FLI-1-driven regulation of endothelial cells in human diseases.

Endothelial cells (ECs) are widely distributed in the human body and play crucial roles in the circulatory and immune systems. ECs dysfunction contributes to the progression of various chronic cardiovascular, renal, and metabolic diseases. As a key transcription factor in ECs, FLI-1 is involved in the differentiation, migration, proliferation, angiogenesis and blood coagulation of ECs. Imbalanced FLI-1 expression in ECs can lead to various diseases. Low FLI-1 expression leads to systemic sclerosis by promoting fibrosis and vascular lesions, to pulmonary arterial hypertension by promoting a local inflammatory state and vascular lesions, and to tumour metastasis by promoting the EndMT process. High FLI-1 expression leads to lupus nephritis by promoting a local inflammatory state. Therefore, FLI-1 in ECs may be a good target for the treatment of the abovementioned diseases. This comprehensive review provides the first overview of FLI-1-mediated regulation of ECs processes, with a focus on its influence on the abovementioned diseases and existing FLI-1-targeted drugs. A better understanding of the role of FLI-1 in ECs may facilitate the design of more effective targeted therapies for clinical applications, particularly for tumour treatment.

Blocking ACSL6 Compromises Autophagy via FLI1-Mediated Downregulation of COLs to Radiosensitize Lung Cancer.

Lung cancer (LC) is the leading cause of cancer-related mortality worldwide. Radiotherapy is the main component of LC treatment; however, its efficacy is often limited by radioresistance development, resulting in unsatisfactory clinical outcomes. Here, we found that LC radiosensitivity is up-regulated by decreased expression of long-chain acyl-CoA synthase 6 (ACSL6) after irradiation. Deletion of ACSL6 results in significant elevation of Friend leukemia integration 1 transcription factor (FLI1) and a marked decline of collagens (COLs). Blocking of ACSL6 impairs the tumor growth and upregulates FLI1, which reduces the levels of COLs and compromises irradiation-induced autophagy, leading to considerable therapeutic benefits during radiotherapy. Moreover, the direct interaction between ACSL6 and FLI1 and engagement between FLI1 and COLs indicates the involvement of the ACSL6-FLI1-COL axis. Finally, the potently adjusted autophagy flux reduces its otherwise contributive capability in surviving irradiation stress and leads to satisfactory radiosensitization for LC radiotherapy. These results demonstrate that enhanced ACSL6 expression promotes the aggressive performance of irradiated LC through increased FLI1-COL-mediated autophagy flux. Thus, the ACSL6-FLI1-Col-autophagy axis may be targeted to enhance the radiosensitivity of LC and improve the management of LC in radiotherapy.

FLI1 in PBMCs contributes to elevated inflammation in combat-related posttraumatic stress disorder.

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition with significant public health implications that arise following exposure to traumatic events. Recent studies highlight the involvement of immune dysregulation in PTSD, characterized by elevated inflammatory markers. However, the precise mechanisms underlying this immune imbalance remain unclear. Previous research has implicated friend leukemia virus integration 1 (FLI1), an erythroblast transformation-specific (ETS) transcription factor, in inflammatory responses in sepsis and Alzheimer's disease. Elevated FLI1 levels in peripheral blood mononuclear cells (PBMCs) have been linked to lupus severity. Yet, FLI1's role in PTSD-related inflammation remains unexplored. In our study, PBMCs were collected from Veterans with and without PTSD. We found significantly increased FLI1 expression in PBMCs from PTSD-afflicted Veterans, particularly in CD4+ T cells, with no notable changes in CD8+ T cells. Stimulation with LPS led to heightened FLI1 expression and elevated levels of inflammatory cytokines IL-6 and IFNγ in PTSD PBMCs compared to controls. Knockdown of FLI1 using Gapmers in PTSD PBMCs resulted in a marked reduction in inflammatory cytokine levels, restoring them to control group levels. Additionally, co-culturing PBMCs from both control and PTSD Veterans with the human brain microglia cell line HMC3 revealed increased inflammatory mediator levels in HMC3. Remarkably, HMC3 cells co-cultured with PTSD PBMCs treated with FLI1 Gapmers exhibited significantly lower inflammatory mediator levels compared to control Gapmer-treated PTSD PBMCs. These findings suggest that suppressing FLI1 may rebalance immune activity in PBMCs and mitigate microglial activation in the brain. Such insights could provide novel therapeutic strategies for PTSD.

EWS-FLI1 and Activator Protein-1 (AP-1) Reciprocally Regulate Extracellular-Matrix Proteins in Ewing sarcoma Cells.

