Analysis of the mechanism of aldo-keto reductase dependent cis-platin resistance in HepG2 cells based on transcriptomic and NADH metabolic state

Background: Aldo-keto oxidoreductase (AKR) inhibitors could reverse the resistance of several cancer cells to cis-platin, but their role in resistance remains unclear. Methods: We verified the difference of AKR1Cs expression by Western blot, RNA sequencing and qRT-PCR. The differences of AKR1Cs expression were analyzed and inferred. Use Assay of NADH and NAD" content to verify the inference. The Docking experience was used to verify the affinity between MPA, MCFLA, MLS and AKR1C3. Results: Our RNA-seq results showed de novo NAD biosynthesis-related genes and NAD(P)H-dependent oxidoreductases were significantly upregulated in cis-platin-resistant HepG2 hepatic cancer cells (HepG2-RC cells) compared with HepG2 cells. At least 63 NAD(P)H-dependent reductase/oxidases were upregulated in HepG2-RC cells at least twofold. Knockdown of AKR1Cs could increase cis-platin sensitivity in HepG2-RC cells about two-fold. Interestingly, the AKR1C inhibitor meclofenamic acid could increase the cis-platin sensitivity of HepG2-RC cells about eight-fold, indicating that the knockdown of AKR1Cs only partially reversed the resistance. Meanwhile, the amount of total NAD and the ratio of NADH/NAD" were increased in HepG2-RC cells compared with HepG2 cells. The ratio of NADH/NAD" in HepG2-RC cells was almost seven-fold higher than in HepG2 or HL-7702 cells. Increased NADH expression could be explained as a directly operating antioxidant to scavenge cis-platin-induced radicals. Conclusion: We report here that NADH, which is produced by NAD(P)H-dependent oxidoreductases, plays a key role in the AKR-associated cis-platin resistance of HepG2 hepatic cancer cells.