Tissue Sarcoma In Children Research Articles

Processo diagnostico di una lesione orale inusuale

ObjectivesRhabdomyosarcoma, which was first described in 1854, is a malignant soft tissue neoplasm of skeletal muscle origin, which accounts for more than 50% of soft tissue sarcomas in children and adolescents. Clinical manifestations of rhabdomyosarcoma are not conclusive, making diagnosis challenging. Materials and methodsWe present a peculiar case of a young 24-year-old adult, who was diagnosed with oral rhabdomyosarcoma after a multi-step diagnostic process. In the diagnostic pathway, dall’odonhistopathology, immunohistochemistry and imaging were necessary and complementary to clinical features. Results and conclusionsEarly diagnosis of malignant oral lesions has a key-role in determining their prognosis. A conscious and critical attitude is mandatory to avoid diagnostic and therapeutic errors. Moreover, suspicious or doubtful cases should be immediately referred to specialized clinical settings, in order to optimize the management of their diagnostic and therapeutic plan.

The Evolution of Pediatric Soft Tissue Sarcoma Classification in the Last 50 Years.

This review discusses the history of the classification of soft tissue sarcomas in children and adolescents, the current transition toward integration of morphology and molecular genetics as new entities emerge, and future perspectives.

The synthetic retinoid ST1926 as a novel therapeutic agent in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children. Despite multiple attempts at intensifying chemotherapeutic approaches to treatment, only moderate improvements in survival have been made for patients with advanced disease. Retinoic acid is a differentiation agent that has shown some antitumor efficacy in RMS cells in vitro; however, the effects are of low magnitude. E-3-(4'-hydroxyl-3'-adamantylbiphenyl-4-yl) acrylic acid (ST1926) is a novel orally available synthetic atypical retinoid, shown to have more potent activity than retinoic acid in several types of cancer cells. We used in vitro and in vivo models of RMS to explore the efficacy of ST1926 as a possible therapeutic agent in this sarcoma. We found that ST1926 reduced RMS cell viability in all tested alveolar (ARMS) and embryonal (ERMS) RMS cell lines, at readily achievable micromolar concentrations in mice. ST1926 induced an early DNA damage response (DDR), which led to increase in apoptosis, in addition to S-phase cell cycle arrest and a reduction in protein levels of the cell cycle kinase CDK1. Effects were irrespective of TP53 mutational status. Interestingly, in ARMS cells, ST1926 treatment decreased PAX3-FOXO1 fusion oncoprotein levels, and this suppression occurred at a post-transcriptional level. In vivo, ST1926 was effective in inhibiting growth of ARMS and ERMS xenografts, and induced a prominent DDR. We conclude that ST1926 has preclinical efficacy against RMS, and should be further developed in this disease in clinical trials.

Genetic heterogeneity in rhabdomyosarcoma revealed by SNP array analysis.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents. Alveolar (ARMS) and embryonal (ERMS) histologies predominate, but rare cases are classified as spindle cell/sclerosing (SRMS). For treatment stratification, RMS is further subclassified as fusion-positive (FP-RMS) or fusion-negative (FN-RMS), depending on whether a gene fusion involving PAX3 or PAX7 is present or not. We investigated 19 cases of pediatric RMS using high resolution single-nucleotide polymorphism (SNP) array. FP-ARMS displayed, on average, more structural rearrangements than ERMS; the single FN-ARMS had a genomic profile similar to ERMS. Apart from previously known amplification (e.g., MYCN, CDK4, and MIR17HG) and deletion (e.g., NF1, CDKN2A, and CDKN2B) targets, amplification of ERBB2 and homozygous loss of ASCC3 or ODZ3 were seen. Combining SNP array with cytogenetic data revealed that most cases were polyploid, with at least one case having started as a near-haploid tumor. Further bioinformatic analysis of the SNP array data disclosed genetic heterogeneity, in the form of subclonal chromosomal imbalances, in five tumors. The outcome was worse for patients with FP-ARMS than ERMS or FN-ARMS (6/8 vs. 1/9 dead of disease), and the only children with ERMS showing intratumor diversity or with MYOD1 mutation-positive SRMS also died of disease. High resolution SNP array can be useful in evaluating genomic imbalances in pediatric RMS.