Ribonucleotide reductase (RNR) is the rate-limiting enzyme in the synthesis of deoxyribonucleotides and the target of multiple chemotherapy drugs, including gemcitabine. We previously identified that inhibition of RNR in Ewing sarcoma tumors upregulates the expression levels of multiple members of the activator protein-1 (AP-1) transcription factor family, including c-Jun and c-Fos, and downregulates the expression of c-Myc. However, the broader functions and downstream targets of AP-1, which are highly context- and cell-dependent, are unknown in Ewing sarcoma tumors. Consequently, in this work, we used genetically defined models, transcriptome profiling, and gene-set -enrichment analysis to identify that AP-1 and EWS-FLI1, the driver oncogene in most Ewing sarcoma tumors, reciprocally regulate the expression of multiple extracellular-matrix proteins, including fibronectins, integrins, and collagens. AP-1 expression in Ewing sarcoma cells also drives, concurrent with these perturbations in gene and protein expression, changes in cell morphology and phenotype. We also identified that EWS-FLI1 dysregulates the expression of multiple AP-1 proteins, aligning with previous reports demonstrating genetic and physical interactions between EWS-FLI1 and AP-1. Overall, these results provide novel insights into the distinct, EWS-FLI1-dependent features of Ewing sarcoma tumors and identify a novel, reciprocal regulation of extracellular-matrix components by EWS-FLI1 and AP-1.

Antibody to Endogenous Cardiotonic Steroid Reverses Vascular Fibrosis and Restores Vasorelaxation in Chronic Kidney Disease.

Marinobufagenin (MBG) is implicated in chronic kidney disease, where it removes Fli1-induced inhibition of the collagen-1. We hypothesized that (i) in nephrectomized rats, aortic fibrosis develops due to elevated plasma MBG and inhibited Fli1, and (ii) that the antibody to MBG reduces collagen-1 and improves vasodilatation. A partial nephrectomy was performed in male Sprague-Dawley rats. Sham-operated animals comprised the control group. At 5 weeks following nephrectomy, rats were administered the vehicle (n = 8), or the anti-MBG antibody (n = 8). Isolated aortic rings were tested for their responsiveness to sodium nitroprusside following endothelin-1-induced constriction. In nephrectomized rats, there was an increase in the intensity of collagen staining in the aortic wall vs. the controls. In antibody-treated rats, the structure of bundles of collagen fibers had ordered organization. Western blots of the aorta had lower levels of Fli1 (arbitrary units, 1 ± 0.05 vs. 0.2 ± 0.01; p < 0.001) and greater collagen-1 (arbitrary units, 1 ± 0.01 vs. 9 ± 0.4; p < 0.001) vs. the control group. Administration of the MBG antibody to rats reversed the effect of the nephrectomy on Fli1 and collagen-1 proteins. Aortic rings pretreated with endothelin-1 exhibited 50% relaxation following the addition of sodium nitroprusside (EC50 = 0.28 µmol/L). The responsiveness of the aortic rings obtained from nephrectomized rats was markedly reduced (EC50 = 3.5 mol/L) compared to the control rings. Treatment of rats with the antibody restored vasorelaxation. Thus, the anti-MBG antibody counteracts the Fli1-collagen-1 system and reduces aortic fibrosis.

TIMP-1 Promotes Expression of MCP-1 and Macrophage Migration by Inducing Fli-1 in Experimental Liver Fibrosis.

Background and Aims: Tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a role in the excessive generation of extracellular matrix in liver fibrosis. This study aimed to explore the pathways through which TIMP-1 controls monocyte chemoattractant protein-1 (MCP-1) expression and promotes hepatic macrophage recruitment. Methods: Liver fibrosis was triggered through carbon tetrachloride, and an adeno-associated virus containing small interfering RNA targeting TIMP-1 (siRNA-TIMP-1) was administered to both rats and mice. We assessed the extent of fibrosis and macrophage recruitment. The molecular mechanisms regulating macrophage recruitment by TIMP-1 were investigated through transwell migration assays, luciferase reporter assays, the use of pharmacological modulators, and an analysis of extracellular vesicles (EVs). Results: siRNA-TIMP-1 alleviated carbon tetrachloride-induced liver fibrosis, reducing macrophage migration and MCP-1 expression. Co-culturing macrophages with hepatic stellate cells (HSCs) post-TIMP-1 downregulation inhibited macrophage migration. In siRNA-TIMP-1-treated HSCs, microRNA-145 (miRNA-145) expression increased, while the expression of Friend leukemia virus integration-1 (Fli-1) and MCP-1 was inhibited. Downregulation of Fli-1 led to decreased MCP-1 expression, whereas Fli-1 overexpression increased MCP-1 expression within HSCs. Transfection with miRNA-145 mimics reduced the expression of both Fli-1 and MCP-1, while miRNA-145 inhibitors elevated the expression of both Fli-1 and MCP-1 in HSCs. miRNA-145 bound directly to the 3'-UTR of Fli-1, and miRNA-145-enriched EVs secreted by HSCs after TIMP-1 downregulation influenced macrophage recruitment. Conclusions: TIMP-1 induces Fli-1 expression through miRNA-145, subsequently increasing MCP-1 expression and macrophage recruitment. MiRNA-145-enriched EVs from HSCs can transmit biological information and magnify the function of TIMP-1.

