RPL13 Variants Cause Spondyloepimetaphyseal Dysplasia with Severe Short Stature.

Variants in genes encoding ribosomal proteins have thus far been associated with Diamond-Blackfan anemia, a rare inherited bone marrow failure, and isolated congenital asplenia. Here, we report one de novo missense variant and three de novo splice variants in RPL13, which encodes ribosomal protein RPL13 (also called eL13), in four unrelated individuals with a rare bone dysplasia causing severe short stature. The three splice variants (c.477+1G>T, c.477+1G>A, and c.477+2 T>C) result in partial intron retention, which leads to an 18-amino acid insertion. In contrast to observations from Diamond-Blackfan anemia, we detected no evidence of significant pre-rRNA processing disturbance in cells derived from two affected individuals. Consistently, we showed that the insertion-containing protein is stably expressed and incorporated into 60S subunits similar to the wild-type protein. Erythroid proliferation in culture and ribosome profile on sucrose gradient are modified, suggesting a change in translation dynamics. We also provide evidence that RPL13 is present at high levels in chondrocytes and osteoblasts in mouse growth plates. Taken together, we show that the identified RPL13 variants cause a human ribosomopathy defined by a rare skeletal dysplasia, and we highlight the role of this ribosomal protein in bone development.

Cytosine methylation of mature microRNAs inhibits their functions and is associated with poor prognosis in glioblastoma multiforme.

BACKGROUND: Literature reports that mature microRNA (miRNA) can be methylated at adenosine, guanosine and cytosine. However, the molecular mechanisms involved in cytosine methylation of miRNAs have not yet been fully elucidated. Here we investigated the biological role and underlying mechanism of cytosine methylation in miRNAs in glioblastoma multiforme (GBM). METHODS: RNA immunoprecipitation with the anti-5methylcytosine (5mC) antibody followed by Array, ELISA, dot blot, incorporation of a radio-labelled methyl group in miRNA, and miRNA bisulfite sequencing were perfomred to detect the cytosine methylation in mature miRNA. Cross-Linking immunoprecipiation qPCR, transfection with methylation/unmethylated mimic miRNA, luciferase promoter reporter plasmid, Biotin-tagged 3'UTR/mRNA or miRNA experiments and in vivo assays were used to investigate the role of methylated miRNAs. Finally, the prognostic value of methylated miRNAs was analyzed in a cohorte of GBM pateints. RESULTS: Our study reveals that a significant fraction of miRNAs contains 5mC. Cellular experiments show that DNMT3A/AGO4 methylated miRNAs at cytosine residues inhibit the formation of miRNA/mRNA duplex and leading to the loss of their repressive function towards gene expression. In vivo experiments show that cytosine-methylation of miRNA abolishes the tumor suppressor function of miRNA-181a-5p miRNA for example. Our study also reveals that cytosine-methylation of miRNA-181a-5p results is associated a poor prognosis in GBM patients. CONCLUSION: Together, our results indicate that the DNMT3A/AGO4-mediated cytosine methylation of miRNA negatively.

Circulating Tumor Cells: A Review of Non-EpCAM-Based Approaches for Cell Enrichment and Isolation.

BACKGROUND: Circulating tumor cells (CTCs) are biomarkers for noninvasively measuring the evolution of tumor genotypes during treatment and disease progression. Recent technical progress has made it possible to detect and characterize CTCs at the single-cell level in blood. CONTENT: Most current methods are based on epithelial cell adhesion molecule (EpCAM) detection, but numerous studies have demonstrated that EpCAM is not a universal marker for CTC detection because it fails to detect both carcinoma cells that undergo epithelial-mesenchymal transition (EMT) and CTCs of mesenchymal origin. Moreover, EpCAM expression has been found in patients with benign diseases. A large proportion of the current studies and reviews about CTCs describe EpCAM-based methods, but there is evidence that not all tumor cells can be detected using this marker. Here we describe the most recent EpCAM-independent methods for enriching, isolating, and characterizing CTCs on the basis of physical and biological characteristics and point out the main advantages and disadvantages of these methods. SUMMARY: CTCs offer an opportunity to obtain key biological information required for the development of personalized medicine. However, there is no universal marker of these cells. To strengthen the clinical utility of CTCs, it is important to improve existing technologies and develop new, non-EpCAM-based systems to enrich and isolate CTCs.

