Interleukin Enhancer-binding Factor 2 Research Articles

Disruption of pulmonary microvascular endothelial barrier by dysregulated claudin-8 and claudin-4: uncovered mechanisms in porcine reproductive and respiratory syndrome virus infection

The pulmonary endothelium is a dynamic and metabolically active monolayer of endothelial cells. Dysfunction of the pulmonary endothelial barrier plays a crucial role in the acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), frequently observed in the context of viral pneumonia. Dysregulation of tight junction proteins can lead to the disruption of the endothelial barrier and subsequent leakage. Here, the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) served as an ideal model for studying ALI and ARDS. The alveolar lavage fluid of pigs infected with HP-PRRSV, and the supernatant of HP-PRRSV infected pulmonary alveolar macrophages were respectively collected to treat the pulmonary microvascular endothelial cells (PMVECs) in Transwell culture system to explore the mechanism of pulmonary microvascular endothelial barrier leakage caused by viral infection. Cytokine screening, addition and blocking experiments revealed that proinflammatory cytokines IL-1β and TNF-α, secreted by HP-PRRSV-infected macrophages, disrupt the pulmonary microvascular endothelial barrier by downregulating claudin-8 and upregulating claudin-4 synergistically. Additionally, three transcription factors interleukin enhancer binding factor 2 (ILF2), general transcription factor III C subunit 2 (GTF3C2), and thyroid hormone receptor-associated protein 3 (THRAP3), were identified to accumulate in the nucleus of PMVECs, regulating the transcription of claudin-8 and claudin-4. Meanwhile, the upregulation of ssc-miR-185 was found to suppress claudin-8 expression via post-transcriptional inhibition. This study not only reveals the molecular mechanisms by which HP-PRRSV infection causes endothelial barrier leakage in acute lung injury, but also provides novel insights into the function and regulation of tight junctions in vascular homeostasis.

Integrating trans-omics, cellular experiments and clinical validation to identify ILF2 as a diagnostic serum biomarker and therapeutic target in gastric cancer.

Gastric cancer (GC) lacks serum biomarkers with clinical diagnostic value. Multi-omics analysis is an important approach to discovering cancer biomarkers. This study aimed to identify and validate serum biomarkers for GC diagnosis by cross-analysis of proteomics and transcriptomics datasets. A cross-omics analysis was performed to identify overlapping differentially expressed genes (DEGs) between our previous aptamer-based GC serum proteomics dataset and the GC tissue RNA-Seq dataset in The Cancer Genome Atlas (TCGA) database, followed by lasso regression and random forest analysis to select key overlapping DEGs as candidate biomarkers for GC. The mRNA levels and diagnostic performance of these candidate biomarkers were analyzed in the original and independent GC datasets to select valuable candidate biomarkers. The valuable candidate biomarkers were subjected to bioinformatics analysis to select those closely associated with the biological behaviors of GC as potential biomarkers. The clinical diagnostic value of the potential biomarkers was validated using serum samples, and their expression levels and functions in GC cells were validated using in vitro cell experiments. Four candidate biomarkers (ILF2, PGM2L1, CHD7, and JCHAIN) were selected. Their mRNA levels differed significantly between tumor and normal tissues and showed different diagnostic performances for GC, with areas under the receiver operating characteristic curve (AUROCs) of 0.629-0.950 in the TCGA dataset and 0.736-0.840 in the Gene Expression Omnibus (GEO) dataset. In the bioinformatics analysis, only ILF2 (interleukin enhancer-binding factor 2) gene levels were associated with immune cell infiltration, some checkpoint gene expression, chemotherapy sensitivity, and immunotherapy response. Serum levels of ILF2 were higher in GC patients than in controls, with an AUROC of 0.944 for the diagnosis of GC, and it was also detected in the supernatants of GC cells. Knockdown of ILF2 by siRNA significantly reduced the proliferation and colony formation of GC cells. Overexpression of ILF2 significantly promotes the proliferation and colony formation of gastric cancer cells. Trans-omics analysis of proteomics and transcriptomics is an efficient approach for discovering serum biomarkers, and ILF2 is a potential diagnostic biomarker and therapeutic target of gastric cancer.