Superficial Neurocristic EWSR1::FLI1 Fusion Tumor: A Distinctive, Clinically Indolent, S100 Protein/SOX10-Positive Neoplasm.

It is now understood that identical gene fusions may be shared by different entities. We report a distinctive neoplasm of the skin and subcutis, harboring the Ewing sarcoma-associated EWSR1::FLI1 fusion but differing otherwise from Ewing sarcoma. Slides and blocks for 5 cutaneous neoplasms coded as other than Ewing sarcoma and harboring EWSR1::FLI1 were retrieved. Immunohistochemical and molecular genetic results were abstracted from reports. Methylation profiling was performed. Clinical information was obtained. The tumors occurred in 4 men and 1 woman (median: 25 years of age; range: 19-69 years) and involved the skin/subcutis of the back (2), thigh, buttock, and chest wall (median: 2.4 cm; range: 1-11 cm). Two tumors were present "years" before coming to clinical attention. The lesions were multinodular and circumscribed and consisted of nests of bland, round cells admixed with hyalinized collagenous bands containing spindled cells. Hemorrhage and cystic change were often present; necrosis was absent. All were diffusely S100 protein/SOX10-positive; 4 of 5 were CD99-negative. One tested case was strongly positive for NKX2.2. A variety of other tested markers were either focally positive (glial fibrillary acidic protein, p63) or negative. Molecular genetic results were as follows: EWSR1 exon 7::FLI1 exon 8, EWSR1 exon 11::FLI1 exon 5, EWSR1 exon 11::FLI1 exon 6, EWSR1 exon 7::FLI1 exon 6, and EWSR1 exon 10::FLI1 exon 6. Methylation profiling (3 cases) showed these to form a unique cluster, distinct from Ewing sarcoma. All patients underwent excision with negative margins; one received 1 cycle of chemotherapy. Clinical follow-up showed all patients to be alive without disease (median: 17 months; range: 11-62 months). Despite similar gene fusions, the morphologic, immunohistochemical, epigenetic, and clinical features of these unique EWSR1::FLI1-fused neoplasms of the skin and subcutis differ substantially from Ewing sarcoma. Interestingly, EWSR1 rearrangements involved exons 10 or 11, only rarely seen in Ewing sarcoma, in a majority of cases. Superficial neurocristic EWSR1::FLI1 fusion tumors should be rigorously distinguished from true cutaneous Ewing sarcomas.

FLI1 is associated with regulation of DNA methylation and megakaryocytic differentiation in FPDMM caused by a RUNX1 transactivation domain mutation.

Familial platelet disorder with associated myeloid malignancies (FPDMM) is an autosomal dominant disease caused by heterozygous germline mutations in RUNX1. It is characterized by thrombocytopenia, platelet dysfunction, and a predisposition to hematological malignancies. Although FPDMM is a precursor for diseases involving abnormal DNA methylation, the DNA methylation status in FPDMM remains unknown, largely due to a lack of animal models and challenges in obtaining patient-derived samples. Here, using genome editing techniques, we established two lines of human induced pluripotent stem cells (iPSCs) with different FPDMM-mimicking heterozygous RUNX1 mutations. These iPSCs showed defective differentiation of hematopoietic progenitor cells (HPCs) and megakaryocytes (Mks), consistent with FPDMM. The FPDMM-mimicking HPCs showed DNA methylation patterns distinct from those of wild-type HPCs, with hypermethylated regions showing the enrichment of ETS transcription factor (TF) motifs. We found that the expression of FLI1, an ETS family member, was significantly downregulated in FPDMM-mimicking HPCs with a RUNX1 transactivation domain (TAD) mutation. We demonstrated that FLI1 promoted binding-site-directed DNA demethylation, and that overexpression of FLI1 restored their megakaryocytic differentiation efficiency and hypermethylation status. These findings suggest that FLI1 plays a crucial role in regulating DNA methylation and correcting defective megakaryocytic differentiation in FPDMM-mimicking HPCs with a RUNX1 TAD mutation.