Tumour Heterogeneity: The Key Advantages of Single-Cell Analysis.

Tumour heterogeneity refers to the fact that different tumour cells can show distinct morphological and phenotypic profiles, including cellular morphology, gene expression, metabolism, motility, proliferation and metastatic potential. This phenomenon occurs both between tumours (inter-tumour heterogeneity) and within tumours (intra-tumour heterogeneity), and it is caused by genetic and non-genetic factors. The heterogeneity of cancer cells introduces significant challenges in using molecular prognostic markers as well as for classifying patients that might benefit from specific therapies. Thus, research efforts for characterizing heterogeneity would be useful for a better understanding of the causes and progression of disease. It has been suggested that the study of heterogeneity within Circulating Tumour Cells (CTCs) could also reflect the full spectrum of mutations of the disease more accurately than a single biopsy of a primary or metastatic tumour. In previous years, many high throughput methodologies have raised for the study of heterogeneity at different levels (i.e., RNA, DNA, protein and epigenetic events). The aim of the current review is to stress clinical implications of tumour heterogeneity, as well as current available methodologies for their study, paying specific attention to those able to assess heterogeneity at the single cell level.

BYL719, a new α-specific PI3K inhibitor: single administration and in combination with conventional chemotherapy for the treatment of osteosarcoma.

It has been established that disturbances in intracellular signaling pathways play a considerable part in the oncologic process. Phosphatidylinositol-3-kinase (PI3K) has become of key interest in cancer therapy because of its high mutation frequency and/or gain in function of its catalytic subunits in cancer cells. We investigated the therapeutic value of BYL719, a new specific PI3Kα inhibitor that blocks the ATP site, on osteosarcoma and bone cells. The in vitro effects of BYL719 on proliferation, apoptosis, and cell cycle were assessed in human and murine osteosarcoma cell. Its impact on bone cells was determined using human mesenchymal stem cells (hMSC) and human CD14+ osteoclast precursors. Two different murine preclinical models of osteosarcoma were used to analyze the in vivo biological activities of BYL719. BYL719 decreased cell proliferation by blocking cell cycle in G0/G1 phase with no outstanding effects on apoptosis cell death in HOS and MOS-J tumor cells. BYL719 inhibited cell migration and can thus be considered as a cytostatic drug for osteosarcoma. In murine preclinical models of osteosarcoma, BYL719 significantly decreased tumor progression and tumor ectopic bone formation as shown by a decrease of Ki67+ cells and tumor vascularization. To explore the maximum therapeutic potential of BYL719, the drug was studied in combination with conventional chemotherapeutic drugs, revealing promising efficacy with ifosfamide. BYL719 also exhibited dual activities on osteoblast and osteoclast differentiation. Overall, the present work shows that BYL719 is a promising drug in either a single or multidrug approach to curing bone sarcoma.

Super-enhancers: drivers of cells' identities and cells' debacles.

Precise spatiotemporal regulations of gene expression are essential for determining cells' fates and functions. Enhancers are cis-acting DNA elements that act as periodic transcriptional thrusters and their activities are cell type specific. Clusters of enhancers, called super-enhancers, are more densely occupied by transcriptional activators than enhancers, driving stronger expression of their target genes, which have prominent roles in establishing and maintaining cellular identities. Here we review the current knowledge on the composition and structure of super-enhancers to understand how they robustly stimulate the expression of cellular identity genes. We also review their involvement in the development of various cell types and both noncancerous and cancerous disorders, implying the therapeutic interest of targeting them to fight against various diseases.

Biological sample collection to advance research and treatment: a Fight Osteosarcoma Through European Research (FOSTER) and Euro Ewing Consortium (EEC) statement.

