85 research outputs found
Contribution of the R-Ras2 GTP-binding protein to primary breast tumorigenesis and late-stage metastatic disease
R-Ras2 is a transforming GTPase that shares downstream effectors with Ras subfamily proteins. However, little information exists about the function of this protein in tumorigenesis and its signalling overlap with classical Ras GTPases. Here we show, by combining loss- and gain-of-function studies in breast cancer cells, mammary epithelial cells and mouse models, that endogenous R-Ras2 has a role in both primary breast tumorigenesis and the late metastatic steps of cancer cells in the lung parenchyma. R-Ras2 drives tumorigenesis in a phosphatidylinostiol-3 kinase (PI3K)-dependent and signalling autonomous manner. By contrast, its prometastatic role requires other priming oncogenic signals and the engagement of several downstream elements. R-Ras2 function is required even in cancer cells exhibiting constitutive activation of classical Ras proteins, indicating that these GTPases are not functionally redundant. Our results also suggest that application of long-term R-Ras2 therapies will result in the development of compensatory mechanisms in breast tumoursFil: Larive, Ramon. Universidad de Salamanca; España. University of Montpellier I and II; FranciaFil: Moriggi, Giulia. Universidad de Salamanca; EspañaFil: Menacho Márquez, Mauricio Ariel. Universidad de Salamanca; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Cañamero, Marta. Centro Nacional de Investigaciones Oncológicas; EspañaFil: de Alava, Enrique. Universidad de Salamanca; España. Hospital Universitario Virgen del Rocío. Sevilla; EspañaFil: Alarcón, Balbino. Centro de Biología Molecular ‘‘Severo Ochoa’. Madrid; EspañaFil: Dosil, Mercedes. Universidad de Salamanca; EspañaFil: Bustelo, Xosé R.. Universidad de Salamanca; Españ
Clinical and Molecular Features of Ewing Sarcoma in a Patient with Triple-X Syndrome
A case of Ewing sarcoma in a 16-year-old girl with 47 XXXc karyotype is reporte
Congenital infiltrating lipoma of the upper limb in a patient with von Willebrand disease
Infiltrating lipoma is a rare variety of lipoma, characterized by an infiltration of the adipose tissue of the muscles. Infiltrating lipomas are usually classified in two groups: intermuscular infiltrating lipoma and intramuscular infiltrating lipoma. Most are acquired, and they usually appear in middle-aged individuals. Exceptionally, they are congenital. In such cases they are not related to other diseases. We report an 8-year-old boy with a congenital infiltrating lipoma of the upper limb and von Willebrand disease. Both diseases are linked to an alteration in chromosome 12, but this clinical association seems to be random rather than causal
Insuficiencia respiratoria neonatal asociada a mutación en el gen de la proteína C del surfactante
La insuficiencia respiratoria en el recién nacido a término
durante las primeras semanas de vida extrauterina
es una situación poco frecuente. Entre sus causas se incluyen
las enfermedades difusas del intersticio pulmonar, un
grupo heterogéneo de enfermedades, la mayoría idiopáticas,
caracterizadas por infiltrados difusos, alteraciones
funcionales de tipo restrictivo y afectación del intercambio
gaseoso. Una forma de enfermedad pulmonar intersticial
que puede afectar a lactantes, niños o adultos jóvenes
es la que se asocia al déficit congénito de proteínas B o C
del surfactante pulmonar. En estos casos los procesos inflamatorios
que evolucionan hacia la fibrosis pulmonar están
precedidos por la acumulación de material proteináceo
en el alvéolo.
Se indagó la presencia de mutaciones en los genes de
las proteínas B y C del surfactante en una familia española
en la cual dos lactantes presentaron insuficiencia
respiratoria progresiva desde el nacimiento, con alteraciones
radiológicas y anatomopatológicas compatibles
con enfermedad del intersticio pulmonar, y el padre
refería historia de problemas respiratorios desde la infancia.
Se encontró que los dos hermanos de esta familia afectados
por la enfermedad presentaban una expresión anómala
del precursor de la proteína C del surfactante y concentraciones
muy bajas de proteína madura. Se describe
además una mutación nueva en el gen que codifica la proteína
C del surfactante y que cosegrega con la enfermedad
en esta familia
Ewing Family Tumors: Potential Prognostic Value of Reverse-Transcriptase Polymerase Chain Reaction Detection of Minimal Residual Disease in Peripheral Blood Samples
In more than 95% of patients, the Ewing family of tumors (ET) has chimeric
transcripts caused by fusion of the EWS gene to either FLI1 or ERG. The presence
of specific EWS-FLI1 or EWS-ERG transcripts in peripheral blood (PB) samples of
patients being treated for ET was prospectively evaluated, and these data were
correlated to their clinical status. The authors studied 113 PB samples from 28
patients with ET. Treatment included chemotherapy, radiotherapy, and surgical
excision of tumor after induction therapy. PB samples were taken prospectively at
least 2 weeks after resection of tumor. Nested reverse-transcriptase polymerase
chain reaction (RT-PCR) followed by Southern blot was performed in all samples.
