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Our examination of RNA helicases for effects on HIV-1 protein production and particle assembly identified Rocaglamide (RocA), a known modulator of eIF4A1 function, as an inhibitor of HIV-1 replication in primary CD4+ T cells and three cell systems. HIV-1 attenuation by low-nM RocA doses was associated with reduced viral particle formation without a marked decrease in Gag production. Rather, the co-localization of Gag and HIV-1 genomic RNA (gRNA) assemblies was impaired by RocA treatment in a reversible fashion. Ribonucleoprotein (RNP) immunoprecipitation studies recapitulated the loss of Gag-gRNA assemblies upon RocA treatment. Parallel biophysical studies determined that neither RocA nor eIF4A1 independently affected the ability of Gag to interact with viral RNA, but together, they distorted the structure of the HIV-1 RNP visualized by electron microscopy. Taken together, several lines of evidence indicate that RocA induces stable binding of eIF4A1 onto the viral RNA genome in a manner that interferes with the ordered assembly of Gag along Gag-gRNA assemblies required to generate infectious virions. [ABSTRACT FROM AUTHOR]

Abstract Esophageal squamous cell carcinoma (ESCC) is one of most prevalent cancers worldwide, especially in China. Lacking in depth mechanism study, effective targets and therapeutics are desperately needed in the clinic. RNA-binding proteins (RBPs) mediate the localization, stability, and translation of the target transcripts and fine-tune the physiological functions of the proteins encoded. Bioinformatics analysis revealed that IGF2BPs were highly expressed in ESCC tissues and at least participated in the regulation of cell proliferation of ESCC cells. Biological researches demonstrated that IGF2BP2 promoted the cell proliferation, migration and invasion of ESCC KYSE30 and KYSE450 cells. IGF2BP2 could bind to EIF4A1 mRNA by recognition of m6A sites and enhanced translation of EIF4A1. IGF2BPs, as m6A reader, IGF2BPs were oncogenic genes in ESCC by regulating the expression of EIF4A1 through m6A sites. IGF2BP2, EIF4A1 and their targets could serve as potential biomarkers and therapeutic targets for ESCC, offering promising novel approaches for the diagnosis and treatment of ESCC.

Esophageal squamous cell carcinoma (ESCC) is one of most prevalent cancers worldwide, especially in China. Lacking in depth mechanism study, effective targets and therapeutics are desperately needed in the clinic. RNA-binding proteins (RBPs) mediate the localization, stability, and translation of the target transcripts and fine-tune the physiological functions of the proteins encoded. Bioinformatics analysis revealed that IGF2BPs were highly expressed in ESCC tissues and at least participated in the regulation of cell proliferation of ESCC cells. Biological researches demonstrated that IGF2BP2 promoted the cell proliferation, migration and invasion of ESCC KYSE30 and KYSE450 cells. IGF2BP2 could bind to EIF4A1 mRNA by recognition of m6A sites and enhanced translation of EIF4A1. IGF2BPs, as m6A reader, IGF2BPs were oncogenic genes in ESCC by regulating the expression of EIF4A1 through m6A sites. IGF2BP2, EIF4A1 and their targets could serve as potential biomarkers and therapeutic targets for ESCC, offering promising novel approaches for the diagnosis and treatment of ESCC. [ABSTRACT FROM AUTHOR]

Our examination of RNA helicases for effects on HIV-1 protein production and particle assembly identified Rocaglamide (RocA), a known modulator of eIF4A1 function, as an inhibitor of HIV-1 replication in primary CD4+ T cells and three cell systems. HIV-1 attenuation by low-nM RocA doses was associated with reduced viral particle formation without a marked decrease in Gag production. Rather, the co-localization of Gag and HIV-1 genomic RNA (gRNA) assemblies was impaired by RocA treatment in a reversible fashion. Ribonucleoprotein (RNP) immunoprecipitation studies recapitulated the loss of Gag-gRNA assemblies upon RocA treatment. Parallel biophysical studies determined that neither RocA nor eIF4A1 independently affected the ability of Gag to interact with viral RNA, but together, they distorted the structure of the HIV-1 RNP visualized by electron microscopy. Taken together, several lines of evidence indicate that RocA induces stable binding of eIF4A1 onto the viral RNA genome in a manner that interferes with the ordered assembly of Gag along Gag-gRNA assemblies required to generate infectious virions.

