TRIM8 modulates the EWS/FLI oncoprotein to promote survival in Ewing sarcoma

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Amyloid precursor-like protein 2 suppresses irradiation-induced apoptosis in Ewing sarcoma cells and is elevated in immune-evasive Ewing sarcoma cells

Despite surgery, chemotherapy, and radiotherapy treatments, the children, adolescents, and young adults who are diagnosed with metastasized Ewing sarcoma face a dismal prognosis. Amyloid precursor-like protein 2 (APLP2) has recently been implicated in the survival of cancer cells and in our current study, APLP2’s contribution to the survival of Ewing sarcoma cells was examined. APLP2 was readily detected in all Ewing sarcoma cell lines analyzed by western blotting, with the TC71 Ewing sarcoma cells expressing the lowest level of APLP2 among the lines. While irradiation induces apoptosis in TC71 Ewing sarcoma cells (as we determined by quantifying the proportion of cells in the sub-G₁ population), transfection of additional APLP2 into TC71 decreased irradiation-induced apoptosis. Consistent with these findings, in parallel studies, we noted that isolates of the TC71 cell line that survived co-culture with lymphokine-activated killer (LAK) cells (which kill by inducing apoptosis in target cells) displayed increased expression of APLP2, in addition to smaller sub-G₁ cell populations after irradiation. Together, these findings suggest that APLP2 lowers the sensitivity of Ewing sarcoma cells to radiotherapy-induced apoptosis and that APLP2 expression is increased in Ewing sarcoma cells able to survive exposure to cytotoxic immune cells.     

PRAS40 deregulates apoptosis in malignant melanoma

Malignant melanoma is the most invasive and deadly form of skin cancer with no effective therapy to treat advanced disease, leading to poor survival rates. Akt3 signaling plays an important role in deregulating apoptosis in approximately 70% of melanomas. Thus, targeting Akt3 signaling in melanoma patients has significant therapeutic potential for inhibiting melanomas, but no Akt3-specific chemotherapeutic agent exists. Unfortunately, nonspecific Akt inhibitors can cause systemic toxicity or increase metastasis. Identifying and targeting the Akt3 substrate that deregulates apoptosis might circumvent these complications but would require demonstration of its functional importance in disrupting normal apoptosis. In this study, PRAS40 was identified as an Akt3 substrate that deregulated apoptosis to promote melanoma tumorigenesis. Levels of phosphorylated PRAS40 (pPRAS40) increased during melanoma tumor progression paralleling increasing Akt3 activity. Majority of melanomas from patients with elevated Akt activity also had correspondingly higher levels of pPRAS40. Targeting PRAS40 or upstream Akt3 similarly reduced anchorage-independent growth in culture and inhibited tumor development in mice. Mechanistically, decreased pPRAS40 increased tumor cell apoptosis as well as sensitivity of melanoma cells to apoptosis-inducing agents, thereby decreasing chemoresistance. Collectively, these studies provide a solid mechanistic basis for targeting PRAS40 to inhibit the Akt3 signaling cascade and thereby retard melanoma development.     

EphA2 receptor is a key player in the metastatic onset of Ewing sarcoma

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‐EphA2^S897), 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‐EphA2^S897. 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‐EphA2^S897 correlates with aggressiveness in ES, so blocking its function may be a promising treatment.     

Palliative radiation therapy for metastatic Ewing sarcoma

BACKGROUND: Although radiotherapy is an accepted component of curative treatment for Ewing sarcoma (EWS), to the authors' knowledge, there are scant data evaluating its use for palliation. The authors reviewed the Duke University Medical Center experience to evaluate treatment response and response durability. METHODS: Between 1980 and 2002, 21 patients with metastatic EWS received palliative radiotherapy. Pain was the primary indication for treatment. The majority of patients were male (n = 16 patients), and the median age at diagnosis was 11.6 years (range, 2.7-28.8 yrs). Fifty-two percent of patients had metastases at initial diagnosis. For the others, the median interval from initial diagnosis to metastases was 1.7 years. RESULTS: Sixty-three metastatic sites were irradiated (median dose, 30 gray [Gy]; range, 4.5-68.5 Gy), and a median of 3 sites were treated per patient (range, 1-16 sites per patient). At the time of last follow-up, 1 patient with a solitary brain metastasis has been disease free for 3.4 years after resection and cranial radiotherapy; all other patients died of their disease. Censoring this survivor, patients lived for a median of 1.0 year after metastatic diagnosis (range, from 17 days to 6.8 years), 41 days of which were spent in treatment (range, 1-93 days). Of all sites, 55% had a complete clinical response of symptoms, and 29% had a partial response. The median response duration was 4.0 months (range, 10 days to 4.8 years). Only the survivor was noted to have a treatment complication (growth hormone insufficiency). CONCLUSIONS: It was possible to treat metastatic EWS effectively with palliative radiotherapy. Because these patients live a median of 1 year after diagnosis of metastases, providing symptom relief without a protracted treatment course is valuable and appropriate therapy.     

Overexpressed PRAME is a potential immunotherapy target in sarcoma subtypes

Background

PRAME (preferentially expressed antigen in melanoma), a member of the cancer-testis antigen family, has been shown to have increased expression in solid tumors, including sarcoma, and PRAME-specific therapies are currently in development for other cancers such as melanoma.

