Impaired condensin complex and Aurora B kinase underlie mitotic and chromosomal defects in hyperdiploid B-cell ALL.

B-cell acute lymphoblastic leukemia (ALL; B-ALL) is the most common pediatric cancer, and high hyperdiploidy (HyperD) identifies the most common subtype of pediatric B-ALL. Despite HyperD being an initiating oncogenic event affiliated with childhood B-ALL, the mitotic and chromosomal defects associated with HyperD B-ALL (HyperD-ALL) remain poorly characterized. Here, we have used 54 primary pediatric B-ALL samples to characterize the cellular-molecular mechanisms underlying the mitotic/chromosome defects predicated to be early pathogenic contributors in HyperD-ALL. We report that HyperD-ALL blasts are low proliferative and show a delay in early mitosis at prometaphase, associated with chromosome-alignment defects at the metaphase plate leading to robust chromosome-segregation defects and nonmodal karyotypes. Mechanistically, biochemical, functional, and mass-spectrometry assays revealed that condensin complex is impaired in HyperD-ALL cells, leading to chromosome hypocondensation, loss of centromere stiffness, and mislocalization of the chromosome passenger complex proteins Aurora B kinase (AURKB) and Survivin in early mitosis. HyperD-ALL cells show chromatid cohesion defects and an impaired spindle assembly checkpoint (SAC), thus undergoing mitotic slippage due to defective AURKB and impaired SAC activity, downstream of condensin complex defects. Chromosome structure/condensation defects and hyperdiploidy were reproduced in healthy CD34+ stem/progenitor cells upon inhibition of AURKB and/or SAC. Collectively, hyperdiploid B-ALL is associated with a defective condensin complex, AURKB, and SAC.

Addressing Doxorubicin Resistance in Bone Sarcomas Using Novel Drug-Resistant Models.

Bone sarcomas have not shown a significant improvement in survival for decades, due, in part, to the development of resistance to current systemic treatments, such as doxorubicin. To better understand those mechanisms mediating drug-resistance we generated three osteosarcoma and one chondrosarcoma cell lines with a stable doxorubicin-resistant phenotype, both in vitro and in vivo. These resistant strains include a pioneer model generated from a patient-derived chondrosarcoma line. The resistant phenotype was characterized by a weaker induction of apoptosis and DNA damage after doxorubicin treatment and a lower migratory capability. In addition, all resistant lines expressed higher levels of ABC pumps; meanwhile, no clear trends were found in the expression of anti-apoptotic and stem cell-related factors. Remarkably, upon the induction of resistance, the proliferation potential was reduced in osteosarcoma lines but enhanced in the chondrosarcoma model. The exposure of resistant lines to other anti-tumor drugs revealed an increased response to cisplatin and/or methotrexate in some models. Finally, the ability to retain the resistant phenotype in vivo was confirmed in an osteosarcoma model. Altogether, this work evidenced the co-existence of common and case-dependent phenotypic traits and mechanisms associated with the development of resistance to doxorubicin in bone sarcomas.

Gemini and Bicephalous Surfactants: A Review on Their Synthesis, Micelle Formation, and Uses.

The use of surfactants in polymerization reactions is particularly important, mainly in emulsion polymerizations. Further, micelles from biocompatible surfactants find use in pharmaceutical dosage forms. This paper reviews recent developments in the synthesis of novel gemini and bicephalous surfactants, micelle formation, and their applications in polymer and nanoparticle synthesis, oil recovery, catalysis, corrosion, protein binding, and biomedical area, particularly in drug delivery.

Mithramycin delivery systems to develop effective therapies in sarcomas.