Initiation of translation is the first of the three obligatory steps required for protein synthesis and is carried out by a large number of protein factors called initiation factors in conjunction with ribosomes. One of the key conserved protein factors in eukaryotes that plays a role in this process is eIF4A, which has three homologues in humans with eIF4A1 being the primary factor playing a role in translation initiation. eIF4As are members of the family of DEAD-box helicases that carry out different biological functions. eIF4A1s are recruited to translation initiation complexes via association with eIF4G and have ATP binding, ATP hydrolysis, RNA binding, and unwinding activities. Plasmodium and trypanosomatids such as Leishmania and Trypanosoma are parasites that cause human disease. While mechanistically the function of eIF4A1s in eukaryotes is well-understood, the orthologues peIF4A1s and keIF4A1s in Plasmodium and trypanosomatids are not well-studied. Here, we have used bioinformatics tools and homology modelling/structure prediction to study the motifs and functional signatures of Plasmodium and trypanosomatid peIF4A1s/keIF4A1s. We report a high degree of sequence conservation, structural conservation, and conservation of protein–protein interaction signatures of Plasmodium and trypanosomatid peIF4A1s/keIF4A1s in comparison with human eIF4A1. Thus, in spite of the great divergence in evolution between these parasites and higher eukaryotes, there is remarkable conservation of motifs and functional signatures in Plasmodium and trypanosomatid peIF4A1s/keIF4A1s. [ABSTRACT FROM AUTHOR]

tRNA-derived small RNAs (tsRNAs) are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases. However, their exact presence and function in hepatocellular carcinoma (HCC) remain unclear. Here, differentially expressed tsRNAs in HCC were profiled. A novel tsRNA, tRNAGln-TTG derived 5′-tiRNA-Gln, is significantly downregulated, and its expression level is correlated with progression in patients. In HCC cells, 5′-tiRNA-Gln overexpression impaired the proliferation, migration, and invasion in vitro and in vivo, while 5′-tiRNA-Gln knockdown yielded opposite results. 5′-tiRNA-Gln exerted its function by binding eukaryotic initiation factor 4A-I (EIF4A1), which unwinds complex RNA secondary structures during translation initiation, causing the partial inhibition of translation. The suppressed downregulated proteins include ARAF, MEK1/2 and STAT3, causing the impaired signaling pathway related to HCC progression. Furthermore, based on the construction of a mutant 5′-tiRNA-Gln, the sequence of forming intramolecular G-quadruplex structure is crucial for 5′-tiRNA-Gln to strongly bind EIF4A1 and repress translation. Clinically, 5′-tiRNA-Gln expression level is negatively correlated with ARAF, MEK1/2, and STAT3 in HCC tissues. Collectively, these findings reveal that 5′-tiRJNA-Gln interacts with EIF4A1 to reduce related mRNA binding through the intramolecular G-quadruplex structure, and this process partially inhibits translation and HCC progression. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a primary liver tumor with high lethality and increasing incidence worldwide. While tumor resection or liver transplantation is effective in the early stages of the disease, the therapeutic options for advanced HCC remain limited and the benefits are temporary. Thus, novel therapeutic targets and more efficacious treatments against this deadly cancer are urgently needed. Here, we investigated the pathogenetic and therapeutic role of eukaryotic initiation factor 4A1 (eIF4A1) in this tumor type. We observed consistent eIF4A1 upregulation in HCC lesions compared with non-tumorous surrounding liver tissues. In addition, eIF4A1 levels were negatively correlated with the prognosis of HCC patients. In HCC lines, the exposure to various eIF4A inhibitors triggered a remarkable decline in proliferation and augmented apoptosis, paralleled by the inhibition of several oncogenic pathways. Significantly, anti-growth effects were achieved at nanomolar concentrations of the eIF4A1 inhibitors and were further increased by the simultaneous administration of the pan mTOR inhibitor, Rapalink-1. In conclusion, our results highlight the pathogenetic relevance of eIF4A1 in HCC and recommend further evaluation of the potential usefulness of pharmacological combinations based on eIF4A and mTOR inhibitors in treating this aggressive tumor. [ABSTRACT FROM AUTHOR]

Abstract In cap‐dependent translation, the eukaryotic translation initiation factor 4A (eIF4A1) is an mRNA helicase is involved in unwinding of the secondary structure, such as the stem‐loops, at the 5′‐leader regions of the key oncogenic mRNAs. This facilitates ribosomal scanning and translation of the oncogenic mRNAs. eIF4A1 has a regulatory role in translating many oncoproteins that have vital roles in several steps of metastases. Sridharan et. al. have discovered and provide a novel insight into how eIF4A1 can play a regulatory role in drug resistance by influencing the levels of pluripotent Yamanaka transcription factors and ATP‐binding cassette (ABC) transporters in triple‐negative breast cancer (TNBC) stem‐like cells. These findings may help us understand the molecular underpinnings of chemoresistance, especially in established metastases in TNBC. Importantly, eIF4A1 may form a novel clinical target in metastatic TNBC and the drug eFT226 from Effector Therapeutics targeting eIF4A1 is already in phase1‐2 clinical trial.