Angiogenic protein profiling, phytochemical screening and in silico anti-cancer targets validation of stem, leaves, fruit, and seeds of Calotropis procera in human liver and breast cancer cell lines.

The main focus of anticancer drug discovery is on developing medications that are gentle on normal cells and should have the ability to target multiple anti-cancer pathways. Liver cancer is becoming a worldwide epidemic due to the highest occurring and reoccurring rate in some countries. Calotropis procera is a xerophytic herbal plant growing wildly in Saudi Arabia. Due to its anti-angiogenic and anticancer capabilities, "C. procera" is a viable option for developing innovative anticancer medicines. However, no study has been done previously, to discover angiogenic and anti-cancer targets which are regulated by C. procera in liver cancer. In this study, leaves, stems, flowers, and seeds of C. procera were used to prepare crude extracts and were fractionated into four solvents of diverse polarities. These bioactivity-guided solvent fractions helped to identify useful compounds with minimal side effects. The phytoconstituents present in the leaves and stem were identified by GC-MS. In silico studies were done to predict the anti-cancer targets by major bioactive constituents present in leaves and stem extracts. A human angiogenesis antibody array was performed to profile novel angiogenic targets. The results from this study showed that C. procera extracts are an ideal anti-cancer remedy with minimum toxicity to normal cells as revealed by zebrafish in vivo toxicity screening assays. The novel antiangiogenic and anticancer targets identified in this study could be explored to design medication against liver cancer.

Inherited thrombocytopenia associated with a variant in the FLI1 binding site in the 5' UTR of ANKRD26.

Variants in the 5' UTR of ANKRD26 are a common cause of inherited thrombocytopenia (ANKRD26-RT), and are associated with sustained ANKRD26 expression, which inhibits megakaryocyte maturation and proplatelet formation. ANKRD26 expression is controlled by the binding of a RUNX1/FLI1 complex to the 5' UTR. To date, all reported ANKRD26-RD associated variants have been within the RUNX1 binding site and a 22 base pair flanking region. Here, we report a novel variant in the 5' UTR of ANKRD26, c.-107C>T. This variant is in the FLI1 binding site, and is predicted to disrupt FLI1 binding due to loss of a hydrogen bond with FLI1. Differentiated PBMCs from affected family members showed impaired megakaryocyte maturation and proplatelet formation and sustained expression of ANKRD26, and platelets from affected family members had higher ANKRD26 expression than control platelets. The variant increased activity of the ANKRD26 promotor in a reporter assay. We also provide evidence that the previously reported c.-140C>G ANKRD26 5' UTR variant is benign and not associated with thrombocytopenia. Identification of the c.-107C>T variant extends the range of the regulatory region in the 5' UTR of ANKRD26 that is associated with ANKRD26-RT.

Primary Ewing's sarcoma of the uterine cervix: a case report and review of the literature.

BACKGROUND: Ewing's sarcoma (ES) is an aggressive cancer of bone and soft tissue, most of which tend to occur in the bone. Extraosseous Ewing's sarcoma (EES) of the cervix is extremely rare. CASE PRESENTATION: In the present work, we reported a 39-year-old cervical EES patient with a 2.5*2.1*1.8 cm tumor mass. According to previous literatures, our case is the smallest tumor found in primary cervical ES ever. The patient initially came to our hospital due to vaginal bleeding, and then the gynecological examination found a neoplasm between the cervical canal and partially in the external cervical orifice. The diagnosis of EES was confirmed below: Hematoxylin & Eosin staining (H&E) revealed small round blue malignant cells in biopsy specimens. Immunohistochemistry (IHC) showed the positive staining for CD99, NKX2.2, and FLI1. Disruption of EWSR1 gene was found by fluorescence in situ hybridization (FISH), and the EWSR1-FLI1 gene fusion was determined by next-generation sequencing (NGS). The patient received laparoscopic wide hysterectomy, bilateral adnexectomy, pelvic lymphadenectomy, and postoperative adjuvant chemotherapy and remained disease free with regular follow-up for 1 year. CONCLUSIONS: Through a systematic review of previously reported cervical ES and this case, we highlighted the importance of FISH and NGS for the accuracy of ESS diagnosis, which could assist on the optimal treatment strategy. However, due to the rarity of the disease, there is no standard treatment schemes. Investigation on molecular pathological diagnosis and standardization of treatment regimens for cervical ES are critical to patients' prognosis.