Methods

To map the landscape of PRAME expression in sarcoma, we used publicly available data from The Cancer Genome Atlas (TCGA) and the Cancer Cell Line Encyclopedia (CCLE) projects and determined which sarcoma subtypes and subsets are associated with increased PRAME expression. We also analyzed how PRAME expression correlates with survival and expression of markers related to antigen presentation and T cell function. Furthermore, tumor and normal tissue expression comparisons were performed using data from the genotype-tissue expression (GTEx) project.

Results

We found that uterine carcinosarcoma highly overexpresses the PRAME antigen, and synovial sarcomas and multifocal leiomyosarcomas also show high expressions suggesting that PRAME may be an effective target of immunotherapies of these tumors. However, we also discovered that PRAME expression negatively correlates with genes involved in antigen presentation, and in synovial sarcoma MHC class I antigen presentation deficiencies are also present, potentially limiting the efficacy of immunotherapies of this malignancy.

Conclusions

We determined that uterine carcinosarcoma, synovial sarcoma, and leiomyosarcoma patients would potentially benefit from PRAME-specific immunotherapies. Tumor escape through loss of antigen presentation needs to be further studied.

     

Chemotherapy response is an important predictor of local recurrence in Ewing sarcoma

BACKGROUND: Local recurrence in Ewing sarcoma is associated with a poor prognosis. The purpose of the study was to determine the factors that predict local recurrence after surgical treatment of the primary tumor. METHODS: Between 1990 and 2001, 64 patients underwent surgical resection of Ewing sarcoma. Surgical margins were assessed histologically and radiologically. Response to preoperative chemotherapy was determined by detailed specimen mapping. Local recurrence-free survival (LRFS) was calculated by Kaplan-Meier analysis. Multivariate analysis was performed with the Cox proportional hazards model. RESULTS: A number of factors were found to be associated with local recurrence on univariate analysis. Patients with a good response to chemotherapy (> or = 90% tumor necrosis), had superior LRFS at 5 years (86% vs 51%, P = .015). Central site of disease was associated with an increased rate of recurrence. The LRFS at 5 years was 50% for the chest wall, 74% for pelvic/scapular, and 86% for extremity tumors (P = .083). Positive surgical margin was not a strong predictor of recurrence (P = .72). A critical analysis of minimal surgical margin based on preoperative magnetic resonance imaging (MRI) and computed tomography (CT) scans also failed to reveal an association between margin and local recurrence. In multivariate analysis, the 2 independent predictors of local recurrence were histological response to chemotherapy and central site of disease. CONCLUSION: Local recurrence after surgical resection is a complex phenomenon. An important predictive factor is the response to chemotherapy. In the current study, this seems to have the largest impact. Central site of disease may be a second independent predictive factor.     

Angiogenesis and vascular targeting in Ewing sarcoma

Ewing sarcoma is the second most common type of bone cancer in children and young adults. In recent years, the mechanisms by which these tumors develop and maintain their vascular supply have been elucidated. Additional work has demonstrated that inhibition of angiogenic pathways or disruption of established vasculature can attenuate the growth of Ewing sarcoma mouse xenografts. Early clinical data suggest that these results also may extend to patients with Ewing sarcoma who are treated with antiangiogenic or antivascular therapies. For the current review, the authors summarized the available data supporting this approach. Cancer 2010. © 2009 American Cancer Society.     

Complications in long-term survivors of Ewing sarcoma

BACKGROUND: Multimodality treatment has dramatically improved the outcome of patients with Ewing sarcoma. However, there appears to be little information concerning treatment-related complications in patients who are long-term survivors. METHODS: Forty-one patients with Ewing sarcoma who were treated between 1960-1980 and who survived the disease by at least 20 years were included in the current study. In a retrospective analysis, all complications related to the multimodality treatment of Ewing sarcoma were assessed. RESULTS: The patient group was comprised of 17 men and 24 women, with a mean age at the time of presentation of 16.8 years (range, 5-51 years). Approximately 20% of the lesions were located in the pelvis. All but 9 patients (78%) received chemotherapy as part of their treatment. The overall follow-up period averaged 25 years (range, 20-36 years). All except 1 patient were alive at the time of final follow-up, with the latter patient dying of radiation-induced secondary malignancy after 33 years. Only 17 patients (41%) were found to be free of any complication. These included metastases, local recurrence, secondary malignancies, pathologic fractures, and radiation-associated and chemotherapy-associated morbidities. CONCLUSIONS: Although the patients in the current study were treated successfully in terms of surviving an aggressive tumor, the high complication rate in this group of long-term survivors is noteworthy and indicates that long-term follow-up should be mandatory.     

Ewing sarcoma of the thoracic wall in a 54-year-old man

Ewing tumor is the second most common bone tumor in children. Its variant, malignant small cell tumor of the thoracopulmonary region, is infrequent in children and extremely rare in adults. A multimodal treatment approach is preferred for this tumor. We describe a rare case of primitive neuroectodermal tumor/Ewing sarcoma arising from the thoracic wall in a 54-year-old man. He underwent extensive resection of the tumor followed by adjuvant chemotherapy and radiotherapy.