The interleukin enhancer binding factor-2 (ILF2) gene in Penaeus japonicus shrimp: cloning, tissue distribution, and antiviral effects

The interleukin enhancer binding factor-2 (ILF2) gene in Penaeus japonicus shrimp: cloning, tissue distribution, and antiviral effects

Abstract 343: Cooperation between PRMT1 and PRMT6 drives lung cancer health disparities among Black/African American men

Abstract Non-Hispanic Black/African American (Black/AA) men in the United States have disproportionally higher incidence and mortality rates of lung cancer compared to non-Hispanic White (NHW) men. Molecular determinants including biological and genetic factors are believed to play critical roles in driving disparities. Yet, several recent large-scale genomic studies fail to identify significant somatic differences in lung cancer driver genes contributing to observed disparities between Black/AA and NHW groups. These findings suggest that epigenetic mechanisms may contribute to lung cancer disparities in Black/AA men. Arginine methylation is a post-translational modification catalyzed by protein arginine methyltransferases (PRMTs) that has gained considerable interest as many cancer types display elevated expression of PRMTs correlating with poor prognosis. Here, we observed a significant difference in the expression levels of PRMT6 between Black/AA men vs. NHW men with non-small cell lung cancer (NSCLC) that may contribute to cancer health disparities. To uncover the molecular mechanism by which PRMT6 drives lung cancer, we performed co-immunoprecipitation, protein arginine methylation, and cell proliferation assays using several NSCLC cell lines. We demonstrated that PRMT6 formed a heteromer complex with PRMT1 and disruption of the complex with a competitive peptide inhibitor significantly reduced cancer cell proliferation. We further showed that PRMT1/PRMT6 heteromer complex recruited and catalyzed arginine methylation of interleukin enhancer-binding factor 2 (ILF2). Disrupting heteromer complex formation leaded to a significant reduction of ILF2 methylation and expression. Finally, downregulation of ILF2 expression reduced the positive effects of PRMT1/PRMT6 complex on cell proliferation. Our findings demonstrate the significant functionality of PRMT1/PRMT6 heteromer complex to positively regulate ILF2 expression that is essential for cancer cell proliferation. Furthermore, we uncover a category of substrates for this complex providing the new insights for more potential therapeutic targets that may set the stage for developing new alternative approach to PRMT inhibition. This approach would potentially allow the ability to overcome the current limitations of PRMT1 or PRMT6 inhibitors, thereby opening up new horizons for efficacious PRMT1/PRMT6-targeted agents that are expected to eliminate lung cancer health disparities in Black/AA men. Citation Format: Ching-Yi Chen, Pei-Ying Wu, Michelle Van Scoyk, Stephanie A. Simko, Chu-Fang Chou, Robert A. Winn. Cooperation between PRMT1 and PRMT6 drives lung cancer health disparities among Black/African American men [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 343.

Reciprocal regulation of LINC00941 and SOX2 promotes progression of esophageal squamous cell carcinoma

LINC00941 is a novel long noncoding RNA (lncRNA) and emerging as an important factor in cancer development. However, the exact function and relative regulatory mechanism of LINC00941 in carcinogenesis of esophageal squamous cell carcinoma (ESCC) remain to be further clarified. The present study was to investigate the expression level, functions, and mechanisms of LINC00941 in ESCC tumorigenesis. LINC00941 was significantly upregulated in ESCC, and upregulated LINC00941 was correlated with dismal patient outcomes. LINC00941 functioned as an oncogene by promoting cells proliferation, stemness, migration, and invasion in ESCC. In terms of mechanisms, SOX2 could bind directly to the promoter region of LINC00941 and activate its transcription. In turn, LINC00941 upregulated SOX2 through interacting with interleukin enhancer binding factor 2 (ILF2) and Y-box binding protein 1 (YBX1) at the transcriptional and post-transcriptional levels. LINC00941 recruited ILF2 and YBX1 to the promoter region of SOX2, leading to upregulation of the transcription of SOX2. Moreover, LINC00941 could promote the binding ability of ILF2 and YBX1 on mRNA of SOX2 and further stabilize SOX2 mRNA. Therefore, LINC00941 contributed to the malignant behaviors of ESCC cells via the unrestricted increase in SOX2 expression. In conclusion, our data indicate that LINC00941 exacerbates ESCC progression through forming a LINC00941-ILF2/YBX1-SOX2 positive feedback loop, and LINC00941 may be a promising prognostic and therapeutic target for ESCC.

514 ILF2 contributes to hyperproliferation of keratinocytes and skin inflammation in a KLHDC7B-DT dependent manner in psoriasis

Background: The extensive involvement of interleukin enhancer binding factor 2 (ILF2) in RNA stability and inflammation response is well documented. Aberrant LncRNAs expression contributes to psoriasis development and progression. However, little is known about the role of ILF2 in psoriasis. Objectives: Aimed to explore the role of ILF2 and KLHDC7B-DT in psoriasis. Methods: Long noncoding RNA (lncRNA) expression in psoriatic tissues was measured by lncRNA microarray and qRT-PCR. Normal human epidermal keratinocytes (NHEKs), HaCaT cells, and Ker-CT cells stimulated by M5 (IL-17A, IL-22, IL-1 α, oncostatin M, and TNF-α) were used to establish a psoriasis model in vitro.

