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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
32.
The polycomb group Ciarapica, R; De Salvo, M; Carcarino, E ...
Oncogene,
08/2014, Volume:
33, Issue:
32
Journal Article
Peer reviewed
The Polycomb group (PcG) proteins regulate stem cell differentiation via the repression of gene transcription, and their deregulation has been widely implicated in cancer development. The PcG protein ...Enhancer of Zeste Homolog 2 (EZH2) works as a catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) by methylating lysine 27 on histone H3 (H3K27me3), a hallmark of PRC2-mediated gene repression. In skeletal AA muscle progenitors, EZH2 prevents an unscheduled differentiation by repressing muscle-specific gene expression and is downregulated during the course of differentiation. In rhabdomyosarcoma (RMS), a pediatric soft-tissue sarcoma thought to arise from myogenic precursors, EZH2 is abnormally expressed and its downregulation in vitro leads to muscle-like differentiation of RMS cells of the embryonal variant. However, the role of EZH2 in the clinically aggressive subgroup of alveolar RMS, characterized by the expression of PAX3-FOXO1 oncoprotein, remains unknown. We show here that EZH2 depletion in these cells leads to programmed cell death. Transcriptional derepression of F-box protein 32 (FBXO32) (Atroginl/MAFbx), a gene associated with muscle homeostasis, was evidenced in PAX3-FOXO1 RMS cells silenced for EZH2. This phenomenon was associated with reduced EZH2 occupancy and H3K27me3 levels at the FBXO32 promoter. Simultaneous knockdown of FBXO32 and EZH2 in PAX3-FOXO1 RMS cells impaired the pro-apoptotic response, whereas the overexpression of FBXO32 facilitated programmed cell death in EZH2-depleted cells. Pharmacological inhibition of EZH2 by either 3- Deazaneplanocin A or a catalytic EZH2 inhibitor mirrored the phenotypic and molecular effects of EZH2 knockdown in vitro and prevented tumor growth in vivo. Collectively, these results indicate that EZH2 is a key factor in the proliferation and survival of PAX3-FOXO1 alveolar RMS cells working, at least in part, by repressing FBXO32. They also suggest that the reducing activity of EZH2 could represent a novel adjuvant strategy to eradicate high-risk PAX3-FOXO1 alveolar RMS. Oncogene (2014) 33, 4173-4184; doi: 10.1038/onc.2013.471; published online 11 November 2013 Keywords: EZH2; FBXO32; histone methyltransferases; PAX3-FOXO1; rhabdomyosarcoma; Polycomb proteins
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Several members of the different glutathione transferase (GST) gene classes are polymorphic. Particular interest has been focused on the GSTP class because this gene class is up-regulated during the ...early stage of oncogenesis and is significantly overexpressed in many human tumors. It has also been shown that high levels of GSTP1 expression are associated directly with tumor drug resistance and with poor patient survival. Our aim was to understand the possible association between GSTP1 polymorphism and cellular response to chemotherapeutic drugs in neuroblastoma. In fact, several antineoplastic drugs used in the neuroblastoma high-risk chemotherapeutic protocol are potential substrates of GSTP1-1 (etoposide, adriamycin and carboplatin). The GSTP1 genotype homozygote *A/*A was identified in 11 patients independent of their response to the chemotherapeutic treatment. Only four patients had a heterozygote genotype A*/B*. Therefore, based on our preliminary data, we were not able to conclude that GSTP1 polymorphism had an impact on patient response to treatment in neuroblastoma.
Tuberous sclerosis complex (TSC) is an autosomal dominant condition whose signs and symptoms may vary from a few hypopigmented skin spots to epilepsy, severe mental retardation, and renal failure. ...The disease is caused by mutations in either TSC1 or TSC2 gene, at chromosome 9q34 and 16p13.3. Inactivation of both alleles at TSC1 or TSC2 loci is associated with the development of hamartomas in different organs, and only rarely with malignant neoplasms. In this study we present a 6-year-old boy with TSC and with a malignant islet cell tumor of the pancreas. Mutation analysis of DNA extracted from peripheral blood cells of the patient identified an R1459X de novo mutation in exon 33 of the TSC2 gene. Immunohistochemical analysis with anti-tuberin antibodies on paraffin-embedded tissue sections showed loss of tuberin immunostaining in tumor cells but normal expression in residual normal pancreas. DNA analysis of tumor and normal cells showed chromosome 16p13 loss of heterozygosity in malignant pancreatic islet cell tumor but not in normal pancreas. These findings suggest a role for tuberin, the TSC2 gene product, in the pathogenesis of malignant pancreatic endocrine tumor.
Thymoma is exceedingly uncommon in children and young adults. 1 Type A has neoplastic epithelial cells with oval/spindle-shaped nuclei and in type B the cells have a predominantly round/polygonal ...appearance.
Ewing sarcoma (ES) and extraosseous ES/primitive neuroectodermal tumors (PNET) share histopathologic features of the ES family of tumors (ESFT). The authors report on their results from a regimen of ...ifosfamide, carboplatin, and etoposide (ICE) with cyclophosphamide, doxorubicin, and vincristine (CAV) dose intensification in patients with high-risk ESFT.
Since 1990, patients with ESFT and with 1 or more of the following risk factors were reviewed: tumor volume > 200 mL, tumor site with a poor prognosis, and pulmonary and/or bone marrow metastases.
Thirty-six patients with ESFT who were involved in the study were divided into 2 arms of 18 patients each. One group received treatment with various regimens, and the other group received treatment with ICE plus CAV. The disease was brought under control more rapidly in the latter patients, for whom surgery was more easily feasible, and up to 90% of patients achieved a major response, with an estimated 3-year overall survival rate of 67% +/- 12%.
The current results showed that ICE plus CAV was tolerated well and was effective in the studied subset of tumors, indicating that dose intensification correlates with better disease control, a high percentage of necrosis, and conservative surgery in patients with high-risk ESFT.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Purpose: Clinicobiological characteristics of neuroblastic tumor (NT) expressing c-kit tyrosine kinase receptor and/or its ligand,
stem cell factor (SCF), are debated. This study aimed at ...investigating the clinicobiological features of primary NTs expressing
c-kit and/or SCF in order to define the clinical relevance of selective therapeutic targeting.
Experimental Design: c-Kit and SCF expression was studied in 168 NTs using immunohistochemistry and in 106 of 168 using Northern blot. Quantitative
determination of c-kit expression in 54 additional NTs was also done using real-time reverse transcription-PCR. Correlations
between c-kit and SCF expression and clinicobiological features were analyzed using χ 2 test, univariate, and multivariate regression analyses.
Results: c-Kit protein was detected in 21 of 168 NTs (13%) and its mRNA in 23 of 106 NTs (22%). SCF protein was shown in 30 of 106
NTs (28%) and its mRNA in 33 of 106 NTs (31%). No mutations in exon 11 of c-kit gene were identified. By univariate analysis, c-kit and SCF expression correlated with advanced stage, MYCN amplification, and 1p36 allelic loss. Cox simple regression analysis showed that overall survival probability was 17% in
the c-kit–positive subset versus 68% in the negative ( P < 0.001), 43% in the SCF-positive subset versus 78% in the negative ( P < 0.001). When using real-time reverse transcription-PCR, significant levels of c-kit mRNA were found in 35 of 54 NTs (65%),
but the correlations with clinicobiological features were no longer documented.
Conclusions: c-Kit expression can be detected in the majority of primary NTs. High levels of expression are preferentially found in tumors
with unfavorable clinicobiological variables. c-Kit may represent a useful therapeutic target in a subset of otherwise untreatable
NTs.
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