Cyclophosphamide versus ifosfamide for paediatric and young adult bone and soft tissue sarcoma patients.

Alkylating agents, such as cyclophosphamide and ifosfamide, play a major role in the improved survival of children and young adults with bone and soft tissue sarcoma. However, there is still controversy as to their comparative anti-tumour efficacy and possible adverse effects. This is the second update of the first systematic review evaluating the state of evidence on the effectiveness of cyclophosphamide as compared to ifosfamide for paediatric and young adult patients with sarcoma. The primary obective was to compare the effectiveness, that is response rate, event-free survival and overall survival, of cyclophosphamide with that of ifosfamide for paediatric and young adult patients with sarcoma. Secondary objectives were to determine effects of these agents on toxicities (including late effects) and quality of life. We searched CENTRAL (The Cochrane Library 2015, issue 2), MEDLINE/PubMed (from 1966 to March 2015) and EMBASE/Ovid (from 1980 to March 2015) with prespecified terms. In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trial databases (www.controlled-trials.com; searched June 2015). Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing cyclophosphamide and ifosfamide for the treatment of different types of sarcoma in paediatric and young adult patients (aged less than 30 years at diagnosis). Chemotherapy other than either cyclophosphamide or ifosfamide should have been the same in both treatment groups. Two authors independently performed the study selection. No studies meeting the inclusion criteria of the review were identified. No RCTs or CCTs comparing the effectiveness of cyclophosphamide and ifosfamide in the treatment of bone and soft tissue sarcoma in children and young adults were identified. Therefore no definitive conclusions can be made about the effects of cyclophosphamide and ifosfamide in these patients. Based on the currently available evidence, we are not able to give recommendations for clinical practice. More high-quality research is needed.

C-type natriuretic peptide/guanylyl cyclase-B (GC-B) system attenuates proliferation of rhabdomyosarcoma in combination with sildenafil: A novel anticancer therapy

Background/purpose Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Since patients with high-risk RMS have limited treatment options and a poor prognosis, and late complications including growth disturbance and secondary cancer induced by chemotherapy or radiation therapy are essential problems, novel therapies are urgently needed. C-type natriuretic peptide (CNP) has physiological activity mainly for mesenchymal cells to inhibit cell proliferation. We hypothesized that CNP attenuates proliferation of human RMS, a malignant mesenchymal tumor and provide rationale for using CNP to treat RMS.

Abstract 3571: Furin activity: A driver of rhabdomyosarcoma progression

Abstract Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. The prognosis and survival rate is often very poor and therefore new therapy approaches are required. Thus, we focus on 1) employing RMS-specific peptides for targeted delivery of chemotherapeutics to the tumor site and 2) identifying novel therapeutic targets. In a previous study we discovered that RMS-homing peptides bind preferably to the proprotein convertase furin. Initial investigations confirmed a high expression of furin throughout different pediatric soft tissue sarcoma types and hinted that furin promotes the tumorigenic phenotype of RMS cells in vitro as well as in corresponding xenografts in vivo. Here we present a novel approach of tetracycline-induced shRNA-based silencing of furin in vitro and in vivo in order to investigate in depth the role of furin in RMS progression. Furin depletion was confirmed at mRNA, protein and activity level and led to impaired maturation furin substrates insulin like growth factor 1 receptor (IGF1R) and transforming growth factor beta 1 (TGFβ-1). We found that loss of furin activity suppresses the malignant phenotype of Rh30 cells by decreasing proliferation and affecting formation of colonies. Furthermore, we observed increased caspase 3/7 activity and enrichment of nucleosomes in the cytoplasm upon furin depletion, thus hinting initiation of apoptotic processes. Induction of furin silencing in RMS xenografts in NOD/SCID mice delayed tumour growth, indicating a crucial role of furin in early phases of tumour growth. Taken together, our data underscore the importance of furin for RMS progression and therefore targeting the activity of furin represents a promising tool for treatment of RMS. Citation Format: Patricia AIM Jaaks, Gianmarco Meier, Beat W. Schäfer, Michele Bernasconi. Furin activity: A driver of rhabdomyosarcoma progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3571. doi:10.1158/1538-7445.AM2015-3571

Abstract 28: Deregulation of NAC complex inhibits muscle differentiation and blocks apoptosis in rhabdomyosarcoma cells