BACKGROUND: Sarcomas comprise a group of aggressive malignancies with very little treatment options beyond standard chemotherapy. Reposition of approved drugs represents an attractive approach to identify effective therapeutic compounds. One example is mithramycin (MTM), a natural antibiotic which has demonstrated a strong antitumour activity in several tumour types, including sarcomas. However, its widespread use in the clinic was limited by its poor toxicity profile. RESULTS: In order to improve the therapeutic index of MTM, we have loaded MTM into newly developed nanocarrier formulations. First, polylactide (PLA) polymeric nanoparticles (NPs) were generated by nanoprecipitation. Also, liposomes (LIP) were prepared by ethanol injection and evaporation solvent method. Finally, MTM-loaded hydrogels (HG) were obtained by passive loading using a urea derivative non-peptidic hydrogelator. MTM-loaded NPs and LIP display optimal hydrodynamic radii between 80 and 105 nm with a very low polydispersity index (PdI) and encapsulation efficiencies (EE) of 92 and 30%, respectively. All formulations show a high stability and different release rates ranging from a fast release in HG (100% after 30 min) to more sustained release from NPs (100% after 24 h) and LIP (40% after 48 h). In vitro assays confirmed that all assayed MTM formulations retain the cytotoxic, anti-invasive and anti-stemness potential of free MTM in models of myxoid liposarcoma, undifferentiated pleomorphic sarcoma and chondrosarcoma. In addition, whole genome transcriptomic analysis evidenced the ability of MTM, both free and encapsulated, to act as a multi-repressor of several tumour-promoting pathways at once. Importantly, the treatment of mice bearing sarcoma xenografts showed that encapsulated MTM exhibited enhanced therapeutic effects and was better tolerated than free MTM. CONCLUSIONS: Overall, these novel formulations may represent an efficient and safer MTM-delivering alternative for sarcoma treatment.

The multikinase inhibitor EC-70124 synergistically increased the antitumor activity of doxorubicin in sarcomas.

Cytotoxic drugs like doxorubicin remain as the most utilized agents in sarcoma treatment. However, advanced sarcomas are often resistant, thus stressing the need for new therapies aimed to overcome this resistance. Multikinase inhibitors provide an efficient way to target several pro-tumorigenic pathways using a single agent and may constitute a valuable strategy in the treatment of sarcomas, which frequently show an aberrant activation of pro-tumoral kinases. Therefore, we studied the antitumor activity of EC-70124, an indolocarbazole analog that have demonstrated a robust ability to inhibit a wide range of pro-survival kinases. Evaluation of the phospho-kinase profile in cell-of-origin sarcoma models and/or sarcoma primary cell lines evidenced that PI3K/AKT/mTOR, JAK/STAT or SRC were among the most highly activated pathways. In striking contrast with the structurally related drug midostaurin, EC-70124 efficiently prevented the phosphorylation of these targets and robustly inhibited proliferation through a mechanism associated to the induction of DNA damage, cell cycle arrest and apoptosis. In addition, EC-70124 was able to partially reduce tumor growth in vivo. Importantly, this compound inhibited the expression and activity of ABC efflux pumps involved in drug resistance. In line with this ability, we found that the combined treatment of EC-70124 with doxorubicin resulted in a synergistic cytotoxic effect in vitro and an increased antitumor activity of this cytotoxic drug in vivo. Altogether, these results uncover the capability of the novel multikinase inhibitor EC-70124 to counteract drug resistance in sarcoma and highlight its therapeutic potential when combined with current treatments.

Role of Activator Protein-1 Complex on the Phenotype of Human Osteosarcomas Generated from Mesenchymal Stem Cells.

Osteosarcoma (OS) is a highly aggressive bone tumor that usually arises intramedullary at the extremities of long bones. Due to the fact that the peak of incidence is in the growth spurt of adolescence, the specific anatomical location, and the heterogeneity of cells, it is believed that osteosarcomagenesis is a process associated with bone development. Different studies in murine models showed that the tumor-initiating cell in OS could be an uncommitted mesenchymal stem cell (MSC) developing in a specific bone microenvironment. However, only a few studies have reported transgene-induced human MSCs transformation and mostly obtained undifferentiated sarcomas. In our study, we demonstrate that activator protein 1 family members induce osteosarcomagenesis in immortalized hMSC. c-JUN or c-JUN/c-FOS overexpression act as tumorigenic factors generating OS with fibroblastic or pleomorphic osteoblastic phenotypes, respectively. Stem Cells 2018;36:1487-1500.

Sarcoma Stem Cell Heterogeneity.

