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Sulforaphane Protects the Liver against CdSe Quantum Dot-Induced Cytotoxicity.

Wang W, He Y, Yu G, Li B, Sexton DW, Wileman T, Roberts AA, Hamilton CJ, Liu R, Chao Y, Shan Y, Bao Y - PLoS ONE (2015)

Bottom Line: Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death.CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment.In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.

View Article: PubMed Central - PubMed

Affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom.

ABSTRACT
The potential cytotoxicity of cadmium selenide (CdSe) quantum dots (QDs) presents a barrier to their use in biomedical imaging or as diagnostic and therapeutic agents. Sulforaphane (SFN) is a chemoprotective compound derived from cruciferous vegetables which can up-regulate antioxidant enzymes and induce apoptosis and autophagy. This study reports the effects of SFN on CdSe QD-induced cytotoxicity in immortalised human hepatocytes and in the livers of mice. CdSe QDs induced dose-dependent cell death in hepatocytes with an IC50 = 20.4 μM. Pre-treatment with SFN (5 μM) increased cell viability in response to CdSe QDs (20 μM) from 49.5 to 89.3%. SFN induced a pro-oxidant effect characterized by depletion of intracellular reduced glutathione during short term exposure (3-6 h), followed by up-regulation of antioxidant enzymes and glutathione levels at 24 h. SFN also caused Nrf2 translocation into the nucleus, up-regulation of antioxidant enzymes and autophagy. siRNA knockdown of Nrf2 suggests that the Nrf2 pathway plays a role in the protection against CdSe QD-induced cell death. Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death. Moreover, the role of autophagy in SFN protection against CdSe QD-induced cell death was confirmed using mouse embryonic fibroblasts lacking ATG5. CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment. In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.

No MeSH data available.


Related in: MedlinePlus

Effect of autophagy inhibitor on the protective effect of SFN on CdSe QD-induced cell death.(A) HHL-5 cells were pre-incubated with wortmannin (0.1 μM) for 6 h, and then exposed to SFN (5 μM) for 24 h. There was a further 24 h exposure with 20 μM CdSe QDs. (B) MEF ATG5-/- cells were pre-incubated with SFN (5 μM) for 24 h and then exposed for a further 24 h with CdSe QDs (10–30 μM). Cytotoxicity was measured by MTT assay. Data are shown as means ± SD (n = 6) (**P<0.01).
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pone.0138771.g006: Effect of autophagy inhibitor on the protective effect of SFN on CdSe QD-induced cell death.(A) HHL-5 cells were pre-incubated with wortmannin (0.1 μM) for 6 h, and then exposed to SFN (5 μM) for 24 h. There was a further 24 h exposure with 20 μM CdSe QDs. (B) MEF ATG5-/- cells were pre-incubated with SFN (5 μM) for 24 h and then exposed for a further 24 h with CdSe QDs (10–30 μM). Cytotoxicity was measured by MTT assay. Data are shown as means ± SD (n = 6) (**P<0.01).

Mentions: Wortmannin acts as a selective inhibitor of type III PI-3K [45]. When wortmannin (0.1 μM) was used to inhibit SFN-induced autophagy, the protective effect of SFN (5 μM) on CdSe QD (20 μM)-induced cell death was suppressed significantly and cell viability decreased from 95 to 78% (Fig 6A). A similar effect was observed using 3-MA, another commonly used autophagy inhibitor, which can also block autophagosome formation via inhibition of type III PI-3K [46]. 3-MA decreased the protective effect of SFN on cell viability from 86.3% to 68.4% (S5 Fig). These results suggest that the induction of autophagy by SFN has a significant role in the protection against CdSe-induced cell death. The role of autophagy was further examined using ATG5-/- MEF that lack autophagy-associated gene 5 (ATG5) which is essential for autophagy. Pre-treatment of ATG5-/- MEF with SFN (5 μM for 24 h) did not protect against cell death induced by CdSe QDs (20–30 μM) signifying the importance of autophagy in the protection (Fig 6B); whereas at low levels of CdSe QDs (5–10 μM) exposure there was a protective effect (7.2–7.5% increase in cell viability, P<0.05) which may be due to the activation of Nrf2 pathway.


