Regulation of EWSR1-FLI1 Function by Post-Transcriptional and Post-Translational Modifications

ChiTaRS 8.0: the comprehensive database of chimeric transcripts and RNA-seq data with applications in liquid biopsy

Gene fusions are nucleotide sequences formed due to errors in replication and transcription control. These errors, resulting from chromosomal translocation, transcriptional errors or trans-splicing, vary from cell to cell. The identification of fusions has become critical as key biomarkers for disease diagnosis and therapy in various cancers, significantly influencing modern medicine. Chimeric Transcripts and RNA-Sequencing database version 8.0 (ChiTaRS 8.0; http://biosrv.org/chitars) is a specialized repository for human chimeric transcripts, containing 47 445 curated RNA transcripts and over 100 000 chimeric sequences in humans. This updated database provides unique information on 1055 chimeric breakpoints derived from public datasets using chromosome conformation capture techniques (the Hi-C datasets). It also includes an expanded list of gene fusions that are potential drug targets, and chimeric breakpoints across 934 cell lines, positioning ChiTaRS 8.0 as a valuable resource for testing personalized cancer therapies. By utilizing text mining on a curated selection of disease-specific RNA-sequencing data from public datasets, as well as patient blood and plasma samples, we have identified novel chimeras-particularly in diseases such as oral squamous cell carcinoma and glioblastoma-now catalogued in ChiTaRS. Thus, ChiTaRS 8.0 serves as an enhanced fusion transcript repository that incorporates insights into the functional landscape of chimeras in cancers and other complex diseases, based on liquid biopsy results.

Genome-wide investigation of VNTR motif polymorphisms in 8,222 genomes: Implications for biological regulation and human traits

Variable number tandem repeat (VNTR) is a pervasive and highly mutable genetic feature that varies in both length and repeat sequence. Despite the well-studied copy-number variants, the functional impacts of repeat motif polymorphisms remain unknown. Here, we present the largest genome-wide VNTR polymorphism map to date, with over 2.5 million VNTR length polymorphisms (VNTR-LPs) and over 11 million VNTR motif polymorphisms (VNTR-MPs) detected in 8,222 high-coverage genomes. Leveraging the large-scale NyuWa cohort, we identified 2,982,456 (31.8%) NyuWa-specific VNTR-MPs, of which 95.3% were rare. Moreover, we found 1,937 out of 38,685 VNTRs that were associated with gene expression through VNTR-MPs in lymphoblastoid cell lines. Specifically, we clarified that the expansion of a likely causal motif could upregulate gene expression by improving the binding concentration of PU.1. We also explored the potential impacts of VNTR polymorphisms on phenotypic differentiation and disease susceptibility. This study expands our knowledge of VNTR-MPs and their functional implications.

Signaling pathways and targeted therapies in Ewing sarcoma

Ewing sarcoma, the second most prevalent malignant bone tumor with potential occurrence in soft tissues, exhibits a high level of aggressiveness, primarily afflicting children and adolescents. It is characterized by fusion proteins arising from chromosomal translocations. The fusion proteins induce aberrations in multiple signaling pathways and molecules, constituting a key event in oncogenic transformation. While diagnostic and therapeutic modalities have advanced in recent decades and multimodal treatments, including surgery, radiotherapy, and chemotherapy, have significantly improved survival of patients with localized tumors, patients with metastatic tumors continue to face poor prognoses. There persists a pressing need for novel alternative treatments, yet the translation of our understanding of Ewing sarcoma pathogenesis into improved clinical outcomes remains a critical challenge. Here, we provide a comprehensive review of Ewing sarcoma, including fusion proteins, various signaling pathways, pivotal pathogenetic molecules implicated in its development, and associated targeted therapies and immunotherapies. We summarize past endeavors, current advancements, and deliberate on limitations and future research directions. It is envisaged that this review will furnish novel insights into prospective treatment avenues for Ewing sarcoma.

Case report: Pulmonary Ewing sarcoma disguised as non-small cell lung cancer

Ewing sarcoma is the second most common primary malignant bone cancer in children and adolescents. This rare type of cancer is characterized by its high malignancy and therefore high risk of metastases. Typically, Ewing sarcomas originate from bones. However, extraosseous Ewing sarcoma such as pulmonary Ewing sarcoma can also be found. In this case report, we present a 55-year old male patient who was initially diagnosed with non-small cell lung cancer at his local district hospital. However, the diagnosis was changed to one of pulmonary Ewing sarcoma after subsequent histopathological and molecular pathological analysis performed in a reference pathology laboratory. After patient referral to a certified (according to the German Cancer Society) high-volume sarcoma center, multimodal chemotherapy was initiated based on recently published clinical data as opposed to the more commonly used treatment regimen in Europe. The patient responded well to treatment and underwent a complete surgical tumor resection followed by radiotherapy. In summary, this case report highlights the importance of a rigorous and timely histopathological examination of biopsy samples by a specialized cancer center to enable a correct diagnosis of the cancer type. Additionally, molecular pathology plays a crucial part in this analysis and allows the necessary differentiation between cancer types. Up to now, there is no international treatment guideline available for the treatment of Ewing sarcoma. Patients should be referred to specialist centers to allow the best possible treatment of the cancer type in view of current published clinical data. In the case of Ewing sarcoma, and in accordance with the most recent research, patients should be treated with vincristine, doxorubicin and cyclophosphamide plus ifosfamide and etoposide in combination with local treatment such as surgery and/or radiotherapy because this has been demonstrated to be the more effective therapy.

