Fusion of the dominant negative transcription regulator CHOP with a novel gene FUS by translocation t(12;16) in malignant liposarcoma

Circular RNA in cancer

Over the past decade, circular RNA (circRNA) research has evolved into a bona fide research field shedding light on the functional consequence of this unique family of RNA molecules in cancer. Although the method of formation and the abundance of circRNAs can differ from their cognate linear mRNA, the spectrum of interacting partners and their resultant cellular functions in oncogenesis are analogous. However, with 10 times more diversity in circRNA variants compared with linear RNA variants, combined with their hyperstability in the cell, circRNAs are equipped to influence every stage of oncogenesis. This is an opportune time to address the breadth of circRNA in cancer focused on their spatiotemporal expression, mutations in biogenesis factors and contemporary functions through each stage of cancer. In this Review, we highlight examples of functional circRNAs in specific cancers, which satisfy critical criteria, including their physical co-association with the target and circRNA abundance at stoichiometrically valid quantities. These considerations are essential to develop strategies for the therapeutic exploitation of circRNAs as biomarkers and targeted anticancer agents.

Updates on Disease Mechanisms and Therapeutics for Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, is a motor neuron disease. In ALS, upper and lower motor neurons in the brain and spinal cord progressively degenerate during the course of the disease, leading to the loss of the voluntary movement of the arms and legs. Since its first description in 1869 by a French neurologist Jean-Martin Charcot, the scientific discoveries on ALS have increased our understanding of ALS genetics, pathology and mechanisms and provided novel therapeutic strategies. The goal of this review article is to provide a comprehensive summary of the recent findings on ALS mechanisms and related therapeutic strategies to the scientific audience. Several highlighted ALS research topics discussed in this article include the 2023 FDA approved drug for SOD1 ALS, the updated C9orf72 GGGGCC repeat-expansion-related mechanisms and therapeutic targets, TDP-43-mediated cryptic splicing and disease markers and diagnostic and therapeutic options offered by these recent discoveries.

Back to the future! Selected bone and soft tissue neoplasms with shared genetic alterations but differing morphological and immunohistochemical phenotypes

Bone and soft tissue tumors (BST) are a highly heterogeneous group largely classified by their line of differentiation, based on their resemblance to their normal counterpart in adult tissue. Yet, rendering a specific diagnosis can be challenging, primarily due to their rarity and overlapping histopathologic features or clinical presentations. Over the past few decades, seemingly histogenetic-specific gene fusions/translocations and amplifications have been discovered, aiding in a more nuanced classification, leading to well-established objective diagnostic criteria and the development of specific surrogate ancillary tests targeting these genetic aberrations (e.g., immunohistochemistry). Ironically, the same research also has revealed that some specific tumor subtypes may be the result of differing and often multiple gene fusions/translocations, but, more interestingly, identical gene fusions may be present in more than one phenotypically and biologically distinct neoplasm, sometimes with entirely different clinical behavior. Prime examples include, EWSR1::ATF1 and, less commonly, EWSR1::CREB1 gene fusions present in both clear cell sarcoma, a malignant high-grade tumor with melanocytic differentiation, and angiomatoid fibrous histiocytoma, a mesenchymal neoplasm of intermediate malignancy with a generally indolent course. Similarly, MDM2 amplification, once deemed to be pathognomonic for atypical lipomatous tumor/well differentiated and dedifferentiated liposarcoma, has been documented in a range of additional distinct tumors, including low grade osteosarcomas (e.g. low grade central and surface parosteal) and high-grade intimal sarcomas, amongst others. Such findings reinforce the importance of careful attention to morphological and clinicoradiological features and correlation with molecular testing before rendering a specific diagnosis. Future classification systems in BST neoplasms cannot be solely based on molecular events and ideally will balance morphologic features with molecular analysis. Herein, we provide a narrative literature review of the more common BST neoplasms with shared genetic events but differing demographics, morphology, immunophenotype, and clinical behavior, re-emphasizing the importance of the hematoxylin and eosin slide and the "eye" of the practicing pathologist.

Gene of the month: DDIT3

DNA damage-inducible transcript 3 (DDIT3) gene, mapped to the human chromosome 12q13.3, encodes a protein that belongs to the CCAAT/enhancer-binding protein family of transcription factors. DDIT3 is involved in the proliferative control that responds to endoplasmic reticulum stress in normal conditions, dimerising other transcription factors with basic leucine zipper (bZIP) structural motifs. DDIT3 plays a significant role during cell differentiation, especially adipogenesis, arresting the maturation of adipoblasts. In disease, FUS/EWSR1::DDIT3 fusion is the pathogenic event that drives the development of myxoid liposarcoma. The amplification of DDIT3 in other adipocytic neoplasms mediates the presence of adipoblast-like elements. Another fusion, GLI1::DDIT3, has rarely been documented in other tumours. This paper reviews the structure and function of DDIT3, its role in disease-particularly cancer-and its use and pitfalls in diagnostic testing, including immunohistochemistry as a tissue-based marker.

Myxoid Pleomorphic Liposarcoma

Myxoid pleomorphic liposarcoma (MPLPS) shows a strong predilection for the mediastinum and can affect a wide age range. Clinically, MPLPS exhibits aggressive behavior and demonstrates a worse overall and progression-free survival than myxoid/round cell liposarcoma (MRLPS) and pleomorphic liposarcoma (PLPS). Histologically, MPLPS is characterized by hybrid morphologic features of MRLPS and PLPS, including myxoid stroma, chicken wire-like vasculature, univacuolated and multivacuolated lipoblasts, and high-grade pleomorphic sarcomatous components. In terms of molecular features, MPLPS is distinct from other lipomatous tumors as it harbors genome-wide loss of heterozygosity.

Novel EWSR1::GFI1B gene fusion in angiofibroma of soft tissue

AIMS

Angiofibroma of soft tissue is a benign soft tissue tumour characterised by bland spindle cells and a distinct branching vascular network. The majority of soft tissue angiofibromas harbour AHRR::NCOA2 gene fusions. Here we present three cases of EWSR1::GFI1B-fused soft tissue tumours that are morphologically most reminiscent of soft tissue angiofibroma.

METHODS AND RESULTS

All three cases presented in male patients with an age range of 35-78 years (median = 54 years). Two cases presented as subcutaneous nodules on the trunk (posterior neck and chest wall); one was an intramuscular foot mass. The tumours were unencapsulated nodules with infiltrative margins ranging from 2.2 to 3.4 cm in greatest dimension. Histologically, the tumours contained uniformly bland fibroblastic spindle cells with ovoid to fusiform nuclei and delicate cytoplasmic processes embedded in a myxoid to myxocollagenous stroma. All three cases were characterised by a thin-walled, branching vascular network evenly distributed throughout the tumour. Overt cytological atypia or conspicuous mitotic activity was absent. The spindle cells had an essentially null immunophenotype. By targeted RNA sequencing, an in-frame gene fusion between EWSR1 exons 1-7 and GFI1B exons 6-11 or 7-11 was detected in all three cases. The tumours were marginally excised. For all three cases, there were no documented local recurrence or distant metastases during a limited follow-up period of 6-10 months.

CONCLUSIONS

We propose that EWSR1::GFI1B may represent a novel fusion variant of soft tissue angiofibroma.