Abstract Rhabdomyosarcoma (RMS) is a common malignant soft tissue sarcoma in children with limited treatment options and high failure rate during standard therapy. New therapeutic targets or strategies are therefore in high demand. The NAC complex performs many diverse biological functions, and the deregulation of its subunits has been correlated with many cancers. We sought to understand the function of NAC complex in normal muscle cells and rhabdomyosarcoma cells. With western blot, quantitative real time PCR (qRT-PCR), chromatin immunoprecipitation and immunostaining analysis, we found that the muscle specific subunit of NAC complex, skNAC, which is the alternatively spliced isoform of NACα, was downregulated in RMS cells. In normal cells, skNAC shuttled from the cytoplasm to the nucleus upon differentiation. We also showed that skNAC associated with muscle specific promoters together with BTF3 in differentiated cells, and this association is dependent on the expression of BTF3. The expression of skNAC was regulated by the splicing factor SRPK3, a serine arginine protein kinase. Overexpression of SPRK3 induced skNAC expression and muscle differentiation. We also detected the deregulation of another NAC complex subunit, NACβ (also known as BTF3). We found that BTF3 is highly overexpressed and localized in the nucleus in both RMS cell lines and human RMS tumor samples compared with normal samples. Depletion of BTF3 induced apoptosis as detected by the strong cleavage of PARP and caspase 3. BTF3 depletion also decreased the cell viability in RMS by a cologenic assay. We also confirmed that BTF3 downregulation promoted muscle gene expression and induced muscle differentiation in RMS cells. However, BTF3 played a different role in normal cells. With the deletion of BTF3 in C2C12 cells, no apoptosis signal was detected and cell differentiation was inhibited, which suggested that a precise level of BTF3 is important for normal cell function. In conclusion, we found that the NAC complex subunits, skNAC and BTF3, were deregulated in RMS cells. The restoration of skNAC by SRPK3 overexpression rescued muscle differentiation. BTF3 functioned as an anti-apoptosis factor in RMS cells and depletion of BTF3 induced apoptosis and promoted differentiation. With no apoptosis effect in normal cells, BTF3 could serve as a cancer specific therapeutic target in RMS cells. Citation Format: Meiling Zhang, Judith Davie. Deregulation of NAC complex inhibits muscle differentiation and blocks apoptosis in rhabdomyosarcoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 28. doi:10.1158/1538-7445.AM2015-28

Abstract 2488: FGFR4 as a potential therapeutic target for monoclonal antibody based intervention in rhabdomyosarcoma

Abstract Background: Rhabdomyosarcoma (RMS) is most common soft tissue sarcoma in childhood and adolescence. There are two major subtypes of RMS - alveolar RMS (ARMS) and embryonal RMS (ERMS). With current treatment modalities the 5 year survival rate of patients with metastatic disease is only about 30%, thus necessitating development of novel targeted therapeutic strategies. Fibroblast Growth Factor Receptor 4 (FGFR4) is highly differentially expressed gene and activating mutations in FGFR4 is associated with increase in RMS metastasis. We hypothesize that FGFR4 can be exploited as a potential therapeutic target in RMS. Monoclonal antibodies (mAbs) against specific cancer cell surface antigens, have gained importance as therapeutic agents in other cancer types. Therefore, mAbs against FGFR4 may be developed either alone or conjugated with a chemotherapeutic agent for treatment of RMS. Methods: We have developed 15 mAbs that are of mouse, rabbit and human origin. The immunogen for rabbit antibodies is human FGFR4 extracellular domain (ECD), while human FGFR4-Fc chimeric protein or hFGFR4 transfected cells were used for mouse antibodies and were produced using hybridoma technology. Using recombinant DNA technology, human immunoglobulin library was selected using FGFR4 ECD to derive human anti-FGFR4 mAbs. All mAbs were purified using affinity chromatography and reactivity was confirmed by ELISA. These mAbs were tested for their ability to bind cell surface FGFR4 and internalization of mAb bound FGFR4 (upon incubation at 37°C) by flow cytometry using RMS cell lines. To further characterize these antibodies we have performed immunohistochemistry (IHC) on tissue microarrays (TMA) of normal tissue, xenografts of RMS cell lines, and primary tumor from RMS patients. Finally, to select a potential mAb candidate as therapeutic agent, we tested appropriate secondary antibody-drug conjugate (ADC) using cell based cytotoxic assay. Results: We observed that tested mAbs bind to both ARMS and ERMS cell lines. The level of FGFR4 expression is variable in both subtypes. Internalization assays demonstrated mAbs bound FGFR4 was internalized in RMS cell lines. Analysis by IHC on TMAs suggests that FGFR4 protein is expressed at a considerably higher level in RMS tumor tissue and xenografts compared to normal tissue. Based on these findings, we are currently screening the mAbs for their ability to elicit a cytotoxic response either alone or in conjunction with secondary ADC. Conclusion: These results suggest anti-FGFR4 mAbs can be used as therapeutic intervention for RMS. High expression of FGFR4 in other cancers such as prostate, melanoma, lung, breast, colorectal, and gastric cancers suggests the potential use of anti-FGFR4 mAbs and their derivatives in these cancers. Citation Format: Sivasubramanian Baskar, Nityashree Shivaprasad, Zhongyu Zhu, Dimiter Dimitrov, Mhairi Sigrist, Poul Sorensen, Marielle Yohe, John Shern, John Maris, Crystal Mackall, Javed Khan. FGFR4 as a potential therapeutic target for monoclonal antibody based intervention in rhabdomyosarcoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2488. doi:10.1158/1538-7445.AM2015-2488

