mTORC1/S6K1 signaling promotes sustained oncogenic translation through modulating CRL3IBTK-mediated ubiquitination of eIF4A1 in cancer cells.

Enhanced protein synthesis is a crucial molecular mechanism that allows cancer cells to survive, proliferate, metastasize, and develop resistance to anti-cancer treatments, and often arises as a consequence of increased signaling flux channeled to mRNA-bearing eukaryotic initiation factor 4F (eIF4F). However, the post-translational regulation of eIF4A1, an ATP-dependent RNA helicase and subunit of the eIF4F complex, is still poorly understood. Here, we demonstrate that IBTK, a substrate-binding adaptor of the Cullin 3-RING ubiquitin ligase (CRL3) complex, interacts with eIF4A1. The non-degradative ubiquitination of eIF4A1 catalyzed by the CRL3IBTK complex promotes cap-dependent translational initiation, nascent protein synthesis, oncogene expression, and cervical tumor cell growth both in vivo and in vitro. Moreover, we show that mTORC1 and S6K1, two key regulators of protein synthesis, directly phosphorylate IBTK to augment eIF4A1 ubiquitination and sustained oncogenic translation. This link between the CRL3IBTK complex and the mTORC1/S6K1 signaling pathway, which is frequently dysregulated in cancer, represents a promising target for anti-cancer therapies.

EIF4A3 modulated circ_000999 promotes epithelial-mesenchymal transition in cadmium-induced malignant transformation through the miR-205-5p/ZEB1 axis.

Cadmium (Cd) is an accumulative toxic metal which poses a serious threat to human health, even in trace amounts. One of the most important steps in the pathophysiology of lung cancer (LC) is the epithelial-mesenchymal transition (EMT). In this investigation, a cell malignant transformation model was established by exposing human bronchial epithelial cells (16HBE) to a low dose of Cd for 30 weeks, after which a highly expressed circular RNA (circ_000999) was identified. Cd-induced EMT was clearly observed in rat lungs and 16HBE cells, which was further enhanced following circ_000999-overexpression. Furthermore, upregulated EIF4A3 interacted with the parental gene AGTPBP1 to promote high expression of circ_000999. Subsequent experiments confirmed that circ_000999 could regulate the EMT process by competitively binding miR-205-5p and inhibiting its activity, consequently upregulating expression of zinc finger E-box binding protein 1 (ZEB1). Importantly, the circ_000999 expression level in LC tissues was significantly increased, exhibiting a strong correlation with EMT indicators. Overall, these findings provide a new objective and research direction for reversing lung EMT and subsequent treatment and prevention of LC.

PDCD4 restricts PRRSV replication in an eIF4A-dependent manner and is antagonized by the viral nonstructural protein 9.

As obligate parasites, viruses have evolved multiple strategies to evade the host immune defense. Manipulation of the host proteasome system to degrade specific detrimental factors is a common viral countermeasure. To identify host proteins targeted for proteasomal degradation by porcine reproductive and respiratory syndrome virus (PRRSV), we conducted a quantitative proteomics screen of PRRSV-infected Marc-145 cells under the treatment with proteasome inhibitor MG132. The data revealed that the expression levels of programmed cell death 4 (PDCD4) were strongly downregulated by PRRSV and significantly rescued by MG132. Further investigation confirmed that PRRSV infection induced the translocation of PDCD4 from the nucleus to the cytoplasm, and the viral nonstructural protein 9 (Nsp9) promoted PDCD4 proteasomal degradation in the cytoplasm by activating the Akt-mTOR-S6K1 pathway. The C-terminal domain of Nsp9 was responsible for PDCD4 degradation. As for the role of PDCD4 during PRRSV infection, we demonstrated that PDCD4 knockdown favored viral replication, while its overexpression significantly attenuated replication, suggesting that PDCD4 acts as a restriction factor for PRRSV. Mechanistically, we discovered eukaryotic translation initiation factor 4A (eIF4A) was required for PRRSV. PDCD4 interacted with eIF4A through four sites (E249, D253, D414, and D418) within its two MA3 domains, disrupting eIF4A-mediated translation initiation in the 5'-untranslated region of PRRSV, thereby inhibiting PRRSV infection. Together, our study reveals the antiviral function of PDCD4 and the viral strategy to antagonize PDCD4. These results will contribute to our understanding of the immune evasion strategies employed by PRRSV and offer valuable insights for developing new antiviral targets.IMPORTANCEPorcine reproductive and respiratory syndrome virus (PRRSV) infection results in major economic losses in the global swine industry and is difficult to control effectively. Here, using a quantitative proteomics screen, we identified programmed cell death 4 (PDCD4) as a host protein targeted for proteasomal degradation by PRRSV. We demonstrated that PDCD4 restricts PRRSV replication by interacting with eukaryotic translation initiation factor 4A, which is required for translation initiation in the viral 5'-untranslated region. Additionally, four sites within two MA3 domains of PDCD4 are identified to be responsible for its antiviral function. Conversely, PRRSV nonstructural protein 9 promotes PDCD4 proteasomal degradation in the cytoplasm by activating the Akt-mTOR-S6K1 pathway, thus weakening the anti-PRRSV function. Our work unveils PDCD4 as a previously unrecognized host restriction factor for PRRSV and reveals that PRRSV develops countermeasures to overcome PDCD4. This will provide new insights into virus-host interactions and the development of new antiviral targets.