Integrated analysis reveals FLI1 regulates the tumor immune microenvironment via its cell-type-specific expression and transcriptional regulation of distinct target genes of immune cells in breast cancer.

BACKGROUND: Immunotherapy is a practical therapeutic approach in breast cancer (BRCA), and the role of FLI1 in immune regulation has gradually been unveiled. However, the specific role of FLI1 in BRCA was conflicted; thus, additional convincing evidence is needed. METHODS: We explored the upstream regulation of FLI1 expression via summary data-based Mendelian randomization (SMR) analysis and ncRNA network construction centering on FLI1 using BRCA genome-wide association study (GWAS) summary data with expression quantitative trait loci (eQTLs) and DNA methylation quantitative trait loci (mQTLs) from the blood and a series of in silico analyses, respectively. We illuminated the downstream function of FLI1 in immune regulation by integrating a series of analyses of single-cell RNA sequence data (scRNA-seq). RESULTS: We verified a causal pathway from FLI1 methylation to FLI1 gene expression to BRCA onset and demonstrated that FLI1 was downregulated in BRCA. FLI1, a transcription factor, served as myeloid and T cells' communication regulator by targeting immune-related ligands and receptor transcription in BRCA tissues. We constructed a ceRNA network centering on FLI1 that consisted of three LncRNAs (CKMT2-AS1, PSMA3-AS1, and DIO3OS) and a miRNA (hsa-miR-324-5p), and the expression of FLI1 was positively related to a series of immune-related markers, including immune cell infiltration, biomarkers of immune cells, and immune checkpoints. CONCLUSION: Low-methylation-induced or ncRNA-mediated downregulation of FLI1 is associated with poor prognosis, and FLI1 might regulate the tumor immune microenvironment via a cell-type-specific target genes manner in BRCA.

FLI1 induces erythroleukemia through opposing effects on UBASH3A and UBASH3B expression.

BACKGROUND: FLI1 is an oncogenic transcription factor that promotes diverse malignancies through mechanisms that are not fully understood. Herein, FLI1 is shown to regulate the expression of Ubiquitin Associated and SH3 Domain Containing A/B (UBASH3A/B) genes. UBASH3B and UBASH3A are found to act as an oncogene and tumor suppressor, respectively, and their combined effect determines erythroleukemia progression downstream of FLI1. METHODS: Promoter analysis combined with luciferase assays and chromatin immunoprecipitation (ChIP) analysis were applied on the UBASH3A/B promoters. RNAseq analysis combined with bioinformatic was used to determine the effect of knocking-down UBASH3A and UBASH3B in leukemic cells. Downstream targets of UBASH3A/B were inhibited in leukemic cells either via lentivirus-shRNAs or small molecule inhibitors. Western blotting and RT-qPCR were used to determine transcription levels, MTT assays to assess proliferation rate, and flow cytometry to examine apoptotic index. RESULTS: Knockdown of FLI1 in erythroleukemic cells identified the UBASH3A/B genes as potential downstream targets. Herein, we show that FLI1 directly binds to the UBASH3B promoter, leading to its activation and leukemic cell proliferation. In contrast, FLI1 indirectly inhibits UBASH3A transcription via GATA2, thereby antagonizing leukemic growth. These results suggest oncogenic and tumor suppressor roles for UBASH3B and UBASH3A in erythroleukemia, respectively. Mechanistically, we show that UBASH3B indirectly inhibits AP1 (FOS and JUN) expression, and that its loss leads to inhibition of apoptosis and acceleration of proliferation. UBASH3B also positively regulates the SYK gene expression and its inhibition suppresses leukemia progression. High expression of UBASH3B in diverse tumors was associated with worse prognosis. In contrast, UBASH3A knockdown in erythroleukemic cells increased proliferation; and this was associated with a dramatic induction of the HSP70 gene, HSPA1B. Accordingly, knockdown of HSPA1B in erythroleukemia cells significantly accelerated leukemic cell proliferation. Accordingly, overexpression of UBASH3A in different cancers was predominantly associated with good prognosis. These results suggest for the first time that UBASH3A plays a tumor suppressor role in part through activation of HSPA1B. CONCLUSIONS: FLI1 promotes erythroleukemia progression in part by modulating expression of the oncogenic UBASH3B and tumor suppressor UBASH3A.