Sarcomas represent an extensive group of divergent malignant diseases, with the only common characteristic of being derived from mesenchymal cells. As such, sarcomas are by definition very heterogeneous, and this heterogeneity does not manifest only upon intertumoral comparison on a bulk tumor level but can be extended to intratumoral level. Whereas part of this intratumoral heterogeneity could be understood in terms of clonal genetic evolution, an essential part includes a hierarchical relationship between sarcoma cells, governed by both genetic and epigenetic influences, signals that sarcoma cells are exposed to, and intrinsic developmental programs derived from sarcoma cells of origin. The notion of this functional hierarchy operating within each tumor implies the existence of sarcoma stem cells, which may originate from mesenchymal stem cells, and indeed, mesenchymal stem cells have been used to establish several crucial experimental sarcoma models and to trace down their respective stem cell populations. Mesenchymal stem cells themselves are heterogeneous, and, moreover, there are alternative possibilities for sarcoma cells of origin, like neural crest-derived stem cells, or mesenchymal committed precursor cells, or - in rhabdomyosarcoma - muscle satellite cells. These various origins result in substantial heterogeneity in possible sarcoma initiation. Genetic and epigenetic changes associated with sarcomagenesis profoundly impact the biology of sarcoma stem cells. For pediatric sarcomas featuring discrete reciprocal translocations and largely stable karyotypes, the translocation-activated oncogenes could be crucial factors that confer stemness, principally by modifying transcriptome and interfering with normal epigenetic regulation; the most extensively studied examples of this process are myxoid/round cell liposarcoma, Ewing sarcoma, and synovial sarcoma. For adult sarcomas, which have typically complex and unstable karyotypes, stemness might be defined more operationally, as a reflection of actual assembly of genetically and epigenetically conditioned stemness factors, with dedifferentiated liposarcoma providing a most thoroughly studied example. Alternatively, stemness can be imposed by tumor microenvironment, as extensively documented in osteosarcoma. In spite of this heterogeneity in both sarcoma initiation and underlying stemness biology, some of the molecular mechanisms of stemness might be remarkably similar in diverse sarcoma types, like abrogation of classical tumor suppressors pRb and p53, activation of Sox-2, or inhibition of canonical Wnt/ß-catenin signaling. Moreover, even some stem cell markers initially characterized for their stem cell enrichment capacity in various carcinomas or leukemias seem to function quite similarly in various sarcomas. Understanding the biology of sarcoma stem cells could significantly improve sarcoma patient clinical care, leading to both better patient stratification and, hopefully, development of more effective therapeutic options.

Preparation of Peppermint Oil-Based Nanodevices Loaded with Paclitaxel: Cytotoxic and Apoptosis Studies in HeLa Cells.

In this work, several normal, oil-in-water (o/w) microemulsions (MEs) were prepared using peppermint essential oil, jojoba oil, trans-anethole, and vitamin E as oil phases to test their capacity to load paclitaxel (PTX). Initially, pseudo-ternary partial phase diagrams were constructed in order to find the normal microemulsion region using d-α-tocopherol polyethylene glycol 1000 succinate (TPGS-1000) as surfactant and isobutanol (iso-BuOH) as co-surfactant. Selected ME formulations were loaded with PTX reaching concentrations of 0.6 mg mL-1 for the peppermint oil and trans-anethole MEs, while for the vitamin E and jojoba oil MEs, the maximum concentration was 0.3 mg mL-1. The PTX-loaded MEs were stable according to the results of heating-cooling cycles and mechanical force (centrifugation) test. Particularly, drug release profile for the PTX-loaded peppermint oil ME (MEPP) showed that ∼ 90% of drug was released in the first 48 h. Also, MEPP formulation showed 70% and 90% viability reduction on human cervical cancer (HeLa) cells after 24 and 48 h of exposure, respectively. In addition, HeLa cell apoptosis was confirmed by measuring caspase activity and DNA fragmentation. Results showed that the MEPP sample presented a major pro-apoptotic capability by comparing with the unloaded PTX ME sample.

Bone microenvironment signals in osteosarcoma development.

The bone is a complex connective tissue composed of many different cell types such as osteoblasts, osteoclasts, chondrocytes, mesenchymal stem/progenitor cells, hematopoietic cells and endothelial cells, among others. The interaction between them is finely balanced through the processes of bone formation and bone remodeling, which regulates the production and biological activity of many soluble factors and extracellular matrix components needed to maintain the bone homeostasis in terms of cell proliferation, differentiation and apoptosis. Osteosarcoma (OS) emerges in this complex environment as a result of poorly defined oncogenic events arising in osteogenic lineage precursors. Increasing evidence supports that similar to normal development, the bone microenvironment (BME) underlies OS initiation and progression. Here, we recapitulate the physiological processes that regulate bone homeostasis and review the current knowledge about how OS cells and BME communicate and interact, describing how these interactions affect OS cell growth, metastasis, cancer stem cell fate and therapy outcome.

