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Stereospecific induction of apoptosis in tumor cells via endogenous C 16 -ceramide and distinct transcripts

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ABSTRACT

Concentration and distribution of individual endogenous ceramide species is crucial for apoptosis induction in response to various stimuli. Exogenous ceramide analogs induce apoptosis and can in turn modify the composition/concentrations of endogenous ceramide species and associated signaling. In this study, we show here that the elevation of endogenous C16-ceramide levels is a common feature of several known apoptosis-inducing triggers like mmLDL, TNF-alpha, H2O2 and exogenous C6-ceramide. Vice versa apoptosis requires elevation of endogenous C16-ceramide levels in cells. Enantiomers of a synthetic ceramide analog HPL-1RS36N have been developed as probes and vary in their capacity to inducing apoptosis in macrophages and HT-29 cells. Apoptosis induction by the two synthetic ceramide analogs HPL-39N and HPL-1R36N correlates with generation of cellular C16-ceramide concentration. In contrast to the S-enantiomer HPL-1S36N, the R-enantiomer HPL-1R36N shows significant effects on the expression of distinct genes known to be involved in cell cycle, cell growth and cell death (CXCL10, CCL5 and TNF-alpha), similarly on apoptosis induction. Enantioselective effects on transcription induced by metabolically stable synthetic probes provide clues on molecular mechanisms of ceramide-induced signaling, as well as leads for future anti-cancer agents.

No MeSH data available.


Effect of mmLDL (54 μg ml−1) and TNF-alpha (3 ng ml−1) on ceramide concentration in macrophages. (a) C16-ceramide and (b) C24:1-ceramide concentrations in macrophages after 4 h treatment are shown as mean±S.E., n=3. One-way ANOVA in combination with post hoc t-tests and Bonferroni's correction for multiple testing, P<0.0001 (one-way ANOVA); significant with P<0.05: *versus control, ** mmLDL versus TNF-alpha.
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fig1: Effect of mmLDL (54 μg ml−1) and TNF-alpha (3 ng ml−1) on ceramide concentration in macrophages. (a) C16-ceramide and (b) C24:1-ceramide concentrations in macrophages after 4 h treatment are shown as mean±S.E., n=3. One-way ANOVA in combination with post hoc t-tests and Bonferroni's correction for multiple testing, P<0.0001 (one-way ANOVA); significant with P<0.05: *versus control, ** mmLDL versus TNF-alpha.

Mentions: We have previously demonstrated that exogenous C6-ceramide provokes an increase in total ceramide levels (determined by diacylglycerolkinase-assay in fibroblasts, an effect inhibitable with our agent NB06.10,11 Here we examined whether these effects accompany changes of endogenous C16- and C24:1-ceramides, especially when compared with the effect observed in response to C6-ceramide stimulation. To further characterize the molecular mechanism of apoptosis induction, we first analyzed changes in total cellular ceramide content, then endogenous C16- and C24:1-ceramide concentrations in response to known stimulatory agents such as mmLDL and TNF-alpha as references (Figure 1).12 We found that both, mmLDL and TNF-alpha, cause a significant rise in endogenous C16-ceramide (2), however, TNFalpha causes significant reduction of C24:1-ceramide concentrations in macrophages.


Stereospecific induction of apoptosis in tumor cells via endogenous C 16 -ceramide and distinct transcripts
Effect of mmLDL (54 μg ml−1) and TNF-alpha (3 ng ml−1) on ceramide concentration in macrophages. (a) C16-ceramide and (b) C24:1-ceramide concentrations in macrophages after 4 h treatment are shown as mean±S.E., n=3. One-way ANOVA in combination with post hoc t-tests and Bonferroni's correction for multiple testing, P<0.0001 (one-way ANOVA); significant with P<0.05: *versus control, ** mmLDL versus TNF-alpha.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4979478&req=5

fig1: Effect of mmLDL (54 μg ml−1) and TNF-alpha (3 ng ml−1) on ceramide concentration in macrophages. (a) C16-ceramide and (b) C24:1-ceramide concentrations in macrophages after 4 h treatment are shown as mean±S.E., n=3. One-way ANOVA in combination with post hoc t-tests and Bonferroni's correction for multiple testing, P<0.0001 (one-way ANOVA); significant with P<0.05: *versus control, ** mmLDL versus TNF-alpha.
Mentions: We have previously demonstrated that exogenous C6-ceramide provokes an increase in total ceramide levels (determined by diacylglycerolkinase-assay in fibroblasts, an effect inhibitable with our agent NB06.10,11 Here we examined whether these effects accompany changes of endogenous C16- and C24:1-ceramides, especially when compared with the effect observed in response to C6-ceramide stimulation. To further characterize the molecular mechanism of apoptosis induction, we first analyzed changes in total cellular ceramide content, then endogenous C16- and C24:1-ceramide concentrations in response to known stimulatory agents such as mmLDL and TNF-alpha as references (Figure 1).12 We found that both, mmLDL and TNF-alpha, cause a significant rise in endogenous C16-ceramide (2), however, TNFalpha causes significant reduction of C24:1-ceramide concentrations in macrophages.

View Article: PubMed Central - PubMed

ABSTRACT

Concentration and distribution of individual endogenous ceramide species is crucial for apoptosis induction in response to various stimuli. Exogenous ceramide analogs induce apoptosis and can in turn modify the composition/concentrations of endogenous ceramide species and associated signaling. In this study, we show here that the elevation of endogenous C16-ceramide levels is a common feature of several known apoptosis-inducing triggers like mmLDL, TNF-alpha, H2O2 and exogenous C6-ceramide. Vice versa apoptosis requires elevation of endogenous C16-ceramide levels in cells. Enantiomers of a synthetic ceramide analog HPL-1RS36N have been developed as probes and vary in their capacity to inducing apoptosis in macrophages and HT-29 cells. Apoptosis induction by the two synthetic ceramide analogs HPL-39N and HPL-1R36N correlates with generation of cellular C16-ceramide concentration. In contrast to the S-enantiomer HPL-1S36N, the R-enantiomer HPL-1R36N shows significant effects on the expression of distinct genes known to be involved in cell cycle, cell growth and cell death (CXCL10, CCL5 and TNF-alpha), similarly on apoptosis induction. Enantioselective effects on transcription induced by metabolically stable synthetic probes provide clues on molecular mechanisms of ceramide-induced signaling, as well as leads for future anti-cancer agents.

No MeSH data available.