. Besides, elevated eIF4E level exhibited a strong relation to metastasis, TNM stage, and differentiation. Kaplan-Meier analysis revealed cases harboring high eIF4E levels faced shortened overall survival compared to cases of low levels (log rank test, P=0.018). Moreover, eIF4E could act as an independent biomarker for the prognosis of BCC of the skin, according to Cox regression analysis. CONCLUSIONS The level of eIF4E was upregulated and significantly correlated with the development of BCC of the skin. Thus, it might be a promising prognostic biomarker and therapy target for BCC of the skin.

Expression of 4E-BP1 and phospho-4E-BP1 correlates with the prognosis of patients with clear cell renal carcinoma

Background

Eukaryotic translation initiation factor 4E (eIF4E) is a key regulator of protein synthesis. Changes in eIF4E activity disproportionally affect the translation of a subset of oncogenic mRNAs in some cancers.

Materials and methods

We have assessed the expression levels of vascular endothelial growth factor C (VEGFC), eIF4E, eIF4E-binding proteins (4E-BPs) and phospho-4E-BP1 in clear cell renal carcinoma (ccRCC; n=101) using immunohistochemistry and analyzed the relevant mRNA levels and survival using online databases.

Results

The protein levels of VEGFC, an eIF4E-regulated gene, were upregulated in ccRCC tissues compared with adjacent normal renal tissues, indicating an enhanced eIF4E activity in ccRCC. The expression of eIF4E had no significant changes in ccRCC tissues. However, 4E-BP1 and phospho-4E-BP1 were found to be overexpressed in ccRCC tissues (P<0.05), and the high mRNA and protein levels of 4E-BP1 and phospho-4E-BP1 correlated with an unfavorable clinical outcome in ccRCC patients. Meanwhile, the mRNA expression of PIK3CD and PIK3CG were enhanced in ccRCC.

Conclusion

From these results, we could infer that the increase in eIF4E activity may be caused by the increased phospho-4E-BP1 level, which was probably due to the activation of phosphoinositide 3-kinase (PI3K) pathway.

Beyond molecular tumor heterogeneity: protein synthesis takes control

One of the daunting challenges facing modern medicine lies in the understanding and treatment of tumor heterogeneity. Most tumors show intra-tumor heterogeneity at both genomic and proteomic levels, with marked impacts on the responses of therapeutic targets. Therapeutic target-related gene expression pathways are affected by hypoxia and cellular stress. However, the finding that targets such as eukaryotic initiation factor (eIF) 4E (and its phosphorylated form, p-eIF4E) are generally homogenously expressed throughout tumors, regardless of the presence of hypoxia or other cellular stress conditions, opens the exciting possibility that malignancies could be treated with therapies that combine targeting of eIF4E phosphorylation with immune checkpoint inhibitors or chemotherapy.

Expression analysis and clinical significance of eIF4E, VEGF-C, E-cadherin and MMP-2 in colorectal adenocarcinoma

The underlying mechanisms of colorectal carcinoma (CRC) metastasis remain to be elucidated. The aim of this study is to investigate clinical significance and the expression of eIF4E, VEGF-C, MMP-2, and E-cadherin in the CRC metastasis. We investigated their expressions in 108 patients, analyzed the relationships between their expressions in CRC and evaluated the relationships between their expressions and clinical pathogenic parameters. Furthermore, their roles in patient survival and in CRC metastasis were also investigated. We found that eIF4E, VEGF-C and MMP-2 were up-regulated in CRC, and their expression frequencies (EFs) were higher in cancerous tissues than in adjacent normal tissues. The EF of E-cadherin is lower in cancerous tissues than in adjacent normal tissues. Totally, their EFs were not associated with sex and age of patient, however, their EFs were associated with tumor differentiation, the depth of invasion, lymph node metastasis and tumor stages. Furthermore, eIF4E, VEGF-C, and MMP-2 shortened and E-cadherin prolonged survival in patient-derived CRC xenografts. Similarly, eIF4E, VEGF-C, and MMP-2 promoted and E-cadherin suppressed the lung metastasis of CRC cells. In addition, knockdown of eIF4E inhibited migration of CRC cells, downregulated VEGF-C, MMP-2 and upregulated E-cadherin. In conclusion, eIF4E promoted CRC metastasis via up-regulating the expression of VEGF-C, MMP-2 and suppressing E-cadherin.