CRISPR-assisted transcription activation by phase-separation proteins

The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system has been widely used for genome engineering and transcriptional regulation in many different organisms. Current CRISPR-activation (CRISPRa) platforms often require multiple components because of inefficient transcriptional activation. Here, we fused different phase-separation proteins to dCas9-VPR (dCas9-VP64-P65-RTA) and observed robust increases in transcriptional activation efficiency. Notably, human NUP98 (nucleoporin 98) and FUS (fused in sarcoma) IDR domains were best at enhancing dCas9-VPR activity, with dCas9-VPR-FUS IDR (VPRF) outperforming the other CRISPRa systems tested in this study in both activation efficiency and system simplicity. dCas9-VPRF overcomes the target strand bias and widens gRNA designing windows without affecting the off-target effect of dCas9-VPR. These findings demonstrate the feasibility of using phase-separation proteins to assist in the regulation of gene expression and support the broad appeal of the dCas9-VPRF system in basic and clinical applications.

FUS-dependent microRNA deregulations identify TRIB2 as a druggable target for ALS motor neurons

MicroRNAs (miRNAs) modulate mRNA expression, and their deregulation contributes to various diseases including amyotrophic lateral sclerosis (ALS). As fused in sarcoma (FUS) is a causal gene for ALS and regulates biogenesis of miRNAs, we systematically analyzed the miRNA repertoires in spinal cords and hippocampi from ALS-FUS mice to understand how FUS-dependent miRNA deregulation contributes to ALS. miRNA profiling identified differentially expressed miRNAs between different central nervous system (CNS) regions as well as disease states. Among the up-regulated miRNAs, miR-1197 targets the pro-survival pseudokinase Trib2. A reduced TRIB2 expression was observed in iPSC-derived motor neurons from ALS patients. Pharmacological stabilization of TRIB2 protein with a clinically approved cancer drug rescues the survival of iPSC-derived human motor neurons, including those from a sporadic ALS patient. Collectively, our data indicate that miRNA profiling can be used to probe the molecular mechanisms underlying selective vulnerability, and TRIB2 is a potential therapeutic target for ALS.

FUS-mediated HypEVs: Neuroprotective effects against ischemic stroke

Few studies have investigated the properties and protein composition of small extracellular vesicles (sEVs) derived from neurons under hypoxic conditions. Presently, the extent of the involvement of these plentiful sEVs in the onset and progression of ischemic stroke remains an unresolved question. Our study systematically identified the characteristics of sEVs derived from neurons under hypoxic conditions (HypEVs) by physical characterization, sEV absorption, proteomics and transcriptomics analysis. The effects of HypEVs on neurites, cell survival, and neuron structure were assessed in vitro and in vivo by neural complexity tests, magnetic resonance imaging (MRI), Golgi staining, and Western blotting of synaptic plasticity-related proteins and apoptotic proteins. Knockdown of Fused in Sarcoma (FUS) small interfering RNA (siRNA) was used to validate FUS-mediated HypEV neuroprotection and mitochondrial mRNA release. Hypoxia promoted the secretion of sEVs, and HypEVs were more easily taken up and utilized by recipient cells. The MRI results illustrated that the cerebral infarction volume was reduced by 45% with the application of HypEVs, in comparison to the non- HypEV treatment group. Mechanistically, the FUS protein is necessary for the uptake and neuroprotection of HypEVs against ischemic stroke as well as carrying a large amount of mitochondrial mRNA in HypEVs. However, FUS knockdown attenuated the neuroprotective rescue capabilities of HypEVs. Our comprehensive dataset clearly illustrates that FUS-mediated HypEVs deliver exceptional neuroprotective effects against ischemic stroke, primarily through the maintenance of neurite integrity and the reduction of mitochondria-associated apoptosis.

Saccharomyces cerevisiae as a research tool for RNA-mediated human disease

The budding yeast, Saccharomyces cerevisiae, has been used for decades as a powerful genetic tool to study a broad spectrum of biological topics. With its ease of use, economic utility, well-studied genome, and a highly conserved proteome across eukaryotes, it has become one of the most used model organisms. Due to these advantages, it has been used to study an array of complex human diseases. From broad, complex pathological conditions such as aging and neurodegenerative disease to newer uses such as SARS-CoV-2, yeast continues to offer new insights into how cellular processes are affected by disease and how affected pathways might be targeted in therapeutic settings. At the same time, the roles of RNA and RNA-based processes have become increasingly prominent in the pathology of many of these same human diseases, and yeast has been utilized to investigate these mechanisms, from aberrant RNA-binding proteins in amyotrophic lateral sclerosis to translation regulation in cancer. Here we review some of the important insights that yeast models have yielded into the molecular pathology of complex, RNA-based human diseases. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Combination of Genomic Landsscape and 3D Culture Functional Assays Bridges Sarcoma Phenotype to Target and Immunotherapy

Genomic-based precision medicine has not only improved tumour therapy but has also shown its weaknesses. Genomic profiling and mutation analysis have identified alterations that play a major role in sarcoma pathogenesis and evolution. However, they have not been sufficient in predicting tumour vulnerability and advancing treatment. The relative rarity of sarcomas and the genetic heterogeneity between subtypes also stand in the way of gaining statistically significant results from clinical trials. Personalized three-dimensional tumour models that reflect the specific histologic subtype are emerging as functional assays to test anticancer drugs, complementing genomic screening. Here, we provide an overview of current target therapy for sarcomas and discuss functional assays based on 3D models that, by recapitulating the molecular pathways and tumour microenvironment, may predict patient response to treatments. This approach opens new avenues to improve precision medicine when genomic and pathway alterations are not sufficient to guide the choice of the most promising treatment. Furthermore, we discuss the aspects of the 3D culture assays that need to be improved, such as the standardisation of growth conditions and the definition of in vitro responses that can be used as a cut-off for clinical implementation.

Targeting epigenetic aberrations of sarcoma in CRISPR era

Sarcomas are rare malignancies that exhibit diverse biological, genetic, morphological, and clinical characteristics. Genetic alterations, such as gene fusions, mutations in transcriptional machinery components, histones, and DNA methylation regulatory molecules, play an essential role in sarcomagenesis. These mutations induce and/or cooperate with specific epigenetic aberrations required for the growth and maintenance of sarcomas. Appropriate mouse models have been developed to clarify the significance of genetic and epigenetic interactions in sarcomas. Studies using the mouse models for human sarcomas have demonstrated major advances in our understanding the developmental processes as well as tumor microenvironment of sarcomas. Recent technological progresses in epigenome editing will not only improve the studies using animal models but also provide a direct clue for epigenetic therapies. In this manuscript, we review important epigenetic aberrations in sarcomas and their representative mouse models, current methods of epigenetic editing using CRISPR/dCas9 systems, and potential applications in sarcoma studies and therapeutics.

Suppression of antitumor cytokine IL‑24 by PRG4 and PAI‑1 may promote myxoid liposarcoma cell survival

Suppression of the antitumor cytokine interleukin-24 (IL-24) is critical for the survival of myxoid liposarcoma (MLS) cells. It has been previously demonstrated by the authors that an MLS-specific chimeric oncoprotein, translocated in liposarcoma-CCAAT/enhancer-binding protein homologous protein (TLS-CHOP), supresses IL24 mRNA expression via induction of proteoglycan 4 (PRG4) to sustain MLS cell proliferation. However, IL-24 has also been revealed to be suppressed by the ubiquitin-proteasome system in human ovarian and lung cancer cells. Therefore, the aim of the present study was to elucidate the mechanism of IL-24 suppression in MLS cells. The results revealed that the proteasome inhibitor, MG-132, induced cell death in MLS cells in vitro; this effect was reduced following IL-24 knockdown. This indicated that proteasomal degradation of IL-24 may be an important process for MLS cell survival. In addition, it was also previously revealed by the authors that knockdown of plasminogen activator inhibitor-1 (PAI-1), a TLS-CHOP downstream molecule, suppressed the growth of MLS cells, thus instigating the investigation of the effect of PAI-1 on IL-24 expression in MLS cells. Double knockdown of PAI-1 and IL-24 negated the growth-suppressive effect of PAI-1 single knockdown in MLS cells. Interestingly, PAI-1 single knockdown did not increase the mRNA expression of IL24, but it did increase the protein abundance of IL-24, indicating that PAI-1 suppressed IL-24 expression by promoting its proteasomal degradation. Moreover, treatment of MLS cells with a PAI-1 inhibitor, TM5275, induced IL-24 protein expression and apoptosis. Collectively, the results of the present as well as previous studies indicated that IL-24 expression may be suppressed at the transcriptional level by PRG4 and at the protein level by PAI-1 in MLS cells. Accordingly, PAI-1 may represent an effective therapeutic target for MLS treatment.