Osteosarcoma and Ewing sarcoma are bone tumours mostly diagnosed in children, adolescents and young adults. Despite multi-modal therapy, morbidity is high and survival rates remain low, especially in the metastatic disease setting. Trials investigating targeted therapies and immunotherapies have not been ground-breaking. Better understanding of biological subgroups, the role of the tumour immune microenvironment, factors that promote metastasis and clinical biomarkers of prognosis and drug response are required to make progress. A prerequisite to achieve desired success is a thorough, systematic and clinically linked biological analysis of patient samples but disease rarity and tissue processing challenges such as logistics and infrastructure have contributed to a lack of relevant samples for clinical care and research. There is a need for a Europe-wide framework to be implemented for the adequate and minimal sampling, processing, storage and analysis of patient samples. Two international panels of scientists, clinicians and patient and parent advocates have formed the Fight Osteosarcoma Through European Research (FOSTER) consortium and the Euro Ewing Consortium (EEC). The consortia shared their expertise and institutional practices to formulate new guidelines. We report new reference standards for adequate and minimally required sampling (time points, diagnostic samples, liquid biopsy tubes), handling and biobanking to enable advanced biological studies in bone sarcoma. We describe standards for analysis and annotation to drive collaboration and data harmonisation with practical, legal and ethical considerations. This position paper provides comprehensive guidelines that should become the new standards of care that will accelerate scientific progress, promote collaboration and improve outcomes.

Tracking Targets of Dynamic Super-Enhancers in Vitro to Better Characterize Osteoclastogenesis and to Evaluate the Effect of Diuron on the Maturation of Human Bone Cells.

BACKGROUND: Osteoclasts are major actors in the maintenance of bone homeostasis. The full functional maturation of osteoclasts from monocyte lineage cells is essential for the degradation of old/damaged bone matrix. Diuron is one of the most frequently encountered herbicides, particularly in water sources. However, despite a reported delayed ossification in vivo, its impact on bone cells remains largely unknown. OBJECTIVES: The objectives of this study were to first better characterize osteoclastogenesis by identifying genes that drive the differentiation of CD14+ monocyte progenitors into osteoclasts and to evaluate the toxicity of diuron on osteoblastic and osteoclastic differentiation in vitro. METHODS: We performed chromatin immunoprecipitation (ChIP) against H3K27ac followed by ChIP-sequencing (ChIP-Seq) and RNA-sequencing (RNA-Seq) at different stages of differentiation of CD14+ monocytes into active osteoclasts. Differentially activated super-enhancers and their potential target genes were identified. Then to evaluate the toxicity of diuron on osteoblasts and osteoclasts, we performed RNA-Seq and functional tests during in vitro osteoblastic and osteoclastic differentiation by exposing cells to different concentrations of diuron. RESULTS: The combinatorial study of the epigenetic and transcriptional remodeling taking place during differentiation has revealed a very dynamic epigenetic profile that supports the expression of genes vital for osteoclast differentiation and function. In total, we identified 122 genes induced by dynamic super-enhancers at late days. Our data suggest that high concentration of diuron (50µM) affects viability of mesenchymal stem cells (MSCs) in vitro associated with a decrease of bone mineralization. At a lower concentration (1µM), an inhibitory effect was observed in vitro on the number of osteoclasts derived from CD14+ monocytes without affecting cell viability. Among the diuron-affected genes, our analysis suggests a significant enrichment of genes targeted by pro-differentiation super-enhancers, with an odds ratio of 5.12 (ρ=2.59×10-5). DISCUSSION: Exposure to high concentrations of diuron decreased the viability of MSCs and could therefore affect osteoblastic differentiation and bone mineralization. This pesticide also disrupted osteoclasts maturation by impairing the expression of cell-identity determining genes. Indeed, at sublethal concentrations, differences in the expression of these key genes were mild during the course of in vitro osteoclast differentiation. Taken together our results suggest that high exposure levels of diuron could have an effect on bone homeostasis. https://doi.org/10.1289/EHP11690.

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.

Origin and Therapies of Osteosarcoma.

