Ewing sarcoma (ES) is the second most common bone malignancy affecting children and young adults with poor prognosis due to high metastasis incidence. Our group previously described that EphA2, a ...tyrosine kinase receptor, promotes angiogenesis in Ewing sarcoma (ES) cells via ligand‐dependent signaling. Now we wanted to explore EphA2 ligand‐independent activity, controlled upon phosphorylation at S897 (p‐EphA2S897), as it has been linked to metastasis in several malignancies. By reverse genetic engineering we explored the phenotypic changes after EphA2 removal or reintroduction. Gene expression microarray was used to identify key players in EphA2 signaling. Mice were employed to reproduce metastatic processes from orthotopically implanted engineered cells. We established a correlation between ES cells aggressiveness and p‐EphA2S897. Moreover, stable overexpression of EphA2 in low EphA2 expression ES cells enhanced proliferation and migration, but not a non‐phosphorylable mutant (S987A). Consistently, silencing of EphA2 reduced tumorigenicity, migration and invasion in vitro, and lung metastasis incidence in experimental and spontaneous metastasis assays in vivo. A gene expression microarray revealed the implication of EphA2 in cell signaling, cellular movement and survival. ADAM19 knockdown by siRNA technology strongly reproduced the negative effects on cell migration observed after EphA2 silencing. Altogether, our results suggest that p‐EphA2S897 correlates with aggressiveness in ES, so blocking its function may be a promising treatment.
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Ewing sarcoma (ES) tumors, the second most frequent bone tumors among children and adolescents, are very aggressive and tend to recur and metastasize. Lack of knowledge regarding the molecular mechanisms that regulate this metastatic process is the main reason for the lack of efficient therapeutics. Here, by using gain‐ and loss‐of‐function experiments and in vitro and in vivo assays, the authors established a correlation between ES aggressiveness and phosphorylation of the tyrosine kinase receptor EphA2. Altogether, the findings suggest that blocking EphA2 expression or its function with drugs or genetic tools may be of use for the treatment of ES.
Angiogenesis is the result of the combined activity of the tumor microenvironment and signaling molecules. The angiogenic switch is represented as an imbalance between pro- and anti-angiogenic ...factors and is a rate-limiting step in the development of tumors. Eph receptor tyrosine kinases and their membrane-anchored ligands, known as ephrins, constitute the largest receptor tyrosine kinase (RTK) subfamily and are considered a major family of pro-angiogenic RTKs. Ewing sarcoma (EWS) is a highly aggressive bone and soft tissue tumor affecting children and young adults. As other solid tumors, EWS are reliant on a functional vascular network for the delivery of nutrients and oxygen and for the removal of waste. Based on the biological roles of EphA2 in promoting angiogenesis, we explored the functional role of this receptor and its relationship with caveolin-1 (CAV1) in EWS angiogenesis. We demonstrated that lack of CAV1 results in a significant reduction in micro vascular density (MVD) on 3 different in vivo models. In vitro, this phenomenon correlated with inactivation of EphA2 receptor, lack of AKT response and downregulation of bFGF. We also demonstrated that secreted bFGF from EWS cells acted as chemoattractant for endothelial cells. Furthermore, interaction between EphA2 and CAV1 was necessary for the right localization and signaling of the receptor to produce bFGF through AKT and promote migration of endothelial cells. Finally, introduction of a dominant-negative form of EphA2 into EWS cells mostly reproduced the effects occurred by CAV1 silencing, strongly suggesting that the axis EphA2-CAV1 participates in the promotion of endothelial cell migration toward the tumors favoring EWS angiogenesis.