eIF4F is a thermo-sensing regulatory node in the translational heat shock response.

Heat-shocked cells prioritize the translation of heat shock (HS) mRNAs, but the underlying mechanism is unclear. We report that HS in budding yeast induces the disassembly of the eIF4F complex, where eIF4G and eIF4E assemble into translationally arrested mRNA ribonucleoprotein particles (mRNPs) and HS granules (HSGs), whereas eIF4A promotes HS translation. Using in vitro reconstitution biochemistry, we show that a conformational rearrangement of the thermo-sensing eIF4A-binding domain of eIF4G dissociates eIF4A and promotes the assembly with mRNA into HS-mRNPs, which recruit additional translation factors, including Pab1p and eIF4E, to form multi-component condensates. Using extracts and cellular experiments, we demonstrate that HS-mRNPs and condensates repress the translation of associated mRNA and deplete translation factors that are required for housekeeping translation, whereas HS mRNAs can be efficiently translated by eIF4A. We conclude that the eIF4F complex is a thermo-sensing node that regulates translation during HS.

EIF4A3-negatively driven circular RNA ß-catenin (circß-catenin) promotes colorectal cancer progression via miR-197-3p/CTNND1 regulatory axis.

BACKGROUND: Circß-catenin, our first reported circRNA, has been reported to mediate tumorigenesis in various cancers. However, its biological functions and underlying mechanisms in colorectal cancer (CRC) remain unknown. METHODS: The qRT-PCR examination was used to detect the expression of circß-catenin, miR-197-3p, and CTNND1 in cells and human tissues. Western blot was conducted to detect the protein expression levels. The biological function of circß-catenin was verified by MTT, colony formation, wound healing, and transwell assays. The in vivo effects of circß-catenin were verified by nude mice xenograft and metastasis models. The regulatory network of circß-catenin/miR-197-3p/CTNND1 was confirmed via dual-luciferase reporter and RIP assays. RESULTS: In the present study, circß-catenin was found to promote CRC cell proliferation and metastasis in vitro and in vivo. Mechanistically, circß-catenin served as miRNA decoy to directly bind to miR-197-3p, then antagonized the repression of the target gene CTNND1, and eventually promoted the malignant phenotype of CRC. More interestingly, the inverted repeated Alu pairs termed AluJb1/2 and AluY facilitated the biogenesis of circß-catenin, which could be partially reversed by EIF4A3 binding to Alu element AluJb2. CONCLUSIONS: Our findings illustrated a novel mechanism of circß-catenin in modulating CRC tumorigenesis and metastasis, which provides a potential therapeutic target for CRC patients.

LINC01572 promotes triple-negative breast cancer progression through EIF4A3-mediated ß-catenin mRNA nuclear exportation.

