Humans ; Carcinoma, Hepatocellular ; Liver Neoplasms ; Ribonucleoproteins ; Eukaryotic Initiation Factor-4E

Translational initiation is regulated in response to nutrient availabilty and growth stimuli and is coupled with cell cycle progression and cell growth. There is now growing body of evidence which suggests links between translational regulation and the disruption of cell behavior that results in the development and progression of cancer. mRNA translation can be overactivated in breast cancer through eIF4E overexpression or abnormal activation of signal transduction pathways. Among them, rapamycin-sensitive signal transduction pathway (mTOR signaling pathway) is now being studied as a novel target for cancer therapy. In this article, the basic principles of translational control, the alterations encountered in cancer and selected therapy targeting mTOR signaling pathway are reviewed and the preclinical study regarding the determinants of rapamycin sensitivity in breast cancer is presented in order to help elucidate new avenues for breast cancer therapy.
Breast Neoplasms* ; Breast* ; Cell Cycle ; Eukaryotic Initiation Factor-4E ; Protein Biosynthesis ; Signal Transduction ; Sirolimus

To explore the regulation of eIF4E, we screened the protein interacting with eIF4E from human cDNA library by using yeast two-hybrid system. Several clones interacting with eIF4E were identified. One of them was homologous with HUWE1 (HECT, UBA and WWE domain containing 1, also named as ARF-BP1, HECTH9 or HUWE1). Cell co-immunoprecipitation showed that eIF4E could bind to HUWE1 in mammalian cells. We also found that HUWE1 bearing the HECT domain is necessary for its association with eIF4E.
Animals ; Eukaryotic Initiation Factor-4E ; metabolism ; Humans ; Ubiquitin-Protein Ligases ; metabolism

OBJECTIVE: To investigate the effect of eukaryotic translation initiation factor 4E(eIF4E) on the autophagy of CD138 plasma cells in multiple myeloma(MM). METHODS: Multiple myeloma CD138 plasma cells were treated with eIF4E inhibitor 4EGI, the changes of autophagy-related factors LC3-II and Beclin1 were detected by fluorescent quantitative PCR and Western blot, the changes of cell proliferation inhibition were detected by MTT assay, and cell apoptosis was detected by flow cytometry. RESULTS: Quantitative fluorescence PCR showed that after treatment of myeloma cells with 4EGI, the expression levels of LC3-II and Beclin1 mRNA gradually increased with the enhancomer of 4EGI concentration and the prolongation of action time, and the differences were statistically significant (48 h: LC3-Ⅱ,r=0.942, Beclin1,r=0.952; 80 μg/ml: LC3-Ⅱ,r=0.966, Beclin1,r=0.998）; Western blot showed that with the enhancement of 4EGI concentration, the expression of LC3-II and Beclin1 protein gradually increased（LC3-Ⅱ,r=0.923, Beclin1,r=0.977）; CCK-8 showed that the inhibition rate of cells gradually increased （r=0.996）; the apoptotic rate of 4EGI-treated groups (23.23±4.47, 7.59±1.67, 2.03±0.19) was significantly different from that of control group (0.03±0.04) (P<0.05). CONCLUSION The inhibition of eIF4E can activate the autophagy of CD138 plasma cells in multiple myeloma and induce the death of myeloma cells.
Autophagy ; Beclin-1 ; Cell Line, Tumor ; Eukaryotic Initiation Factor-4E ; Humans ; Multiple Myeloma

Post-stroke depression (PSD) is a serious and common complication of stroke, which seriously affects the rehabilitation of stroke patients. To date, the pathogenesis of PSD is unclear and effective treatments remain unavailable. Here, we established a mouse model of PSD through photothrombosis-induced focal ischemia. By using a combination of brain imaging, transcriptome sequencing, and bioinformatics analysis, we found that the hippocampus of PSD mice had a significantly lower metabolic level than other brain regions. RNA sequencing revealed a significant reduction of miR34b-3p, which was expressed in hippocampal neurons and inhibited the translation of eukaryotic translation initiation factor 4E (eIF4E). Furthermore, silencing eIF4E inactivated microglia, inhibited neuroinflammation, and abolished the depression-like behaviors in PSD mice. Together, our data demonstrated that insufficient miR34b-3p after stroke cannot inhibit eIF4E translation, which causes PSD by the activation of microglia in the hippocampus. Therefore, miR34b-3p and eIF4E may serve as potential therapeutic targets for the treatment of PSD.
Animals ; Mice ; Depression ; Eukaryotic Initiation Factor-4E/metabolism* ; MicroRNAs/metabolism* ; Neurons/metabolism* ; Stroke/metabolism*