The spectrum and significance of secondary (co-occurring) genetic alterations in sarcomas: the hallmarks of sarcomagenesis

Bone and soft tissue tumors are generally classified into complex karyotype sarcomas versus those with recurrent genetic alterations, often in the form of gene fusions. In this review, we provide an overview of important co-occurring genomic alterations, organized by biological mechanisms and covering a spectrum of genomic alteration types: mutations (single-nucleotide variations or indels) in oncogenes or tumor suppressor genes, copy number alterations, transcriptomic signatures, genomic complexity indices (e.g. CINSARC), and complex genomic structural variants. We discuss the biological and prognostic roles of these so-called secondary or co-occurring alterations, arguing that recognition and detection of these alterations may be significant for our understanding and management of mesenchymal tumors. On a related note, we also discuss major recurrent alterations in so-called complex karyotype sarcomas. These secondary alterations are essential to sarcomagenesis via a variety of mechanisms, such as inactivation of tumor suppressors, activation of proliferative signal transduction, telomere maintenance, and aberrant regulation of epigenomic/chromatin remodeling players. The use of comprehensive genomic profiling, including targeted next-generation sequencing panels or whole-exome sequencing, may be incorporated into clinical workflows to offer more comprehensive, potentially clinically actionable information. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Laparoscopic resection of a metastatic myxoid liposarcoma in the mesentery of the small intestine: a case report

BACKGROUND

Myxoid liposarcoma (MLS), with its risk factors, tends to spread to the lungs and extraperitoneally, with intraperitoneal metastases occurring rarely. We present an unusual case of a myxoid liposarcoma that metastasized to the abdominal organs.

CASE PRESENTATION

A 60-year-old female patient was referred to our hospital for the evaluation of a right upper limb tumor that had been growing for 7 years. The patient refused surgery, and during follow-up, tumor hemorrhage resulted in hemorrhagic shock. The patient's right upper limb was immediately amputated. MLS was diagnosed histopathologically. Subsequently, the patient underwent adjuvant chemotherapy. Computed tomography (CT) revealed a right buttock mass, a pelvic mass, and left cardiophrenic angle lymph nodes 3 years after the initial surgery. Contrast-enhanced abdominal CT revealed a relatively low-density, lobulated pelvic tumor. Contrast-enhanced pelvic magnetic resonance imaging (MRI) revealed a low-intensity, lobulated mass on T1-weighted images and a high-intensity mass on T2-weighted images. The pelvic mass showed no significant fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)-CT. On clinical examination, gynecological malignancies were ruled out as the origin of the pelvic lesions. After resection of the right buttock mass, pelvic mass, and left cardiophrenic angle lymph nodes, the patient underwent laparoscopic surgery for a preoperative diagnosis of small intestinal mesenteric metastasis of MLS. A tumor was found in the mesentery of the small intestine and removed with a margin of 5 cm on both the proximal and distal sides. The specimen measured 10 × 8 × 5 cm and contained a multifocal mass. The tumor was found in the mesentery of the small intestine, with no mucosal or submucosal invasion. The patient was diagnosed with MLS with small mesenteric intestinal metastases. On postoperative day 8, the patient was discharged after an uneventful postoperative course. Twelve months after the surgery, there was no evidence of local or distant recurrence.

CONCLUSIONS

Small intestinal mesenteric metastases of MLSs are rare. Moreover, there are few reports on laparoscopic resection. In this case, the laparoscopic approach was useful in detecting the tumor location and determining the range of resection.

Patterns of Metastatic Recurrence of Genetically Confirmed Myxoid Liposarcoma

BACKGROUND

Most sarcomas metastasize predominantly to the lungs, and chest x-ray, or computed tomography, is the most commonly used staging investigation. Myxoid liposarcomas (MLSs) are rare tumors with a tendency to metastasize to extrapulmonary loci. The aim of this study was to assess the locations of the first metastases in MLS patients, to guide the design of effective staging and follow-up imaging protocols.

METHODS

Patients treated for MLS between 1987 and 2017 were identified in a prospectively maintained register. Histology of the tumors was reassessed. In addition, the presence of one of the pathognomonic gene translocations was confirmed, uniquely for a retrospective series. The surgical and oncological outcomes were reviewed. A comprehensive review of the literature was performed on the metastatic pattern of MLS, including series with 10 or more MLS patients with metastatic disease.

RESULTS

A total of 32 patients with genetically confirmed MLS were identified, with a median follow-up of 7.6 years. Seven patients (22%) developed metastatic disease, five initially intra-abdominally and only one to the lungs. The comprehensive review included 14 series with 1853 patients, 348 (19%) of whom had metastases. The location of the first metastases was soft tissues in 32% of patients, intra-abdominal in 26%, pulmonary in 24%, and bone in 17%.

CONCLUSIONS

MLSs metastasize often intra-abdominally and to extra-abdominal soft tissues. Thus, whole-body imaging may be indicated during the initial assessment and follow-up of these patients.

ALS-causing hPFN1 mutants differentially disrupt LLPS of FUS prion-like domain

hPFN1 mutations including C71G cause ALS by gain of toxicity but the mechanism still remains unknown. Stress granules (SGs) are formed by phase separation of the prion-like domain (PLD) of RNA-binding proteins including FUS, whose inclusion was also associated with ALS. C71G-hPFN1 triggers seed-dependent co-aggregation with FUS/TDP-43 to manifest the prion-like propagandation but its biophysical basis remains unexplored. Here by DIC imaging we first showed that three hPFN1 mutants have differential capacity in disrupting the dynamics of liquid droplets formed by phase separation of FUS prion-like domain (PLD). C71G-hPFN1 co-exists with the folded and unfolded states, thus allowing to simultaneously characterize conformations, hydrodynamics and dynamics of the interactions of both states with the phase separated FUS PLD by NMR. The results reveal that the folded state is not significantly affected while by contrast, the unfolded state has extensive interactions with FUS PLD. As a consequence, the dynamics of FUS liquid droplets become significantly reduced. Such interactions might act to recruit C71G-hPFN1 into the droplets, thus leading to the increase of the local concentrations and subsequent co-aggregation of C71G-hPFN1 with FUS. Our study sheds the first light on the biophysical basis by which hPFN1 mutants gain toxicity to cause ALS. As other aggregation-prone proteins have no fundamental difference from hPFN1 mutants, aggregation-prone proteins might share a common capacity in disrupting phase separation responsible for organizing various membrane-less organelles. As such, the mechanism for C71G-hPFN1 might also be utilized by other aggregation-prone proteins for gain of toxicity to trigger diseases and aging.

