54 research outputs found
Hox-C9 activates the intrinsic pathway of apoptosis and is associated with spontaneous regression in neuroblastoma
Neuroblastoma is an embryonal malignancy of the sympathetic nervous system. Spontaneous regression and differentiation of neuroblastoma is observed in a subset of patients, and has been suggested to represent delayed activation of physiologic molecular programs of fetal neuroblasts. Homeobox genes constitute an important family of transcription factors, which play a fundamental role in morphogenesis and cell differentiation during embryogenesis. In this study, we demonstrate that expression of the majority of the human HOX class I homeobox genes is significantly associated with clinical covariates in neuroblastoma using microarray expression data of 649 primary tumors. Moreover, a HOX gene expression-based classifier predicted neuroblastoma patient outcome independently of age, stage and MYCN amplification status. Among all HOX genes, HOXC9 expression was most prominently associated with favorable prognostic markers. Most notably, elevated HOXC9 expression was significantly associated with spontaneous regression in infant neuroblastoma. Re-expression of HOXC9 in three neuroblastoma cell lines led to a significant reduction in cell viability, and abrogated tumor growth almost completely in neuroblastoma xenografts. Neuroblastoma growth arrest was related to the induction of programmed cell death, as indicated by an increase in the sub-G1 fraction and translocation of phosphatidylserine to the outer membrane. Programmed cell death was associated with the release of cytochrome c from the mitochondria into the cytosol and activation of the intrinsic cascade of caspases, indicating that HOXC9 re-expression triggers the intrinsic apoptotic pathway. Collectively, our results show a strong prognostic impact of HOX gene expression in neuroblastoma, and may point towards a role of Hox-C9 in neuroblastoma spontaneous regression
Integrative DNA methylation and gene expression analysis in high-grade soft tissue sarcomas
BACKGROUND: High-grade soft tissue sarcomas are a heterogeneous, complex group of aggressive malignant tumors showing mesenchymal differentiation. Recently, soft tissue sarcomas have increasingly been classified on the basis of underlying genetic alterations; however, the role of aberrant DNA methylation in these tumors is not well understood and, consequently, the usefulness of methylation-based classification is unclear. RESULTS: We used the Infinium HumanMethylation27 platform to profile DNA methylation in 80 primary, untreated high-grade soft tissue sarcomas, representing eight relevant subtypes, two non-neoplastic fat samples and 14 representative sarcoma cell lines. The primary samples were partitioned into seven stable clusters. A classification algorithm identified 216 CpG sites, mapping to 246 genes, showing different degrees of DNA methylation between these seven groups. The differences between the clusters were best represented by a set of eight CpG sites located in the genes SPEG, NNAT, FBLN2, PYROXD2, ZNF217, COL14A1, DMRT2 and CDKN2A. By integrating DNA methylation and mRNA expression data, we identified 27 genes showing negative and three genes showing positive correlation. Compared with non-neoplastic fat, NNAT showed DNA hypomethylation and inverse gene expression in myxoid liposarcomas, and DNA hypermethylation and inverse gene expression in dedifferentiated and pleomorphic liposarcomas. Recovery of NNAT in a hypermethylated myxoid liposarcoma cell line decreased cell migration and viability. CONCLUSIONS: Our analysis represents the first comprehensive integration of DNA methylation and transcriptional data in primary high-grade soft tissue sarcomas. We propose novel biomarkers and genes relevant for pathogenesis, including NNAT as a potential tumor suppressor in myxoid liposarcomas
Migration rules: tumours are conglomerates of self-metastases
Tumours are heterogeneous populations composed of different cells types: stem cells with the capacity for self-renewal and more differentiated cells lacking such ability. The overall growth behaviour of a developing neoplasm is determined largely by the combined kinetic interactions of these cells. By tracking the fate of individual cancer cells using agent-based methods in silico, we apply basic rules for cell proliferation, migration and cell death to show how these kinetic parameters interact to control, and perhaps dictate defining spatial and temporal tumour growth dynamics in tumour development. When the migration rate is small, a single cancer stem cell can only generate a small, self-limited clone because of the finite life span of progeny and spatial constraints. By contrast, a high migration rate can break this equilibrium, seeding new clones at sites outside the expanse of older clones. In this manner, the tumour continually ‘self-metastasises'. Counterintuitively, when the proliferation capacity is low and the rate of cell death is high, tumour growth is accelerated because of the freeing up of space for self-metastatic expansion. Changes to proliferation and cell death that increase the rate at which cells migrate benefit tumour growth as a whole. The dominating influence of migration on tumour growth leads to unexpected dependencies of tumour growth on proliferation capacity and cell death. These dependencies stand to inform standard therapeutic approaches, which anticipate a positive response to cell killing and mitotic arrest
Apoptosis resistance in pigmented villonodular synovitis
Objective: Pigmented villonodular synovitis
(PVNS) is a proliferative lesion originating from
synovial tissue with a locally aggressive behaviour. We
analysed the pathogenetic role of apoptosis resistance for
sustained cell proliferation in PVNS. Methods: The
expression of bcl-2, p53 and Ki-67 was examined in 80
cases of PVNS using immunohistochemistry. In 43 of
these cases, DNA content and distribution of cell-cycle
phases were investigated by flow cytometry.