FLI-1 is expressed in a wide variety of hematolymphoid neoplasms: a special concern in the differential diagnosis.

Friend Leukemia Virus Integration 1 (FLI-1) is a member of E26 transformation-specific family of transcription factors that participates in hematopoietic and vascular endothelial cell development. Immunohistochemical detection of FLI-1 has been widely used to diagnose vascular tumors or, more evidently, Ewing's sarcoma. However, the expression pattern of FLI-1 in hematolymphoid neoplasms remains unclear. Therefore, in this study, we aimed to investigate the expression of FLI-1 in these tumors, focusing on high-grade lesions, which presents a diagnostic challenge by mimicking Ewing's sarcoma. We evaluated the expression FLI-1 in various types of lymphoid and plasmacytic tumors, including 27 plasmablastic lymphomas, 229 diffuse large B-cell lymphomas, 22 precursor T- or B-lymphoblastic lymphomas, 24 angioimmunoblastic-type nodal T-follicular helper cell lymphomas, 52 peripheral T-cell lymphomas, NOS, 18 Burkitt lymphomas, 18 non-gastric lymphomas of mucosa-associated lymphoid tissue, 38 chronic lymphocytic leukemia/small lymphocytic lymphomas, 15 mantle cell lymphomas, 23 gastric MALT lymphomas, 50 plasma cell myelomas, and 38 follicular lymphomas. We calculated the H-scores of FLI-1 immunostaining, ranging from 0 to 200, and used the scores to analyze the clinicopathological significance of FLI-1 statistically. FLI-1 was expressed to varying degrees in all types of hematological tumors. FLI-1 expression was detected in 84.1% of patients (466/554). FLI-1 was highly expressed in precursor T- or B-lymphoblastic lymphomas. Follicular lymphomas exhibited low FLI-1 expression. In plasmablastic lymphoma, 85.2% of the patients were focally positive for FLI-1. FLI-1 expression did not correlate with clinicopathological variables, such as demographic data or disease stage, in patients with plasmablastic lymphoma and diffuse large B-cell lymphoma. However, FLI-1 overexpression was associated with poorer overall survival in patients with plasmablastic lymphoma. This study demonstrates that FLI-1 is expressed in various hematolymphoid neoplasms. FLI-1 expression can lead to diagnostic confusion, especially in small blue round cell tumors, such as lymphoblastic lymphoma, plasmablastic lymphoma, and plasma cell myeloma, when distinguishing tumors positive for CD99 and CD56 without CD3, CD20, or CD45. Our findings also suggested the possibility of FLI-1 as a potential prognostic biomarker for plasmablastic lymphoma.

Clinical analysis of 21 cases of primary Ewing sarcoma of the thoracic wall / 中国癌症杂志

Background and Purpose:Primary Ewing sarcoma of the thoracic wall(PEST)is a rare extraosseous Ewing sarcoma that occurs in the chest wall or thoracic cavity with a short survival,poor prognosis and a high rate of recurrence.Early diagnosis and treatment are the best way to prolong survival time since the cause of PEST is not clear.This study aimed to explore the clinicopathologic characteristics,diagnosis and treatment of PEST to improve clinical understanding of this disease.Methods:A total of 21 cases with PEST were treated at The First Affiliated Hospital of Soochow University,and reviews were published from 2018 to 2023.Clinical data,pathological features,treatment and follow-up of the patients were analyzed respectively.The survival was from the start of treatment to the death of the patient or the end of the follow-up.Cumulative survival was estimated by Kaplan-Meier method.Results:A total of 21 cases with PEST(male/female ratio,13∶8;sites of left/right chest ratio,6∶15;median age,20 years;mean age,28 years;median diameter of the tumor,8.0 cm;mean diameter of the tumor,18.1 cm)met the inclusion criteria.65.2%of the patients presented with the pain in the ipsilateral thoracic and abdominal area.In 47.1%of cases,the ipsilateral ribs were invaded with pleural effusion.Pathological morphology microscopy showed most tumor cells were tightly packed or lobular distribution of small blue round cells.In immunohistochemistry,CD99 and vimentin were positive in 100%and 80%cases respectively while neurogenic markers were expressed to varying degrees.EWSR1 separated signal was found by fluorescence in situ hybridization(FISH),and the EWSR1-FLI1 fusion was detected by next-generation sequencing(NGS)in two cases at our hospital.Two cases received neoadjuvant chemotherapy,10 patients received chemotherapy and radiotherapy after operation,5 cases were treated with radiotherapy only,1 case received surgery only,and 3 cases had no surgical data.A total of 14 cases were followed up for 3-38 month while 7 cases were lost to visit.Cumulative survival correlates with age at disease.The mean survival time was 19.98 months,and the median survival time was 13.00 months.Conclusion:Young males,right chest and the mass larger than 8 cm are more often found.Most cases can be initially diagnosed using histopathology and immunohistochemical markers.FISH or NGS of the EWSR1 gene test are a highly accurate method for diagnosis.The prognosis of PEST is extremely poor,and the cumulative survival rate is negatively correlated with the age of onset.Surgery,radiotherapy and chemotherapy are the main treatments for this disease.