Long noncoding RNAs have been reported to be involved in the development of breast cancer. LINC01572 was previously reported to promote the development of various tumors. However, the potential biological function of LINC01572 in breast cancer remains largely unknown. R language was used to perform bioinformatic analysis of The Cancer Genome Atlas data. The expression level of RNAs was examined by RT-qPCR. The effect of knocking down or overexpression LINC01572 in triple-negative breast cancer (TNBC) cell lines was evaluated by detecting cell proliferation, migrant action. RNA immunoprecipitation assay and RNA pull-down assay were performed to explore the regulatory relationship between LINC01572, EIF4A3, and ß-catenin. Bioinformatics analysis identifies LINC01572 as an oncogene of breast cancer. LINC01572 is over-expressed in TNBC tissues and cell lines, correlated with poor clinical prognosis in BC patients. Cell function studies confirmed that LINC01572 facilitated the proliferation and migration of TNBC cells in both vivo and vitro. Mechanistically, ß-catenin mRNA and EIF4A3 combine spatially to form a complex, LINC01572 helps transport this complex from the nucleus to the cytoplasm, thereby facilitating the translation of ß-catenin. Our findings confirm that LINC01572 acts as a tumor promoter and may act as a biomarker in TNBC. In addition, novel molecular regulatory relationships involving LINC01572/EIF4A3/ß-catenin are critical to the development of TNBC, which led to a new understanding of the mechanisms of TNBC progression and shows a new target for precision treatment for TNBC.

Hsa_circ_0005397 promotes hepatocellular carcinoma progression through EIF4A3.

PURPOSE: The purpose of this study was to explore the expression and potential mechanism of hsa_circ_0005397 in hepatocellular carcinoma progression. METHODS: Quantitative reverse transcription-polymerase chain reaction(qRT-PCR) was used to measure the expression level of hsa_circ_0005397 and EIF4A3 from paired HCC tissues and cell lines. Western Blot (WB) and immunohistochemistry (IHC) were used to verify the protein level of EIF4A3. The specificity of primers was confirmed by agarose gel electrophoresis. Receiver Operating Characteristic (ROC) Curve was drawn to analyze diagnostic value. Actinomycin D and nuclear and cytoplasmic extraction assays were utilized to evaluate the characteristics of hsa_circ_0005397. Cell Counting kit-8 (CCK-8) and colony formation assays were performed to detect cell proliferation. Flow cytometry analysis was used to detect the cell cycle. Transwell assay was performed to determine migration and invasion ability. RNA-binding proteins (RBPs) of hsa_circ_0005397 in HCC were explored using bioinformatics websites. The relationship between hsa_circ_0005397 and Eukaryotic Translation Initiation Factor 4A3 (EIF4A3) was verified by RNA Binding Protein Immunoprecipitation (RIP) assays, correlation and rescue experiments. RESULTS: In this study, hsa_circ_0005397 was found to be significantly upregulated in HCC, and the good diagnostic sensitivity and specificity shown a potential diagnostic capability. Upregulated expression of hsa_circ_0005397 was significantly related to tumor size and stage. Hsa_circ_0005397 was circular structure which more stable than liner mRNA, and mostly distributed in the cytoplasm. Upregulation of hsa_circ_0005397 generally resulted in stronger proliferative ability, clonality, and metastatic potency of HCC cells; its downregulation yielded the opposite results. EIF4A3 is an RNA-binding protein of hsa_circ_0005397, which overexpressed in paired HCC tissues and cell lines. In addition, expression of hsa_circ_0005397 decreased equally when EIF4A3 was depleted. RIP assays and correlation assay estimated that EIF4A3 could interacted with hsa_circ_0005397. Knockdown of EIF4A3 could reverse hsa_circ_0005397 function in HCC progression. CONCLUSIONS: Hsa_circ_0005397 promotes progression of hepatocellular carcinoma through EIF4A3. These research findings may provide novel clinical value for hepatocellular carcinoma.

Mutant U2AF1-Induced Mis-Splicing of mRNA Translation Genes Confers Resistance to Chemotherapy in Acute Myeloid Leukemia.