Eicosapentaenoic Acid (EPA) Modulates Expression of Inflammatory Proteins in Pulmonary Endothelial Cells following Exposure to Air Pollution Particles

Lead Author's Financial Disclosures Nothing to disclose. Study Funding Amarin Pharma Inc. and Elucida Research. Background/Synopsis Air pollution contributes to global mortality by causing systemic inflammation and endothelial dysfunction in vascular disease, including atherosclerosis. The omega-3 fatty acid eicosapentaenoic acid (EPA) reduced cardiovascular events in high-risk patients (REDUCE-IT). EPA and omega-3 fatty acids can improve cardiac function and lipid levels in subjects exposed to air pollution particulate matter (PM) but underlying the mechanism is not understood. Objective/Purpose To test the ability of EPA to modulate expression of inflammatory proteins and related pathways in pulmonary endothelial cells following exposure to air pollution PMs of different sizes. Methods Human pulmonary ECs (PECs) were pretreated with EPA (40 micromolar) for 2 h before addition of particulate matter (PMs) with two different diameter ranges for 8 h. The PMs had an average of 5.9 micrometers from collected urban air (urban PMs) and 2.8 micrometers (fine PMs). PMs were delivered to the cells at 50 microgram/mL. Cell extracts from each treatment group were analyzed with LC/MS-based proteomics to measure relative expression levels of proteins. Only significant (p<0.05) changes in expression between treatment groups >1- fold were analyzed using differential enrichment analysis of proteomics data (DEP) and included in gene set enrichment analysis (GSEA). Results EPA significantly modulated expression of 205 and 347 proteins relative to fine and urban PMs, respectively. Among pathways modulated by both PMs was neutrophil degranulation (Gene Ontology ID: 0043312), where fine and urban PMs modulated 36 and 13 proteins, respectively. Common to both PMs were eight proteins, including 1.5-fold and 1.3-fold increases in C-X-C motif chemokine 6 (CXCL6). EPA treatment modulated 22 and 35 proteins associated with neutrophil degranulation compared to fine and urban PMs, respectively. Relative to fine PMs, EPA increased expression of heat shock protein 90-β; and decreased expression of interleukin enhancer-binding factor 2 (ILF2). Compared to urban PMs, EPA decreased expression of CXCL6 and increased expression of glutathione S-transferase P. Conclusions EPA significantly modulated expression of various inflammatory proteins in pulmonary ECs during exposure to multiple air pollution PMs. These findings support a novel vascular benefit for EPA under inflammatory conditions caused by air pollution PMs. Nothing to disclose.

Abstract 3233: Interleukin enhancer-binding factor 2 amplification controls mRNA stability and enhances DNA damage response in metastatic melanoma

Abstract Background: 1q21.3 amplification is frequently observed in metastatic melanoma. Interleukin enhancer-binding factor 2 (ILF2) is in the 1q21.3 amplified region. The functional role of ILF2 as well as its contribution in promoting an aggressive phenotype in cutaneous metastatic melanoma is unknown. Methods: In silico analyses were performed using the TCGA SKCM dataset with clinical annotations. The results were validated in three melanoma cohort microarray datasets from the GEO database. Melanoma tissues mRNA levels were assessed by RNA in situ hybridization and protein levels were analyzed by immunohistochemistry. Four stable metastatic melanoma cell lines were established for in vitro ILF2 functional characterization. Results: Our results showed that the ILF2 copy number variation (CNV) is positively correlated with ILF2 mRNA expression (r=0.68, p&amp;lt;0.0001). Additionally, ILF2 mRNA expression significantly increased with melanoma progression (p&amp;lt;0.0001) and is significantly associated with poor overall survival in metastatic melanoma patients (p=0.026). In vitro, ILF2 overexpression (ILF2-OV) enhances cellular proliferation, whereas ILF2 knockdown decreases cellular proliferation by blocking the cell cycle. Mechanistically, we demonstrated the interaction between ILF2 and the splicing factor U2AF2. Reinforcing their functions as a complex, the U2AF2 knockdown reverses the cellular proliferation effects mediated by ILF2-OV. The levels of U2AF2 mRNA and protein levels increased during melanoma progression. Stage IIIB-C melanoma patients with high ILF2-U2AF2 expression showed significantly shorter overall survival (p=0.024). Functional assays showed that enhanced ILF2/U2AF2 expression promotes a more efficient DNA-damage repair by increasing RAD50 and ATM mRNA expression. Paradoxically, metastatic melanoma cell lines with ILF2-OV were more sensitive to ATM inhibitors. Conclusion: Our study uncovered that the ILF2 and U2AF2 complex may have biological implications in controlling the mRNA stability of RAD50 and ATM in metastatic melanoma. Clinically, ILF2 amplification is associated with melanoma progression, triggers a functional downstream pathway in metastatic melanoma that promotes DNA damage repair, and increases the sensitivity to ATM inhibitors. Citation Format: Xiaoqing Zhang, Matias A. Bustos, Rebecca Gross, Romela Irene Ramos, Teh-Ling Takeshima, Gordon B. Mills, Qiang Yu, Dave S. Hoon. Interleukin enhancer-binding factor 2 amplification controls mRNA stability and enhances DNA damage response in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3233.