Insights into Molecular Diversity within the FET Family: Unraveling Phase Separation of the N-Terminal Low Complexity Domain from RNA-Binding Protein EWS.

The FET family proteins, which includes FUS, EWS, and TAF15, are RNA chaperones instrumental in processes such as mRNA maturation, transcriptional regulation, and the DNA damage response. These proteins have clinical significance: chromosomal rearrangements in FET proteins are implicated in Ewing family tumors and related sarcomas. Furthermore, point mutations in FUS and TAF15 are associated with neurodegenerative conditions like amyotrophic lateral sclerosis and frontotemporal lobar dementia. The fusion protein EWS::FLI1, the causative mutation of Ewing sarcoma, arises from a genomic translocation that fuses the low-complexity domain (LCD) of EWS (EWSLCD) with the DNA binding domain of the ETS transcription factor FLI1. This fusion not only alters transcriptional programs but also hinders native EWS functions like splicing. However, the precise function of the intrinsically disordered EWSLCD is still a topic of active investigation. Due to its flexible nature, EWSLCD can form transient interactions with itself and other biomolecules, leading to the formation of biomolecular condensates through phase separation - a mechanism thought to be central to the oncogenicity of EWS::FLI1. In our study, we used paramagnetic relaxation enhancement NMR, analytical ultracentrifugation, light microscopy, and all-atom molecular dynamics (MD) simulations to better understand the self-association and phase separation tendencies of EWSLCD. Our aim was to elucidate the molecular events that underpin EWSLCD-mediated biomolecular condensation. Our NMR data suggest tyrosine residues primarily drive the interactions vital for EWSLCD phase separation. Moreover, a higher density and proximity of tyrosine residues amplify the likelihood of condensate formation. Atomistic MD simulations and hydrodynamic experiments revealed that the tyrosine-rich N and C-termini tend to populate compact conformations, establishing unique contact networks, that are connected by a predominantly extended, tyrosine-depleted, linker region. MD simulations provide critical input on the relationship between contacts formed within a single molecule (intramolecular) and inside the condensed phase (intermolecular), and changes in protein conformations upon condensation. These results offer deeper insights into the condensate-forming abilities of the FET proteins and highlights unique structural and functional nuances between EWS and its counterparts, FUS and TAF15.

Primary Intracranial Ewing Sarcoma With EWSR1-FLI1 Gene Translocation Mimicking a Meningioma and a Multidisciplinary Therapeutic Approach: A Case Report and Systematic Review of Literatures.

Ewing sarcoma and peripheral primitive neuroectodermal tumor (ES/pPNET) is an undifferentiated malignant tumor that is most prevalent in children and young adults and often radiologically mimics a meningioma. A 38-year-old female patient visited our hospital with complaints of right-sided tinnitus, right hemiparesis, and imbalance. She underwent preoperative imaging and was subsequently diagnosed as having a meningioma on the petrous ridge. After partial resection, EWSR1-FLI1 gene fusion was confirmed, and she was diagnosed with ES/pPNET. The tumor was successfully treated using a multidisciplinary approach of adjuvant chemo- and radiotherapy. This case is noteworthy because it is an extremely rare case of an intracranial ES/pPNET, and it is worth sharing our clinical experience that the tumor was successfully treated through a multidisciplinary therapeutic approach even though complete resection was not achieved.

EWS/FLI1 Characterization, Activation, Repression, Target Genes and Therapeutic Opportunities in Ewing Sarcoma.

