255 research outputs found
Gangliosides Link the Acidic Sphingomyelinase– Mediated Induction of Ceramide to 12-Lipoxygenase– Dependent Apoptosis of Neuroblastoma in Response to Fenretinide
No full textThe lipid second messenger ceramide, which is
generated by acidic and neutral sphingomyelinases or ceramide
synthases, is a common intermediate of many apoptotic
pathways. Metabolism of ceramide involves several enzymes,
including glucosylceramide synthase and GD3
synthase, and results in the formation of gangliosides (GM3,
GD3, and GT3), which in turn promote the generation of
reactive oxygen species (ROS) and apoptosis. Fenretinide, a
retinoic acid derivative, is thought to induce apoptosis via
increases in ceramide levels, but the link between ceramide
and subsequent apoptosis in neuroblastoma cells is unclear.
Methods: SH-SY5Y and HTLA230 neuroblastoma cells were
treated with fenretinide in the presence or absence of inhibitors
of enzymes important in ceramide metabolism (fumonisin
B1, inhibitor of ceramide synthase; desipramine, inhibitor
of acidic and neutral sphingomyelinases; and PDMP,
inhibitor of glucosylceramide). Small interfering RNAs were
used to specifically block acidic sphingomyelinase or GD3
synthase activities. Apoptosis, ROS, and GD3 expression
were measured by flow cytometry. Results: In neuroblastoma
cells, ROS generation and apoptosis were associated
with fenretinide-induced increased levels of ceramide, glucosylceramide
synthase activity, GD3 synthase activity, and
GD3. Fenretinide also induced increased levels of GD2, a
ganglioside derived from GD3. Inhibition of acidic sphingomyelinase
but not of neutral sphingomyelinase or ceramide
synthase, blocked fenretinide-induced increases in ceramide,
ROS, and apoptosis. Exogenous GD3 induced ROS and apoptosis
in SH-SY5Y cells but not in SH-SY5Y cells treated
with baicalein, a specific 12-lipoxygenase inhibitor. Exogenous
GD2 did not induce apoptosis. Conclusions: A novel
pathway of fenretinide-induced apoptosis is mediated by
acidic sphingomyelinase, glucosylceramide synthase, and
GD3 synthase, which may represent targets for future drug
development. GD3 may be a key signaling intermediate leading
to apoptosis via the activation of 12-lipoxygenas
Molecular mechanisms of fenretinide-induced apoptosis of neuroblastoma
No full textSynthetic retinoids such as fenretinide [N-(4-hydroxyphenyl)retinamide] induce apoptosis of neuroblastoma cells, act synergistically with chemotherapeutic drugs, and may provide opportunities for novel approaches to neuroblastoma therapy. Fenretinide-induced cell death of neuroblastoma cells is caspase dependent and results in the release of cytochrome c from mitochondria independently of changes in permeability transition. This is mediated by a signaling pathway characterized by the generation of reactive oxygen species (ROS) via 12-lipoxygenase (12-LOX), and an oxidative-stress-dependent induction of the transcription factor, GADD153 and the BCL2-related protein BAK. Upstream events of fenretinide-induced signaling involve increased levels of ceramide as a result of increased sphingomyelinase activity, and the subsequent metabolism of ceramide to gangliosides via glucosylceramide synthase and GD3 synthase. These gangliosides may be involved in the regulation of 12-LOX leading to oxidative stress and apoptosis via the induction of GADD153 and BAK. The targeting of sphingomyelinases or downstream effectors such as 12-LOX or GADD153 may present novel approaches for the development of more effective and selective drugs for neuroblastoma therapy
Fenretinide-induced ER-Stress and Apoptosis in Neuroectodermal Tumors
No full textThe synthetic retinoid fenretinide induces apoptosis via oxidative stress, and this is accompanied by induction of the ER stress transcription factor GADD153; however, the link between the induction of oxidative stress and Gadd153 is not yet clear.
Here we show that fenretinide-induced cellular oxidative status results in ER-stress and subsequent apoptosis. ER-stress induction is mediated by eIF2a phosphorilation and Xbp-I splicing.
Furthermore, results from microarray analysis revealed the involvement of other two ER-related genes, ERdj5 and ERp57, as genes upregulated during fenretinide-induced ER-stress in neuroectodermal tumor cells. siRNA of either ERdj5 and ERp57 resulted in enhanced sensitivity of neuroectodermal cells to apoptosis in response to fenretinide.
