Fig 2: A and B the protein expression of Nrf2 was investigated by western blotting in HK2 cells (n = 6). C–E, the expressions of HSP22 and HO-1 were detected by western blotting in HK2 cells (n = 6). C, F, and G the expressions of pro-oxidative stress proteins, such as NOX-2 and NOX-4, were detected by western blotting in HK2 cells (n = 6). C, H, and I the expressions of antioxidant proteins, such as SOD-1 and SOD-2, were detected by western blotting in HK2 cells (n = 6). J, K, and L the protein expressions of pro-apoptosis protein Bax and anti-apoptosis protein Bcl-2 were investigated by western blotting in HK2 cells (n = 6). ns means no statistically significant, *p < 0.05, **p < 0.01 and ***p < 0.001. Data represent the mean ± SD of at least 3 times of separate experiments.

Fig 3: Antioxidant enzyme activities, OxPhos coupling, and oxidative damage accumulation in MNCs isolated from CCS before and after NAC treatment. Data reported in this figure were obtained on MNCs isolated from n = 20 CCS of solid tumor (sCCS; aged under 40 y.o.) and n = 22 CCS of hematological tumors (hCCS; aged under 40 y.o.) treated or not with NAC. (A) G6PD activity; (B) H6PD activity; (C) GR activity; (D) GPx activity; (E) SOD activity; (F) CAT activity; (G) ROS production; (H) P/O value as an OxPhos efficiency marker; (I) Malondialdehyde (MDA) intracellular concentration, as a lipid peroxidation marker; (J) 4-hydroxynonenal (4-HNE) intracellular concentration, as a lipid peroxidation marker; (K) 8-Hydroxy-2′-deoxyguanosine (8-OHdG) intracellular concentration, as a DNA oxidative damage marker; (L) Nitrotyrosine intracellular level, as a protein oxidative damage marker. **** indicates a p < 0.0001.

Fig 4: Activity and protein expression of SOD and CAT in MNCs isolated from CCS, age-matched healthy subjects, and elderly healthy controls. Data reported in Panels (A,B) were obtained on MNCs isolated from age-matched healthy controls (<10 y.o., n = 18; 11–20 y.o., n = 32; 21–40 y.o., n = 20), CCS of solid tumor (sCCS; <10 y.o., n = 27; 11–20 y.o., n = 29; 21–40 y.o., n = 18), CCS of hematological tumors (hCCS; <10 y.o., n = 25; 11–20 y.o., n = 28; 21–40 y.o., n = 22), healthy donors aged between 41–60 y.o., n = 19; healthy donors aged between 61–80 y.o., n = 25; healthy donors aged over 80 y.o., n = 22. Data reported in Panels (C–F) are representative of three independent experiments, each on n = 3 age-matched healthy donors (<40 y.o); n = 3 (CCS < 40 y.o.), and n = 3 elderly healthy subjects (>60 y.o.). (A) SOD activity; (B) CAT activity; (C) Representative Western blot signals of SOD1 (cytosolic form), SOD2 (mitochondrial form), and CAT. Actin was evaluated as a housekeeping signal. (D) Densitometric analysis of SOD1 signal normalized against actin signal; (E) Densitometric analysis of SOD2 signal normalized against actin signal; (F) Densitometric analysis of CAT signal normalized against actin signal. ROD = Relative Optical Density. *, **** indicate a p < 0.05, 0.0001. In panels (A,B), ##, and ### indicate a p < 0.01, or 0.001, respectively, between sCCS or hCCS and healthy donors over 80 y.o.

Fig 5: Nrf2 and antioxidant enzymes protein expression in MNCs isolated from CCS before and after NAC treatment. Data reported in this figure are representative of three independent experiments, each on n = 3 CCS and n = 3 same CCS treated with NAC. (A) Representative Western blot signals of Nrf2, G6PD, H6PD, GR, GPx, SOD1, SOD2, and CAT. Actin was evaluated as a housekeeping signal. (B) Densitometric analysis of Nrf2 signal normalized against actin signal; (C) Densitometric analysis of G6PD signal normalized against actin signal; (D) Densitometric analysis of H6PD signal normalized against actin signal; (E) Densitometric analysis of GR signal normalized against actin signal; (F) Densitometric analysis of GPx signal normalized against actin signal; (G) Densitometric analysis of SOD1 (cytosolic form) signal normalized against actin signal; (H) Densitometric analysis of SOD2 (mitochondrial form) signal normalized against actin signal; (I) Densitometric analysis of CAT signal normalized against actin signal. ROD = Relative Optical Density. **** indicates a p < 0.0001.