Resected tumors were reviewed for the degree of response to chemotherapy and
volume. Seventy-seven PB samples from 28 patients had EWS-FLI1/ERG transcripts.
In 11 patients, PB samples became negative with treatment, and, in 5 of them, the
samples remained negative throughout the study. Samples taken during progression
were always positive and, in 4 patients, became positive before progression was
clinically evident. All patients with transcripts other than EWS-FLI1 type 1 (n =
3) died from tumor progression. This is a sensitive assay to monitor circulating
tumor cells in Ewing tumors. The preliminary data suggest that progression is
preceded by positive samples and may be related to specific transcript types
Association of EWS-FLI1 Type 1 Fusion with Lower Proliferative Rate in Ewing’s Sarcoma
The Ewing's sarcoma (ES) family of tumors, including peripheral neuroectodermal
tumor (PNET), is defined genetically by specific chromosomal translocations
resulting in fusion of the EWS gene with a member of the ETS family of
transcription factors, either FLI1 (90-95%) or ERG (5-10%). A second level of
molecular genetic heterogeneity stems from the variation in the location of the
translocation breakpoints, resulting in the inclusion of different combinations
of exons from EWS and FLI1 (or ERG) in the fusion products. The most common type
of EWS-FLI1 fusion transcript, type 1, is associated with a favorable prognosis
and appears to encode a functionally weaker transactivator, compared to other
fusion types. We sought to determine whether the observed covariation of
structure, function, and clinical course correlates with tumor cell kinetic
parameters such as proliferative rate and apoptosis, and with expression of the
receptor for insulin-like growth factor I (IGF-1R). In a group of 86 ES/PNET with
defined EWS-ETS fusions (45 EWS-FLI1 type 1, 27 EWS-FLI1 non-type 1, 14 EWS-ERG),
we assessed proliferation rate by immunostaining for Ki-67 using MIB1 antibody (n
= 85), apoptosis by TUNEL assay (n = 66), and IGF-1R expression by immunostaining
with antibody 1H7 (n = 78). Ki-67 proliferative index was lower in tumors with
EWS-FLI1 type 1 than those with non-type 1 EWS-FLI1, whether analyzed as a
continuous (P = 0.049) or categorical (P = 0.047) variable. Logistic regression
analysis suggests that this association was secondary to the association of type
1 EWS-FLI1 and lower IGF-1R expression (P = 0.04). Comparing EWS-FLI1 to EWS-ERG
cases, Ki-67 proliferative index was higher in the latter (P = 0.01, Mann-Whitney
test; P = 0.02, Fisher's exact test), but there was no significant difference in
IGF-1R. TUNEL results showed no significant differences between groups. Our
results suggest that clinical and functional differences between alternative
forms of EWS-FLI1 are paralleled by differences in proliferative rate, possibly
mediated by differential regulation of the IGF-1R pathway
Hippo pathway effectors YAP1/TAZ induce an EWS–FLI1‐opposing gene signature and associate with disease progression in Ewing sarcoma
YAP1 and TAZ (WWTR1) oncoproteins are the final transducers of the Hippo tumor suppressor pathway. Deregulation of the pathway leads to YAP1/TAZ activation fostering tumorigenesis in multiple malignant tumor types, including sarcoma. However, oncogenic mutations within the core components of the Hippo pathway are uncommon. Ewing sarcoma (EwS), a pediatric cancer with low mutation rate, is characterized by a canonical fusion involving the gene EWSR1 and FLI1 as the most common partner. The fusion protein is a potent driver of oncogenesis, but secondary alterations are scarce, and little is known about other biological factors that determine the risk of relapse or progression. We have observed YAP1/TAZ expression and transcriptional activity in EwS cell lines. Analyses of 55 primary human EwS samples revealed that high YAP1/TAZ expression was associated with progression of the disease and predicted poorer outcome. We did not observe recurrent SNV or copy number gains/losses in Hippo pathway‐related loci. However, differential CpG methylation of the RASSF1 locus (a regulator of the Hippo pathway) was observed in EwS cell lines compared with mesenchymal stem cells, the putative cell of origin of EwS. Hypermethylation of RASSF1 correlated with the transcriptional silencing of the tumor suppressor isoform RASFF1A, and transcriptional activation of the pro‐tumorigenic isoform RASSF1C, which promotes YAP1/TAZ activation. Knockdown of YAP1/TAZ decreased proliferation and invasion abilities of EwS cells and revealed that YAP1/TAZ transcription activity is inversely correlated with the EWS–FLI1 transcriptional signature. This transcriptional antagonism could be explained partly by EWS–FLI1‐mediated transcriptional repression of TAZ. Thus, YAP1/TAZ may override the transcriptional program induced by the fusion protein, contributing to the phenotypic plasticity determined by dynamic fluctuation of the fusion protein, a recently proposed model for disease dissemination in EwS