Potential roles of the endoplasmic reticulum stress pathway in amyotrophic lateral sclerosis

The endoplasmic reticulum (ER) is a major organelle involved in protein quality control and cellular homeostasis. ER stress results from structural and functional dysfunction of the organelle, along with the accumulation of misfolded proteins and changes in calcium homeostasis, it leads to ER stress response pathway such as unfolded protein response (UPR). Neurons are particularly sensitive to the accumulation of misfolded proteins. Thus, the ER stress is involved in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, prion disease and motor neuron disease (MND). Recently, the complex involvement of ER stress pathways has been demonstrated in experimental models of amyotrophic lateral sclerosis (ALS)/MND using pharmacological and genetic manipulation of the unfolded protein response (UPR), an adaptive response to ER stress. Here, we aim to provide recent evidence demonstrating that the ER stress pathway is an essential pathological mechanism of ALS. In addition, we also provide therapeutic strategies that can help treat diseases by targeting the ER stress pathway.

Phase separation of low-complexity domains in cellular function and disease

In this review, we discuss the ways in which recent studies of low-complexity (LC) domains have challenged our understanding of the mechanisms underlying cellular organization. LC sequences, long believed to function in the absence of a molecular structure, are abundant in the proteomes of all eukaryotic organisms. Over the past decade, the phase separation of LC domains has emerged as a fundamental mechanism driving dynamic multivalent interactions of many cellular processes. We review the key evidence showing the role of phase separation of individual proteins in organizing cellular assemblies and facilitating biological function while implicating the dynamics of phase separation as a key to biological validity and functional utility. We also highlight the evidence showing that pathogenic LC proteins alter various phase separation-dependent interactions to elicit debilitating human diseases, including cancer and neurodegenerative diseases. Progress in understanding the biology of phase separation may offer useful hints toward possible therapeutic interventions to combat the toxicity of pathogenic proteins.

The Role of CDK Pathway Dysregulation and Its Therapeutic Potential in Soft Tissue Sarcoma

Soft tissue sarcomas (STSs) are tumors that are challenging to treat due to their pathologic and molecular heterogeneity and their tumor biology that is not yet fully understood. Recent research indicates that dysregulation of cyclin-dependent kinase (CDK) signaling pathways can be a strong driver of sarcogenesis. CDKs are enzyme forms that play a crucial role in cell-cycle control and transcription. They belong to the protein kinases group and to the serine/threonine kinases subgroup. Recently identified CDK/cyclin complexes and established CDK/cyclin complexes that regulate the cell cycle are involved in the regulation of gene expression through phosphorylation of critical components of transcription and pre-mRNA processing mechanisms. The current and continually growing body of data shows that CDKs play a decisive role in tumor development and are involved in the proliferation and growth of sarcoma cells. Since the abnormal expression or activation of large numbers of CDKs is considered to be characteristic of cancer development and progression, dysregulation of the CDK signaling pathways occurs in many subtypes of STSs. This review discusses how reversal and regulation can be achieved with new therapeutics and summarizes the current evidence from studies regarding CDK modulation for STS treatment.

Blood-derived lncRNAs as biomarkers for cancer diagnosis: the Good, the Bad and the Beauty

Cancer ranks as one of the deadliest diseases worldwide. The high mortality rate associated with cancer is partially due to the lack of reliable early detection methods and/or inaccurate diagnostic tools such as certain protein biomarkers. Cell-free nucleic acids (cfNA) such as circulating long noncoding RNAs (lncRNAs) have been proposed as a new class of potential biomarkers for cancer diagnosis. The reported correlation between the presence of tumors and abnormal levels of lncRNAs in the blood of cancer patients has notably triggered a worldwide interest among clinicians and oncologists who have been actively investigating their potentials as reliable cancer biomarkers. In this report, we review the progress achieved (“the Good”) and challenges encountered (“the Bad”) in the development of circulating lncRNAs as potential biomarkers for early cancer diagnosis. We report and discuss the diagnostic performance of more than 50 different circulating lncRNAs and emphasize their numerous potential clinical applications (“the Beauty”) including therapeutic targets and agents, on top of diagnostic and prognostic capabilities. This review also summarizes the best methods of investigation and provides useful guidelines for clinicians and scientists who desire conducting their own clinical studies on circulating lncRNAs in cancer patients via RT-qPCR or Next Generation Sequencing (NGS).

The transformation of isolated gastric myeloid sarcoma into acute myeloid leukemia presenting with a complex karyotype and TLS-ERG gene fusion: A case report

RATIONALE

Isolated myeloid sarcoma (MS) is characterized by the rapid proliferation of myeloblasts of acute myeloid leukemia (AML), without any blood or bone marrow involvement. This disease can manifest with extramedullary organ involvement, such as the skin, lymph nodes, bone, brain, breast cervix, and visceral organs, while the occurrence of myeloid sarcomas in the stomach is rare. Isolated MS has been associated with acute myeloid leukemia (AML), but the rapid progression of MS to acute myeloid leukemia with a complex karyotype and TLS-ERG fusion gene is even rarer.

PATIENT CONCERNS

A 33-year-old woman suffered from persistent epigastric pain accompanied by two months of anorexia and nausea, as well as 1-week of melena.

DIAGNOSIS

This patient was initially diagnosed with gastric MS that eventually transformed into AML with a complex karyotype and TLS-ERG fusion gene, 4 months later.

INTERVENTIONS

Only palliative care, including nutrition support, antacids, blood transfusion, anti-infection methods were used on this patient to determine the cachexia status and the family's requirement.

OUTCOMES

Routine follow-up results demonstrated this patient had died due to cerebral hemorrhage five months after the diagnosis of MS.

LESSONS

Comprehensive integration of patient history, imaging features, mass and bone marrow biopsy, and molecular cytogenetic may provide insights that could help us avoid the misdiagnosis of gastric MS. Isolated gastric MS can rapidly progress to AML with a poor prognosis if the patient does not receive appropriate treatment.

First-line chemotherapy in advanced intrabdominal well-differentiated/dedifferentiated liposarcoma: An EORTC Soft Tissue and Bone Sarcoma Group retrospective analysis

BACKGROUND

No prospective trial with anthracycline-based chemotherapy has individually assessed response in a well-differentiated (WD)/dedifferentiated (DD) liposarcoma patient cohort. We conducted a retrospective analysis of first-line chemotherapy in liposarcoma of intra-abdominal origin (IA-LPS) in patients who had entered the European Organisation for Research and Treatment of Cancer (EORTC)/Soft Tissue and Bone Sarcoma Group (STBSG) trials.

METHODS

We searched for all adult patients treated with first-line chemotherapy for advanced IA-LPS in the EORTC STBSG phase 2 and 3 trials from 1978. Treatment was aggregated into 5 groups: anthracycline alone, ifosfamide alone, doxorubicin plus ifosfamide (D+IFO), doxorubicin/cyclophosphamide/vincristine/dacarbazine, and "other" (brostallicin, trabectedin). Response was assessed prospectively by Response Evaluation Criteria in Solid Tumors or World Health Organization criteria. Progression-free survival (PFS) and overall survival (OS) were computed by Kaplan-Meier method.

RESULTS

A total of 109 patients with IA-LPS from 13 trials were identified (104 evaluable for response). Overall, there were 10/109 (9.2%) responders: 3/48 (6.3%) in the anthracycline alone group, 2/15 (13%) in the ifosfamide alone group, and 4/18 (22%) in the D+IFO group. At the 10-month median follow-up (interquartile range, 6-24), the median OS was 19 months (95% CI, 15-21) and median PFS 4 months (95% CI, 3-6). D+IFO achieved a not statistically significant longer median PFS (12 months) and median OS (31 months) than observed with other regimens. Univariate/multivariate analysis did not identify prognostic factors.