Patients with primary refractory acute myeloid leukemia (AML) have a dismal long-term prognosis. Elucidating the resistance mechanisms to induction chemotherapy could help identify strategies to improve AML patient outcomes. Herein, we retrospectively analyzed the multiomics data of more than 1,500 AML cases and found that patients with spliceosome mutations had a higher risk of developing refractory disease. RNA splicing analysis revealed that the mis-spliced genes in refractory patients converged on translation-associated pathways, promoted mainly by U2AF1 mutations. Integrative analyses of binding and splicing in AML cell lines substantiated that the splicing perturbations of mRNA translation genes originated from both the loss and gain of mutant U2AF1 binding. In particular, the U2AF1S34F and U2AF1Q157R mutants orchestrated the inclusion of exon 11 (encoding a premature termination codon) in the eukaryotic translation initiation factor 4A2 (EIF4A2). This aberrant inclusion led to reduced eIF4A2 protein expression via nonsense-mediated mRNA decay. Consequently, U2AF1 mutations caused a net decrease in global mRNA translation that induced the integrated stress response (ISR) in AML cells, which was confirmed by single-cell RNA sequencing. The induction of ISR enhanced the ability of AML cells to respond and adapt to stress, contributing to chemoresistance. A pharmacologic inhibitor of ISR, ISRIB, sensitized U2AF1 mutant cells to chemotherapy. These findings highlight a resistance mechanism by which U2AF1 mutations drive chemoresistance and provide a therapeutic approach for AML through targeting the ISR pathway. SIGNIFICANCE: U2AF1 mutations induce the integrated stress response by disrupting splicing of mRNA translation genes that improves AML cell fitness to enable resistance to chemotherapy, which can be targeted to improve AML treatment.

The structure of a human translation initiation complex reveals two independent roles for the helicase eIF4A.

Eukaryotic translation initiation involves recruitment of the 43S pre-initiation complex to the 5' end of mRNA by the cap-binding complex eIF4F, forming the 48S translation initiation complex (48S), which then scans along the mRNA until the start codon is recognized. We have previously shown that eIF4F binds near the mRNA exit channel of the 43S, leaving open the question of how mRNA secondary structure is removed as it enters the mRNA channel on the other side of the 40S subunit. Here we report the structure of a human 48S that shows that, in addition to the eIF4A that is part of eIF4F, there is a second eIF4A helicase bound at the mRNA entry site, which could unwind RNA secondary structures as they enter the 48S. The structure also reveals conserved interactions between eIF4F and the 43S, probaby explaining how eIF4F can promote mRNA recruitment in all eukaryotes.

EIF4A3-mediated biogenesis of circSTX6 promotes bladder cancer metastasis and cisplatin resistance.

BACKGROUND: Cisplatin (CDDP)-based chemotherapy is a standard first-line treatment for metastatic bladder cancer (BCa) patients, and chemoresistance remains a major challenge in clinical practice. Circular RNAs (circRNAs) have emerged as essential regulators in carcinogenesis and cancer progression. However, the role of circRNAs in mediating CDDP chemosensitivity has yet to be well elucidated in BCa. METHODS: CircSTX6 (hsa_circ_0007905) was identified by mining the public circRNA datasets and verified by Sanger sequencing, agarose gel electrophoresis, RNase R treatment and qRT-PCR assays. Then, function experiments were performed to evaluate the effects of circSTX6 on BCa metastasis. Luciferase reporter assay, RNA pull-down, RNA immunoprecipitation (RIP), RNA stability assay, Fluorescence in situ hybridization (FISH) and Immunofluorescence (IF) were conducted to evaluate the interaction among circSTX6, miR-515-3p, PABPC1 and SUZ12. Animal experiments were performed to explore the function of circSTX6 in tumor metastasis and CDDP sensitivity. RESULTS: We identified that circSTX6 was significantly upregulated in clinical samples and cells of BCa. Functionally, circSTX6 promoted cell migration and invasion both in vitro and in vivo. Mechanistically, circSTX6 could act as a miR-515-3p sponge and abolish its effect on SUZ12. Moreover, circSTX6 was confirmed to increase the stability of SUZ12 mRNA by interacting with a mRNA stabilizer PABPC1 and subsequently promote the expression of SUZ12. Importantly, silencing of circSTX6 improved the chemosensitivity of CDDP-resistant bladder cancer cells to CDDP. Furthermore, in vivo analysis supported that knockdown of circSTX6 attenuated CDDP resistance in BCa tumors. CONCLUSION: These studies demonstrate that circSTX6 plays a pivotal role in BCa metastasis and chemoresistance, and has potential to serve as a therapeutic target for treatment of BCa.