Bone environment is essential for osteosarcoma development from transformed mesenchymal stem cells.

The cellular microenvironment plays a relevant role in cancer development. We have reported that mesenchymal stromal/stem cells (MSCs) deficient for p53 alone or together with RB (p53(-/-)RB(-/-)) originate leiomyosarcoma after subcutaneous (s.c.) inoculation. Here, we show that intrabone or periosteal inoculation of p53(-/-) or p53(-/-)RB(-/-) bone marrow- or adipose tissue-derived MSCs originated metastatic osteoblastic osteosarcoma (OS). To assess the contribution of bone environment factors to OS development, we analyzed the effect of the osteoinductive factor bone morphogenetic protein-2 (BMP-2) and calcified substrates on p53(-/-)RB(-/-) MSCs. We show that BMP-2 upregulates the expression of osteogenic markers in a WNT signaling-dependent manner. In addition, the s.c. coinfusion of p53(-/-)RB(-/-) MSCs together with BMP-2 resulted in appearance of tumoral osteoid areas. Likewise, when p53(-/-)RB(-/-) MSCs were inoculated embedded in a calcified ceramic scaffold composed of hydroxyapatite and tricalciumphosphate (HA/TCP), tumoral bone formation was observed in the surroundings of the HA/TCP scaffold. Moreover, the addition of BMP-2 to the ceramic/MSC implants further increased the tumoral osteoid matrix. Together, these data indicate that bone microenvironment signals are essential to drive OS development.

Expression of FUS-CHOP fusion protein in immortalized/transformed human mesenchymal stem cells drives mixoid liposarcoma formation.

Increasing evidence supports that mesenchymal stromal/stem cells (MSCs) may represent the target cell for sarcoma development. Although different sarcomas have been modeled in mice upon expression of fusion oncogenes in MSCs, sarcomagenesis has not been successfully modeled in human MSCs (hMSCs). We report that FUS-CHOP, a hallmark fusion gene in mixoid liposarcoma (MLS), has an instructive role in lineage commitment, and its expression in hMSC sequentially immortalized/transformed with up to five oncogenic hits (p53 and Rb deficiency, hTERT over-expression, c-myc stabilization, and H-RAS(v12) mutation) drives the formation of serially transplantable MLS. This is the first model of sarcoma based on the expression of a sarcoma-associated fusion protein in hMSC, and allowed us to unravel the differentiation processes and signaling pathways altered in the MLS-initiating cells. This study will contribute to test novel therapeutic approaches and constitutes a proof-of-concept to use hMSCs as target cell for modeling other fusion gene-associated human sarcomas.

Advanced Materials for Biomedical Applications, Editorial Article.

Advanced materials (AMs) encompass materials that feature improved properties compared to common counterparts [...].

Molecular and morphological identification of larvae of Carangidae (Teleostei, Carangiformes) species from southern Gulf of California.

The description of diagnostic morphological characters and DNA barcoding of fish larvae from nine species of the carangid family are provided from specimens collected during a weekly zooplankton time-series (2016-2017) at Cabo Pulmo National Park, Gulf of California, Mexico. Five nominal species (Caranxsexfasciatus, C.caballus, Naucratesductor, Selarcrumenophthalmus, and Seleneperuviana) and three morphotypes of Decapterus spp. and one of Caranx spp. were identified and separated based on morphological, meristic, and pigmentary diagnostic characters. All larvae were genetically sequenced for a fragment of the cytochrome c oxidase subunit I mitochondrial gene. Sequences of larval Caranx and Decapterus showed high genetic similarity (> 99%), low intraspecific divergence (< 1%), and an interspecific divergence between 6% and 11%, allowing the discrimination of diagnostic pigmentation patterns of fish larvae among three sibling species from each genus: Caranx (C.caballus, C.caninus, and C.sexfasciatus) and Decapterus (D.macarellus, D.macrosoma, and D.muroadsi). DNA barcoding supported the presence of Caranxcaballus, C.caninus, C.sexfasciatus, Decapterusmacarellus, D.muroadsi, Selarcrumenophthalmus, and Seleneperuviana, and for the first time Naucratesductor and D.macrosoma at the CPNP. Abundance of these nine species (confirmed molecularly) was estimated throughout the 2016-2017 weekly time series. Decapterusmacarellus and Caranxcaninus were the most abundant species. The morphological and molecular taxonomic methods allowed us to infer the species number and abundance of these commercial species at the CPNP to improve conservation in protected areas and fishery management.