Arginine methyltransferase inhibitor 1 inhibits gastric cancer by downregulating eIF4E and targeting PRMT5

Arginine methylation is carried out by protein arginine methyltransferase (PRMTs) family. Arginine methyltransferase inhibitor 1 (AMI-1) is mainly used to inhibit type I PRMT activity in vitro. However, the effects of AMI-1 on type II PRMT5 activity and gastric cancer (GC) remain unclear. In this study, we provided the first evidence that AMI-1 significantly inhibited GC cell proliferation and migration while induced GC cell apoptosis, and reduced the expression of PRMT5, eukaryotic translation initiation factor 4E (eIF4E), symmetric dimethylation of histone 3 (H3R8me2s) and histone 4 (H4R3me2s). In addition, AMI-1 inhibited tumor growth, downregulated eIF4E, H4R3me2s and H3R8me2s expression in mice xenografts model of GC. Collectively, our results suggest that AMI-1 inhibits GC by downregulating eIF4E and targeting type II PRMT5.

Genetic polymorphisms of mTOR and cancer risk: a systematic review and updated meta-analysis

mTOR regulates several cellular processes that are critical for tumorigenesis. However, previous studies on the association of mTOR polymorphisms with predisposition to different cancer types are somewhat contradictory. Therefore, we performed a systematic review and updated meta-analysis of the available evidence regarding the relationship between mTOR single nucleotide polymorphisms (SNPs) and cancer risk. Up to November 2015, 23 original publications were identified covering 20 mTOR SNPs, of which seven SNPs (rs2536, rs2295080, rs1883965, rs1034528, rs17036508, rs3806317 and rs1064261) were included in the final meta-analysis. We estimated the summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for mTOR polymorphisms and cancer risk, and used the model-free approach to investigate the biological effect of each polymorphism. Our meta-analysis found that rs1883965, rs1034528, and rs17036508 were correlated with increased cancer risk in the complete over-dominant model (rs1883965 GA versus GG/AA: fixed-effects OR=1.15, 95% CI 1.02-1.29; rs1034528 GC versus GG/CC: fixed-effects OR=1.30, 95% CI 1.13-1.48; rs17036508 TC versus CC/TT: fixed-effects OR=1.23, 95% CI 1.06-1.43). Stratifying analyses by cancer type, we found that the rs2295080 G allele was associated with a significantly higher risk of acute leukemia in the recessive model (GG versus GT/TT: fixed-effects OR=2.08, 95% CI 1.34-3.22) and a lower risk of genitourinary cancers in the dominant model (TG/GG versus TT: fixed-effects OR=0.77, 95% CI 0.68-0.86). Interestingly, further expression analysis showed that homozygous variant genotype carriers of rs1883965, rs1034528 and rs17036508 had lower mTOR transcript levels, based on HapMap data.

Updated overview of current biomarkers in head and neck carcinoma

Squamous cell cancer is the most common type of malignancy arising from the epithelial cells of the head and neck region. Head and neck squamous cell carcinoma (HNSCC) is one of the predominant causes of cancer related casualties worldwide. Overall prognosis in this disease has improved to some extent with the advancements in therapeutic modalities but detection of primary tumor at its initial stage and prevention of relapse are the major targets to be achieved for further improvement in terms of survival rate of patients. Latest achievements in basic research regarding molecular characterization of the disease has helped in better perception of the molecular mechanisms involved in HNSCC progression and also in recognizing and targeting various molecular biomarkers associated with HNSCC. In the present article, we review the information regarding latest and potential biomarkers for the early detection of HNSCC. A detailed molecular characterization, ultimately, is likely to improve the development of new therapeutic strategies, potentially relevant to diagnosis and prognosis of head and neck cancers. The need for more accurate and timely disease prediction has generated enormous research interests in this field.

Overexpression of eIF4E in colorectal cancer patients is associated with liver metastasis

Purpose

Liver metastasis is one of the leading causes of death in colorectal cancer (CRC) patients. The present study aimed to evaluate the value of eIF4E as a prognostic marker of colorectal liver metastasis (CLM) and identify the functional role of eIF4E in CRC metastasis.

Patients and methods

The expression level of eIF4E in CRC tissues was analyzed by immunohistochemical staining and Western blot. Expression of eIF4E in CRC cell lines was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot. Cell Counting Kit-8 (CCK-8) and Transwell assays were performed to assess the effects of eIF4E on cell proliferation, migration, and invasion. Western blot was further used to investigate the mechanism of eIF4E in tumor metastasis.