ILF2 Contributes to Hyperproliferation of Keratinocytes and Skin Inflammation in a KLHDC7B-DT-Dependent Manner in Psoriasis.

Background: The extensive involvement of interleukin enhancer binding factor 2 (ILF2) in RNA stability and the inflammatory response is well documented. Aberrant long noncoding RNA (lncRNA) expression contributes to the pathogenesis of psoriasis. However, little is known about the role of ILF2 in psoriasis. Objective: To investigate the role of ILF2 and KLHDC7B-DT in psoriasis. Methods: LncRNA expression in psoriatic tissues was measured by lncRNA microarray and qRT–PCR. Normal human epidermal keratinocytes (NHEKs), HaCaT cells, and Ker-CT cells stimulated with M5 (IL-17A, IL-22, IL-1α, oncostatin M, and TNF-α) were used to establish a psoriasis model in vitro. Fluorescence in situ hybridization was used to detect the distribution of KLHDC7B-DT and ILF2 in keratinocytes. The proliferative effects of KLHDC7B-DT and ILF2 on keratinocytes were demonstrated by EdU assay and flow cytometry. ELISA was used to detect the secretion levels of cytokines. RNA pull-down and RNA immunoprecipitation (RIP) were used to detect the direct binding of KLHDC7B-DT with ILF2. Western blotting was used to detect the proteins related to STAT3/JNK signalling pathways. Results: ILF2 and KLHDC7B-DT were significantly overexpressed in psoriatic tissues and M5-induced keratinocytes. KLHDC7B-DT promoted the proliferation of keratinocytes and induced the secretion of IL-6 and IL-8. KLHDC7B-DT could directly bind to ILF2 and activate the STAT3 and JNK signalling pathways. KLHDC7B-DT expression was regulated by ILF2. M5-induced proliferation and inflammatory cytokine secretion in keratinocytes was inhibited after ILF2 knockdown. Furthermore, we found that ILF2 promoted keratinocyte proliferation and the inflammatory response in a KLHDC7B-DT-dependent manner. Conclusions: ILF2 and KLHDC7B-DT are involved in the hyperproliferation of keratinocytes and skin inflammation in psoriasis. In addition, ILF2 functions in a KLHDC7B-DT-dependent manner.

Serine hydroxymethyltransferase 2 (SHMT2) potentiates the aggressive process of oral squamous cell carcinoma by binding to interleukin enhancer-binding factor 2 (ILF2)

ABSTRACT Oral squamous cell carcinoma (OSCC) is a frequent threatening head and neck malignancy. Serine hydroxymethyltransferase 2 (SHMT2) was identified to be upregulated in OSCC and its high expression was associated with poor patient prognosis. This paper set out to assess the influence of SHMT2 on OSCC progression and the potential mechanisms related to interleukin enhancer-binding factor 2 (ILF2). First of all, reverse transcription-quantitative PCR (RT-qPCR) and western blot examined the expression of SHMT2 and ILF2 in OSCC cells. Cell Counting Kit-8 (CCK-8) and colony formation assays appraised cell proliferation. Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling (TUNEL) staining was to estimate the apoptotic rate of cells. Further, wound healing and transwell assays verified the migration and invasion of cells. Western blot was adopted to detect the expression of factors related to apoptosis, migration, and epithelial–mesenchymal transition (EMT). The possible interaction of SHMT2 and ILF2 was predicted by a Molecular INTeraction (MINT) and BioGRID databases and determined using co-immunoprecipitation (IP) assay. Subsequently, ILF2 was overexpressed to investigate whether SHMT2 regulated OSCC progression by binding to ILF2. Results implied that SHMT2 possessed increased expression in OSCC cells, and OSCC cell viability, migration, invasion, EMT were inhibited and apoptosis was potentiated after its silencing. ILF2 bound to SHMT2 and ILF2 expression was downregulated after SHMT2 silencing in OSCC cells. Importantly, ILF2 overexpression abolished the suppressive role of SHMT2 interference in the progression of OSCC. Collectively, SHMT2 could promote the progression of OSCC by binding to ILF2.

Interleukin enhancer-binding factor 2 promotes cell proliferation and DNA damage response in metastatic melanoma.