Despite their clonal origins, tumors eventually develop into complex communities made up of phenotypically different cell subpopulations, according to mounting evidence. Tumor cell-intrinsic programming and signals from geographically and temporally changing microenvironments both contribute to this variability. Furthermore, the mutational load is typically lacking in childhood malignancies of adult cancers, and they still exhibit high cellular heterogeneity levels largely mediated by epigenetic mechanisms. Ewing sarcomas represent highly aggressive malignancies affecting both bone and soft tissue, primarily afflicting adolescents. Unfortunately, the outlook for patients facing relapsed or metastatic disease is grim. These tumors are primarily fueled by a distinctive fusion event involving an FET protein and an ETS family transcription factor, with the most prevalent fusion being EWS/FLI1. Despite originating from a common driver mutation, Ewing sarcoma cells display significant variations in transcriptional activity, both within and among tumors. Recent research has pinpointed distinct fusion protein activities as a principal source of this heterogeneity, resulting in markedly diverse cellular phenotypes. In this review, we aim to characterize the role of the EWS/FLI fusion protein in Ewing sarcoma by exploring its general mechanism of activation and elucidating its implications for tumor heterogeneity. Additionally, we delve into potential therapeutic opportunities to target this aberrant fusion protein in the context of Ewing sarcoma treatment.

Friend leukemia integration 1 overexpression decreases endometrial receptivity and induces embryo implantation failure by promoting PART1 transcription in the endometrial epithelial cells.

Background: In vitro fertilization-embryo transfer (IVF-ET) is a crucial assisted reproductive technology for treating infertility. However, recurrent implantation failure (RIF), a significant challenge in IVF-ET success, remains unresolved. This study aimed to explore the role and mechanism of FLI1 in endometrial receptivity and RIF. Methods: Differential endometrial cell proportions between patients with RIF and control subjects were assessed using single-cell RNA sequencing (scRNA-seq) analysis. The chromatin accessibility of FLI1 in the luteal endometrial tissue of patients with RIF and control subjects was examined using the single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq). FLI1 mRNA and protein levels were gauged by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Cell viability and migration were examined via cell counting kit (CCK)-8 and scratch healing assays. Epithelial-mesenchymal transition markers were analyzed using western blotting. Mechanisms underlying FLI1's regulation of PART1 transcription and expression in endometrial epithelial cells were explored using chromatin immunoprecipitation and dual-luciferase reporter assays. Adeno-associated virus (AAV) carrying epithelial cell-specific FLI1/PART1 overexpression sequences was uterinely injected in mice to assess FLI1/PART1 effects. Results: scRNA-seq revealed diminished endometrial epithelial cell proportions in RIF patients. Meanwhile, scATAC-seq indicated enhanced chromatin accessibility of FLI1 in these cells. FLI1 exhibited specific expression in RIF patients' endometrial epithelial cells. Specific FLI1 overexpression inhibited embryo implantation, while knockdown enhanced it. Pregnant mice injected with AAV encoding FLI1 overexpression had significantly lower implantation than AAV-negative controls. FLI1 binding to PART1 promoter heightened PART1 transcription and expression in endometrial epithelial cells. Rescue experiments illustrated FLI1's role in embryo implantation by boosting PART1 expression. PART1 was notably elevated in RIF patients' luteal endometrial tissue and non-receptive endometrial epithelial cells (HEC-1-A). Specific PART1 overexpression dampened embryo implantation, whereas knockdown promoted it. Pregnant mice injected with AAV encoding PART1 had lower implantation than negative controls. PART1 knockdown mitigated FLI1's inhibitory impact on HEC-1-A cell viability and migration. Conclusions: FLI1 overexpression in the endometrial epithelial cells of patients with RIF inhibited embryo implantation by binding to the PART1 promoter region to promote PART1 expression. These findings can aid in the development of novel therapeutic targets for RIF.

Ewing sarcoma from molecular biology to the clinic.

In Europe, with an incidence of 7.5 cases per million, Ewing sarcoma (ES) is the second most common primary malignant bone tumor in children, adolescents and young adults, after osteosarcoma. Since the 1980s, conventional treatment has been based on the use of neoadjuvant and adjuvant chemotherapeutic agents combined with surgical resection of the tumor when possible. These treatments have increased the patient survival rate to 70% for localized forms, which drops drastically to less than 30% when patients are resistant to chemotherapy or when pulmonary metastases are present at diagnosis. However, the lack of improvement in these survival rates over the last decades points to the urgent need for new therapies. Genetically, ES is characterized by a chromosomal translocation between a member of the FET family and a member of the ETS family. In 85% of cases, the chromosomal translocation found is (11; 22) (q24; q12), between the EWS RNA-binding protein and the FLI1 transcription factor, leading to the EWS-FLI1 fusion protein. This chimeric protein acts as an oncogenic factor playing a crucial role in the development of ES. This review provides a non-exhaustive overview of ES from a clinical and biological point of view, describing its main clinical, cellular and molecular aspects.