Osteosarcoma (OS) is the most frequent primary bone tumor, mainly affecting children and young adults. Despite therapeutic advances, the 5-year survival rate is 70% but drastically decreases to 20-30% for poor responders to therapies or for patients with metastasis. No real evolution of the survival rates has been observed for four decades, explained by poor knowledge of the origin, difficulties related to diagnosis and the lack of targeted therapies for this pediatric tumor. This review will describe a non-exhaustive overview of osteosarcoma disease from a clinical and biological point of view, describing the origin, diagnosis and therapies.

The p53 Family Members p63 and p73 Roles in the Metastatic Dissemination: Interactions with microRNAs and TGFß Pathway.

TP53 (TP53), p73 (TP73), and p63 (TP63) are members of the p53 transcription factor family, which has many activities spanning from embryonic development through to tumor suppression. The utilization of two promoters and alternative mRNA splicing has been shown to yield numerous isoforms in p53, p63, and p73. TAp73 is thought to mediate apoptosis as a result of nuclear accumulation following chemotherapy-induced DNA damage, according to a number of studies. Overexpression of the nuclear ΔNp63 and ΔNp73 isoforms, on the other hand, suppresses TAp73's pro-apoptotic activity in human malignancies, potentially leading to metastatic spread or inhibition. Another well-known pathway that has been associated to metastatic spread is the TGF pathway. TGFs are a family of structurally related polypeptide growth factors that regulate a variety of cellular functions including cell proliferation, lineage determination, differentiation, motility, adhesion, and cell death, making them significant players in development, homeostasis, and wound repair. Various studies have already identified several interactions between the p53 protein family and the TGFb pathway in the context of tumor growth and metastatic spread, beginning to shed light on this enigmatic intricacy.

Ubiquitin-specific proteases as therapeutic targets in paediatric primary bone tumours?

In children and young adults, primary malignant bone tumours are mainly composed of osteosarcoma and Ewing's sarcoma. Despite advances in treatments, nearly 40% of patients succumb to these diseases. In particular, the clinical outcome of metastatic osteosarcoma or Ewing's sarcoma remains poor, with less than 30% of patients who develop metastases surviving five years after initial diagnosis. Over the last decade, the cancer research community has shown considerable interest in the processes of protein ubiquitination and deubiquitination. In particular, a growing number of studies show the relevance to target the ubiquitin-specific protease (USP) family in various cancers. This review provides an update on the current knowledge regarding the implication of these USPs in the progression of bone sarcoma: osteosarcoma and Ewing's sarcoma.

Mechanisms of Resistance to Conventional Therapies for Osteosarcoma.

Osteosarcoma (OS) is the most common primary bone tumor, mainly occurring in children and adolescents. Current standard therapy includes tumor resection associated with multidrug chemotherapy. However, patient survival has not evolved for the past decades. Since the 1970s, the 5-year survival rate is around 75% for patients with localized OS but dramatically drops to 20% for bad responders to chemotherapy or patients with metastases. Resistance is one of the biological processes at the origin of therapeutic failure. Therefore, it is necessary to better understand and decipher molecular mechanisms of resistance to conventional chemotherapy in order to develop new strategies and to adapt treatments for patients, thus improving the survival rate. This review will describe most of the molecular mechanisms involved in OS chemoresistance, such as a decrease in intracellular accumulation of drugs, inactivation of drugs, improved DNA repair, modulations of signaling pathways, resistance linked to autophagy, disruption in genes expression linked to the cell cycle, or even implication of the micro-environment. We will also give an overview of potential therapeutic strategies to circumvent resistance development.

Development of prohibitin ligands against osteoporosis.

Current therapeutic approaches to osteoporosis display some potential adverse effects and a limited efficacy on non-vertebral fracture reduction. Some sulfonylamidines targeting the scaffold proteins prohibitins-1 and 2 (PHB1/2) have been showed to inhibit the formation of osteoclasts in charge of bone resorption. Herein, we report the development of a second generation of anti-osteoclastic PHB ligands. The most potent compound, IN45, showed 88% inhibition at the low concentration of 5 µM, indicates that it might serve as a basis for the development of new antiosteoporotic drugs.