CONCLUSIONS

Cytotoxic chemotherapy, in particular anthracycline alone, had marginal activity in advanced IA-LPS. Ifosfamide-containing regimens showed higher activity, although it was not statistically significant and in a small number of cases, with the combination of doxorubicin and ifosfamide appearing to be the more active regimen available in fit patients. This series provides a benchmark for future trials on new drugs in WD/DD liposarcoma.

Stress granules in the spinal muscular atrophy and amyotrophic lateral sclerosis: The correlation and promising therapy

Increasing genetic and biochemical evidence has broadened our view of the pathomechanisms that lead to Spinal muscular atrophy (SMA) and Amyotrophic lateral sclerosis (ALS), two fatal neurodegenerative diseases with similar symptoms and causes. Stress granules are dynamic cytosolic storage hubs for mRNAs in response to stress exposures, that are evolutionarily conserved cytoplasmic RNA granules in somatic cells. A lot of previous studies have shown that the impaired stress granules are crucial events in SMA/ALS pathogenesis. In this review, we described the key stress granules related RNA binding proteins (SMN, TDP-43, and FUS) involved in SMA/ALS, summarized the reported mutations in these RNA binding proteins involved in SMA/ALS pathogenesis, and discussed the mechanisms through which stress granules dynamics participate in the diseases. Meanwhile, we described the applications and limitation of current therapies targeting SMA/ALS. We futher proposed the promising targets on stress granules in the future therapeutic interventions of SMA/ALS.

The FUS::DDIT3 fusion oncoprotein inhibits BAF complex targeting and activity in myxoid liposarcoma

Mammalian SWI/SNF (mSWI/SNF or BAF) ATP-dependent chromatin remodeling complexes play critical roles in governing genomic architecture and gene expression and are frequently perturbed in human cancers. Transcription factors (TFs), including fusion oncoproteins, can bind to BAF complex surfaces to direct chromatin targeting and accessibility, often activating oncogenic gene loci. Here, we demonstrate that the FUS::DDIT3 fusion oncoprotein hallmark to myxoid liposarcoma (MLPS) inhibits BAF complex-mediated remodeling of adipogenic enhancer sites via sequestration of the adipogenic TF, CEBPB, from the genome. In mesenchymal stem cells, small-molecule inhibition of BAF complex ATPase activity attenuates adipogenesis via failure of BAF-mediated DNA accessibility and gene activation at CEBPB target sites. BAF chromatin occupancy and gene expression profiles of FUS::DDIT3-expressing cell lines and primary tumors exhibit similarity to SMARCB1-deficient tumor types. These data present a mechanism by which a fusion oncoprotein generates a BAF complex loss-of-function phenotype, independent of deleterious subunit mutations.

Generation of a heterozygous FUS-Q290X knock in human embryonic stem cell line (WAe009-A-83) using CRISPR/Cas9 system

Fused in Sarcoma (FUS) gene encodes FUS RNA binding protein, a multifunctional protein component of the heterogeneous nuclear ribonucleoprotein complex, which is involved in pre-mRNA splicing and the export of fully processed mRNA to the cytoplasm, and it has been implicated in regulation of gene expression, maintenance of genomic integrity and mRNA/microRNA processing. FUS gene mutations result in amyotrophic lateral sclerosis and Liposarcoma. This heterozygous FUS-Q290X knock in hESC line will be a valuable tool to investigate the disease mechanisms of amyotrophic lateral sclerosis and Liposarcoma.

Pediatric liposarcoma: A case series and literature review

Liposarcoma is arare soft tissue sarcoma in children. While prognosis, clinical behavior, and response to therapy among the various histologic subtypes are well described in adults, data in children are limited. Here, we describe our experience treating 14 children with liposarcoma at a large, academic pediatric center and review the available pediatric literature. This comprehensive report adds treatment, survival, and genomic data to pediatric liposarcoma literature.

Establishment of multiplex RT-PCR to detect fusion genes for the diagnosis of Ewing sarcoma

Background

Detection of the tumor-specific EWSR1/FUS-ETS fusion gene is essential to diagnose Ewing sarcoma. Reverse transcription–polymerase chain reaction (RT–PCR) and fluorescence in situ hybridization are commonly used to detect the fusion gene, and assays using next-generation sequencing have recently been reported. However, at least 28 fusion transcript variants have been reported, making rapid and accurate detection difficult.

Methods

We constructed two sets of multiplex PCR assays and evaluated their utility using cell lines and clinical samples.

Results

EWSR1/FUS-ETS was detected in five of six tumors by the first set, and in all six tumors by the second set. The fusion gene detected only by the latter was EWSR1-ERG, which completely lacked exon 7 of EWSR1. The fusion had a short N-terminal region of EWSR1 and showed pathologically atypical features.

Conclusions

We developed multiplex RT–PCR assays to detect EWSR1-ETS and FUS-ETS simultaneously. These assays will aid the rapid and accurate diagnosis of Ewing sarcoma. In addition, variants of EWSR1/FUS-ETS with a short N-terminal region that may have been previously missed can be easily detected.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01164-6.

Adrenal myelolipomas

Adrenal myelolipomas are benign, lipomatous tumours with elements of myeloid cells, most of which present as adrenal incidentalomas and comprise 3·3-6·5% of all adrenal masses. Adrenal myelolipomas are usually unilateral (in 95% of cases), variable in size, most often found during midlife, and affect both sexes almost equally. On imaging, adrenal myelolipomas show pathognomonic imaging features consistent with the presence of macroscopic fat. Large adrenal myelolipomas can cause symptoms of mass effect, and can occasionally be complicated by haemorrhage. In the event of a concomitant adrenal cortical adenoma or hyperplasia, adrenal hormone excess might be detected in patients with adrenal myelolipoma. Patients with congenital adrenal hyperplasia exhibit a higher prevalence of adrenal myelolipomas than other patient groups, and are at risk of developing large and bilateral lesions. This Review discusses the pathogenesis, clinical presentation, and management of adrenal myelolipomas.

Role of Protein Arginine Methyltransferases and Inflammation in Muscle Pathophysiology

Arginine methylation mediated by protein arginine methyltransferases (PRMTs) is a post-translational modification of both histone and non-histone substrates related to diverse biological processes. PRMTs appear to be critical regulators in skeletal muscle physiology, including regeneration, metabolic homeostasis, and plasticity. Chronic inflammation is commonly associated with the decline of skeletal muscle mass and strength related to aging or chronic diseases, defined as sarcopenia. In turn, declined skeletal muscle mass and strength can exacerbate chronic inflammation. Thus, understanding the molecular regulatory pathway underlying the crosstalk between skeletal muscle function and inflammation might be essential for the intervention of muscle pathophysiology. In this review, we will address the current knowledge on the role of PRMTs in skeletal muscle physiology and pathophysiology with a specific emphasis on its relationship with inflammation.