Sulforaphane Protects the Liver against CdSe Quantum Dot-Induced Cytotoxicity.

Wang W, He Y, Yu G, Li B, Sexton DW, Wileman T, Roberts AA, Hamilton CJ, Liu R, Chao Y, Shan Y, Bao Y - PLoS ONE (2015)

Effect of autophagy inhibitor on the protective effect of SFN on CdSe QD-induced cell death.(A) HHL-5 cells were pre-incubated with wortmannin (0.1 μM) for 6 h, and then exposed to SFN (5 μM) for 24 h. There was a further 24 h exposure with 20 μM CdSe QDs. (B) MEF ATG5-/- cells were pre-incubated with SFN (5 μM) for 24 h and then exposed for a further 24 h with CdSe QDs (10–30 μM). Cytotoxicity was measured by MTT assay. Data are shown as means ± SD (n = 6) (**P<0.01).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581733&req=5

pone.0138771.g006: Effect of autophagy inhibitor on the protective effect of SFN on CdSe QD-induced cell death.(A) HHL-5 cells were pre-incubated with wortmannin (0.1 μM) for 6 h, and then exposed to SFN (5 μM) for 24 h. There was a further 24 h exposure with 20 μM CdSe QDs. (B) MEF ATG5-/- cells were pre-incubated with SFN (5 μM) for 24 h and then exposed for a further 24 h with CdSe QDs (10–30 μM). Cytotoxicity was measured by MTT assay. Data are shown as means ± SD (n = 6) (**P<0.01).
Mentions: Wortmannin acts as a selective inhibitor of type III PI-3K [45]. When wortmannin (0.1 μM) was used to inhibit SFN-induced autophagy, the protective effect of SFN (5 μM) on CdSe QD (20 μM)-induced cell death was suppressed significantly and cell viability decreased from 95 to 78% (Fig 6A). A similar effect was observed using 3-MA, another commonly used autophagy inhibitor, which can also block autophagosome formation via inhibition of type III PI-3K [46]. 3-MA decreased the protective effect of SFN on cell viability from 86.3% to 68.4% (S5 Fig). These results suggest that the induction of autophagy by SFN has a significant role in the protection against CdSe-induced cell death. The role of autophagy was further examined using ATG5-/- MEF that lack autophagy-associated gene 5 (ATG5) which is essential for autophagy. Pre-treatment of ATG5-/- MEF with SFN (5 μM for 24 h) did not protect against cell death induced by CdSe QDs (20–30 μM) signifying the importance of autophagy in the protection (Fig 6B); whereas at low levels of CdSe QDs (5–10 μM) exposure there was a protective effect (7.2–7.5% increase in cell viability, P<0.05) which may be due to the activation of Nrf2 pathway.

Bottom Line: Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death.CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment.In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.

View Article: PubMed Central - PubMed

Affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom.

ABSTRACT
The potential cytotoxicity of cadmium selenide (CdSe) quantum dots (QDs) presents a barrier to their use in biomedical imaging or as diagnostic and therapeutic agents. Sulforaphane (SFN) is a chemoprotective compound derived from cruciferous vegetables which can up-regulate antioxidant enzymes and induce apoptosis and autophagy. This study reports the effects of SFN on CdSe QD-induced cytotoxicity in immortalised human hepatocytes and in the livers of mice. CdSe QDs induced dose-dependent cell death in hepatocytes with an IC50 = 20.4 μM. Pre-treatment with SFN (5 μM) increased cell viability in response to CdSe QDs (20 μM) from 49.5 to 89.3%. SFN induced a pro-oxidant effect characterized by depletion of intracellular reduced glutathione during short term exposure (3-6 h), followed by up-regulation of antioxidant enzymes and glutathione levels at 24 h. SFN also caused Nrf2 translocation into the nucleus, up-regulation of antioxidant enzymes and autophagy. siRNA knockdown of Nrf2 suggests that the Nrf2 pathway plays a role in the protection against CdSe QD-induced cell death. Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death. Moreover, the role of autophagy in SFN protection against CdSe QD-induced cell death was confirmed using mouse embryonic fibroblasts lacking ATG5. CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment. In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.

No MeSH data available.


Related in: MedlinePlus