Results

The upregulation frequency of eIF4E in the CLM group (82.5%) was higher than that in the non-CLM group (65.0%). Of the 80 patients recruited for the follow-up study, 23 were in the low eIF4E group (ratio of tumor to nontumor tissue <twofold), and 57 were in the high eIF4E group (ratio of tumor to nontumor tissue ≥twofold). In addition, the group exhibiting high eIF4E expression had a higher rate of liver metastasis (47.4%) than the group exhibiting low eIF4E expression (13.0%). In CRC cell lines, the expression of eIF4E was higher than in the normal cells. In vitro functional studies indicated that eIF4E knockdown inhibited the proliferation, migration, and invasion of Lovo and SW480 cells, and suppressed the expression of cyclin D1, VEGF, MMP-2, and MMP-9.

Conclusion

The results of the present study indicated that high eIF4E levels in CRC patients predicted a high risk of liver metastasis. Knockdown of eIF4E inhibited CRC cell metastasis in part through regulating the expression of cyclin D1, VEGF, MMP-2, and MMP-9.

The synergistic inhibition of breast cancer proliferation by combined treatment with 4EGI-1 and MK2206

Cap-dependent translation is a potential cancer-related target (oncotarget) due to its critical role in cancer initiation and progression. 4EGI-1, an inhibitor of eIF4E/eIF4G interaction, was discovered by screening chemical libraries of small molecules. 4EGI-1 inhibits cap-dependent translation initiation by impairing the assembly of the eIF4E/eIF4G complex, and therefore is a potential anti-cancer agent. Here, we report that 4EGI-1 also inhibits mTORC1 signaling independent of its inhibitory role on cap-dependent translation initiation. The inhibition of mTORC1 signaling by 4EGI-1 activates Akt due to both abrogation of the negative feedback loops from mTORC1 to PI3K and activation of mTORC2. We further validated that mTORC2 activity is required for 4EGI-1-mediated Akt activation. The activated Akt counteracted the anticancer effects of 4EGI-1. In support of this model, inhibition of Akt potentiates the antitumor activity of 4EGI-1 both in vitro and in a xenograft mouse model in vivo. Our results suggest that a combination of 4EGI-1and Akt inhibitor is a rational approach for the treatment of cancer.

miR-34c-3p functions as a tumour suppressor by inhibiting eIF4E expression in non-small cell lung cancer

OBJECTIVES

MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression and mediate diverse physiological processes. In this study, we investigated functions of miRNA miR-34c-3p in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

miR-34c-3p expression was evaluated by qPCR. Cell viability was examined by MTT and proliferation by cell cycle analysis. Cell migration and invasion were tested using Transwells with/without Matrigel coating. Western blot analysis was performed for eIF4E, c-Myc, Cyclin D1, survivin and Mcl-1 protein expression.

RESULTS

miR-34c-3p expression was significantly reduced in tissues and serum samples from NSCLC patients and in NSCLC cell lines A549, H460, H23, H157 and H1299. Overexpression of miR-34c-3p in A549 and H157 cells reduced cell proliferation, migration and invasion, whereas transfection with miR-34c-3p inhibitor (miR-34c-3p-in) produced opposite effects. Target analysis using algorithms miRanda, TargetScan and DIANA identified eIF4E as a potential target of miR-34c-3p. Luciferase assay using the eIF4E 3'-UTR reporter carrying a putative miR-34c-3p target sequence revealed eIF4E to be a specific target of miR-34c-3p. Overexpression of miR-34c-3p in NSCLS cell lines led to significant reduction in mRNA and protein levels of eIF4E, whereas inhibition of miR-34c-3p resulted in significant increase in eIf4e protein levels, confirming eIF4E to be a direct target of miR-34c-3p in NSCLS. Overexpression of eIF4E in A549 cells promoted cell proliferation, migration and invasion, which were partially reversed by miR-34c-3p.

CONCLUSION

miR-34c-3p directly targeted eIF4E and reduced miR-34c-3p expression in NSCLC, promoting cell cycle progression, proliferation, migration and invasion.

Targeted polymeric nanoparticles for cancer gene therapy

In this article, advances in designing polymeric nanoparticles for targeted cancer gene therapy are reviewed. Characterization and evaluation of biomaterials, targeting ligands, and transcriptional elements are each discussed. Advances in biomaterials have driven improvements to nanoparticle stability and tissue targeting, conjugation of ligands to the surface of polymeric nanoparticles enable binding to specific cancer cells, and the design of transcriptional elements has enabled selective DNA expression specific to the cancer cells. Together, these features have improved the performance of polymeric nanoparticles as targeted non-viral gene delivery vectors to treat cancer. As polymeric nanoparticles can be designed to be biodegradable, non-toxic, and to have reduced immunogenicity and tumorigenicity compared to viral platforms, they have significant potential for clinical use. Results of polymeric gene therapy in clinical trials and future directions for the engineering of nanoparticle systems for targeted cancer gene therapy are also presented.

