We sought to determine whether caspase 8l is present in neuroblastoma and whether over-expression of this protein could inhibit caspase 8-dependent apoptosis.
We propose the simultaneous analysis of hypermethylation of APAF1, TMS1 and CASP8 apoptotic genes on primary NB tumour as a good prognostic factor of disease progression.
We investigated whether the levels of survivin and caspase 8 and the ratio between these 2 apoptotic factors correlate with tumor biology and predicts outcome in patients with neuroblastoma.
We established N-myc-downregulated IMR-32 cells using shRNA lentiviral particles targeting N-myc and examined the effect the N-myc inhibition on TRAIL susceptibility in human neuroblastoma IMR-32 cells expressing caspase-8.
Thus, by demonstrating that 5-dAzaC and IFN-gamma at relatively low individual concentrations cooperate to restore caspase-8 expression and sensitize resistant neuroblastoma and medulloblastoma cells to TRAIL-induced apoptosis, our findings have important implications for novel strategies targeting defective apoptosis pathways in neuroectodermal tumors.
These results indicate that the profile of caspase 8 expression is an important determinant of the response of neuroblastoma cells to Fas-mediated cell death.
These findings define caspase-8 as a metastasis suppressor gene that, together with integrins, regulates the survival and invasive capacity of neuroblastoma cells.
These data indicate that the pattern of expression of these neural-enriched IG20-SVs regulates the expression and activation of caspase-8 in certain neuroblastoma cells, and that manipulation of IG20-SV expression pattern may represent a potent therapeutic strategy in the therapy of neuroblastoma and perhaps other cancers.
These data indicate that Fas-mediated apoptosis in neuroblastoma cells is mitochondria-dependent and inhibited both at the mitochondrial level and at the level of caspase 8 activation.
The retinoic acid analogue 4HPR, IFN-gamma, and the demethylating agent 5-aza-cytidine activate this promoter in NB cells that lack endogenous caspase-8, indicating that this element may regulate both constitutive and inducible CASP8 expression.
The combined data suggest that FOXO3 is activated by 5-azadC treatment and triggers expression of caspase-8 in caspase-8-negative neuroblastoma, which may have important implication for metastasis, therapy, and death resistance of this childhood malignancy.
The authors found that interferon-gamma induces caspase-8 expression in neuroblastoma cells irrespective of the gene silenced by hypermethylation of caspase-8 promoter.
Subsequently others have also shown that caspase-8 is silenced by methylation in neuroblastoma and peripheral neural ectodermal tumors, and that the caspase-9 regulator Apaf-1 is silenced by methylation in melanoma cell lines and patient samples.
Subcellular fractionation analysis revealed caspase-8 activity in both cytosol and plasma membrane fractions in both NB7 reconstituted caspase-8 cell lines, as well the LNCaP prostate cancer cells.
Sixty-two NBs (45 primary tumors and 17 NBs at relapse) were studied in terms of the methylation status of 19 genes (p15INK4a, p16INK4a, p14ARF, APC, RB1, RASSF1A, BLU, FHIT, RARbeta, INI1, TIMP3, NF2, MGMT, DAPK, FLIP, ECAD, CASP8, and the receptors DcR1 and DcR2).
Re-expression of caspase-8 in neuroblastoma cells lacking endogenous caspase-8 expression was found to promote cell adhesion to extracellular matrix and to activate adhesion-dependent signaling pathways, such as the Erk kinase cascade.
Our results show that restoration of active caspase-8 expression in a caspase-8-deficient NB cell line is necessary and sufficient to fully restore TRAIL sensitivity.
However, approximately 20% of the neuroblastoma cell lines with methylated CASP8 alleles are also highly resistant to staurosporine (STS)- and radiation-induced cell death, presumably because cytochrome c is not released from mitochondria.
Here we show that four different retinoic acid (RA) derivatives also increase caspase-8 protein expression in neuroblastoma, medulloblastoma and small cell lung carcinoma cell lines.
Furthermore, the methylation pattern of 14.3.3sigma, RASSF1A and of an intragenic segment of CASP8 was significantly different between MYCN amplified and single copy neuroblastoma suggesting a specific role of epigenetic alterations in aggressive neuroblastoma.
Furthermore, gemcitabine-induced apoptosis was observed irrespective of the caspase-8 status of neuroblastoma cells, which indicates that apoptosis depends on the mitochondrial pathway.