Fused in sarcoma regulates DNA replication timing and kinetics

Fused in sarcoma (FUS) encodes an RNA-binding protein with diverse roles in transcriptional activation and RNA splicing. While oncogenic fusions of FUS and transcription factor DNA-binding domains are associated with soft tissue sarcomas, dominant mutations in FUS can cause amyotrophic lateral sclerosis. FUS has also been implicated in genome maintenance. However, the underlying mechanisms of its actions in genome stability are unknown. Here, we applied gene editing, functional reconstitution, and integrated proteomics and transcriptomics to illuminate roles for FUS in DNA replication and repair. Consistent with a supportive role in DNA double-strand break repair, FUS-deficient cells exhibited subtle alterations in the recruitment and retention of double-strand break-associated factors, including 53BP1 and BRCA1. FUS-/- cells also exhibited reduced proliferative potential that correlated with reduced speed of replication fork progression, diminished loading of prereplication complexes, enhanced micronucleus formation, and attenuated expression and splicing of S-phase-associated genes. Finally, FUS-deficient cells exhibited genome-wide alterations in DNA replication timing that were reversed upon re-expression of FUS complementary DNA. We also showed that FUS-dependent replication domains were enriched in transcriptionally active chromatin and that FUS was required for the timely replication of transcriptionally active DNA. These findings suggest that alterations in DNA replication kinetics and programming contribute to genome instability and functional defects in FUS-deficient cells.

Aberrant Stress Granule Dynamics and Aggrephagy in ALS Pathogenesis

Stress granules are conserved cytosolic ribonucleoprotein (RNP) compartments that undergo dynamic assembly and disassembly by phase separation in response to stressful conditions. Gene mutations may lead to aberrant phase separation of stress granules eliciting irreversible protein aggregations. A selective autophagy pathway called aggrephagy may partially alleviate the cytotoxicity mediated by these protein aggregates. Cells must perceive when and where the stress granules are transformed into toxic protein aggregates to initiate autophagosomal engulfment for subsequent autolysosomal degradation, therefore, maintaining cellular homeostasis. Indeed, defective aggrephagy has been causally linked to various neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). In this review, we discuss stress granules at the intersection of autophagy and ALS pathogenesis.

The atypical RNA-binding protein Taf15 regulates dorsoanterior neural development through diverse mechanisms in Xenopus tropicalis

The FET family of atypical RNA-binding proteins includes Fused in sarcoma (FUS), Ewing's sarcoma (EWS) and the TATA-binding protein-associate factor 15 (TAF15). FET proteins are highly conserved, suggesting specialized requirements for each protein. Fus regulates splicing of transcripts required for mesoderm differentiation and cell adhesion in Xenopus, but the roles of Ews and Taf15 remain unknown. Here, we analyze the roles of maternally deposited and zygotically transcribed Taf15, which is essential for the correct development of dorsoanterior neural tissues. By measuring changes in exon usage and transcript abundance from Taf15-depleted embryos, we found that Taf15 may regulate dorsoanterior neural development through fgfr4 and ventx2.1. Taf15 uses distinct mechanisms to downregulate Fgfr4 expression, namely retention of a single intron within fgfr4 when maternal and zygotic Taf15 is depleted, and reduction in the total fgfr4 transcript when zygotic Taf15 alone is depleted. The two mechanisms of gene regulation (post-transcriptional versus transcriptional) suggest that Taf15-mediated gene regulation is target and co-factor dependent, contingent on the milieu of factors that are present at different stages of development.

Wild-Type and Mutant FUS Expression Reduce Proliferation and Neuronal Differentiation Properties of Neural Stem Progenitor Cells

Nervous system development involves proliferation and cell specification of progenitor cells into neurons and glial cells. Unveiling how this complex process is orchestrated under physiological conditions and deciphering the molecular and cellular changes leading to neurological diseases is mandatory. To date, great efforts have been aimed at identifying gene mutations associated with many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Mutations in the RNA/DNA binding protein Fused in Sarcoma/Translocated in Liposarcoma (FUS/TLS) have been associated with motor neuron degeneration in rodents and humans. Furthermore, increased levels of the wild-type protein can promote neuronal cell death. Despite the well-established causal link between FUS mutations and ALS, its role in neural cells remains elusive. In order to shed new light on FUS functions we studied its role in the control of neural stem progenitor cell (NSPC) properties. Here, we report that human wild-type Fused in Sarcoma (WT FUS), exogenously expressed in mouse embryonic spinal cord-derived NSPCs, was localized in the nucleus, caused cell cycle arrest in G1 phase by affecting cell cycle regulator expression, and strongly reduced neuronal differentiation. Furthermore, the expression of the human mutant form of FUS (P525L-FUS), associated with early-onset ALS, drives the cells preferentially towards a glial lineage, strongly reducing the number of developing neurons. These results provide insight into the involvement of FUS in NSPC proliferation and differentiation into neurons and glia.

FUS oncofusion protein condensates recruit mSWI/SNF chromatin remodeler via heterotypic interactions between prion-like domains

Fusion transcription factors generated by genomic translocations are common drivers of several types of cancers including sarcomas and leukemias. Oncofusions of the FET (FUS, EWSR1, and TAF15) family proteins result from the fusion of the prion-like domain (PLD) of FET proteins to the DNA-binding domain (DBD) of certain transcription regulators and are implicated in aberrant transcriptional programs through interactions with chromatin remodelers. Here, we show that FUS-DDIT3, a FET oncofusion protein, undergoes PLD-mediated phase separation into liquid-like condensates. Nuclear FUS-DDIT3 condensates can recruit essential components of the global transcriptional machinery such as the chromatin remodeler SWI/SNF. The recruitment of mammalian SWI/SNF (mSWI/SNF) is driven by heterotypic PLD-PLD interactions between FUS-DDIT3 and core subunits of SWI/SNF, such as the catalytic component BRG1. Further experiments with single-molecule correlative force-fluorescence microscopy support a model wherein the fusion protein forms condensates on DNA surface and enrich BRG1 to activate transcription by ectopic chromatin remodeling. Similar PLD-driven co-condensation of mSWI/SNF with transcription factors can be employed by other oncogenic fusion proteins with a generic PLD-DBD domain architecture for global transcriptional reprogramming.

Biochemical Timekeeping Via Reentrant Phase Transitions

Appreciation for the role of liquid-liquid phase separation in the functional organization of cellular matter has exploded in recent years. More recently there has been a growing effort to understand the principles of heterotypic phase separation, the demixing of multiple proteins and nucleic acids into a single functional condensate. A phase transition is termed reentrant if it involves the transformation of a system from one state into a macroscopically similar or identical state via at least two phase transitions elicited by variation of a single parameter. Reentrant liquid-liquid phase separation can occur when the condensation of one species is tuned by another. Reentrant phase transitions have been modeled in vitro using protein and RNA mixtures. These biochemical studies reveal two features of reentrant phase separation that are likely important to functional cellular condensates: (1) the ability to generate condensates with layered functional topologies, and (2) the ability to generate condensates whose composition and duration are self-limiting to enable a form of biochemical timekeeping. We relate these biochemical studies to potential cellular examples and discuss how layered topologies and self-regulation may impact key biological processes.

Cellular Radiosensitivity of Soft Tissue Sarcoma

Currently, all soft tissue sarcomas (STS) are irradiated by the same regimen, disregarding possible subtype-specific radiosensitivities. To gain further insight, cellular radiosensitivity was investigated in a panel of sarcoma cell lines. Fourteen sarcoma cell lines, derived from synovial sarcoma, leiomyosarcoma, fibrosarcoma and liposarcoma origin, were submitted to clonogenic survival assays. Cells were irradiated with single doses from 1-8 Gy and surviving fraction (SF) was calculated from the resulting response data. Alpha/beta (α/β) ratios were inferred from radiation-response curves using the linear-quadratic (LQ)-model. Cellular radiosensitivities varied largely in this panel, indicating a considerable degree of heterogeneity. Surviving fraction after 2 Gy (SF2) ranged from 0.27 to 0.76 with evidence of a particular radiosensitive phenotype in only few cell lines. D37% on the mean data was 3.4 Gy and the median SF2 was 0.52. The median α/β was 4.9 Gy and in six cell lines the α/β was below 4 Gy. A fairly homogeneous radiation response was observed in myxoid liposarcoma cell lines with SF2 between 0.64 and 0.67. Further comparing sarcomas of different origin, synovial sarcomas, as a group, showed the lowest SF2 values (mean 0.35) and was significantly more radiosensitive than myxoid liposarcomas and leiomyosarcomas (P = 0.0084 and 0.024, respectively). This study demonstrates a broad spectrum of radiosensitivities across STS cell lines and reveals subtype-specific radiation responses. The particular cellular radiosensitivity of synovial sarcoma cells supports consideration of the different sarcoma entities in clinical studies that aim to optimize sarcoma radiotherapy.