Prediction of sustained remission of chronic hepatitis C after a 12-month course of alfa interferon
alpha-Interferon therapy normalizes aminotransferase levels in approximately 50% of the patients with chronic hepatitis C, but post-therapy relapses are common and predictive factors of sustained response remain largely unknown. We retrospectively assessed several parameters as predictors of sustained remission after a 12-month course of lymphoblastoid alpha-interferon: the Knodell histological activity index, serum levels of procollagen type III peptide, serum HCV-RNA, anti-alpha-interferon antibodies, and anti-HCV antibodies (C-100-3), all at month 12. Thirty-seven patients were studied. Fourteen patients were non-responders (38%), 15 patients experienced a sustained response (40.5%) and eight patients responded similarly but relapsed after alpha-interferon withdrawal (21.5%). A decrease in the histological activity index above 5, normalization of procollagen type III peptide levels (< 12 ng/ml) and the absence of viremia after treatment were all significantly associated with a sustained response (p = 0.008, p = 0.007 and p = 0.037, respectively). Anti-interferon antibodies were detected in only one non-responder patient. Anti-C-100-3 antibodies became undetectable at month 12 in 5 of the 15 sustained responders. The best prediction of sustained response was obtained from the three variables independent of multivariate analysis according to the following equation: F = 0.872 + 0.067 x K (decrease of histological index) -0.052 x P (procollagen type III peptide levels at month 12) -0.28 x R (HCV-RNA at month 12; R = 2 when present and R = 1 when absent). A score higher than 0 predicted sustained remission with a 100% sensitivity and specificity in this series of patients
Imatinib inhibits proliferation of Ewing tumor cells mediated by the stem cell factor/KIT receptor pathway, and sensitizes cells to vincristine and doxorubicin-induced apoptosis
Purpose and Experimental Design: The stem cell factor/
KIT receptor loop may represent a novel target for molecular-
based therapies of Ewing tumor. We analyzed the in
vitro impact of KIT blockade by imatinib in Ewing tumor
cell lines.
Results: KIT expression was detected in 4 of 4 Ewing
tumor cell lines and in 49 of 110 patient samples (44.5%) by
immunohistochemistry and/or Western blot analysis. KIT
expression was stronger in Ewing tumors showing EWSFLI1
nontype 1 fusions. Despite absence of c-kit mutations,
constitutive and ligand-inducible phosphorylation of KIT
was found in all tumor cell lines, indicating an active receptor.
Treatment with KIT tyrosine kinase inhibitor imatinib
(0.5–20 M) induced down-regulation of KIT phosphorylation
and dose response inhibition of cell proliferation (IC50,
12–15 M). However, imatinib administered alone at doses
close to IC50 for growth inhibition (10 M) did not induce a
significant increase in apoptosis. We then analyzed if blockade
of KIT loop through imatinib (10 M) was able to
increase the antitumor in vitro effect of doxorubicin (DXR)and vincristine (VCR), drugs usually used in Ewing tumor
treatment. Addition of imatinib decreased in 15–20 and
15–36% of the proliferative rate of Ewing tumor cells exposed
to DXR and VCR, respectively, and increased in 15
and 30% of the apoptotic rate of Ewing tumor cells exposed
to the same drugs.
Conclusions: Inhibition of Ewing tumor cell proliferation
by imatinib is mediated through blockade of KIT receptor
signaling. Inhibition of KIT increases sensitivity of
these cells to DXR and VCR. This study supports a potential
role for imatinib in the treatment of Ewing tumor
EphA2-induced angiogenesis in ewing sarcoma cells works through bFGF production and is dependent on caveolin-1
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
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