Background1q21.3 amplification, which is frequently observed in metastatic melanoma, is associated with cancer progression. Interleukin enhancer‐binding factor 2 (ILF2) is located in the 1q21.3 amplified region, but its functional role or contribution to tumour aggressiveness in cutaneous melanoma is unknown.MethodsIn silico analyses were performed using the TCGA SKCM dataset with clinical annotations and three melanoma microarray cohorts from the GEO datasets. RNA in situ hybridisation and immunohistochemistry were utilised to validate the gene expression in melanoma tissues. Four stable melanoma cell lines were established for in vitro ILF2 functional characterisation.ResultsOur results showed that the ILF2 copy number variation (CNV) is positively correlated with ILF2 mRNA expression (r = 0.68, p < .0001). Additionally, ILF2 expression is significantly increased with melanoma progression (p < .0001), and significantly associated with poor overall survival for metastatic melanoma patients (p = .026). The overexpression of ILF2 (ILF2‐OV) promotes proliferation in metastatic melanoma cells, whereas ILF2 knockdown decreases proliferation by blocking the cell cycle. Mechanistically, we demonstrated the interaction between ILF2 and the splicing factor U2AF2, whose knockdown reverses the proliferation effects mediated by ILF2‐OV. Stage IIIB–C melanoma patients with high ILF2‐U2AF2 expression showed significantly shorter overall survival (p = .024). Enhanced ILF2/U2AF2 expression promotes a more efficient DNA‐damage repair by increasing RAD50 and ATM mRNA expression. Paradoxically, metastatic melanoma cells with ILF2‐OV were more sensitive to ATM inhibitors.ConclusionOur study uncovered that ILF2 amplification of the 1q21.3 chromosome is associated with melanoma progression and triggers a functional downstream pathway in metastatic melanoma promoting drug resistance.

Metabolomic Characterization Reveals ILF2 and ILF3 Affected Metabolic Adaptions in Esophageal Squamous Cell Carcinoma.

Esophageal cancer (EC) is a common malignant disease in eastern countries. However, a study of the metabolomic characteristics associated with other biological factors in esophageal squamous cell carcinoma (ESCC) is limited. Interleukin enhancer binding factor 2 (ILF2) and ILF3, double-stranded RNA-binding proteins, have been reported to contribute to the occurrence and development of various types of malignancy. Nevertheless, the underlying functions of ILF2 and ILF3 in ESCC metabolic reprogramming have never been reported. This study aimed to contribute to the metabolic characterization of ESCC and to investigate the metabolomic alterations associated with ILF2 and ILF3 in ESCC tissues. Here, we identified 112 differential metabolites, which were mainly enriched in phosphatidylcholine biosynthesis, fatty acid metabolism, and amino acid metabolism pathways, based on liquid chromatography–mass spectrometry and capillary electrophoresis–mass spectrometry approaches using ESCC tissues and paired para-cancer tissues from twenty-eight ESCC patients. In addition, ILF2 and ILF3 expression were significantly elevated in EC tissues compared to the histologically normal samples, and closely associated with PI3K/AKT and MAPK signaling pathways in ESCC. Moreover, in ESCC tissues with a high ILF2 expression, several short-chain acyl-carnitines (C3:0, C4:0, and C5:0) related to the BCAA metabolic pathway and long-chain acyl-carnitines (C14:0, C16:0, C16:0-OH, and C18:0) involved in the oxidation of fatty acids were obviously upregulated. Additionally, a series of intermediate metabolites involved in the glycolysis pathway, including G6P/F6P, F1,6BP, DHAP, G3P, and 2,3BPG, were remarkably downregulated in highly ILF3-expressed ESCC tissues compared with the corresponding para-cancer tissues. Overall, these findings may provide evidence for the roles of ILF2 and ILF3 during the process of ESCC metabolic alterations, and new insights into the development of early diagnosis and treatment for ESCC. Further investigation is needed to clarify the underlying mechanism of ILF2 and ILF3 on acyl-carnitines and the glycolysis pathway, respectively.

CRNDE-h transcript/miR-136-5p axis regulates interleukin enhancer binding factor 2 expression to promote hepatocellular carcinoma cell proliferation