These results demonstrate as ER-stress plays a pivotal role in fenretinide-induced cell death of neuroectodermal tumor cells and suggest as ERdj5 and ERp57 may represent new targets for future drug developmen
Combining homeostatic mechanisms of ER Stress to increase susceptibility of cancer cell to ER stress-induced apoptosis: The role of stress proteins ERdj5 and ERp57
No full textEndoplasmic Reticulum (ER) malfunction, leading to ER stress, can be a consequence of genome instability and hypoxic tissue environments. Cancer cells survive by acquiring or enhancing survival mechanisms to counter the effects of ER stress and these homeostatic responses may represent new therapeutic targets. Understanding the links between ER stress and apoptosis may be approached using drugs to specifically target ER stress responses in cancer cells. Currently there is considerable clinical interest in the use of two ER stress inducing agents, fenretinide (FenR,a synthetic retinoid) and velcade (a 26S proteasome inhibitor) for the treatment of neuroectodermal tumours. Both agents induce potent apoptosis of both neuroblastoma and melanoma cells together with inducing the ER stress response genes ERdj5, ERp57, GRP78, calreticulin and calnexin. Since ERdj5 and ERp57 are induced as a consequence of ER stress, the aim of this study was to test the hypothesis that knockdown of these homeostatic response genes would increase the efficacy of either fenretinide or velcad
The role of gangliosides in fenretinide-induced apoptosis of neuroblastoma
No full textFenretinide is thought to induce apoptosis via increases in ceramide levels but the mechanisms of ceramide generation and the link between ceramide and subsequent apoptosis in neuroblastoma cells is unclear. In SH-SY5Y neuroblastoma cells, evidence suggests that acid sphingomyelinase activity is essential for the induction of ceramide and apoptosis in response to fenretinide. Downstream of ceramide, apoptosis in response to fenretinide is mediated by increased glucosylceramide synthase activity resulting in increased levels of gangliosides GD3 and GD2 via GD3 synthase. GD3 is a key signalling intermediate leading to apoptosis via the activation of 12-Lipoxygenase, and the parallel induction of GD2 suggests that fenretinide might enhance the response of neuroblastoma to therapy with anti-GD2 antibodies
Gadd153 Mediates Apoptosis in Response to Fenretinide but Not Synergy between Fenretinide and Chemotherapeutic Drugs in Neuroblastoma
No full textFenretinide induces apoptosis of neuroblastoma cells in vitro
and interacts synergistically with the chemotherapeutic drugs
cisplatin and etoposide. The stress-inducible transcription factor
known as growth and DNA damage (GADD)-inducible transcription
factor 153 is induced in response to fenretinide and in
other cell types modulates apoptosis via pro- and antiapoptotic
members of the BCL2 family. Because BCL2-family proteins
are important in apoptosis induced by chemotherapeutic
drugs, GADD153 may be a key mediator of synergy between
fenretinide and chemotherapeutic drugs. To investigate this,
GADD153 cDNA in sense and antisense orientations was stably
transfected into SH-SY5Y neuroblastoma cells using a tetracycline-
inducible vector. Increased expression of GADD153
raised the background level of apoptosis and increased apoptosis
induced by fenretinide or the chemotherapeutic drugs
cisplatin and etoposide. However, there was no increase in
synergy between fenretinide and chemotherapeutic drugs.
Conversely, expression of antisense-GADD153 virtually abolished
the induction of apoptosis in response to fenretinide but
overall had no significant effect on apoptosis induced by chemotherapeutic
drugs. The effect of antisense-GADD153 on
synergy between chemotherapeutic drugs and fenretinide varied
with the drug used: there was no effect on synergy between
fenretinide and cisplatin, but the combination of fenretinide with
etoposide became antagonistic. These results suggest that
mechanisms mediating synergy between fenretinide and chemotherapeutic
drugs lie upstream of GADD15
The NF-kB pathway mediates fenretinide-induced apoptosis in SH-SY5Y neuroblastoma cells
No full text1590911
Distinct properties of fenretinide and CD437 lead to synergistic responses with chemotherapeutic reagents
No full textFenretinide-induced apoptosis via endoplasmic reticulum stress- new targets for melanoma therapy?
No full textFenretinide, a synthetic derivative of retinoic acid, induces apoptosis of neuroectodermal tumour cells including melanoma. The signalling mechanism of fenretinide-induced apoptosis is mediated by ceramide accumulation with subsequent metabolism to the diasialoganglioside GD3, resulting in oxidative stress, ROS generation through increased 12-lipoxygenase activity, and induction of the DNA damage-inducible transcription factor GADD153. GADD153 induction is also a hallmark of apoptosis induced by endoplasmic reticulum (ER) stress. Since ER stress-induced apoptosis is a potential target pathway for therapy of melanoma, resistant to apoptosis mediated by death receptor ligation or DNA damage, we have tested the hypothesis that fenretinide-induced apoptosis of melanoma results from ER stress.
In SK Mel 110 and A375 melanoma cells, fenretinide induced phosphorylation of the translational initiation factor eIF2a, and splicing of Xbp-I; these are both key markers of the unfolded protein response to ER stress. Several ER stress response genes were also induced including Gadd153, Grp78, calnexin and calreticulin. We have also found thet ERp57 and ERdj5, two genes forming part of the protein folding machinery of the ER, are induced in response to fenretinide. siRNA-mediated knockdown of these two gene increased the susceptibility of melanoma cells to fenretinide-induced apoptosis. These results suggest therefore, that targeting mechanisms protecting against ER stress in combination with ER stress-inducing agents such as fenretinide may define a novel and more effective therapeutic strategy for melanom
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