Colorectal cancer is the second cause of cancer-related death in the western world, and although the genetic and molecular mechanisms involved in the initiation and progression of these tumors are ...among the best characterized, there are significant gaps in our understanding of this disease. The role of EPHB signaling in colorectal cancer has only recently been realized. Here, we use animal models to investigate the role of EphB4 in intestinal tumorigenesis. Modulation of EPHB4 levels in colon cancer cell lines resulted in significant differences in tumor growth in a xenograft model, with low levels of EPHB4 associated with faster growth. In addition, using a genetic model of intestinal tumorigenesis where adenomatous polyposis coli (Apc) mutations lead to initiation of the tumorigenic process (Apc(min) mice), we show that inactivation of a single allele of EphB4 results in higher proliferation in both the normal epithelium and intestinal tumors, significantly larger tumors in the small intestine, and a 10-fold increase in the number of tumors in the large intestine. This was associated with a 25% reduction in the lifespan of Apc(min) mice (P < 0.0001). Gene expression analysis showed that EphB4 mutations result in a profound transcriptional reprogramming, affecting genes involved in cell proliferation, remodeling of the extracellular matrix, and cell attachment to the basement membrane among other functional groups of genes. Importantly, in agreement with the expression profiling experiments, using an in vitro assay, we show that loss of EPHB4 in colon cancer cells results in a significantly increased potential to invade through a complex extracellular matrix. Collectively, these results indicate that EphB4 has tumor suppressor activities and that regulation of cell proliferation, extracellular matrix remodeling, and invasive potential are important mechanisms of tumor suppression.
Cell death can occur through different mechanisms, defined by their nature and physiological implications. Correct assessment of cell death is crucial for cancer therapy success. Sarcomas are a large ...and diverse group of neoplasias from mesenchymal origin. Among cell death types, apoptosis is by far the most studied in sarcomas. Albeit very promising in other fields, regulated necrosis and other cell death circumstances (as so-called "autophagic cell death" or "mitotic catastrophe") have not been yet properly addressed in sarcomas. Cell death is usually quantified in sarcomas by unspecific assays and in most cases the precise sequence of events remains poorly characterized. In this review, our main objective is to put into context the most recent sarcoma cell death findings in the more general landscape of different cell death modalities.
Sacral neuromodulation (SNM) is a minimally invasive therapy for defecatory disorders. PEAK Plasma Blade™ (Medtronic) has been used as an alternative to the conventional electric scalpel and scissors ...in 3 procedures of neuromodulation. PEAK PlasmaBlade™ uses less total energy, operating at significantly lower temperatures than electrosurgical technology. No damage to the wires or pulse generators or patient complications were detected during the surgery or follow-up. A reduction in the duration of the procedures was noted.
Alveolar and embryonal rhabdomyosarcomas are childhood tumors that do not respond well to current chemotherapies. Here, we report that the glycolytic inhibitor 2-deoxyglucose (2-DG) can efficiently ...promote cell death in alveolar, but not embryonal, rhabdomyosarcoma cell lines. Notably, 2-DG also induced cell differentiation accompanied by downregulation of PAX3/FOXO1a, the chromosome translocation-encoded fusion protein that is a central oncogenic driver in this disease. Cell death triggered by 2-DG was associated with its ability to activate Bax and Bak. Overexpression of the antiapoptotic Bcl-2 homologues Bcl-x(L) and Mcl-1 prevented apoptosis, indicating that cell death proceeds through the mitochondrial pathway. Mechanistic investigations indicated that Mcl-1 downregulation and Noxa upregulation were critical for 2-DG-induced apoptosis. In addition, 2-DG promoted eIF2α phosphorylation and inactivation of the mTOR pathway. Mcl-1 loss and cell death were prevented by downregulation of the endoplasmic reticulum (ER) stress-induced protein ATF4 and by incubating cells in the presence of mannose, which reverted 2-DG-induced ER stress but not ATP depletion. Thus, energetic stresses created by 2-DG were not the primary cause of cell death. Together, our findings suggest that glycolysis inhibitors such as 2-DG may be highly effective in treating alveolar rhabdomyosarcoma and that Noxa could offer a prognostic marker to monitor the efficacy of such agents.
The MAPK pathway is a signaling network that plays a key role in many normal cellular processes and in a large number of human malignancies. One of its effectors, MEK, is essential for the ...carcinogenesis of different tumors. In recent years, several drugs able to inhibit MEK have been assessed in clinical trials. Trametinib has recently become the first MEK inhibitor licensed for cancer treatment (advanced melanoma).
