The protective effects of maltol on cisplatin-induced nephrotoxicity through the AMPK-mediated PI3K/Akt and p53 signaling pathways

Figures

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  Figure 1. Protective effects of maltol pretreatment against cisplatin-evoked renal toxicity in mice. After cisplatin challenge, all mice were euthanized and their serums and kidneys were collected. (A) Kidney GSH level. (B) Kidney MDA level. (C) Kidney CAT level. (D) Kidney SOD level. All values were expressed as mean ± S.D. (n = 8 in each group). **p < 0.01, ***p < 0.001 vs. normal group; #p < 0.05, ###p < 0.001 vs. cisplatin group.

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  Figure 2. Maltol attenuated cisplatin-induced morphological changes. (A,B) H&E staining and PAS stain of kidney sections from normal group, cisplatin group, maltol (50 mg/kg) + cisplatin group and maltol (100 mg/kg) + cisplatin group. Note: The condensation of the cell necrosis (green arrow) and protein cast (yellow arrow) in cisplatin mice. Red arrows refer to vacuolization of the renal cortex (magnification ×400). The renal injury score (C) was determined. All values were expressed as mean ± S.D. **p < 0.01 vs. normal group; #p < 0.05, ##p < 0.01 vs. cisplatin group.

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  Figure 3. Renal tissues stained with TUNEL staining (A) and Hoechst 33258. (B) The existence of TUNEL positive cells were assessed by image analyzer. (C) The relative levels of fluorescence intensity were quantified. Magnification ×200. Values are expressed as mean ± S.D. **p < 0.01 vs. normal group; #p < 0.05, ##p < 0.01 vs. cisplatin group.

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  Figure 4. Effects of maltol on the levels of inflammation cytokines in cisplatin-induced renal toxicity. (A) Effects of maltol on the positive expressions of Bax, Bcl-2, iNOS and COX-2 in renal tissues were examined by IHC in renal tissues (magnification × 200), And the column chart shows stained area, semiquantitative analysis of Bax, Bcl-2, iNOS and COX-2 expression in kidneys to IHC. (B) Inflammation cytokines level of TNF-α, IL-1β, iNOS and NF-κB in serum of mice were measured by ELISA kits. All values were expressed as mean ± S.D. *p < 0.05, **p < 0.01 vs. normal group; #p < 0.05, ##p < 0.01 vs. cisplatin group.

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  Figure 5. Protective effects of maltol on cisplatin-induced injury in HEK293 cells. (A) The cytotoxic effects of cisplatin on HEK293 cells. (B) Effect of maltol on the activity of normal cells. (C) The viability of HEK293 cells incubated with maltol after cisplatin exposure. Effects of maltol on the protein expression levels of Bcl-2, Bax and caspase 3, 8, 9 as well as GAPDH protein was used as a loading control. (D) Cells were used for western blot analysis of indicated proteins (upper panel). Column chart represents relative protein levels compared with the control group after normalization to GAPDH levels (lower panel) Values are expressed as mean ± S.D. n = 8. **p < 0.01 vs. normal group; #p < 0.05, ##p < 0.01 vs. cisplatin group.

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  Figure 6. Effects of maltol on cisplatin-induced protein expression of PI3K/AKT signaling pathway. (A) Effects of maltol on the protein expression levels of AMPK/PI3K/Akt signaling pathway as well as GAPDH protein was used as a loading control. (B) Effects of maltol on the protein expression levels of p53 protein (left panel). Column charts show antibodies relative expression, protein expression was performed by quantification of relative protein expression analysis in HEK293 cells from each group (right panel). Values are expressed as mean ± S.D. n = 8. **p < 0.01 vs. normal group; #p < 0.05, ##p < 0.01 vs. cisplatin group.

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  Figure 7. Scheme summarizing the inhibition of cisplatin-induced nephrotoxicity by maltol via the down-regulation of AMPK through PI3K/Akt pathway.