Comparative Proteomic Characterization of Serum-Free Cultivated HepG2 Cells Reveals Upregulated Drug Metabolism and Increased Oxidative Stress Protection.

Fetal bovine serum (FBS) is commonly used in cell culture models despite being considered critical from both an ethical and scientific standpoint. Since it has been used for many years with a variety of different cells and cell types, research has become dependent on its use, and scientists hesitate to change their working model without solid data demonstrating the usability of serum-free cultivated cells in their desired applications. To shed light on the highly complex issue of dietary demands of cells in culture and the impact of media supplements on cellular behavior, we performed a comparative proteomic characterization between HepG2 cells cultivated in serum-free or FBS-containing conditions with a focus set on drug metabolism and oxidative stress response, the main application field of the HepG2 cell line. We observed the predicted upregulation of multiple pathways associated with drug metabolism and oxidative stress protection, as well as a strong overexpression of multiple antioxidative enzymes such as glutathione peroxidase and glutathione S-transferase at the protein expression level. We confirmed that increased enzyme expression correlates with higher enzyme activity in vitro and linked increased glutathione peroxidase activity to selenium supranutrition under serum-free conditions.