A second-generation eIF4A RNA helicase inhibitor exploits translational reprogramming as a vulnerability in triple-negative breast cancer.

In this study, we aimed to address the current limitations of therapies for macro-metastatic triple-negative breast cancer (TNBC) and provide a therapeutic lead that overcomes the high degree of heterogeneity associated with this disease. Specifically, we focused on well-documented but clinically underexploited cancer-fueling perturbations in mRNA translation as a potential therapeutic vulnerability. We therefore developed an orally bioavailable rocaglate-based molecule, MG-002, which hinders ribosome recruitment and scanning via unscheduled and non-productive RNA clamping by the eukaryotic translation initiation factor (eIF) 4A RNA helicase. We demonstrate that MG-002 potently inhibits mRNA translation and primary TNBC tumor growth without causing overt toxicity in mice. Importantly, given that metastatic spread is a major cause of mortality in TNBC, we show that MG-002 attenuates metastasis in pre-clinical models. We report on MG-002, a rocaglate that shows superior properties relative to existing eIF4A inhibitors in pre-clinical models. Our study also paves the way for future clinical trials exploring the potential of MG-002 in TNBC and other oncological indications.

Circ ubiquitin-like-containing plant homeodomain and RING finger domains protein 1 increases the stability of G9a and ubiquitin-like-containing plant homeodomain and RING finger domains protein 1 messenger RNA through recruiting eukaryotic translation initiation factor 4A3, transcriptionally inhibiting PDZ and homeobox protein domain protein 1, and promotes the metastasis of hepatocellular carcinoma.

BACKGROUND AND AIM: Circular ubiquitin-like, containing PHD and ring finger domains 1 (circUHRF1) is aberrantly upregulated in human hepatocellular carcinoma (HCC) tissues. However, the underlying molecular mechanisms remain obscure. The present study aimed at elucidating the interactive function of circUHRF1-G9a-ubiquitin-like, containing PHD and ring finger domains 1 (UHRF1) mRNA-eukaryotic translation initiation factor 4A3 (EIF4A3)-PDZ and LIM domain 1 (PDLIM1) network in HCC. METHODS: Expression of circUHRF1, mRNAs of G9a, UHRF1, PDLIM1, epithelial-mesenchymal transition (EMT)-related proteins, and Hippo-Yap pathway components was determined by quantitative polymerase chain reaction (Q-PCR), immunofluorescence, or Western blot analysis. Tumorigenic and metastatic capacities of HCC cells were examined by cellular assays including Cell Counting Kit-8, colony formation, wound healing, and transwell assays. Molecular interactions between EIF4A3 and UHRF1 mRNA were detected by RNA pull-down experiment. Complex formation between UHRF1 and PDLIM1 promoter was detected by chromatin immunoprecipitation assay. Co-immunoprecipitation was performed to examine the binding between UHRF1 and G9a. RESULTS: Circular ubiquitin-like, containing PHD and ring finger domains 1, G9a, and UHRF1 were upregulated, while PDLIM1 was downregulated in HCC tissue samples and cell lines. Cellular silencing of circUHRF1 repressed HCC proliferation, invasion, migration, and EMT. G9a formed a complex with UHRF1 and inhibited PDLIM1 transcription. CONCLUSION: Eukaryotic translation initiation factor 4A3 regulated circUHRF1 expression by binding to UHRF1 mRNA promoter. circUHRF1 increased the stability of G9a and UHRF1 mRNAs through recruiting EIF4A3. Overexpression of circUHRF1 aggravated HCC progression through Hippo-Yap pathway and PDLIM1 inhibition. By elucidating the molecular function of circUHRF1-G9a-UHRF1 mRNA-EIF4A3-PDLIM1 network, our data shed light on the HCC pathogenesis and suggest a novel therapeutic strategy for future HCC treatment.