The Eukaryotic Translation Initiation Factor 4E (eIF4E) as a Therapeutic Target for Cancer

Cancer cells depend on cap-dependent translation more than normal tissue. This explains the emergence of proteins involved in the cap-dependent translation as targets for potential anticancer drugs. Cap-dependent translation starts when eIF4E binds to mRNA cap domain. This review will present eIF4E's structure and functions. It will also expose the use of eIF4E as a therapeutic target in cancer.

Protein expression of eIF4E and integrin αvβ6 in colon cancer can predict clinical significance, reveal their correlation and imply possible mechanism of interaction

Background

Both eukaryotic translation initiation factor 4E (eIF4E) and integrin αvβ6 play an important role in the development and progression of cancer. The aim of this study was to investigate the expression of eIF4E and Integrin αvβ6, their clinical significance as well as the two proteins’ correlation in colonic carcinoma tissues.

Results

The expression levels of eIF4E and integrin αvβ6 were analyzed in colon cancerous and paraneoplastic tissues of 138 cases via tissue microarray (TMA)- immunohistochemistry. And their clinical significance as well as the two proteins’ correlation was also investigated. The expression of eIF4E was significantly associated with clinical TNM stage (P = 0.009), while T stage (P = 0.011) and TNM stage (P = 0.012) were significantly associated with integrin αvβ6 expression. Moderately weak correlation exists between the two proteins (r =0.299, P <0.001). The survival analysis by Kaplan-Meier and Cox regression model showed that protein expression of high eIF4E and positive integrin αvβ6, as independent prognostic factors (RR = 2.417, P = 0.001 and RR = 2.393, P = 0.001), tended to have a significantly poorer 5-year survival rate (P = 0.013 and 0.025, respectively, the log-rank test).

Conclusion

eIF4E and Integrin αvβ6 were indicators of tumor’s progression and poor prognosis of patients with colon cancer. And the potential signaling loop involving them may provide a helpful therapeutic target in prevention and treatment of colon cancer.

Resistance to EGFR-TKI can be mediated through multiple signaling pathways converging upon cap-dependent translation in EGFR-wild type NSCLC

INTRODUCTION

For the majority of patients with non-small-cell lung cancer (NSCLC), response to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is suboptimal. In models of acquired resistance to EGFR-TKI, activation of Akt phosphorylation is frequently observed. Because Akt activation results in downstream initiation of cap-dependent protein translation, we hypothesized that a strategy of targeting cap-dependent translation in combination with erlotinib might enhance therapy.

METHODS

NSCLC cells that are wild type for EGFR were assayed for sensitivity to erlotinib. Serum-starved NSCLC cells were assayed for EGFR signaling and downstream pathway activation by immunoblot after stimulation with epidermal growth factor. EGFR signaling and signaling mediators of cap-dependent translation were assayed by immunoblot under serum-replete conditions 24 hours after treatment with erlotinib. Finally, combination treatment with erlotinib and two different cap-dependent translation inhibitors were done to assess the effect on cell viability.

RESULTS

EGFR signaling is coupled to activation of cap-dependent translation in EGFR wild-type cells. Erlotinib inhibits EGFR phosphorylation in EGFR-TKI resistant cells, however, results in activation of downstream signaling molecules including Akt and extracellular regulated kinase, ERK 1/2, resulting in maintenance of eukaryotic initiation factor 4F (eIF4F) activation. eIF4F cap-complex formation is maintained in erlotinib-resistant cells, but not in erlotinib-sensitive cells. Finally, using an antisense oligonucleotide against eukaryotic translation initiation factor 4E and a small-molecule inhibitor to disrupt eIF4F formation, we show that cap-dependent translation inhibition can enhance sensitivity to erlotinib.

CONCLUSION

The results of these studies support further clinical development of translation inhibitors for treatment of NSCLC in combination with erlotinib.