Crosstalk of methylation and tamoxifen in breast cancer (Review)

Tamoxifen is a widely used anti‑estrogen drug in the endocrine therapy of breast cancer (BC). It blocks estrogen signaling by competitively binding to estrogen receptor α (ERα), thereby inhibiting the growth of BC cells. However, with the long‑term application of tamoxifen, a subset of patients with BC have shown resistance to tamoxifen, which leads to low overall survival and progression‑free survival. The molecular mechanism of resistance is mainly due to downregulation of ERα expression and abnormal activation of the PI3K/AKT/mTOR signaling pathway. Moreover, the downregulation of targeted gene expression mediated by DNA methylation is an important regulatory mode to control protein expression. In the present review, methylation and tamoxifen are briefly introduced, followed by a focus on the effect of methylation on tamoxifen resistance and sensitivity. Finally, the clinical application of methylation for tamoxifen is described, including its use as a prognostic indicator. Finally, it is hypothesized that when methylation is used in combination with tamoxifen, it could recover the resistance of tamoxifen.

FusOn-pLM: A Fusion Oncoprotein-Specific Language Model via Focused Probabilistic Masking

Fusion oncoproteins, a class of chimeric proteins arising from chromosomal translocations, drive and sustain various cancers, particularly those impacting children. Unfortunately, due to their intrinsically disordered nature, large size, and lack of well-defined, druggable pockets, they have been historically challenging to target therapeutically: neither small molecule-based methods nor structure-based approaches for binder design are strong options for this class of molecules. Recently, protein language models (pLMs) have demonstrated success at representing protein sequences with information-rich embeddings, enabling downstream design applications from sequence alone. However, no current pLM has been trained on fusion oncoprotein sequences and thus may not produce optimal representations for these proteins. In this work, we introduce FusOn-pLM, a novel pLM that fine-tunes the state-of-the-art ESM-2 model on fusion oncoprotein sequences. We specifically introduce a novel masked language modeling (MLM) strategy, employing a binding-site probability predictor to focus masking on key amino acid residues, thereby generating more optimal fusion oncoprotein-aware embeddings. Our model improves performance on both fusion oncoprotein-specific benchmarks and disorder prediction tasks in comparison to baseline ESM-2 representations, as well as manually-constructed biophysical embeddings, motivating downstream usage of FusOn-pLM embeddings for therapeutic design tasks targeting these fusions. We have made our model publicly available to the community at https://huggingface.co/ChatterjeeLab/FusOn-pLM.

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.

Rare origin - Ewing's sarcoma of the pleura: a case report and literature review

Ewing sarcoma (ES) was first reported by Ewing in 1921. It is the second largest malignant bone tumor in children and adolescents, typically occurring in the bones of trunk or limbs . Extraskeletal Ewing sarcoma (EES) was first reported by Tefft et al. in 1969 and is extremely rare, accounting for less than 1% of all sarcomas. It can occur in any part of soft tissue, mostly in the trunk and lower limbs, and rarely in the pleura. We report a 22-year-old case of extraosseous Ewing sarcoma of pleural origin discovered and pathologically confirmed by physical examination. We report its CT manifestations and pathological results, and review the literature to summarize and analyze the clinical and imaging characteristics of extraosseous Ewing sarcoma, in order to improve our understanding of the disease.

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.

Primary mediastinum Ewing's sarcoma with pleural effusion: A case report and literature review

Ewing's sarcoma (ES) is an aggressive cancer in young adults. Primary ES occurring in the chest with pleural effusion is even rarer. We report the case of a 15-year-old girl who presented with intermittent chest pain occurring for more than 2 months and cough and wheezing for 10 days. Radiological imaging showed a large soft tissue mass with multiple small vessel shadows near the left mediastinum and bloody pleural effusion in the left thorax. ES was diagnosed by positive immunostaining for CD99, FLI-1, and NKX2 combined with fluorescence in situ hybridization detection of the EWSR1 gene arrangement. With chemotherapy, lung computed tomography revealed that the tumor had become much smaller, and the fluid was absorbed. We report a case of extraskeletal Ewing's sarcoma (EES) in the mediastinum with pleural effusion, which is unusual and challenging. EES is a highly malignant tumor with a poor prognosis. Early diagnosis and treatment can improve the survival rate of patients.

Decoding Oncofusions: Unveiling Mechanisms, Clinical Impact, and Prospects for Personalized Cancer Therapies

Cancer-associated gene fusions, also known as oncofusions, have emerged as influential drivers of oncogenesis across a diverse range of cancer types. These genetic events occur via chromosomal translocations, deletions, and inversions, leading to the fusion of previously separate genes. Due to the drastic nature of these mutations, they often result in profound alterations of cellular behavior. The identification of oncofusions has revolutionized cancer research, with advancements in sequencing technologies facilitating the discovery of novel fusion events at an accelerated pace. Oncofusions exert their effects through the manipulation of critical cellular signaling pathways that regulate processes such as proliferation, differentiation, and survival. Extensive investigations have been conducted to understand the roles of oncofusions in solid tumors, leukemias, and lymphomas. Large-scale initiatives, including the Cancer Genome Atlas, have played a pivotal role in unraveling the landscape of oncofusions by characterizing a vast number of cancer samples across different tumor types. While validating the functional relevance of oncofusions remains a challenge, even non-driver mutations can hold significance in cancer treatment. Oncofusions have demonstrated potential value in the context of immunotherapy through the production of neoantigens. Their clinical importance has been observed in both treatment and diagnostic settings, with specific fusion events serving as therapeutic targets or diagnostic markers. However, despite the progress made, there is still considerable untapped potential within the field of oncofusions. Further research and validation efforts are necessary to understand their effects on a functional basis and to exploit the new targeted treatment avenues offered by oncofusions. Through further functional and clinical studies, oncofusions will enable the advancement of precision medicine and the drive towards more effective and specific treatments for cancer patients.