OBJECTIVETo analyze the interaction between the microRNA-338 and its targeting proteins during the cerebral ischemia and reperfusion injury.

METHODSTargetScan was used to predict the targets of microRNA-338. The potential targeting proteins were then selected according to their secondary structures using RNA structure 4.6 software and their involvement in cerebral ischemia and reperfusion injury was studied. Dual-luciferase reporter assay was used to testify whether microRNA-338 can recognize the 3'UTR of target protein. Western blot was applied to analyze the expression of eiF4E3 in both experimental group and control group.

RESULTEiF4E3 was the most likely potential targeting protein of microRNA-338. The secondary structure of local region of eiF4E3 recognizing microRNA-338 was conservative. The ratio of firefly to renilla luciferase activity in the experimental group was much higher than that of control group. However, there was no significant difference in the expression of eiF4E3 between these two groups.

CONCLUSIONMicroRNA-338 can recognize the 3'UTR of eiF4E3 while it has no significant effect on the expression of eiF4E3. The post-target-recognizing regulation for miRNA do exist and this mechanism is possibly related to the tertiary structure of target mRNA.

3' Untranslated Regions ; genetics ; Animals ; Eukaryotic Initiation Factor-4E ; genetics ; Gene Expression Regulation ; MicroRNAs ; genetics ; PC12 Cells ; Protein Structure, Secondary ; Protein Transport ; genetics ; RNA, Messenger ; genetics ; Rats

OBJECTIVETo determine whether the eukaryotic initiation factor-4E (eIF-4E) is involved in the cap-dependent translational regulation of heparanase and study the correlation between heparanase expression and metastatic potential of LS-174T cells.

METHODSThe protein and mRNA levels of inhibited eIF-4E were tested by Western blot and RT-PCR. Heparanase activity was defined as the ability to degrade high molecular weight (40-100 000) radiolabeled ((35)S) heparan sulfate (HS) substrate into low molecular weight (5-15 000) HS fragments. The invasive potential of tumor cells in vitro was observed by Matrigel invasion assay system.

RESULTSThe 20-mer antisense oligonucleotide (asODN) against eIF-4E specifically and significantly inhibited eIF-4E expression at both transcriptional and translational levels. The expression and the activity of heparanase were effectively lowered, which further decreased the invasive potential of LS-174T.

CONCLUSIONeIF-4E, probably being involved in translational regulation of heparanase in colon adenocarcinoma cell line LS-174T, can be a particularly interesting target for heparanase regulation, based on of its critical function.

Adenocarcinoma ; enzymology ; pathology ; Cell Line, Tumor ; Colonic Neoplasms ; enzymology ; pathology ; Eukaryotic Initiation Factor-4E ; antagonists & inhibitors ; genetics ; physiology ; Glucuronidase ; metabolism ; Humans ; Neoplasm Invasiveness

OBJECTIVETo explore the clinical significance of eukaryotic initiation factor 4 E (eIF4E) and mammalian target of rapamycin (mTOR) expressions in esophageal squamous carcinoma tissues.

METHODSClinicopathological data and paraffin samples of resected tumor tissue from 148 patients with esophageal squamous carcinoma undergoing resection in our department between January 2010 and December 2012 were collected retrospectively. Expressions of eIF4E and mTOR were detected in above carcinoma tissues, counterpart para-carcinoma tissues (1 cm distance to carcinoma) and normal tissues (5 cm distance to carcinoma) with Western blot and immunohistochemistry. Their relevance with clinicopathological features was analyzed.