RNA-protein interactions: an overview

RNA binding proteins (RBPs) are key players in the regulation of gene expression. In this chapter we discuss the main protein-RNA recognition modes used by RBPs in order to regulate multiple steps of RNA processing. We discuss traditional and state-of-the-art technologies that can be used to study RNAs bound by individual RBPs, or vice versa, for both in vitro and in vivo methodologies. To help highlight the biological significance of RBP mediated regulation, online resources on experimentally verified protein-RNA interactions are briefly presented. Finally, we present the major tools to computationally infer RNA binding sites according to the modeling features and to the unsupervised or supervised frameworks that are adopted. Since some RNA binding site search algorithms are derived from DNA binding site search algorithms, we discuss the commonalities and novelties introduced to handle both sequence and structural features uniquely characterizing protein-RNA interactions.

Translational control in cancer etiology

The link between perturbations in translational control and cancer etiology is becoming a primary focus in cancer research. It has now been established that genetic alterations in several components of the translational apparatus underlie spontaneous cancers as well as an entire class of inherited syndromes known as "ribosomopathies" associated with increased cancer susceptibility. These discoveries have illuminated the importance of deregulations in translational control to very specific cellular processes that contribute to cancer etiology. In addition, a growing body of evidence supports the view that deregulation of translational control is a common mechanism by which diverse oncogenic pathways promote cellular transformation and tumor development. Indeed, activation of these key oncogenic pathways induces rapid and dramatic translational reprogramming both by increasing overall protein synthesis and by modulating specific mRNA networks. These translational changes promote cellular transformation, impacting almost every phase of tumor development. This paradigm represents a new frontier in the multihit model of cancer formation and offers significant promise for innovative cancer therapies. Current research, in conjunction with cutting edge technologies, will further enable us to explore novel mechanisms of translational control, functionally identify translationally controlled mRNA groups, and unravel their impact on cellular transformation and tumorigenesis.

EIF4E over-expresses and enhances cell proliferation and cell cycle progression in nasopharyngeal carcinoma

Eukaryotic translation initiation factor 4E (eIF4E) is involved in integration and amplification of many carcinogenesis signals in tumors. However, it remains unclear whether eIF4E over-expresses in NPC and whether it is associated with the development of NPC. Here, we analyzed the expression state of eIF4E, c-Myc, and MMP9 in 24 nasopharyngitises and 64 nasopharyngeal carcinomas (NPC) tissues and studied the influences of eIF4E on the proliferation and cell cycle in NPC cell lines. The results indicate that eIF4E might over-express in NPC and the over-expression of eIF4E promotes NPC growth and cell cycle progression through enhancing the translational expression of c-Myc and MMP9. The finding certainly adds new knowledge in the understanding of the carcinogenesis of NPC and provides a potential molecular target for the NPC therapy and prevention.

Putative role of the mTOR/4E-BP1 signaling pathway in the carcinogenesis and progression of gastric cardiac adenocarcinoma

The mammalian target of rapamycin/eukaryotic translation inititiation factor 4E binding protein 1 (mTOR/4E-BP1) transduction pathway is activated in a range of malignant cancers, but its role in human gastric cardiac adenocarcinoma (GCA) has not been well defined. The present study used western blotting and reverse transcription polymerase chain reaction (RT-PCR) to assess the expression of mTOR, 4E-BP1 and eukaryotic translation initiation factor 4E (eIF4E) at the protein and mRNA levels in 33 cases of GCA and paired adjacent normal gastric mucosal tissues. The expression of mTOR at the protein level in GCA was significantly lower than that in the corresponding normal gastric mucosa (0.296 ± 0.27 vs. 1.348 ± 0.80, P<0.05), but the ratio of p-mTOR to mTOR was significantly increased in tumor tissues (1.425 ± 1.07 vs. 0.450 ± 0.24, P<0.05). The expression of 4E-BP1 was significantly decreased in GCA compared with normal tissues (p<0.05), while the levels of phosphorylated 4E-BP1 (p-4E-BP1) were markedly increased in tumor tissues (p<0.05). The levels of phosphorylated eIF4E (p‑eIF4E) were significantly higher in the tumors in comparison to the corresponding normal tissues (1.822 ± 0.63 vs. 0.997 ± 0.38, P<0.05), and the levels of p-eIF4E were closely correlated with lymph node metastasis (p<0.05). The mTOR/4E-BP1 signaling pathway is activated in GCA, with mTOR activated mainly through increased mTOR phosphorylation rather than protein overexpression.

Detection of eukaryotic translation initiation factor 4E and its clinical significance in hepatocellular carcinoma

AIM: To study the expression of eukaryotic translation initiation factor 4E (eIF4E), which is closely correlated with malignant tumors, and its relationship to prognosis in hepatocellular carcinoma.