AimsHepatocellular carcinoma (HCC) is a primary malignancy of the hepatocyte. Interleukin enhancer binding factor 2 (ILF2) plays a role in the development of HCC. However, the regulatory mechanisms of ILF2 expression in HCC remain unclear. In this study, we aimed to identify ILF2-targeting microRNAs (miRNAs) and to explore how they affect ILF2 expression in HCC. Main methodsThe tissue specimens were collected from 25 HCC patients. The underlying regulatory mechanism of ILF2 expression in HCC progression was determined using luciferase reporter assay, quantitative real-time PCR, Western blotting, and BrdU incorporation assay. Key findingsOf predicted miRNA candidates (miR-122-5p, miR-425-5p, miR-136-5p, miR-7-5p, miR-421 and miR-543), a statistically significant inverse correlation by linear correlation analysis was observed between miR-136-5p and ILF2 mRNA expressions in patients with HCC (r = −0.627, P < 0.001). Further analysis demonstrated that ILF2 was directly regulated by miR-136-5p. In addition, we showed that long noncoding RNA colorectal neoplasia differentially expressed-h (lncRNA CRNDE-h) transcript expression was significantly up-regulated in HCC, and a miR-136-5p binding site was newly found in the lncRNA CRNDE-h transcript sequence using IntaRNA tool. In terms of mechanism, highly-expressed lncRNA CRNDE-h transcript can sponge miR-136-5p, thereby preventing it from interacting with target ILF2 mRNA while promoting the proliferation of HCC cells. SignificanceThe lncRNA CRNDE-h/miR-136-5p/ILF2 axis plays a significant regulatory role in HCC progression, which may partly explain the pathogenic mechanisms of HCC and may provide promising potential targets for the diagnosis, treatment, and prognosis of HCC.

Nicotine-Induced ILF2 Facilitates Nuclear mRNA Export of Pluripotency Factors to Promote Stemness and Chemoresistance in Human Esophageal Cancer.

Balancing mRNA nuclear export kinetics with its nuclear decay is critical for mRNA homeostasis control. How this equilibrium is aberrantly disrupted in esophageal cancer to acquire cancer stem cell properties remains unclear. Here we find that the RNA-binding protein interleukin enhancer binding factor 2 (ILF2) is robustly upregulated by nicotine, a major chemical component of tobacco smoke, via activation of JAK2/STAT3 signaling and significantly correlates with poor prognosis in heavy-smoking patients with esophageal cancer. ILF2 bound the THO complex protein THOC4 as a regulatory cofactor to induce selective interactions with pluripotency transcription factor mRNAs to promote their assembly into export-competent messenger ribonucleoprotein complexes. ILF2 facilitated nuclear mRNA export and inhibited hMTR4-mediated exosomal degradation to promote stabilization and expression of SOX2, NANOG, and SALL4, resulting in enhanced stemness and tumor-initiating capacity of esophageal cancer cells. Importantly, inducible depletion of ILF2 significantly increased the therapeutic efficiency of cisplatin and abrogated nicotine-induced chemoresistance in vitro and in vivo. These findings reveal a novel role of ILF2 in nuclear mRNA export and maintenance of cancer stem cells and open new avenues to overcome smoking-mediated chemoresistance in esophageal cancer. SIGNIFICANCE: This study defines a previously uncharacterized role of nicotine-regulated ILF2 in facilitating nuclear mRNA export to promote cancer stemness, suggesting a potential therapeutic strategy against nicotine-induced chemoresistance in esophageal cancer.

Cereblon Promotes the Ubiquitination and Proteasomal Degradation of Interleukin Enhancer-Binding Factor 2.

Interleukin enhancer-binding factor 2 (ILF2) forms a heterodimer with interleukin enhancer-binding factor 3 (ILF3) via double-stranded RNA-binding motif and zinc finger associated domain and thus regulates gene expression and cancer cell growth. However, how ILF2 is degraded in cells remains elusive. In this work, using stable isotope labeling by amino acids in cell culture (SILAC) quantitative proteomics, we find that ILF2 is downregulated in cells expressing cereblon (CRBN). Using affinity purification and immunoblotting analysis, we demonstrate that CRBN interacts with ILF2 and functions as a substrate receptor of the cullin-4 RING E3 ligase complex. Biochemical experiments disclose that CRBN expression reduces ILF2 protein level and this reduction is diminished when the proteasome is inhibited. Upon protein synthesis inhibition, the degradation of ILF2 is enhanced by CRBN. Moreover, CRBN promotes the ubiquitination of ILF2 and thus results in the ubiquitin-mediated proteasomal degradation. Analyses of previously identified post-translational modification sites and the crystal structure of ILF2 discover the potential ubiquitination sites on ILF2. Through mutagenesis and biochemical experiments, we further reveal that the K45R mutation completely abolishes the effect of CRBN on ILF2, suggesting that this is the key residue responsible for its ubiquitination. Taken together, we identify an E3 ligase that regulates ILF2 and uncover a molecular pathway for its degradation. This work might be helpful to elucidate the molecular mechanism by which CRBN regulates diverse cellular functions.

Interleukin Enhancer Binding Factor 2 Regulates Cell Viability and Apoptosis of Human Brain Vascular Smooth Muscle Cells.