Clonal architecture in mesothelioma is prognostic and shapes the tumour microenvironment

Malignant Pleural Mesothelioma (MPM) is typically diagnosed 20-50 years after exposure to asbestos and evolves along an unknown evolutionary trajectory. To elucidate this path, we conducted multi-regional exome sequencing of 90 tumour samples from 22 MPMs acquired at surgery. Here we show that exomic intratumour heterogeneity varies widely across the cohort. Phylogenetic tree topology ranges from linear to highly branched, reflecting a steep gradient of genomic instability. Using transfer learning, we detect repeated evolution, resolving 5 clusters that are prognostic, with temporally ordered clonal drivers. BAP1/-3p21 and FBXW7/-chr4 events are always early clonal. In contrast, NF2/-22q events, leading to Hippo pathway inactivation are predominantly late clonal, positively selected, and when subclonal, exhibit parallel evolution indicating an evolutionary constraint. Very late somatic alteration of NF2/22q occurred in one patient 12 years after surgery. Clonal architecture and evolutionary clusters dictate MPM inflammation and immune evasion. These results reveal potentially drugable evolutionary bottlenecking in MPM, and an impact of clonal architecture on shaping the immune landscape, with potential to dictate the clinical response to immune checkpoint inhibition.

Prognostic value of FUS immunoexpression for Gleason patterns and prostatic adenocarcinoma progression

BACKGROUND

Risk assessment is important when planning treatment for prostatic adenocarcinoma. Gleason score is a strong predictor of disease progression, despite the possibility of mismatches between biopsy and prostatectomy. In order to increase the accuracy of Gleason scores, several markers have been proposed. One of these, FUS (fused in sarcoma), plays a role in RNA processing, chromosome stability and gene transcription.

PATIENTS AND METHODS

Non-neoplastic tissue and Gleason pattern 3, 4 and 5 adenocarcinoma samples were submitted to tissue microarrays. Gleason pattern 3 and 4 were compared to the final Gleason score. We also conducted univariate and multivariate tests to probe the association between FUS expression in adenocarcinoma samples and outcome: biochemical persistence and biochemical recurrence (separately or pooled as biochemical progression), biochemical failure after salvage radiotherapy, and systemic progression.

RESULTS

Our cohort consisted of 636 patients. Non-neoplastic tissue stained less frequently (36.5%) than neoplastic tissue (47.4%), with expression increasing from Gleason pattern 3 towards pattern 5. FUS-positive Gleason pattern 3 was significantly associated with final Gleason scores >6 (HR = 1.765 [1.203-2.589]; p = 0.004). Likewise, FUS-positive Gleason pattern 4 was significantly associated with final Gleason scores ≥7 (4 + 3). The association between FUS positivity and biochemical persistence and recurrence observed in the univariate analysis was not maintained in the multivariate analysis (HR = 1.147 [0.878-1.499]; p = 0.313).

CONCLUSION

Non-neoplastic tissue was less frequently FUS-positive than neoplastic tissue. FUS positivity in Gleason pattern 3 and 4 increased the risk of high grade adenocarcinoma and was associated with clinical/laboratory progression in the univariate, but not in multivariate analysis.

Aberrant phase separation and cancer

Eukaryotic cells are intracellularly divided into numerous compartments or organelles, which coordinate specific molecules and biological reactions. Membrane-bound organelles are physically separated by lipid bilayers from the surrounding environment. Biomolecular condensates, also referred to membraneless organelles, are micron-scale cellular compartments that lack membranous enclosures but function to concentrate proteins and RNA molecules, and these are involved in diverse processes. Liquid-liquid phase separation (LLPS) driven by multivalent weak macromolecular interactions is a critical principle for the formation of biomolecular condensates, and a multitude of combinations among multivalent interactions may drive liquid-liquid phase transition (LLPT). Dysregulation of LLPS and LLPT leads to aberrant condensate and amyloid formation, which causes many human diseases, including neurodegeneration and cancer. Here, we describe recent findings regarding abnormal forms of biomolecular condensates and aggregation via aberrant LLPS and LLPT of cancer-related proteins in cancer development driven by mutation and fusion of genes. Moreover, we discuss the regulatory mechanisms by which aberrant LLPS and LLPT occur in cancer and the drug candidates targeting these mechanisms. Further understanding of the molecular events regulating how biomolecular condensates and aggregation form in cancer tissue is critical for the development of therapeutic strategies against tumorigenesis.

DDIT3 Immunohistochemistry Is a Useful Tool for the Diagnosis of Myxoid Liposarcoma

Myxoid liposarcoma is a malignant adipogenic neoplasm characterized by prominent arborizing capillaries, occasional lipoblasts, and primitive-appearing spindle cells in a myxoid background. A recurrent translocation in myxoid liposarcoma results in an oncoprotein consisting of full-length DDIT3 (CHOP) fused to an N-terminal segment of either FUS (TLS) or, less often, EWSR1. Here, we explore the diagnostic significance of DDIT3 expression in myxoid liposarcoma using a mouse monoclonal antibody recognizing an epitope in the N-terminal region. Studying a total of 300 tumors, we find diffuse, moderate-to-strong nuclear-localized anti-DDIT3 immunoreactivity in all 46 cases of myxoid liposarcoma representing 36 unique tumors, including 6 cases with high-grade (round cell) morphology. DDIT3 immunohistochemistry also highlighted a distinctive vasculocentric growth pattern in 7 myxoid liposarcomas treated with neoadjuvant radiation. In contrast, the vast majority of other examined lipomatous and myxoid neoplasms exhibited no DDIT3 expression; limited, weak immunoreactivity in <10% of cells was infrequently observed in dedifferentiated liposarcoma (6/39, 15%), solitary fibrous tumor (3/12, 25%), pleomorphic liposarcoma (1/15, 7%), and high-grade myxofibrosarcoma (2/17, 12%). Although this minimal DDIT3 expression did not correlate with DDIT3 amplification or myxoid liposarcoma-like morphology in dedifferentiated liposarcoma, there was evidence among sarcomas (excluding myxoid liposarcoma) of a relationship between expression and exposure to neoadjuvant radiation or cytotoxic chemotherapy. The constellation of findings indicates that DDIT3 immunohistochemistry may have utility in the evaluation of myxoid and lipomatous neoplasms to support the diagnosis of myxoid liposarcoma.

Redox-mediated regulation of low complexity domain self-association

Eukaryotic cells express thousands of protein domains long believed to function in the absence of molecular order. These intrinsically disordered protein (IDP) domains are typified by gibberish-like repeats of only a limited number of amino acids that we refer to as domains of low sequence complexity. A decade ago, it was observed that these low complexity (LC) domains can undergo phase transition out of aqueous solution to form either liquid-like droplets or hydrogels. The self-associative interactions responsible for phase transition involve the formation of specific cross-β structures that are unusual in being labile to dissociation. Here we give evidence that the LC domains of two RNA binding proteins, ataxin-2 and TDP43, form cross-β interactions that specify biologically relevant redox sensors.

