Changes of oxidative stress and expression of N⁶ methyladenosine modification enzymes during cell damage induced by cadmium in renal cells

Background N⁶ methyladenosine (m⁶A) modification enzymes participate in the process of cell damage. However, the changes of m⁶A modification enzymes in renal cell damage induced by cadmium remain unclear.

Objective This experiment investigates changes of m⁶A modification enzymes during the process of CdSO₄-induced cell damage in human renal tubules cells (HK-2 cells).

Methods HK-2 cells were treated with different concentrations of CdSO₄ (0, 4, 8, and 16 μmol·L^-1) for 24 h and corresponding indicators were tested. The apoptotic level was observed after Hoechst staining by counting normal cells and apoptotic cells in a random field under microscope and the apoptotic rate was calculated; the activity of superoxide dismutase (SOD), the activity of glutathione peroxidase (GSH-PX), and the content of malondialdehyde (MDA) were detected using corresponding kits; the protein expression levels of methyltransferase like 3 (METTL3) and fat mass and obesity associated protein (FTO) were detected by Western blotting, and the mRNA expression levels of YTH domain family protein 1 (YTHDF1) and YTH domain family protein 3 (YTHDF3) were detected by real-time PCR.

Results After administration with CdSO₄ at 0, 4, 8, and 16 μmol·L^-1, the cell apoptotic rates were 6.83%, 5.17%, 21.17%, and 35.80%, respectively. Compared with the 0 μmol·L^-1 CdSO₄ group, the SOD activities of the 4, 8, and 16 μmol·L^-1 CdSO₄ groups were decreased(15.41±0.96), (13.57±1.42), and (10.96±0.61)×10³U·g^-1, respectively (P < 0.05), the GSH-PX activity of the 8μmol·L^-1 CdSO₄ group was decreased to (8.74±3.91) U·g^-1, and the MDA content of the 8 and 16 μmol·L^-1 CdSO₄ groups were increased to (87.69±3.05) and (93.42±4.71) μmol·g^-1 (P < 0.05). The results of Western blotting showed that the protein expression levels of METTL3 of the 4, 8, and 16 μmol·L^-1 CdSO₄ groups increased to 1.09, 1.25, and 1.33 times of the 0 μmol·L^-1 CdSO₄ group respectively, and the protein expression levels of FTO of the 8 and 16 μmol·L^-1 CdSO₄ groups decreased to 0.81 and 0.74 times of the 0 μmol·L^-1 CdSO₄ group respectively (P < 0.05). At 4 μmol·L^-1 CdSO₄, the mRNA expression level of YTHDF1 increased to 7.62 times of the 0 μmol·L^-1 CdSO₄ group, and at 4 and 16 μmol·L^-1 CdSO₄, the mRNA expression levels of YTHDF3 increased to 2.65 and 2.26 times of the 0 μmol·L^-1 CdSO₄ group respectively (P < 0.05).

Conclusion The protein expressions of METTL3 and FTO as well as the mRNA expressions of YTHDF1 and YTHDF2 are changed in the process of CdSO₄-induced cell damage in HK-2 cells.