Abstract 2102: TBX2 promotes rhabdomyosarcoma (RMS) tumorigenesis by repression of PTEN expression

Abstract RMS is most common soft tissue sarcoma in children. We previously identified TBX2 as an oncogene and showed that TBX2 is required for tumor formation. Here, we identified the tumor suppressor PTEN as a novel target of TBX2 in RMS and normal muscle. PTEN, which regulates the PI3K-AKT pathway, is repressed in RMS. Our work shows that TBX2 functions to regulate PTEN expression and thus, PI3K-AKT signaling, to enhance the malignancy of RMS tumors. Both quantitative real time PCR and western blot assays were used to assay PTEN expression at the level of mRNA and protein respectively. Immunofluorescence staining was performed to assay the protein expression in human RMS tumor samples. Muscle tissue slides of proliferating myoblasts were assayed by co-immunofluorescence staining, and the proliferating myoblasts were induced by activating satellite cells with cardiotoxin induced muscle damage. Reporter constructs for luciferase assay were based on PTEN promoter. Chromatin immunoprecipitation (ChIP) assays were used to detect protein binding on gene promoters. Xenograft assays were conducted to assay TBX2 function in tumor malignancy. We have found that PTEN was up-regulated upon muscle differentiation, but little expression of PTEN was observed in RMS cells. Although TBX2 was expressed in proliferating myoblasts, it was highly down-regulated upon myogenic differentiation. Human RMS tumor samples showed a down-regulation of PTEN and an up-regulation of TBX2 compared with normal tissues. Over-expression of TBX2 repressed PTEN expression in both C2C12 myoblasts and 10T1/2 fibroblasts. Either depletion of TBX2 or a dominant negative TBX2 increased PTEN expression in RMS cells. Luciferase assays confirmed the regulation of PTEN by TBX2 and ChIP assays demonstrated that TBX2 recruited HDAC1 to the PTEN promoter for repression. The role of HDAC1 in repression of PTEN was confirmed by treatment with HDAC inhibitors, which abrogated the repression of PTEN by TBX2. This work demonstrates that the high expression of TBX2 in RMS is involved in the activation of PI3K-AKT signaling pathway by repressing PTEN, underlying the oncogenic function of TBX2 in tumor cells. Citation Format: Bo K. Zhu, Judith K. Davie. TBX2 promotes rhabdomyosarcoma (RMS) tumorigenesis by repression of PTEN expression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2102. doi:10.1158/1538-7445.AM2015-2102