Implications of androgen receptor and FUS expression on tumor progression in urothelial carcinoma

Androgen receptor (AR) interact with many pathways involved in bladder cancer development and progression. FUS (fused in liposarcoma), a multifunctional protein essential for different cellular processes, has been demonstrated as a key link between androgen receptor signaling and cell-cycle progression in prostate cancer but has not been examined in urothelial carcinoma (UC) despite an intimate association between prostate and bladder carcinogenesis.

AIM

To examine the immunohistochemical expression of AR and FUS in urothelial carcinoma in relation to prognostic parameters and to extrapolate any possible link between the expression of both markers and tumor progression.

STUDY DESIGN

Retrospective study using immunohistochemical staining for AR and FUS on (88) cases of urothelial carcinoma.

RESULTS

AR shows statistically significant relations with late tumor stage, high tumor grade, and non-papillary tumor pattern. On the other hand, FUS expression correlates with early tumor stage, low tumor grade and papillary pattern. An inverse relation is found between AR and FUS expression (p=0.001). Cases with high AR IHC expression show statistically significant shorter OS, RFS and PFS compared to cases with low AR expression. Cases with high FUS IHC expression reveal statistically significant longer OS, RFS and PFS compared to cases with low FUS expression.

CONCLUSION

FUS expression is associated with favorable prognostic parameters of UC. A possible interaction is suggested between FUS and AR pathways involved in urothelial cancer progression. Manipulating FUS levels and androgen deprivation therapy can provide new promising targets for treatment trials.

miR-4478 sensitizes ovarian cancer cells to irradiation by inhibiting Fus and attenuating autophagy

Ovarian cancer (OC) is a type of cancer with high prevalence and shocking mortality in women around the world. Radioresistance is a major reason for OC relapse. Mounting studies have shown the significant function of dysregulated microRNAs (miRNAs) in cancer progression and the cellular response to irradiation. The present study inquired about the function and mechanism of microRNA (miR)-4478 in regulating radiosensitivity of OC cells. Results showed that miR-4478 was downregulated in OC, and a low miR-4478 level indicated a disappointing prognosis for OC patients. Besides, in OC cells exposed to irradiation, the expression of miR-4478 decreased over time. Functionally, the upregulation of miR-4478 retarded OC cell proliferation and sensitized OC cells to irradiation. Mechanistically, miR-4478 targeted and inhibited fused in sarcoma (Fus). Additionally, Fus was upregulated in OC and its expression further elevated in OC cells under irradiation. Furthermore, miR-4478 targeted Fus to inhibit autophagy, therefore sensitizing OC cells to irradiation. Collectively, our study uncovered miR-4478 as a novel radiosensitizer by targeting Fus in OC cells, which may shed a new light on developing targets for treating patients with OC, particularly those with radioresistance.

FUS-dependent loading of SUV39H1 to OCT4 pseudogene-lncRNA programs a silencing complex with OCT4 promoter specificity

The resurrection of pseudogenes during evolution produced lncRNAs with new biological function. Here we show that pseudogene-evolution created an Oct4 pseudogene lncRNA that is able to direct epigenetic silencing of the parental Oct4 gene via a 2-step, lncRNA dependent mechanism. The murine Oct4 pseudogene 4 (mOct4P4) lncRNA recruits the RNA binding protein FUS to allow the binding of the SUV39H1 HMTase to a defined mOct4P4 lncRNA sequence element. The mOct4P4-FUS-SUV39H1 silencing complex holds target site specificity for the parental Oct4 promoter and interference with individual components results in loss of Oct4 silencing. SUV39H1 and FUS do not bind parental Oct4 mRNA, confirming the acquisition of a new biological function by the mOct4P4 lncRNA. Importantly, all features of mOct4P4 function are recapitulated by the human hOCT4P3 pseudogene lncRNA, indicating evolutionary conservation. Our data highlight the biological relevance of rapidly evolving lncRNAs that infiltrate into central epigenetic regulatory circuits in vertebrate cells.

The role of DNA damage response in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly disabling and fatal neurodegenerative disease. Due to insufficient disease-modifying treatments, there is an unmet and urgent need for elucidating disease mechanisms that occur early and represent common triggers in both familial and sporadic ALS. Emerging evidence suggests that impaired DNA damage response contributes to age-related somatic accumulation of genomic instability and can trigger or accelerate ALS pathological manifestations. In this review, we summarize and discuss recent studies indicating a direct link between DNA damage response and ALS. Further mechanistic understanding of the role genomic instability is playing in ALS disease pathophysiology will be critical for discovering new therapeutic avenues.

Liposarcomas of the mediastinum

Liposarcoma is a malignant tumor of adipocytic differentiation that rarely arises within the mediastinum. Most of the existing data available comes from scattered case reports and a few small series. The World Health Organization (WHO) recognizes four basic types of liposarcoma: well-differentiated/atypical lipomatous tumor (ALT), dedifferentiated, myxoid and pleomorphic liposarcoma (PLS). All of these liposarcoma subtypes have been recorded to occur within the mediastinum. On morphologic grounds liposarcoma can present a challenge for diagnosis as it can be difficult to distinguish from benign adipocytic neoplasms, or in the case of dedifferentiated liposarcoma (DDLS), from virtually any other type of sarcoma. Molecularly the most common subtypes of liposarcoma are characterized by specific, recurrent genetic alterations involving amplification events of MDM2 and CDK4 in well-differentiated liposarcoma (WDL) and a recurrent t(12;16)(q13;p11) in myxoid liposarcoma (MLS). MDM2 and CDK4 amplification can be assessed by immunohistochemistry, fluorescence in situ hybridization, or molecular techniques that evaluate copy number alterations and amplifications such as array based assays and next generation sequencing (NGS). In addition to WDL and MLS, a few additional rare subtypes of liposarcoma may occur in the mediastinum including PLS, myxoid WDL, thymoliposarcoma, and sclerosing high-grade liposarcoma. The present review will focus on the clinicopathologic features of the various histologic types of liposarcoma described in the mediastinum and their differential diagnosis. Data is derived from review of the largest series published in the more recent literature on these tumors.

Fused in Sarcoma (FUS) in DNA Repair: Tango with Poly(ADP-ribose) Polymerase 1 and Compartmentalisation of Damaged DNA

The fused in sarcoma (FUS) protein combines prion-like properties with a multifunctional DNA/RNA-binding domain and has functions spanning the regulation of RNA metabolism, including transcription, pre-mRNA splicing, mRNA transport and translation. In addition to its roles in RNA metabolism, FUS is implicated in the maintenance of DNA integrity. In this review, we examine the participation of FUS in major DNA repair pathways, focusing on DNA repair associated with poly(ADP-ribosyl)ation events and on how the interaction of FUS with poly(ADP-ribose) may orchestrate transient compartmentalisation of DNA strand breaks. Unravelling how prion-like RNA-binding proteins control DNA repair pathways will deepen our understanding of the pathogenesis of some neurological diseases and cancer as well as provide the basis for the development of relevant innovative therapeutic technologies. This knowledge may also extend the range of applications of poly(ADP-ribose) polymerase inhibitors to the treatment of neurodegenerative diseases related to RNA-binding proteins in the cell, e.g., amyotrophic lateral sclerosis and frontotemporal lobar degeneration.