Simple Summary: Lung cancer is a common cancer throughout the world. Despite advanced treatment strategies, the outcome is still poor. Based on the results of the present study, EIF4A1 interacting with EIF4H manipulates cell cycle regulation and immune microenvironment reprogramming in lung adenocarcinoma. The results specify EIF4A1 in lung adenocarcinoma tumorigenesis. Treatment derived from EIF4A1 would be worthy of further investigation. Lung adenocarcinoma (LUAD) is a common type of lung cancer. Although the diagnosis and treatment of LUAD have significantly improved in recent decades, the survival for advanced LUAD is still poor. It is necessary to identify more targets for developing potential agents against LUAD. This study explored the dysregulation of translation initiation factors, specifically eukaryotic initiation factors 4A1 (EIF4A1) and EIF4A2, in developing LUAD, as well as their underlying mechanisms. We found that the expression of EIF4A1, but not EIF4A2, was higher in tumor tissue and associated with poor clinical outcomes in LUAD patients. Elevated expression of EIF4H with poor prognosis may potentiate the oncogenic role of EIF4A1. Functional enrichment analysis revealed that upregulation of EIF4A1 was related to cell cycle regulation and DNA repair. The oncogenic effect of EIF4A1 was further elucidated by Gene Set Variation Analysis (GSVA). The GSVA score of the gene set positively correlated with EIF4A1 was higher in tumors and significantly associated with worse survival. In the meantime, gene set enrichment analysis (GSEA) also indicated that elevated EIF4A1 expression in LUAD patients was associated with a decreased infiltration score for immune cells by reducing anticancer immune cell types and recruiting immunosuppressive cells. Consistent with the results, the GSVA score of genes whose expression was negatively correlated with EIF4A1 was lower in the tumor tissue of LUAD cases with worse clinical outcomes and was strongly associated with the disequilibrium of anti-cancer immunity by recruiting anticancer immune cells. Based on the results from the present study, we hypothesize that the dysregulation of EIF4A1 might be involved in the pathophysiology of LUAD development by promoting cancer growth and changing the tumor immune microenvironment. This can be used to develop potential diagnostic biomarkers or therapeutic targets for LUAD. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a primary liver tumor with high lethality and increasing incidence worldwide. While tumor resection or liver transplantation is effective in the early stages of the disease, the therapeutic options for advanced HCC remain limited and the benefits are temporary. Thus, novel therapeutic targets and more efficacious treatments against this deadly cancer are urgently needed. Here, we investigated the pathogenetic and therapeutic role of eukaryotic initiation factor 4A1 (eIF4A1) in this tumor type. We observed consistent eIF4A1 upregulation in HCC lesions compared with non-tumorous surrounding liver tissues. In addition, eIF4A1 levels were negatively correlated with the prognosis of HCC patients. In HCC lines, the exposure to various eIF4A inhibitors triggered a remarkable decline in proliferation and augmented apoptosis, paralleled by the inhibition of several oncogenic pathways. Significantly, anti-growth effects were achieved at nanomolar concentrations of the eIF4A1 inhibitors and were further increased by the simultaneous administration of the pan mTOR inhibitor, Rapalink-1. In conclusion, our results highlight the pathogenetic relevance of eIF4A1 in HCC and recommend further evaluation of the potential usefulness of pharmacological combinations based on eIF4A and mTOR inhibitors in treating this aggressive tumor.

