7,8-Dihydroxyflavone enhances recombinant proteins expression in CHO cells by modulating SIRT1 signalling to improve mitochondrial respiratory capacity and redox homeostasis.

Chinese hamster ovary (CHO) cells serve as a critical mammalian system for producing therapeutic proteins in biopharmaceuticals. However, these cells exhibit highly active aerobic glycolysis during culture, which leads to reduced energy conversion efficiency and excessive lactic acid accumulation. This metabolic dysregulation can further impair cell growth and recombinant protein expression. Enhancing the endogenous NAD⁺ level is critical for improving cellular metabolism; however, current technical approaches face significant challenges. In the present study, we found that 7,8-dihydroxyflavone increased the expression of recombinant proteins in CHO cells by 1.6- and 1.5-fold, respectively, while reducing antibody aggregation by approximately 6.0%. Transcriptome and metabolic pathway analyses revealed that the elevated intracellular NAD⁺ content activated the SIRT1-PGC-1β pathway, which modulates mitochondrial energy synthesis and enhances antioxidant capacity while mitigating lactate accumulation in the glycolytic pathway. Furthermore, 7,8-dihydroxyflavone significantly inhibited apoptosis by upregulating BCL-2 expression and downregulating BAX and cleaved caspase-3 expression. Taken together, these findings indicate that 7,8-dihydroxyflavone may serve as a promising metabolic modulator for recombinant protein production.