METHODS: Western blotting was performed to quantify the elF4E protein expression in the normal human liver cell line L02 and the hepatoma cell lines Hep3B, HepG2, and Huh7. Forty-six hepatocellular carcinoma samples with complete clinical data were obtained from Changzheng Hospital during the period of December 2008 to July 2009. The expression of eIF4E in the tumor samples and their adjacent tissues were detected by immunohistochemistry. The relationship between the test results and hepatocellular carcinoma (HCC) prognosis was statistically analysed by using a COX proportional hazard model.

RESULTS: Western blotting analysis showed that there were distinct eIF4E protein bands in all three of the hepatoma cell lines. In particular, the HepG2 cell line had the highest level of eIF4E protein expression. The L02 cell group had a low eIF4E expression. Immunohistochemical assay showed that there were 32 cases in which the tumour tissue expression was higher than their adjacent tissues, accounting for 69.57%. There were also 14 cases in which the tumour tissue expression was lower or no significant difference was found, accounting for 30.43%. COX proportional hazards model analysis showed that HCC prognosis was related to the depth of invasion, the overexpression of eIF4E and p53, possibly as independent HCC prognostic predictors.

CONCLUSION: In summary, eIF4E expression is associated with liver cancer, and patients with high eIF4E expression levels have a higher risk of recurrence.

Development of biochemical assays for the identification of eIF4E-specific inhibitors

Control of mRNA translation plays a critical role in cell growth, proliferation, and differentiation and is tightly regulated by AKT and RAS oncogenic pathways. A key player in the regulation of this process is the mRNA 5' cap-binding protein, eukaryotic translation initiation factor 4E (eIF4E). eIF4E contributes to malignancy by selectively enabling the translation of a limited pool of mRNAs that generally encode key proteins involved in cell cycle progression, angiogenesis, and metastasis. Several data indicate that the inhibition of eIF4E in tumor cell lines and xenograft models impairs tumor growth and induces apoptosis; eIF4E, therefore, can be considered a valuable target for cancer therapy. Targeting the cap-binding pocket of eIF4E should represent a way to inhibit all the eIF4E cellular functions. We present here the development and validation of different biochemical assays based on fluorescence polarization and surface plasmon resonance techniques. These assays could support high-throughput screening, further refinement, and characterization of eIF4E inhibitors, as well as selectivity assessment against CBP80/CBP20, the other major cap-binding complex of eukaryotic cells, overall providing a robust roadmap for development of eIF4E-specific inhibitors.

Elevated expression of eukaryotic translation initiation factor 4E is associated with proliferation, invasion and acquired resistance to erlotinib in lung cancer

Eukaryotic translation initiation factor 4E (eIF4E) is the rate-limiting factor for cap-dependent translation initiation, which is known to regulate oncogenesis. Elevated eIF4E and its negative impact on prognosis in human non-small cell lung cancer (NSCLC) have been reported previously. However, its potential as a therapeutic target and role in regulation of sensitivity to EGFR inhibitors is an area of ongoing investigations. In this study, we detected increased levels of eIF4E in 16 human NSCLC cell lines compared with their normal bronchial epithelial cells. Consistently, human tissue array analysis showed that eIF4E expression was significantly higher in human NSCLC tissues than normal tissues. Inhibition of eIF4E using eIF4E siRNA inhibited the growth and invasion of NSCLC cells. These data suggest that eIF4E overexpression plays a crucial role in positive regulation of the growth and invasion of NSCLC cells. By proteomics, we found that eIF4E levels were elevated in erlotinib-resistant cell lines compared with the sensitive parental cell line. In agreement, assembly of the eIF4F cap complex and several oncogenic proteins regulated by the cap-dependent translation mechanism, were also increased in erlotinib-resistant cells. Thus, erlotinib-resistant cells exhibit elevated eIF4E expression and cap-dependent translation. Inhibition of eIF4F with different means (e.g., gene knockdown) downregulated c-Met expression and partially restored cell sensitivity to erlotinib, suggesting that elevated eIF4E contributes to development of erlotinib resistance, likely through positive regulation of c-Met expression. Taken together, we suggest that elevated eIF4E in NSCLC cells is associated with proliferation, invasion and acquired erlotinib resistance.