The proliferation and migration of vascular smooth muscle cells (VSMCs) are involved in the pathogenesis of intracranial aneurysm (IA) formation and rupture. Interleukin enhancer binding factor 2 (ILF2) is known as the nuclear factor of activated T cells and regulates cell growth. This study was aimed to explore the effects of ILF2 on IA progression. Human brain VSMCs (hBVSMCs) were transfected with pCDNA3.1(+), pCDNA3.1(+)-ILF2, siRNA-negative control, and siRNA-ILF2. The transfection efficiency was then evaluated by determining ILF2 expression. The cell viability and apoptosis were determined using Cell Counting Kit-8 and Annexin V-FITC cell apoptosis assay kit, respectively. Real-time quantification PCR (RT-qPCR) was applied to measure the expression levels of apoptosis-related and inflammation-related genes. Finally, western blot was used to detect the expression level of Fas cell surface death receptor 95 (CD95) and Caspase 8. Overexpression of ILF2 could significantly increase cell viability and decrease cell apoptosis (P < 0.05), while knock-down of ILF2 showed opposite trends for hBVSMCs on cell viability and apoptosis (P < 0.05). RT-qPCR results showed that ILF2 knock-down downregulated the expression levels of BCL2 apoptosis regulator (BCL2), transcriptional regulator Myc-like (c-Myc), and caspase 1 (ICE) whereas upregulated the expression levels of CD95, p21, p53, and interleukin-13 (IL-13). Additionally, the protein expression levels of CD95 and Caspase 8 were significantly decreased after ILF2 overexpression while were significantly increased after ILF2 knock-down (P < 0.05). ILF2 knock-down may inhibit cell viability and promote cell apoptosis of hBVSMCs by regulating the expression levels of apoptosis-related genes and suppressing inflammatory response.

Deletion of interleukin enhancer binding factor 2 (ILF2) resulted in defective biliary development and bile flow blockage

PurposeBiliary atresia (BA) is a devastating obstructive bile duct disease of newborns. BA has the highest incidence in Asians (1/5000), and its pathogenesis is unclear. We identified BA-private rare copy number variants (CNVs; 22 duplications and 6 deletions). ILF2 gene locates in the chromosome region (Chr1:153410347–153,634,058) which was deleted in a nonsyndromic BA patient. However, it is still not known whether ILF2 plays a role in hepatobiliary development and its deletion impacts on the bile duct development. MethodsTo investigate if ILF2 is required for biliary development, we knock-out the zebrafish homologs of ILF2 by CRISPR/Cas9 approach, and discover that deletion of ILF2 causes a defective biliary development and a lack of bile flow from the liver to the gall bladder in zebrafish, which is a resemblance of phenotypes of BA. ResultsOur data indicate that ILF2 gene is required for biliary development; deletion of ILF2 impairs bile duct development and could contribute to BA pathogenesis. This will be the first study to functionally evaluate the genes interfered by BA-private CNVs in hepatobiliary development and in BA pathogenesis. ConclusionsSuch functional study may reveal the potential value of these BA-private CNVs in the disease pathogenesis for BA. Level of evidenceN/A (animal and laboratory study).

LncRNA AK085865 Promotes Macrophage M2 Polarization in CVB3-Induced VM by Regulating ILF2-ILF3 Complex-Mediated miRNA-192 Biogenesis

Accumulating evidence indicates that macrophage polarization plays a crucial role in coxsackievirus B3 (CVB3)-induced viral myocarditis (VM). Our previous study demonstrated that long noncoding ribonucleic acid (lncRNA) AK085865 ablation confers susceptibility to VM by regulating macrophage polarization. However, the detailed molecular mechanisms by which AK085865 regulates macrophage polarization remain to be explored. In this study, we found that AK085865 specifically interacts with interleukin enhancer-binding factor 2 (ILF2) and facilitates M2 macrophage polarization by functioning as a negative regulator in the ILF2-ILF3 complex-mediated microRNA (miRNA or miR) processing pathway. miR-192 was downregulated, whereas the levels of pri-miR-192 were significantly increased in bone marrow-derived macrophages (BMDMs) from AK085865−/− mice compared with the BMDMs from wild-type (WT) mice. Conversely, knockdown of ILF2 resulted in elevated levels of mature miR-192 and decreased expression of pri-miR-192 in BMDMs from AK085865−/− mice. Moreover, miR-192 overexpression promoted macrophage M2 polarization in vitro, and interleukin-1 receptor-associated kinase 1 (IRAK1) was identified as a direct target. miR-192 overexpression effectively rescued mice from lethal myocarditis caused by CVB3 infection and switched myocardial-infiltrating macrophages to a predominant M2 phenotype. Collectively, our findings uncover a critical mechanism of AK085865 in the regulation of macrophage polarization in vitro and in vivo and provide a potential, clinically significant therapeutic target.