M6A reader YTHDF1 promotes malignant progression of laryngeal squamous carcinoma through activating the EMT pathway by EIF4A3.

Laryngeal squamous cell carcinoma (LSCC) is one of the common malignant tumors in the head and neck region, and its high migration and invasion seriously threaten the survival and health of patients. In cancer development, m6A RNA modification plays a crucial role in regulating gene expression and signaling. This study delved into the function and mechanism of the m6A reading protein YTHDF1 in LSCC. It was found that YTHDF1 was highly expressed in the GEO database and LSCC tissues. Cell function experiments confirmed that the downregulation of YTHDF1 significantly inhibited the proliferation, migration, and invasion ability of LSCC cells. Further studies revealed that EIF4A3 was a downstream target gene of YTHDF1, and knockdown of EIF4A3 similarly significantly inhibited the malignant progression of LSCC in both in vivo and in vitro experiments. The molecular mechanism studies suggested that YTHDF1-EIF4A3 may promote the malignant development of LSCC by activating the EMT signaling pathway. This study provides important clues for an in-depth understanding of the pathogenesis of LSCC and is a solid foundation for the discovery of new therapeutic targets and approaches.

RNA helicase EIF4A1-mediated translation is essential for the GC response.

EIF4A1 and cofactors EIF4B and EIF4H have been well characterised in cancers, including B cell malignancies, for their ability to promote the translation of oncogenes with structured 5' untranslated regions. However, very little is known of their roles in nonmalignant cells. Using mouse models to delete Eif4a1, Eif4b or Eif4h in B cells, we show that EIF4A1, but not EIF4B or EIF4H, is essential for B cell development and the germinal centre response. After B cell activation in vitro, EIF4A1 facilitates an increased rate of protein synthesis, MYC expression, and expression of cell cycle regulators. However, EIF4A1-deficient cells remain viable, whereas inhibition of EIF4A1 and EIF4A2 by Hippuristanol treatment induces cell death.

Identification and characterization of differentially expressed circular RNAs in extraocular muscle of oculomotor nerve palsy.

BACKGROUND: Oculomotor nerve palsy (ONP) is a neuroparalytic disorder resulting in dysfunction of innervating extraocular muscles (EOMs), of which the pathological characteristics remain underexplored. METHODS: In this study, medial rectus muscle tissue samples from four ONP patients and four constant exotropia (CXT) patients were collected for RNA sequencing. Differentially expressed circular RNAs (circRNAs) were identified and included in functional enrichment analysis, followed by interaction analysis with microRNAs and mRNAs as well as RNA binding proteins. Furthermore, RT-qPCR was used to validate the expression level of the differentially expressed circRNAs. RESULTS: A total of 84 differentially expressed circRNAs were identified from 10,504 predicted circRNAs. Functional enrichment analysis indicated that the differentially expressed circRNAs significantly correlated with skeletal muscle contraction. In addition, interaction analyses showed that up-regulated circRNA_03628 was significantly interacted with RNA binding protein AGO2 and EIF4A3 as well as microRNA hsa-miR-188-5p and hsa-miR-4529-5p. The up-regulation of circRNA_03628 was validated by RT-qPCR, followed by further elaboration of the expression, location and clinical significance of circRNA_03628 in EOMs of ONP. CONCLUSIONS: Our study may shed light on the role of differentially expressed circRNAs, especially circRNA_03628, in the pathological changes of EOMs in ONP.

EIF4A3-regulated hsa_circ_0001445 can inhibit the progression of laryngeal squamous cell carcinoma via hsa-miR-432-5p-dependent up-regulation of RGMA expression.