Tumor MYCN amplification is seen in high-risk neuroblastoma, yet direct targeting of this oncogenic transcription factor has been challenging. Here, we take advantage of the dependence of MYCN-amplified neuroblastoma cells on increased protein synthesis to inhibit the activity of eukaryotic translation initiation factor 4A1 (eIF4A1) using an amidino-rocaglate, CMLD012824. Consistent with the role of this RNA helicase in resolving structural barriers in 5′ untranslated regions (UTRs), CMLD012824 increased eIF4A1 affinity for polypurine-rich 5′ UTRs, including that of the MYCN and associated transcripts with critical roles in cell proliferation. CMLD012824-mediated clamping of eIF4A1 spanned the full lengths of mRNAs, while translational inhibition was mediated through 5′ UTR binding in a cap-dependent and -independent manner. Finally, CMLD012824 led to growth inhibition in MYCN-amplified neuroblastoma models without generalized toxicity. Our studies highlight the key role of eIF4A1 in MYCN-amplified neuroblastoma and demonstrate the therapeutic potential of disrupting its function. [Display omitted] • MYCN-amplified neuroblastomas have preferentially increased expression of eIF4A1 • Amidino-rocaglates augment eIF4A1 binding across the full length of cellular mRNAs • MYCN mRNA is directly inhibited by amidino-rocaglates • Polypurine ranking of mRNA 5′ UTRs predicts amidino-rocaglate sensitivity in neuroblastoma MYCN amplification is a key driver of high-risk neuroblastoma. Volegova et al. capitalize on the dependence of MYCN-amplified neuroblastoma cells on increased protein synthesis by using amidino-rocaglates to inhibit translation initiation factor eIF4A1, resulting in direct targeting of the MYCN mRNA and selective cytotoxicity in animal models. [ABSTRACT FROM AUTHOR]

Lung adenocarcinoma (LUAD) is a common type of lung cancer. Although the diagnosis and treatment of LUAD have significantly improved in recent decades, the survival for advanced LUAD is still poor. It is necessary to identify more targets for developing potential agents against LUAD. This study explored the dysregulation of translation initiation factors, specifically eukaryotic initiation factors 4A1 (EIF4A1) and EIF4A2, in developing LUAD, as well as their underlying mechanisms. We found that the expression of EIF4A1, but not EIF4A2, was higher in tumor tissue and associated with poor clinical outcomes in LUAD patients. Elevated expression of EIF4H with poor prognosis may potentiate the oncogenic role of EIF4A1. Functional enrichment analysis revealed that upregulation of EIF4A1 was related to cell cycle regulation and DNA repair. The oncogenic effect of EIF4A1 was further elucidated by Gene Set Variation Analysis (GSVA). The GSVA score of the gene set positively correlated with EIF4A1 was higher in tumors and significantly associated with worse survival. In the meantime, gene set enrichment analysis (GSEA) also indicated that elevated EIF4A1 expression in LUAD patients was associated with a decreased infiltration score for immune cells by reducing anticancer immune cell types and recruiting immunosuppressive cells. Consistent with the results, the GSVA score of genes whose expression was negatively correlated with EIF4A1 was lower in the tumor tissue of LUAD cases with worse clinical outcomes and was strongly associated with the disequilibrium of anti-cancer immunity by recruiting anticancer immune cells. Based on the results from the present study, we hypothesize that the dysregulation of EIF4A1 might be involved in the pathophysiology of LUAD development by promoting cancer growth and changing the tumor immune microenvironment. This can be used to develop potential diagnostic biomarkers or therapeutic targets for LUAD.

Inhibition of eukaryotic translation initiation through unscheduled RNA clamping of the DEAD-box (DDX) RNA helicases eIF4A1 and eIF4A2 has been documented for pateamine A (PatA) and rocaglates-two structurally different classes of compounds that share overlapping binding sites on eIF4A. Clamping of eIF4A to RNA causes steric blocks that interfere with ribosome binding and scanning, rationalizing the potency of these molecules since not all eIF4A molecules need to be engaged to elicit a biological effect. In addition to targeting translation, PatA and analogs have also been shown to target the eIF4A homolog, eIF4A3-a helicase necessary for exon junction complex (EJC) formation. EJCs are deposited on mRNAs upstream of exon-exon junctions and, when present downstream from premature termination codons (PTCs), participate in nonsense-mediated decay (NMD), a quality control mechanism aimed at preventing the production of dominant-negative or gain-of-function polypeptides from faulty mRNA transcripts. We find that rocaglates can also interact with eIF4A3 to induce RNA clamping. Rocaglates also inhibit EJC-dependent NMD in mammalian cells, but this does not appear to be due to induced eIF4A3-RNA clamping, but rather a secondary consequence of translation inhibition incurred by clamping eIF4A1 and eIF4A2 to mRNA., (© 2023 Naineni et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.)