Additionally, 10 cases of PVNS were analysed by multiparametric
flow cytometry for expression of p53,
caspase3, and bcl-2 and by TUNEL to detect DNA
fragmentation. Results: No apoptotic cell fractions were
detected in any investigated cases. Expression of bcl-2
was found in 84% of cases (up to 6.5% of cells) and was
significantly associated with DNA-fragmentation
observed by TUNEL (p=0.037). Orthologous p53
expression was observed in 37% of cases. The level of
p53 expression correlated with the proliferative activity
and the expression of both caspase3 (p=0.017) and bcl-2
(p=0.0013). (No statistically significant correlations
between expression of bcl-2, p53, caspase3, DNA
fragmentation or proliferative index and age, sex of
patients, disease recurrence, growth pattern or size of
lesion were found). Conclusion: Apoptosis resistance is
a critical event in the progression of PVNS and may
contribute to the survival of the proliferating synovial
cells in PVNS and to the permanent slow progression of
these lesions
Comparative analysis of cell populations involved in the proliferative and inflammatory processes in diffuse and localised pigmented villonodular synovitis
The aim of the present study was a
comparative quantitative evaluation of cell populations
involved in the proliferative and inflammatory
compartment in both localised and diffuse pigmented
synovitis villonodularis (PVNS). 15 cases of each
localised and diffuse PVNS were examined by flow
cytometry, immunohistochemistry, double immunofluorescence
and confocal microscopy with quantitative
evaluation of CD3-, CD4-, CD8-, CD20-, CD57-,
CD55-, CD68-, CD163- and h4Ph positive (+) cells. The
proliferative compartment of localised and diffuse PVNS
was mainly composed of double-positive CD68+/h4Ph+
(CD163+/CD55+) synoviocytes. The number of doublepositive
synoviocytes for macrophage and fibroblast
markers was significantly higher in diffuse compared to
localised PVNS. The accompanying inflammatory
infiltrate showed a predominance of cytotoxic cells
(CD8+, CD57+), whereby the number of CD3+ and
CD20+ cells was significantly higher in localised PVNS.
The number of CD57+ NK cells was significantly higher
in diffuse PVNS. The proliferating macrophage- like
synovial cells and the cytotoxic lymphocytes could
contribute to the aggressive behaviour of localised and
diffuse PVNS. Moreover, with regard to the quantitative
differences in cell composition between diffuse and
localised PVNS and their different clinical behaviour, further studies should continue to analyse localised and
diffuse PVNS separately
Expression pattern of cell cycle-related gene products in synovial stroma and synovial lining in active and quiescent stages of rheumatoid arthritis
Objective: To investigate the expression
pattern of cell cycle related gene products in active and
quiescent Rheumatoid arthritis (RA). Methods: Synovial
tissue from 20 patients with active proliferative RA and
28 patients with RA in remission was
immunohistochemically examined for expression of p53,
p63, p21, p27, p16, cyclin D1, CDK4, RB, E2F, Ki-67
on tissue microarrays and by DNA flow cytometry for
cell cycle phases. Results: Elevated expression of p53
and p27 was found in synovial lining and in stromal cells
in proliferative active RA. In the remission stage this
finding was confined to the synovial lining. Most of the
cells were in the G0-phase. Ki-67 proliferation index
was maximum 10% in synovial cells. Conclusion: The
p53 pathway is activated in synovial cells in active RA
as well as in quiescent stage of disease. Differences in
the spatial expression pattern of proteins involved in the
p53 pathway in RA in remission compared to actively
proliferating RA reflect the phasic nature of the disease
and support in our opinion the concept of adaptive role
of p53 pathway in R
Centrosome amplification as a possible mechanism for numerical chromosome aberrations in cerebral primitive neuroectodermal tumors with TP53 mutations
Although alterations in chromosome number have frequently been detected in human tumor cells and associated with tumor initiation and progression, the causal mechanisms are still not understood. One protein known to be involved in maintaining genetic stability is tumor suppressor p53. In mice, p53 has been implicated in the maintenance of diploidy (Cross et al., 1995) and the regulation of centrosome duplication (Fukasawa et al., 1996). Here we report on cerebral primitive neuroectodermal tumors that lacked the wild-type p53 gene (TP53) and showed multiple numerical chromosome aberrations, as detected by comparative genomic hybridization. In these tumors, the centrosome number was significantly higher than in a control tumor without a detected TP53 mutation and with few chromosomal imbalances. These findings indicate that abnormal centrosome amplification can occur in human tumors lacking wild-type TP53 and may be a mechanism by which numerical chromosome aberrations are generated
Histone deacetylase inhibitor Helminthosporium carbonum (HC)-toxin suppresses the malignant phenotype of neuroblastoma cells
The survival rate of children with advanced neuroblastoma (NB) is dismal despite intensive multimodal therapy. The limited efficacy and the frequent and serious side effects of currently used therapeutic regimens necessitate the development of new, less toxic treatment strategies. This study shows that the histone deacetylase inhibitor Helminthosporium carbonum (HC)-toxin suppresses the malignant phenotype of both established NB cell lines and primary NB cells with and without amplified MYCN at dosages lower than 20 nM. HC-toxin induces cell cycle arrest and apoptosis as well as neuronal differentiation and diminishes both colony formation and invasive growth. These cellular changes are accompanied by the transcriptional repression of cell cycle regulators of the retinoblastoma (RB) tumor suppressor network found at high levels in NBs with poor prognosis, like E2F-1 and its targets Skp2, N-myc, Mad2 and survivin. The levels of the hypophosphorylated active form of RB, and of cyclin-dependent kinase inhibitors including p15(INK4b), p16(INK4a), p21(cip1/waf-1) and p27(kip1) are increased. In conclusion, nanomolar doses of the HDACI HC-toxin cause a shift to a differentiated and benign phenotype of NB cells that is associated with an activation of the RB tumor suppressor network
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