Hedgehog Inhibitors in Rhabdomyosarcoma: A Comparison of Four Compounds and Responsiveness of Four Cell Lines.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and is divided into two major histological subgroups, i.e., embryonal (ERMS) and alveolar RMS (ARMS). RMS can show HEDGEHOG/SMOOTHENED (HH/SMO) signaling activity and several clinical trials using HH inhibitors for therapy of RMS have been launched. We here compared the antitumoral effects of the SMO inhibitors GDC-0449, LDE225, HhA, and cyclopamine in two ERMS (RD, RUCH-2) and two ARMS (RMS-13, Rh41) cell lines. Our data show that the antitumoral effects of these SMO inhibitors are highly divers and do not necessarily correlate with inhibition of HH signaling. In addition, the responsiveness of the RMS cell lines to the drugs is highly heterogeneous. Whereas some SMO inhibitors (i.e., LDE225 and HhA) induce strong proapoptotic and antiproliferative effects in some RMS cell lines, others paradoxically induce cellular proliferation at certain concentrations (e.g., 10 μM GDC-0449 or 5 μM cyclopamine in RUCH-2 and Rh41 cells) or can increase HH signaling activity as judged by GLI1 expression (i.e., LDE225, HhA, and cyclopamine). Similarly, some drugs (e.g., HhA) inhibit PI3K/AKT signaling or induce autophagy (e.g., LDE225) in some cell lines, whereas others cannot (e.g., GDC-0449). In addition, the effects of SMO inhibitors are concentration-dependent (e.g., 1 and 10 μM GDC-0449 decrease GLI1 expression in RD cells whereas 30 μM GDC-0449 does not). Together these data show that some SMO inhibitors can induce strong antitumoral effects in some, but not all, RMS cell lines. Due to the highly heterogeneous response, we propose to conduct thorough pretesting of SMO inhibitors in patient-derived short-term RMS cultures or patient-derived xenograft mouse models before applying these drugs to RMS patients.

The synthetic retinoid ST1926 as a novel therapeutic agent in rhabdomyosarcoma.

e21010 Background: Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children. Despite multiple attempts at intensifying chemotherapeutic approaches to treatment, only moderate imp...

Risk-based treatment for synovial sarcoma in patients under 30 years of age: Children’s Oncology Group study ARST0332.

10012 Background: Synovial sarcoma (SS) is the second most common soft tissue sarcoma in children. ARST0332 evaluated a risk-based treatment strategy for young soft tissue sarcoma patients designed...

Aldehyde Dehydrogenase 1 (ALDH1) Is a Potential Marker for Cancer Stem Cells in Embryonal Rhabdomyosarcoma.

Cancer stem cells (CSCs) are defined as a small population of cancer cells with the properties of high self-renewal, differentiation, and tumor-initiating functions. Recent studies have demonstrated that aldehyde dehydrogenase 1 (ALDH1) is a marker for CSCs in adult cancers. Although CSCs have been identified in some different types of pediatric solid tumors, there have been no studies regarding the efficacy of ALDH1 as a marker for CSCs. Therefore, in order to elucidate whether ALDH1 can be used as a marker for CSCs of pediatric sarcoma, we examined the characteristics of a population of cells with a high ALDH1 activity (ALDH1high cells) in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. We used the human embryonal RMS (eRMS) cell lines RD and KYM-1, and sorted the cells into two subpopulations of ALDH1high cells and cells with a low ALDH1 activity (ALDH1low cells). Consequently, we found that the ALDH1high cells comprised 3.9% and 8.2% of the total cell population, respectively, and showed a higher capacity for self-renewal and tumor formation than the ALDH1low cells. With regard to chemoresistance, the survival rate of the ALDH1high cells was found to be higher than that of the ALDH1low cells following treatment with chemotherapeutic agents for RMS. Furthermore, the ALDH1high cells exhibited a higher degree of pluripotency and gene expression of Sox2, which is one of the stem cell markers. Taken together, the ALDH1high cells possessed characteristics of CSCs, including colony formation, chemoresistance, differentiation and tumor initiation abilities. These results suggest that ALDH1 is a potentially useful marker of CSCs in eRMS.