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor in the head and neck, the 5-year relative survival rate of patients diagnosed with laryngeal cancer was estimated to be 61% from 2012 to 2018. An increasing number of studies have shown that circular RNAs (circRNAs) play a key role in the occurrence and development of cancer and may function as cancer biomarkers and new therapeutic targets. At present, the research on the relationship between circRNAs and LSCC is still in its infancy and needs further exploration. In this study, we found a circRNA (hsa_circ_0001445) associated with LSCC based on bioinformatics analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) assay indicated that the expression of hsa_circ_0001445 was down-regulated in LSCC tissues and cell lines. Notably, the expression of hsa_circ_0001445 was negatively correlated with aggressive clinicopathological features and poor prognosis. Then, functional experiments found that overexpression of hsa_circ_0001445 inhibited the proliferation, migration and invasion of LSCC cells and tumor growth in vivo. Mechanistically, RNA immunoprecipitation (RIP), biotin-labeled probe pull-down, luciferase reporter assay and western blot experiments were employed and found that EIF4A3 reduced the expression of hsa_circ_0001445, and the direct binding of hsa_circ_0001445 to hsa-miR-432-5p attenuated the inhibitory effect of hsa-miR-432-5p on RGMA. In summary, our research suggests that hsa_circ_0001445 may be used as a potential prognostic biomarker and therapeutic target for LSCC.

Identification of m6A suppressor EIF4A3 as a novel cancer prognostic and immunotherapy biomarker through bladder cancer clinical data validation and pan-cancer analysis.

EIF4A3 represents a novel m6A suppressor that exerts control over the global m6A mRNA modification level, therefore influencing gene destiny. Despite increasing evidence that highlights a pivotal role of EIF4A3 in tumor progression and immunity, a comprehensive pan-cancer analysis of EIF4A3 has yet to be conducted, in order to ascertain whether EIF4A3 could be a viable biomarker for cancer screening, prediction of prognosis, and to facilitate accurate therapy design in various human malignancies. We analyzed the expression levels of EIF4A3 in bladder cancer compared to para-cancer tissue. Subsequently survival analysis was conducted to ascertain the potential association between EIF4A3 expression and patient prognosis. To further corroborate this evidence, we conducted an extensive data mining process of several publicly available databases, including UCSC Xena database, TCGA, and GTEx. Raw data from the UCSC Xena database was processed using online tools to obtain results that could be subjected to further analysis. Our study unveiled a considerable increase in the expression levels of EIF4A3 in bladder cancer compared to para-cancer tissue. Subsequent validation experiments confirmed that bladder cancer patients exhibiting higher levels of EIF4A3 expression have significantly worse prognostic outcomes. Next, our pan-cancer analysis found that the expression level of EIF4A3 is significantly higher in most cancers. Notably, high expression levels of EIF4A3 were negatively associated with patient prognosis across various cancer types. Furthermore, as a novel m6A suppressor, EIF4A3 was found to be correlated with numerous RNA modification genes in multiple cancer types. Meanwhile, analysis of publicly available databases revealed that EIF4A3 expression was significantly related to immune score and immune cell levels in most cancer types. Interestingly, EIF4A3 was also identified as a superior immunotherapy biomarker when compared to several traditional immunotherapy biomarkers. Lastly, genetic alterations analysis revealed that amplification was the most frequently occurring abnormality in the EIF4A3 gene. EIF4A3 emerges as a promising biomarker with the potential to significantly enhance tumor screening, prognostic evaluation, and the design of individualized treatment strategies across a diverse array of malignancies.

CircCDK1 blocking IGF2BP2-mediated m6A modification of CPPED1 promotes laryngeal squamous cell carcinoma metastasis via the PI3K/AKT signal pathway.