We comprehensively review the safety and clinical efficacy of the family of MEK inhibitors, either alone or in combination with other drugs. We discuss data ranging from the Phase III trial of trametinib in melanoma to the most recent drugs with early signs of antitumor activity. In addition, we explain the reasons for the unsuccessful results of the early trials with MEK inhibitors and provide a view of their role in cancer treatment in forthcoming years.
MEK inhibitors are a potentially safe and active treatment option for the treatment of many human malignancies. The information provided by a large series of studies currently ongoing will be very valuable in order to optimize their use. Adequate selection of patients is crucial for achieving successful results with these compounds.
INTRODUCTIONDuring the state of alarm established in Spain due to the COVID-19 pandemic, most of the face-to-face outpatient consultations were cancelled and a telephone consultation was established ...to follow up coloproctological patients. The objective of this study was to analyse the efficacy of telemedicine (by telephone) in monitoring patients in a coloproctology unit, in the context of the COVID-19 pandemic. METHODProspective descriptive study of consecutive patients in a single centre. The result of the teleconsultation was classified as discharge, resolved visit or reprogramming and was analysed by different diagnostic groups. RESULTSFrom March 19th to April 17th, 2020, the teleconsultation of 190 patients was carried out. The response rate was 94.2% (179). The diagnostic categories of the patients attended were: 51 (26.9%) colorectal neoplasia, 48 (25.3%) proctological pathology, 72 (37.9%) pelvic floor dysfunctions and 19 (10%) other benign pathologies. 105 (55.26%) could be recited as if they had come in person. Eleven (5.8%) patients were discharged. No significant differences were found between the different diagnostic categories and the resolution of the teleconsultation. The reasons for reprogramming are analyzed in the study. CONCLUSIONIn the context of a pandemic, teleconsultation has allowed 61% of follow-up visits to be definitively solved, avoiding the reprogramming of 116 patients. The new social and health paradigm after the pandemic will require a rethinking of our healthcare model, and in many aspects, telemedicine can offer tools for this.
Abstract
Pediatric sarcomas are a heterogeneous group of bone and soft tissue malignancies affecting children and young adults. One of the most important prognostic factors of those diseases is the ...presence of metastasis at diagnosis. In that context, we have developed a novel orthotopic model which consists in injecting Ewing Sarcoma (ES) or Rhabdomyosarcoma (RMS) tumor cells at the gastrocnemius muscle of mice and extracting the tumor at a of 10 mm x 13 mm volume. After surgery, animals maintain a complete functional extremity and can live until lung metastasis detection (about 60 days post-injection).
Moreover, we have validated the suitability of the model with an Ewing Sarcoma EphA2-low expression cell line. Epha2 is a tyrosine kinase receptor that has been found overexpressed in a wide variety of tumors and correlated with malignant phenotype. In this study we report that EphA2 receptor is phosphorylated at S897 in a panel of ES cell lines, which is related to the oncogenic properties of the receptor. Stable silencing of EphA2 in two different ES cell lines resulted in a decrease in the clonogenic, proliferation, migration and invasion capacity in vitro. Moreover, we performed an experimental metastasis assay, injecting tumor cells through the tail vain of mice and observed a reduction in the lung metastasis incidence in EphA2 silenced cells. We then used this new orthotopic metastasis model to validate the impairment in the invasion capacity of EphA2 silenced cells and confirm the decrease in lung metastasis incidence, indicating an oncogenic role for EphA2 in ES. This novel orthotopic metastasis model is a valuable tool both for the study of spontaneous metastasis and also for evaluating therapeutic index in the onset of metastasis, which can also be applied to the study of other pedriatric sarcomas.
Citation Format: Silvia Garcia Monclús, Juan Huertas Martínez, Laura Lagares Tena, Santiago Rello Varona, Olga Almacellas Rabaiget, David Herrero Martin, Roser López Alemany, Oscar Martinez Tirado. A novel orthotopic mouse model in sarcomas abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1929. doi:10.1158/1538-7445.AM2017-1929
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