Clear cell renal cell carcinoma (ccRCC) is a worldwide malignancy with high morbidity and mortality. Translation initiation factor 4A1 (eIF4A1), which is an ATP-dependent RNA helicase as a part of eIF4F complex, has been linked to malignant transformation and progression, and a variety of cancers display dysregulation of this enzyme. However, its role in ccRCC remains unclear. In our study, we examined its potential effects in ccRCC. Based on Proteomic data, TCGA and ONCOMINE database, RCC cell lines and tissues, the expression of eIF4A1 between ccRCC and normal tissues were investigated. A correlation was evaluated between the prognostic model for OS and ccRCC progression. Analysis of functional enrichment and PPI network were performed. After examining differentially expressed genes between the eIF4A1 high and low-expression groups, we performed GSEA analysis. Furthermore, we investigated immune cell infiltration of eIF4A1. Then we determined eIF4A1 functions in the establishment and maintenance of cell viability, migration and invasion of cell lines. Flow cytometry was utilized to detect cell cycle. The eIF4A1 was up-regulated in ccRCC tissues and cell lines. An increased level of eIF4A1 was linked to lower survival rates and impaired immunity. Depletion of eIF4A1 could arrest tumor cells in G1 phase, so as to seriously limit cell proliferation and weaken the capacity of cell migration. ccRCC patients with high eIF4A1 expression are at increased risk of poor prognosis, furthermore eIF4A1 plays a prominent role in facilitating tumor cell proliferation and migration which may further be a potential prognostic biomarker and therapeutic target. • High-expression of eIF4A1 in ccRCC. • Interference of eIF4A1 inhibited the cell viability, migration and invasion. • Knockdown of eIF4A1 induced cell cycle arrest. [ABSTRACT FROM AUTHOR]

In cap-dependent translation, the eukaryotic translation initiation factor 4A (eIF4A1) is an mRNA helicase is involved in unwinding of the secondary structure, such as the stem-loops, at the 5'-leader regions of the key oncogenic mRNAs. This facilitates ribosomal scanning and translation of the oncogenic mRNAs. eIF4A1 has a regulatory role in translating many oncoproteins that have vital roles in several steps of metastases. Sridharan et. al. have discovered and provide a novel insight into how eIF4A1 can play a regulatory role in drug resistance by influencing the levels of pluripotent Yamanaka transcription factors and ATP-binding cassette (ABC) transporters in triple-negative breast cancer (TNBC) stem-like cells. These findings may help us understand the molecular underpinnings of chemoresistance, especially in established metastases in TNBC. Importantly, eIF4A1 may form a novel clinical target in metastatic TNBC and the drug eFT226 from Effector Therapeutics targeting eIF4A1 is already in phase1-2 clinical trial., (© 2020 The Authors. Cancer Reports published by Wiley Periodicals LLC.)

Astragaloside IV (AS-IV) is an inartificial saponin separated from astragalus membranaceus, which has exhibited key anti-tumor regulation in some cancers. Circular RNAs (circRNAs) are important regulators in malignant development of gastric cancer (GC). Herein, we focused on the molecular mechanism of AS-IV with circRNA dihydrolipoamide S-succinyltransferase (circDLST) in GC. CircDLST, microRNA-489-3p (miR-489-3p), and eukaryotic translation initiation factor 4A1 (EIF4A1) levels were detected by quantitative real-time polymerase-chain reaction and western blot. Cell functions were assessed by cell counting kit-8 assay, ethynyl-2'-deoxyuridine assay, colony formation assay, and transwell assay. The interaction between miR-489-3p and circDLST or EIF4A1 was analyzed by dual-luciferase reporter assay. Xenograft tumor assay was adopted to check the role of circDLST and AS-IV in vivo . CircDLST and EIF4A1 were upregulated but miR-489-3p was downregulated in GC cells. AS-IV restrained cell proliferation and metastasis in GC cells by downregulating circDLST. CircDLST served as a miR-489-3p sponge, and miR-489-3p inhibition reversed anti-tumor function of AS-IV. EIF4A1 was a target for miR-489-3p and circDLST sponged miR-489-3p to regulate EIF4A1. AS-IV suppressed GC cell progression via circDLST-mediated downregulation of EIF4A1. Also, AS-IV recued tumor growth in vivo via targeting circDLST to regulate miR-489-3p/EIF4A1 axis. AS-IV inhibited the development of GC through circDLST/miR-489-3p/EIF4A1 axis.