Circular RNA 406961 interacts with ILF2 to regulate PM2.5-induced inflammatory responses in human bronchial epithelial cells via activation of STAT3/JNK pathways

Fine particulate matter (PM2.5) has been verified to augmented the incidence of pneumonia, asthma, pulmonary fibrosis, and other pulmonary diseases. Airway inflammation is the pathological basis of the respiratory system, and understanding the molecular mechanisms responsible for airway inflammation may thus support the diagnosis and treatment of respiratory diseases. In our study, human bronchial epithelial cells (BEAS-2B) were exposed to various concentrations of PM2.5 for 48 h. PM2.5 entered the cells, resulting in increased production of interleukin 6 (IL-6) and interleukin 8 (IL-8) and decreased the expression of circular RNA 406961 (circ_406961). Further, PM2.5 with a concentration of 75 μg/mL was applied to mechanism study. Functional experiments further confirmed that circ_406961 inhibited PM2.5-induced BEAS-2B cell inflammation. RNA pull-down and mass spectrometry showed that circ_406961 interacted with interleukin enhancer-binding factor 2 (ILF2), which could regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase 8 (MAPK8, JNK). Our studies showed that circ_406961 inhibited activation of STAT3/JNK pathways via interacting with ILF2 protein, thereby inhibiting the PM2.5-induced inflammatory reaction.

Abstract P6-03-11: Interleukin-enhancer binding factor 2 expression associates with chemotherapy response in triple-negative breast cancer

Abstract Background: Triple-Negative Breast Cancer (TNBC) is one of the aggressive breast cancer (BC) subtype and the most difficult to treat once metastasis occurs. The lack of hormone receptors prevents the usage of standard targeted therapy; moreover the heterogeneity of the TNBC subtype and the high risk of metastasis worsens the problem. Systemic chemotherapy is one of the best option to treat metastatic TNBC. However, the response to chemotherapy treatment is variable and tumors develop resistance. Enhancing the expression of specific splicing factors which generate gene variants is a mechanism the TNBC tumor cells to promote resistance. Interleukin-enhancer binding factor 2 (ILF2) is an RNA binding protein (RBP) involved in RNA metabolism and tumorigenesis. We hypothesize that the binding of the splicing factor Y-Box Binding Protein 1 (YBX1) to ILF2 generates alternative splicing of genes involved in DNA-Damage Response (DDR), in particular after chemotherapy treatment. Methods and Results: To test our hypothesis, we utilized KMplot software (http://kmplot.com/analysis/). Of clinical importance, Relapsed-Free Survival (RFS) after 5 years was analyzed for BC patients with basal subtype. High ILF2 expression determined poorer prognosis in patients with basal subtype and high ILF2 expression (upper quartile, n=154) compared to rest of the patients (n=464) (Log-rank test p=0.0032, HR= 1.53 (1.15-2.03)); furthermore when considered only patients receiving chemotherapy with high ILF2 expression (n=75) compared to rest of the patients (n=224) the prognosis was worst (Log-rank test p=0.000077, HR= 2.11 (1.44-3.07)). In assessing the potential relation of ILF2 expression and BC subtypes, we reviewed the BC TCGA and METABRIC dataset to assess ILF2 expression. A significant higher expression of ILF2 in primary tumors (n=1041) and metastatic (n=7) BC than normal tissue (n=113) was observed using TCGA; similar results were obtained using METABRIC dataset. Moreover, BC primary tumors with basal-like (n=98) subtype presented the highest ILF2 expression compare to other BC subtypes. Likewise, we demonstrated that enhanced expression of ILF2 is associated with copy number amplification in TNBC. In order to select models of TNBC, we profiled TNBC cell lines using western blot; TNBC cells presented higher levels of ILF2 expression than a normal-like cells. Then, using lentiviral transduction we generated stable clones overexpressing ILF2 in MDA-MB-231 cell lines. By functional assays, we demonstrated that higher ILF2 expression enhanced cell growth rates. To identify proteins interacting with ILF2 in TNBC, we performed immunoprecipitation assays and showed that ILF2 interacts with YBX1 in TNBC cell lines. Moreover, in TNBC patients ILF2 and YBX1 expression positively correlate. To validate our findings, we performed immunohistochemistry analysis for ILF2 in a TMA (100 BC and 10 normal breast tissues) and showed that patients with TNBC subtype displayed significantly enhanced ILF2 expression. Conclusions: ILF2 is highly expressed in TNBC cell lines and tumor tissues. ILF2 interacts with YBX1 in TNBC cells. In vitro models showed that overexpression of ILF2 promotes tumor growth. Clinically, increased ILF2 is associated with poorer prognosis and increased chance to relapse in patients with basal subtypes receiving chemotherapy treatment. Citation Format: Matias A Bustos, Xiaoqing Zhang, Dave SB Hoon. Interleukin-enhancer binding factor 2 expression associates with chemotherapy response in triple-negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-03-11.