A Patient-Derived Xenograft Model of Parameningeal Embryonal Rhabdomyosarcoma for Preclinical Studies

Embryonal rhabdomyosarcoma (eRMS) is one of the most common soft tissue sarcomas in children and adolescents. Parameningeal eRMS is a variant that is often more difficult to treat than eRMS occurring at other sites. A 14-year-old female with persistent headaches and rapid weight loss was diagnosed with parameningeal eRMS. She progressed and died despite chemotherapy with vincristine, actinomycin-D, and cyclophosphamide plus 50.4 Gy radiation therapy to the primary tumor site. Tumor specimens were acquired by rapid autopsy and tumor tissue was transplanted into immunodeficient mice to create a patient-derived xenograft (PDX) animal model. As autopsy specimens had an ALK R1181C mutation, PDX tumor bearing animals were treated with the pan-kinase inhibitor lestaurtinib but demonstrated no decrease in tumor growth, suggesting that single agent kinase inhibitor therapy may be insufficient in similar cases. This unique parameningeal eRMS PDX model is publicly available for preclinical study.

Alternative Splicing of MEF2C pre-mRNA Controls Its Activity in Normal Myogenesis and Promotes Tumorigenicity in Rhabdomyosarcoma Cells

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Many cellular disruptions contribute to the progression of this pediatric cancer, including aberrant alternative splicing. The MEF2 family of transcription factors regulates many developmental programs, including myogenesis. MEF2 gene transcripts are subject to alternate splicing to generate protein isoforms with divergent functions. We found that MEF2Cα1 was the ubiquitously expressed isoform that exhibited no myogenic activity and that MEF2Cα2, the muscle-specific MEF2C isoform, was required for efficient differentiation. We showed that exon α in MEF2C was aberrantly alternatively spliced in RMS cells, with the ratio of α2/α1 highly down-regulated in RMS cells compared with normal myoblasts. Compared with MEF2Cα2, MEF2Cα1 interacted more strongly with and recruited HDAC5 to myogenic gene promoters to repress muscle-specific genes. Overexpression of the MEF2Cα2 isoform in RMS cells increased myogenic activity and promoted differentiation in RMS cells. We also identified a serine protein kinase, SRPK3, that was down-regulated in RMS cells and found that expression of SRPK3 promoted the splicing of the MEF2Cα2 isoform and induced differentiation. Restoration of either MEF2Cα2 or SPRK3 inhibited both proliferation and anchorage-independent growth of RMS cells. Together, our findings indicate that the alternative splicing of MEF2C plays an important role in normal myogenesis and RMS development. An improved understanding of alternative splicing events in RMS cells will potentially reveal novel therapeutic targets for RMS treatment.

Rhabdomyosarcoma of the head and neck in children.

Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children. It is localized in the head and neck region in 40% of cases. Treatment of RMS is complex, including multi-drug chemotherapy, radiotherapy and surgery. The progress that has been accomplished in oncology in recent decades significantly improved outcomes. The 5-year survival rate raised from 25% in 1970 to 73% in 2001, according to IRS-IV data. The outcome is influenced by primary tumor localization, clinical staging, histological tumor type and age at the moment of diagnosis. The relatively rare incidence of these tumors resulted in difficulties in creating more standardized therapeutic protocols. Comparison of outcomes in large patients groups led to an increase in the number of patients with complete remission. Although survival rates of RMS patients have improved, searching for new therapeutic modalities and substances is still essential to improve outcomes in cases of more advanced stages and unfavorable tumor localizations.

Deep Sequencing the microRNA profile in rhabdomyosarcoma reveals down-regulation of miR-378 family members.

BackgroundRhabdomyosarcoma (RMS) is a highly malignant tumour accounting for nearly half of soft tissue sarcomas in children. MicroRNAs (miRNAs) represent a class of short, non-coding, regulatory RNAs which play a critical role in different cellular processes. Altered miRNA levels have been reported in human cancers, including RMS.MethodsUsing deep sequencing technology, a total of 685 miRNAs were investigated in a group of alveolar RMSs (ARMSs), embryonal RMSs (ERMSs) as well as in normal skeletal muscle (NSM). Q-PCR, MTT, cytofluorimetry, migration assay, western blot and immunofluorescence experiments were carried out to determine the role of miR-378a-3p in cancer cell growth, apoptosis, migration and differentiation. Bioinformatics pipelines were used for miRNA target prediction and clustering analysis.ResultsNinety-seven miRNAs were significantly deregulated in ARMS and ERMS when compared to NSM. MiR-378 family members were dramatically decreased in RMS tumour tissue and cell lines. Interestingly, members of the miR-378 family presented as a possible target the insulin-like growth factor receptor 1 (IGF1R), a key signalling molecule in RMS. MiR-378a-3p over-expression in an RMS-derived cell line suppressed IGF1R expression and affected phosphorylated-Akt protein levels. Ectopic expression of miR-378a-3p caused significant changes in apoptosis, cell migration, cytoskeleton organization as well as a modulation of the muscular markers MyoD1, MyoR, desmin and MyHC. In addition, DNA demethylation by 5-aza-2′-deoxycytidine (5-aza-dC) was able to up-regulate miR-378a-3p levels with a concomitant induction of apoptosis, decrease in cell viability and cell cycle arrest in G2-phase. Cells treated with 5-aza-dC clearly changed their morphology and expressed moderate levels of MyHC.ConclusionsMiR-378a-3p may function as a tumour suppressor in RMS and the restoration of its expression would be of therapeutic benefit in RMS. Furthermore, the role of epigenetic modifications in RMS deserves further investigations.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-880) contains supplementary material, which is available to authorized users.