Translational control gone awry: a new mechanism of tumorigenesis and novel targets of cancer treatments

Translational control is one of primary regulation mechanisms of gene expression. Eukaryotic translational control mainly occurs at the initiation step, the speed-limiting step, which involves more than ten translation initiation factors [eIFs (eukaryotic initiation factors)]. Changing the level or function of these eIFs results in abnormal translation of specific mRNAs and consequently abnormal growth of cells that leads to human diseases, including cancer. Accumulating evidence from recent studies showed that the expression of many eIFs was associated with malignant transformation, cancer prognosis, as well as gene expression regulation. In the present paper, we perform a critical review of recent advances in understanding the role and mechanism of eIF action in translational control and cancer as well as the possibility of targeting eIFs for therapeutic development.

Oncogenic AKTivation of translation as a therapeutic target

The AKT signalling pathway is a major regulator of protein synthesis that impinges on multiple cellular processes frequently altered in cancer, such as proliferation, cell growth, survival, and angiogenesis. AKT controls protein synthesis by regulating the multistep process of mRNA translation at every stage from ribosome biogenesis to translation initiation and elongation. Recent studies have highlighted the ability of oncogenic AKT to drive cellular transformation by altering gene expression at the translational level. Oncogenic AKT signalling leads to both global changes in protein synthesis as well as specific changes in the translation of select mRNAs. New and developing technologies are significantly advancing our ability to identify and functionally group these translationally controlled mRNAs into gene networks based on their modes of regulation. How oncogenic AKT activates ribosome biogenesis, translation initiation, and translational elongation to regulate these translational networks is an ongoing area of research. Currently, the majority of therapeutics targeting translational control are focused on blocking translation initiation through inhibition of eIF4E hyperactivity. However, it will be important to determine whether combined inhibition of ribosome biogenesis, translation initiation, and translation elongation can demonstrate improved therapeutic efficacy in tumours driven by oncogenic AKT.

[Expression and its clinical significance of eIF4E in non-small cell lung cancer]

BACKGROUND AND OBJECTIVE

precious studies proven that the overexpression of eukaryotic translation initiation factor 4E (eIF4E) in a variety of solid tumors has linked with malignant tumorigenesis, invasion and metastasis. The aim of this work is to explore the expression of eIF4E and its clinical significance in non-small cell lung cancer (NSCLC) through immunohistochemical method.

METHODS

seventy NSCLC specimens were constructed into tissue microarray, simultaneously took 19 cases adjacent tissues and 20 cases normal lung tissue as control, all performed using immunohistochemistry (Envision).

RESULTS

eIF4E expression in NSCLC was significantly higher than that in adjacent tissues and normal lung tissues, statistically significant difference between the groups. The eIF4E positive expression in lymph node metastasis group was significantly higher than that in no-lymph node metastasis. eIF4E protein positive expression of WD/MD cancer tissue was significantly lower than those in PD/ND cancer tissue. There were no significant differences of positive expression of eIF4E with the tumor diameter, age, smoking status, gender of NSCLC patients (P > 0.05).

CONCLUSIONS

there were highly over expression rate of eIF4E, and closely correlated with lymphnode metastasis in NSCLC, which implies that the eIF4E expression may be related to tumorgenesis, invasion and metastasis of lung cancer. eIF4E may be a new marker for lung cancer and objective indicators assessing the development of lung cancer.

Ribavirin as an anti-cancer therapy: acute myeloid leukemia and beyond?

Ribavirin was discovered nearly 40 years ago as a broad-spectrum antiviral drug. Recent data suggest that ribavirin may also be an effective cancer therapy. In this case, ribavirin targets an oncogene, the eukaryotic translation initiation factor eIF4E, elevated in approximately 30% of cancers including many leukemias and lymphomas. Specifically, ribavirin impedes eIF4E mediated oncogenic transformation by acting as an inhibitor of eIF4E. In a phase II clinical trial, ribavirin treatment led to substantial clinical benefit in patients with poor-prognosis acute myeloid leukemia (AML). Here molecular targeting of eIF4E correlated with clinical response. Ribavirin also targets a key enzyme in the guanosine biosynthetic pathway, inosine monophosphate dehydrogenase (IMPDH), and also modulates immunity. Parallels with known antiviral mechanisms could be informative; however, after 40 years, these are not entirely clear. The antiviral effects of ribavirin appear cell-type specific. This variation likely arises for many reasons, including cell specific variations in ribavirin metabolism as well as virus specific factors. Thus, it seems that the mechanisms for ribavirin action in cancer therapy may also vary in terms of the cancer/tissue under study. Here we review the anticancer activities of ribavirin and discuss the possible utility of incorporating ribavirin into diverse cancer therapeutic regimens.