BACKGROUND: Circular RNA (circRNA) is a novel noncoding RNA (ncRNA) that plays a critical role in various cancers. However, the clinical significance, biological function, and molecular mechanisms of circRNAs in laryngeal squamous cell carcinoma (LSCC) remain unclear. METHODS: A circRNA array was performed to identify the differentially expressed circRNAs. In vitro and in vivo assays were proceeded to verify the biological function of circCDK1 in LSCC. RNA pulldown assays and RNA immunoprecipitation (RIP) were used to confirm the binding between circCDK1 and insulin-like growth factor 2 mRNA binding protein 2(IGF2BP2). The MeRIP assay was then used to identified the N6-methyladenisine (m6A) methylation of calcineurin like phosphatase domain containing1 (CPPED1). RESULTS: Hsa_circ_0005774 (circCDK1) was found upregulated in LSCC tissues compared to adjacent normal tissues. The level of circCDK1 was positively correlated with poor prognosisof LSCC patients. In vitro and in vivo, circCDK1 promoted migration and invasion of LSCC cells. Mechanistically, eukaryotic translation initiation factor4A3(EIF4A3) induced biogenesis of circCDK1 by binding to its flanking. By competitively binding to IGF2BP2, circCDK1 blocked the m6A modification of CPPED1 in IGF2BP2-dependent manner. Moreover, the circCDK1-mediated decrease of CPPED1 activated the PI3K/AKT signal pathway to facilitate progression of LSCC. CONCLUSIONS: Our findings demonstrated that EIF4A3-induced upregulation of circCDK1 promoted LSCC metastasis via EIF4A3-circCDK1-IGF2BP2-CPPED1 to activate PI3K-AKT signal pathway. CircCDK1 might serve as a new diagnostic and prognostic marker or potential therapeutic target for LSCC.

Broad anti-pathogen potential of DEAD box RNA helicase eIF4A-targeting rocaglates.

Inhibition of eukaryotic initiation factor 4A has been proposed as a strategy to fight pathogens. Rocaglates exhibit the highest specificities among eIF4A inhibitors, but their anti-pathogenic potential has not been comprehensively assessed across eukaryotes. In silico analysis of the substitution patterns of six eIF4A1 aa residues critical to rocaglate binding, uncovered 35 variants. Molecular docking of eIF4A:RNA:rocaglate complexes, and in vitro thermal shift assays with select recombinantly expressed eIF4A variants, revealed that sensitivity correlated with low inferred binding energies and high melting temperature shifts. In vitro testing with silvestrol validated predicted resistance in Caenorhabditis elegans and Leishmania amazonensis and predicted sensitivity in Aedes sp., Schistosoma mansoni, Trypanosoma brucei, Plasmodium falciparum, and Toxoplasma gondii. Our analysis further revealed the possibility of targeting important insect, plant, animal, and human pathogens with rocaglates. Finally, our findings might help design novel synthetic rocaglate derivatives or alternative eIF4A inhibitors to fight pathogens.

Eukaryotic initiation factor 4 A-3 promotes glioblastoma growth and invasion through the Notch1-dependent pathway.

BACKGROUND: As an adult tumor with the most invasion and the highest mortality rate, the inherent heterogeneity of glioblastoma (GBM) is the main factor that causes treatment failure. Therefore, it is important to have a deeper understanding of the pathology of GBM. Some studies have shown that Eukaryotic Initiation Factor 4A-3 (EIF4A3) can promote the growth of many people's tumors, and the role of specific molecules in GBM remains unclear. METHODS: The correlation between the expression of EIF4A3 gene and its prognosis was studied in 94 GBM patients using survival analysis. Further in vitro and in vivo experiments, the effect of EIF4A3 on GBM cells proliferation, migration, and the mechanism of EIF4A3 on GBM was explored. In addition, combined with bioinformatics analysis, we further confirmed that EIF4A3 contributes to the progress of GBM. RESULTS: The expression of EIF4A3 was upregulated in GBM tissues, and high expression of EIF4A3 is associated with poor prognosis in GBM. In vitro, knockdown of EIF4A3 significantly reduced the proliferation, migration, and invasion abilities of GBM cells, whereas overexpression of EIF4A3 led to the opposite effect. The analysis of differentially expressed genes related to EIF4A3 indicates that it is involved in many cancer-related pathways, such as Notch and JAK-STAT3 signal pathway. In Besides, we demonstrated the interaction between EIF4A3 and Notch1 by RNA immunoprecipitation. Finally, the biological function of EIF4A3-promoted GBM was confirmed in living organisms. CONCLUSION: The results of this study suggest that EIF4A3 may be a potential prognostic factor, and Notch1 participates in the proliferation and metastasis of GBM cells mediated by EIF4A3.