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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 SFN on the cytotoxicity of CdSe QDs in HHL-5 cells.Effect of SFN pre-treatment on CdSe QD-induced cytotoxicity. HHL-5 cells were pre-treated with SFN (5 μM) for 24 h, and then incubated with 20–30 μM CdSe QDs for another 24 h. Cytotoxicity was measured by MTT assay, and data shown as means ± SD (n = 6). **P<0.01.
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pone.0138771.g001: Effect of SFN on the cytotoxicity of CdSe QDs in HHL-5 cells.Effect of SFN pre-treatment on CdSe QD-induced cytotoxicity. HHL-5 cells were pre-treated with SFN (5 μM) for 24 h, and then incubated with 20–30 μM CdSe QDs for another 24 h. Cytotoxicity was measured by MTT assay, and data shown as means ± SD (n = 6). **P<0.01.

Mentions: CdSe (10:1) QDs showed notable cytotoxicity in HHL-5 cells after 12 h exposure. The cytotoxicity was more significant after 24 h with an IC50 = 20.4 μM CdSe pairs which is equivalent to 0.78 nmol core QDs/ml. However, when the cells were pre-treated with 5 μM SFN for 24 h, the cytotoxicity induced by 20 μM CdSe QDs (24 h exposure) significantly decreased, raising cell viability from 49.5 to 89.3% (P<0.01, Fig 1). Moreover, CdSe QDs (15–25 μM) caused a concomitant rise in the percentage of necrotic (PI positive cells) and putative late stage apoptotic cells (double positive), as indicated by Annexin V/PI staining (Fig 2). CdSe QD-associated-fluorescence could account for the majority of double positives observed. True Annexin V positive cells were observed at higher fluorescence levels in all samples. CdSe QD-associated fluorescence was limited in the PI channel and does not account for the two log decade shift in fluorescence seen in CdSe treated samples. Furthermore, absolute sample cell counts and the appearance of cellular debris indicated loss of cellular integrity in CdSe QD-treated samples. Thus, overall, the data indicated that CdSe QD exposure led to necrotic cell death. Pretreatment with 5 μM SFN abrogated cytotoxicity induced by CdSe QDs with an observable increase in the viable cell percentage (double negative) relative to the non-pretreated control cells (Fig 2) as well as increased absolute cell counts and minimal cellular debris.


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 SFN on the cytotoxicity of CdSe QDs in HHL-5 cells.Effect of SFN pre-treatment on CdSe QD-induced cytotoxicity. HHL-5 cells were pre-treated with SFN (5 μM) for 24 h, and then incubated with 20–30 μM CdSe QDs for another 24 h. Cytotoxicity was measured by MTT assay, and data 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.g001: Effect of SFN on the cytotoxicity of CdSe QDs in HHL-5 cells.Effect of SFN pre-treatment on CdSe QD-induced cytotoxicity. HHL-5 cells were pre-treated with SFN (5 μM) for 24 h, and then incubated with 20–30 μM CdSe QDs for another 24 h. Cytotoxicity was measured by MTT assay, and data shown as means ± SD (n = 6). **P<0.01.
Mentions: CdSe (10:1) QDs showed notable cytotoxicity in HHL-5 cells after 12 h exposure. The cytotoxicity was more significant after 24 h with an IC50 = 20.4 μM CdSe pairs which is equivalent to 0.78 nmol core QDs/ml. However, when the cells were pre-treated with 5 μM SFN for 24 h, the cytotoxicity induced by 20 μM CdSe QDs (24 h exposure) significantly decreased, raising cell viability from 49.5 to 89.3% (P<0.01, Fig 1). Moreover, CdSe QDs (15–25 μM) caused a concomitant rise in the percentage of necrotic (PI positive cells) and putative late stage apoptotic cells (double positive), as indicated by Annexin V/PI staining (Fig 2). CdSe QD-associated-fluorescence could account for the majority of double positives observed. True Annexin V positive cells were observed at higher fluorescence levels in all samples. CdSe QD-associated fluorescence was limited in the PI channel and does not account for the two log decade shift in fluorescence seen in CdSe treated samples. Furthermore, absolute sample cell counts and the appearance of cellular debris indicated loss of cellular integrity in CdSe QD-treated samples. Thus, overall, the data indicated that CdSe QD exposure led to necrotic cell death. Pretreatment with 5 μM SFN abrogated cytotoxicity induced by CdSe QDs with an observable increase in the viable cell percentage (double negative) relative to the non-pretreated control cells (Fig 2) as well as increased absolute cell counts and minimal cellular debris.

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