RESULTSExpression of mTOR located mainly in cytoplasm and elF4E mainly in cellular membrane, presenting as yellow grains. These two markers showed strong expression in carcinoma tissues and weak or none in para-carcinoma tissues. In esophageal squamous carcinoma tissues, counterpart para-carcinoma tissues and normal tissues, mTOR protein expression was 85.8% (127/148), 35.1% (52/148) and 3.4% (5/148), eIF4E protein expression was 93.9% (139/148), 35.1% (52/148) and 12.8% (19/148), with a downtrend respectively (all P<0.05). Expressions of mTOR and eIF4E were associated with tumor invasion depth and lymphatic metastasis (all P<0.05), while mTOR expression was associated with differentiation degree (P=0.003), but eIF4E expression was not. Both expressions were not associated with gender, age, and tumor size (all P>0.05).

CONCLUSIONSExpressions of eIF4E and mTOR are up-regulated in esophageal squamous carcinoma tissues, which may be associated with tumor malignance and lymphatic metastasis of esophageal squamous carcinoma. Combined detection of two markers may be helpful to predict the tumor malignance and the prognosis of patients.

Carcinoma, Squamous Cell ; diagnosis ; metabolism ; Esophageal Neoplasms ; diagnosis ; metabolism ; Eukaryotic Initiation Factor-4E ; metabolism ; Humans ; Immunohistochemistry ; Lymphatic Metastasis ; Prognosis ; Retrospective Studies ; TOR Serine-Threonine Kinases ; metabolism

In order to clone the full-length cDNA of a novel EST which is probably related to acute leukemia relapse and to analyse the sequences, the electronic cloning technique combined with RT-PCR was used to clone the full-length cDNA, and the sequences were analyzed by bioinformatics. The results showed that the two novel splicing variants of eIF4E named as splicing variant 1 and 2 of eIF4E were obtained. Bioinformatics analysis showed that variant 1 and 2 exhibited 84% and 47% similarity to eIF4E mRNA, and were localized on eIF4E locus on chromosome 4. The lengths of 2 variants are 1 904 bp and 3 393 bp, encoding 245 amino acids and 132 amino acids respectively. BLAST results showed that the both variants mentioned above contains seven exons. Among them, the sequences of the three exons at 5' end of variant 1, variant 2 and eIF4E mRNA were different from each other. Protein BLAST showed that they are partially different from eIF4E protein. It is concluded that the two novel splicing variants of eIF4E were cloned, and their relation to acute leukemia relapse needs to be further investigated.
Base Sequence ; Cloning, Molecular ; Computational Biology ; DNA, Complementary ; genetics ; DNA, Recombinant ; Eukaryotic Initiation Factor-4E ; genetics ; Humans ; Molecular Sequence Data ; Protein Isoforms ; genetics ; Reverse Transcriptase Polymerase Chain Reaction

MicroRNAs (miRNAs) recruit the RNA-induced silencing complex (RISC) to repress the translation of target mRNAs. While the 5' 7-methylguanosine cap of target mRNAs has been well known to be important for miRNA repression, the underlying mechanism is not clear. Here we show that TNRC6A interacts with eIF4E2, a homologue of eIF4E that can bind to the cap but cannot interact with eIF4G to initiate translation, to inhibit the translation of target mRNAs. Downregulation of eIF4E2 relieved miRNA repression of reporter expression. Moreover, eIF4E2 downregulation increased the protein levels of endogenous IMP1, PTEN and PDCD4, whose expression are repressed by endogenous miRNAs. We further provide evidence showing that miRNA enhances eIF4E2 association with the target mRNA. We propose that miRNAs recruit eIF4E2 to compete with eIF4E to repress mRNA translation.
Autoantigens ; metabolism ; Cell Line ; Eukaryotic Initiation Factor-4E ; metabolism ; Gene Silencing ; Humans ; MicroRNAs ; genetics ; Protein Transport ; RNA, Messenger ; biosynthesis ; genetics ; RNA-Binding Proteins ; metabolism