A personalized medicine approach identifies enasidenib as an efficient treatment for IDH2 mutant chondrosarcoma.

BACKGROUND: Sarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. Among sarcomas, the clinical management of chondrosarcomas remains a complex challenge, as high-grade tumours do not respond to current therapies. Mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes are among the most common mutations detected in chondrosarcomas and may represent a therapeutic opportunity. The presence of mutated IDH (mIDH) enzymes results in the accumulation of the oncometabolite 2-HG leading to molecular alterations that contribute to drive tumour growth. METHODS: We developed a personalized medicine strategy based on the targeted NGS/Sanger sequencing of sarcoma samples (n = 6) and the use of matched patient-derived cell lines as a drug-testing platform. The anti-tumour potential of IDH mutations found in two chondrosarcoma cases was analysed in vitro, in vivo and molecularly (transcriptomic and DNA methylation analyses). FINDINGS: We treated several chondrosarcoma models with specific mIDH1/2 inhibitors. Among these treatments, only the mIDH2 inhibitor enasidenib was able to decrease 2-HG levels and efficiently reduce the viability of mIDH2 chondrosarcoma cells. Importantly, oral administration of enasidenib in xenografted mice resulted in a complete abrogation of tumour growth. Enasidenib induced a profound remodelling of the transcriptomic landscape not associated to changes in the 5 mC methylation levels and its anti-tumour effects were associated with the repression of proliferative pathways such as those controlled by E2F factors. INTERPRETATION: Overall, this work provides preclinical evidence for the use of enasidenib to treat mIDH2 chondrosarcomas. FUNDING: Supported by the Spanish Research Agency/FEDER (grants PID2022-142020OB-I00; PID2019-106666RB-I00), the ISC III/FEDER (PI20CIII/00020; DTS18CIII/00005; CB16/12/00390; CB06/07/1009; CB19/07/00057); the GEIS group (GEIS-62); and the PCTI (Asturias)/FEDER (IDI/2021/000027).

Exploring the Use of Cold Atmospheric Plasma to Overcome Drug Resistance in Cancer.

Drug resistance is a major problem in cancer treatment, as it limits the effectiveness of pharmacological agents and can lead to disease progression. Cold atmospheric plasma (CAP) is a technology that uses ionized gas (plasma) to generate reactive oxygen and nitrogen species (RONS) that can kill cancer cells. CAP is a novel approach for overcoming drug resistance in cancer. In recent years, there has been a growing interest in using CAP to enhance the effectiveness of chemotherapy drugs. In this review, we discuss the mechanisms behind this phenomenon and explore its potential applications in cancer treatment. Going through the existing literature on CAP and drug resistance in cancer, we highlight the challenges and opportunities for further research in this field. Our review suggests that CAP could be a promising option for overcoming drug resistance in cancer and warrants further investigation.

Cold plasma-treated medium preferentially eliminates doxorubicin-resistant osteosarcoma cells.

Osteosarcoma (OS) is an aggressive bone cancer with poor prognosis, largely due to the limited effectiveness of current treatments such as doxorubicin (DX). Developing ways to overcome DX resistance is a significant clinical challenge. Here, we used two DX-resistant models to study the potential of Cold Plasma Treated Medium (PTM) to prevent DX resistance in OS. During the acquisition of the resistant phenotype upon long-term DX exposure, OS resistant cells became less proliferative, overexpressed the drug resistance-related efflux pump MDR1 and displayed a concomitant loss of SOD2 or GPX1. According to the reduced expression of these antioxidant enzymes, PTM treatment produced higher levels of oxidative express and was more effective in eradicating DX-resistant cells. Moreover, PTM reduced the expression of MDR1, thus sensitizing resistant cells to DX. These findings uncover new vulnerabilities of DX-resistant cells related with their inability to cope with excessive oxidative stress and their dependence on MDR1 that can be exploited using PTM-based treatments to provide new therapeutic approaches for the management of drug resistance in OS.

Cold plasma and inhibition of STAT3 selectively target tumorigenicity in osteosarcoma.