Molecular Chaperones in Osteosarcoma: Diagnosis and Therapeutic Issues.

Osteosarcoma (OS) is the most common form of primary bone tumor affecting mainly children and young adults. Despite therapeutic progress, the 5-year survival rate is 70%, but it drops drastically to 30% for poor responders to therapies or for patients with metastases. Identifying new therapeutic targets is thus essential. Heat Shock Proteins (HSPs) are the main effectors of Heat Shock Response (HSR), the expression of which is induced by stressors. HSPs are a large family of proteins involved in the folding and maturation of other proteins in order to maintain proteostasis. HSP overexpression is observed in many cancers, including breast, prostate, colorectal, lung, and ovarian, as well as OS. In this article we reviewed the significant role played by HSPs in molecular mechanisms leading to OS development and progression. HSPs are directly involved in OS cell proliferation, apoptosis inhibition, migration, and drug resistance. We focused on HSP27, HSP60, HSP70 and HSP90 and summarized their potential clinical uses in OS as either biomarkers for diagnosis or therapeutic targets. Finally, based on different types of cancer, we consider the advantage of targeting heat shock factor 1 (HSF1), the major transcriptional regulator of HSPs in OS.

Involvement of the TGF-ß Signaling Pathway in the Development of YAP-Driven Osteosarcoma Lung Metastasis.

BACKGROUND: The poor survival rate of patients with osteosarcoma (OS), specifically with metastases at diagnosis, undergoes the urgency to develop new therapeutic strategies. Although we recently demonstrated the key role of YAP/TEAD signaling in the growth of OS primary tumor, the molecular mechanisms by which YAP regulates metastases development remain poorly understood. METHODS: The molecular mechanisms by which YAP regulates metastases development were studied using an overexpression of mutated forms of YAP able or not able to interact with TEAD. Molecular signatures were identified using RNA-sequencing analysis and gene set enrichment. Interactions between YAP and Smad3 were studied using proximity ligation assay (PLA), immunoprecipitation, and promoter/specific gene assays. The involvement of the TGF-ß pathway in the ability of YAP to stimulate metastatic development in vivo was studied using an inhibitor of the TGF-ß cascade in a preclinical model of OS and in vitro on the ability of OS cells to migrate and invade. RESULTS: Our work shows that a high YAP expression is associated with the presence of lung metastases which predicts a poor prognosis. Molecular analysis indicates that TGF-ß signaling is involved in YAP-driven osteosarcoma cell pro-migratory phenotype, epithelial mesenchymal transition, cell migration, and in vivo lung metastasis development. Regardless of its ability to bind to TEAD, YAP interacts with Smad3 and stimulates the transcriptional activity of TGF-ß/Smad3, thereby enhancing the ability of TGF-ß to stimulate lung metastasis development. CONCLUSIONS: We demonstrated the crucial involvement of the TGF-ß/Smad3 signaling pathway in YAP-driven lung metastasis development in OS.

Overexpression of the Ubiquitin Specific Proteases USP43, USP41, USP27x and USP6 in Osteosarcoma Cell Lines: Inhibition of Osteosarcoma Tumor Growth and Lung Metastasis Development by the USP Antagonist PR619.

Osteosarcoma (OS) is the most common malignant bone tumor in children and teenagers. In many cases, such as poor response to treatment or the presence of metastases at diagnosis, the survival rate of patients remains very low. Although in the literature, more and more studies are emerging on the role of Ubiquitin-Specific Proteases (USPs) in the development of many cancers, few data exist regarding OS. In this context, RNA-sequencing analysis of OS cells and mesenchymal stem cells differentiated or not differentiated into osteoblasts reveals increased expression of four USPs in OS tumor cells: USP6, USP27x, USP41 and USP43. Tissue microarray analysis of patient biopsies demonstrates the nucleic and/or cytoplasmic expression of these four USPs at the protein level. Interestingly, Kaplan-Meyer analysis shows that the expression of two USPs, USP6 and USP41, is correlated with patient survival. In vivo experiments using a preclinical OS model, finally demonstrate that PR619, a USP inhibitor able to enhance protein ubiquitination in OS cell lines, reduces primary OS tumor growth and the development of lung metastases. In this context, in vitro experiments show that PR619 decreases the viability of OS cells, mainly by inducing a caspase3/7-dependent cell apoptosis. Overall, these results demonstrate the relevance of targeting USPs in OS.