The role of MNK proteins and eIF4E phosphorylation in breast cancer cell proliferation and survival

eIF4E is over-expressed in many tumours, including a high proportion of breast cancers. eIF4E is an oncogene, and signalling pathways which promote eIF4E activity represent potential targets for therapeutic intervention in cancer. MNKs phosphorylate eIF4E on serine 209, a modification that can be required for eIF4E-dependent cell transformation. There is therefore a clear requirement to determine the role of MNKs in the proliferation and survival of cells from the major human tumours, such as breast cancer. Phosphorylated eIF4E protein was readily detectable in some breast tumour samples, but was below the limits of detection in others. Of 6 breast cancer cell lines representing the major sub-types of breast cancer, phosphorylated eIF4E was readily detectable in 5 of them, with MCF-7 cells displaying markedly lower levels. Long term colony forming assays demonstrated that all the five lines with high levels of phosphorylated eIF4E were highly sensitive to a MNK inhibitor. In short term assays, a range of responses was revealed. MCF-7 cells were insensitive in both assays. The anti-proliferative effects of the MNK inhibitor in breast cancer cells are primarily cytostatic, rather than cytotoxic, and are potentially due to the inhibition of cyclin D1 synthesis. Our data provide evidence that the sensitivity of breast cancer cells to MNK inhibition may correlate with baseline levels of eIF4E phosphorylation, and suggest that a proportion of breast cancers could be sensitive to inhibiting MNK kinase activity, and that the presence of phosphorylated eIF4E could provide a biomarker for the identification of responsive tumours.

Targeting eukaryotic translation initiation factor 4E (eIF4E) in cancer

Recent advances in understanding the role of eukaryotic translation initiator factor 4E (eIF4E) in tumorigenesis and cancer progression have generated significant interest in therapeutic agents that indirectly or directly target aberrant activation of eIF4E in cancer. Here, we address the general function of eIF4E in translation initiation and cancer, present evidence supporting its role in cancer initiation and progression, and highlight emerging therapeutics that efficiently target hyperactivated eIF4E. In doing so, we also highlight the major differences between these therapeutics that may influence their mechanism of action.

Overexpression of phospho-eIF4E is associated with survival through AKT pathway in non-small cell lung cancer

PURPOSE

The eukaryotic translation initiation factor complex 4E (eIF4E) is downstream in the mammalian target of rapamycin (mTOR) pathway. This study explored expression of eIF4E and its relationship with the PTEN/AKT and RAS/MEK/ERK pathways in non-small cell lung carcinoma (NSCLC).

EXPERIMENTAL DESIGN

The status of phosphorylated eIF4E (p-eIF4E), phosphorylated AKT (p-AKT), PTEN, phosphorylated tuberin (p-TSC2), phosphorylated mTOR (p-mTOR), phosphorylated S6 (p-S6), and phosphorylated Erk1/2 (p-Erk1/2) was studied using immunohistochemical analysis applied to a tissue microarray containing 300 NSCLCs. Staining results for each antibody were compared with clinical and pathologic features, and the relationship between staining results was explored.

RESULTS

Overexpression of p-eIF4E, p-AKT, p-TSC2, p-mTOR, p-S6, and p-Erk1/2 in NSCLC was found in 39.9%, 78.8%, 5.1%, 46.7%, 27.1%, and 16.6% of tumors, respectively. The phenotype of p-eIF4E correlated positively with that of p-AKT, p-TSC2, and p-S6 (P < 0.001). Overall survival in NSCLC patients was significantly shorter in cases with overexpression of p-eIF4E and p-AKT alone and in combination (log-rank P < 0.001, each). Cases with underexpression of PTEN were limited (6.4%), and this phenotype did not correlate with any clinical variable. In cluster analysis, the p-AKT/p-mTOR/p-eIF4E/p-S6-positive group had significantly shorter survival compared with the survival of all cases (P < 0.001). Multivariate analysis showed that p-eIF4E overexpression is an independent prognostic factor for NSCLC (P = 0.004).

CONCLUSIONS

This study shows that p-eIF4E expression in addition to p-AKT predicts poor prognosis in NSCLC. Moreover, the correlation between expression of p-eIF4E with p-AKT, as well as p-TSC2 and p-S6, indicates that eIF4E activation through the AKT pathway plays an important role in the progression of NSCLC.