Osteosarcoma (OS) is a malignant type of bone cancer that arises in periods of increased bone formation. Curative strategies for these types of tumors have remained essentially unchanged for decades and the overall survival for most advanced cases is still dismally low. This is in part due to the existence of drug resistant Cancer Stem Cells (CSC) with progenitor properties that are responsible for tumor relapse and metastasis. In the quest for therapeutic alternatives for OS, Cold Atmospheric Plasmas and Plasma-Treated Liquids (PTL) have come to the limelight as a source of Reactive Oxygen and Nitrogen Species displaying selectivity towards a variety of cancer cell lines. However, their effects on CSC subpopulations and in vivo tumor growth have been barely studied to date. By employing bioengineered 3D tumor models and in vivo assays, here we show that low doses of PTL increase the levels of pro-stemness factors and the self-renewal ability of OS cells, coupled to an enhanced in vivo tumor growth potential. This could have critical implications to the field. By proposing a combined treatment, our results demonstrate that the deleterious pro-stemness signals mediated by PTL can be abrogated when this is combined with the STAT3 inhibitor S3I-201, resulting in a strong suppression of in vivo tumor growth. Overall, our study unveils an undesirable stem cell-promoting function of PTL in cancer and supports the use of combinatorial strategies with STAT3 inhibitors as an efficient treatment for OS avoiding critical side effects. We anticipate our work to be a starting point for wider studies using relevant 3D tumor models to evaluate the effects of plasma-based therapies on tumor subpopulations of different cancer types. Furthermore, combination with STAT3 inhibition or other suitable cancer type-specific targets can be relevant to consolidate the development of the field.

Parkinson's disease updates: Addressing the pathophysiology, risk factors, genetics, diagnosis, along with the medical and surgical treatment.

After only Alzheimer's disease (AD), Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. The incidence of this disease increases with age, especially for those above 70 years old. There are many risk factors that are well-established in the contribution to the development of PD, such as age, gender, ethnicity, rapid eye movement sleep disorder, high consumption of dairy products, traumatic brain injury, genetics, and pesticides/herbicides. Interestingly, smoking, consumption of caffeine, and physical activities are the protective factors of PD. A deficiency of dopamine in the substantia nigra of the brainstem is the main pathology. This, subsequently, alters the neurotransmitter, causing an imbalance between excitatory and inhibitory signals. In addition, genetics is also involved in the pathogenesis of the disease. As a result, patients exhibit characteristic motor symptoms such as tremors, stiffness, bradykinesia, and postural instability, along with non-motor symptoms, including dementia, urinary incontinence, sleeping disturbances, and orthostatic hypotension. PD may resemble other diseases; therefore, it is important to pay attention to the diagnosis criteria. Parkinson's disease dementia can share common features with AD; this can include behavioral as well as psychiatric symptoms, in addition to the pathology being protein aggregate accumulation in the brain. For PD management, the administration of pharmacological treatment depends on the motor symptoms experienced by the patients. Non-pharmacological treatment plays a role as adjuvant therapy, while surgical management is indicated in chronic cases. This paper aims to review the etiology, risk factors, protective factors, pathophysiology, signs and symptoms, associated conditions, and management of PD.

Abrogation of stemness in osteosarcoma by the mithramycin analog EC-8042 is mediated by its ability to inhibit NOTCH-1 signaling.

Osteosarcomas are frequently associated to a poor prognosis and a modest response to current treatments. EC-8042 is a well-tolerated mithramycin analog that has demonstrated an efficient ability to eliminate tumor cells, including cancer stem cell subpopulations (CSC), in sarcomas. In transcriptomic and protein expression analyses, we identified NOTCH1 signaling as one of the main pro-stemness pathways repressed by EC-8042 in osteosarcomas. Overexpression of NOTCH-1 resulted in a reduced anti-tumor effect of EC-8042 in CSC-enriched 3D tumorspheres cultures. On the other hand, the depletion of the NOTCH-1 downstream target HES-1 was able to enhance the action of EC-8042 on CSCs. Moreover, HES1 depleted cells failed to recover after treatment withdrawal and showed reduced tumor growth potential in vivo. In contrast, mice xenografted with NOTCH1-overexpressing cells responded worse than parental cells to EC-8042. Finally, we found that active NOTCH1 levels in sarcoma patients was associated to advanced disease and lower survival. Overall, these data highlight the relevant role that NOTCH1 signaling plays in mediating stemness in osteosarcoma. Moreover, we demonstrate that EC-8042 is powerful inhibitor of NOTCH signaling and that the anti-CSC activity of this mithramycin analog highly rely on its ability to repress this pathway.