Impairment of Lysosomal Activity as a Therapeutic Modality Targeting Cancer Stem Cells of Embryonal Rhabdomyosarcoma Cell Line RD

Rhabdomyosarcoma is the most frequent soft tissue sarcoma in children and adolescents, with a high rate of relapse that dramatically affects the clinical outcome. Multiagent chemotherapy, in combination with surgery and/or radiation therapy, is the treatment of choice. However, the relapse rate is disappointingly high and identification of new therapeutic tools is urgently needed. Under this respect, the selective block of key features of cancer stem cells (CSC) appears particularly promising. In this study, we isolated rhabdomyosarcoma CSC with stem-like features (high expression of NANOG and OCT3/4, self-renewal ability, multipotency). Rhabdomyosarcoma CSC showed higher invasive ability and a reduced cytotoxicity to doxorubicin in comparison to native cells, through a mechanism unrelated to the classical multidrug resistance process. This was dependent on a high level of lysosome acidity mediated by a high expression of vacuolar ATPase (V-ATPase). Since it was not associated with other paediatric cancers, like Ewing’s sarcoma and neuroblastoma, V-ATPase higher expression in CSC was rhabdomyosarcoma specific. Inhibition of lysosomal acidification by the V-ATPase inhibitor omeprazole, or by specific siRNA silencing, significantly enhanced doxorubicin cytoxicity. Unexpectedly, lysosomal targeting also blocked cell growth and reduced the invasive potential of rhabdomyosarcoma CSC, even at very low doses of omeprazole (10 and 50 µM, respectively). Based on these observations, we propose lysosome acidity as a valuable target to enhance chemosensitivity of rhabdomyosarcoma CSC, and suggest the use of anti-V-ATPase agents in combination with standard regimens as a promising tool for the eradication of minimal residual disease or the prevention of metastatic disease.

Apoptotic effect of α-Fe2O3 and SiO2 nanoparticles in human rhabdomyosarcoma cell line

Nanotechnology provides the opportunity for the development of new materials in the nanometer size range, with many potential applications in biological sciences and clinical medicine. It has been reported that RD (muscle cancer cell line) is the most common soft tissue sarcoma in children originating from immature cells, comprising 2.9% of all malignancies in patients younger than 20 years old, with 350 cases diagnosed annually in the United States. Soft tissue is the most common target organ for nanoparticles after they gain significant entry into the target site through any of the possible routes. RD cell lines have been used as an experimental biological model in this article. A suitable environment was provided until 75% of RD cell confluence was reached. Prior to determination of toxicity of hematite (α-Fe2O3) and SiO2 nanoparticles, the sizes and shapes were confirmed using scanning electron microscopy (SEM), and the sizes were about 66 and 250 nm respectively. Moreover, 10–80 μg ml−1 of α-Fe2O3 and SiO2 nanoparticles dispersed in solution were labeled for each row of 96 well plates. The present study evaluates the suppression factor of the said particles, which leads to cell killing phenomena. After successful measurements in the above mentioned experiment, the author will be able to give the actual cause of cell killing effects. The given study has provided valuable insights into a feasible mechanism of apoptosis caused by α-Fe2O3 and SiO2 nanoparticles. An underlying promising mechanism of apoptosis due to α-Fe2O3 and SiO2 nanoparticle exposure should be further investigated at the in vivo level.