N6-Adenosine Methylation of miRNA-200b-3p Influences Its Functionality and Is a Theranostic Tool.

MicroRNAs (miRNAs or miRs) play crucial roles in biological and pathological processes. Some miRNAs also appear as promising biomarkers and therapeutic tools. However, the epitranscriptomic regulation of miRNAs is not yet fully elucidated in all of their fields of application. We report that adenosine methylation of miR-200b-3p inhibits its repressive function toward its mRNA targets such as XIAP by blocking the formation of the miRNA/3' UTRmRNA duplex. Our data indicate that the adenosine methylation of miR-200b-3p is associated with the survival of glioblastoma patients. Collectively, our data support the idea that the adenosine methylation of miR-200b-3p can be used as a prodrug having a selective cytotoxicity against cancer cells (while being harmless to peripheral blood mononuclear cells [PBMCs], astrocytes, neurons, and hepatocytes).

Ribosomopathies: New Therapeutic Perspectives.

Ribosomopathies are a group of rare diseases in which genetic mutations cause defects in either ribosome biogenesis or function, given specific phenotypes. Ribosomal proteins, and multiple other factors that are necessary for ribosome biogenesis (rRNA processing, assembly of subunits, export to cytoplasm), can be affected in ribosomopathies. Despite the need for ribosomes in all cell types, these diseases result mainly in tissue-specific impairments. Depending on the type of ribosomopathy and its pathogenicity, there are many potential therapeutic targets. The present manuscript will review our knowledge of ribosomopathies, discuss current treatments, and introduce the new therapeutic perspectives based on recent research. Diamond-Blackfan anemia, currently treated with blood transfusion prior to steroids, could be managed with a range of new compounds, acting mainly on anemia, such as L-leucine. Treacher Collins syndrome could be managed by various treatments, but it has recently been shown that proteasomal inhibition by MG132 or Bortezomib may improve cranial skeleton malformations. Developmental defects resulting from ribosomopathies could be also treated pharmacologically after birth. It might thus be possible to treat certain ribosomopathies without using multiple treatments such as surgery and transplants. Ribosomopathies remain an open field in the search for new therapeutic approaches based on our recent understanding of the role of ribosomes and progress in gene therapy for curing genetic disorders.

Implication of the p53-Related miR-34c, -125b, and -203 in the Osteoblastic Differentiation and the Malignant Transformation of Bone Sarcomas.

The formation of the skeleton occurs throughout the lives of vertebrates and is achieved through the balanced activities of two kinds of specialized bone cells: the bone-forming osteoblasts and the bone-resorbing osteoclasts. Impairment in the remodeling processes dramatically hampers the proper healing of fractures and can also result in malignant bone diseases such as osteosarcoma. MicroRNAs (miRNAs) are a class of small non-coding single-strand RNAs implicated in the control of various cellular activities such as proliferation, differentiation, and apoptosis. Their post-transcriptional regulatory role confers on them inhibitory functions toward specific target mRNAs. As miRNAs are involved in the differentiation program of precursor cells, it is now well established that this class of molecules also influences bone formation by affecting osteoblastic differentiation and the fate of osteoblasts. In response to various cell signals, the tumor-suppressor protein p53 activates a huge range of genes, whose miRNAs promote genomic-integrity maintenance, cell-cycle arrest, cell senescence, and apoptosis. Here, we review the role of three p53-related miRNAs, miR-34c, -125b, and -203, in the bone-remodeling context and, in particular, in osteoblastic differentiation. The second aim of this study is to deal with the potential implication of these miRNAs in osteosarcoma development and progression.