Media composition and O2 levels determine effects of 17b-estradiol and selective estrogen receptor modulators on mitochondrial bioenergetics and cellular reactive oxygen species

Estradiol (E2) and selective estrogen receptor modulators (SERMs) have broad-ranging cellular effects that include mitochondrial respiration and reactive oxygen species (ROS) metabolism. Many of these effects have been studied using cell culture models. Recent advances have revealed the extent to which cellular metabolism is affected by the culture environment. Cell culture media with metabolite composition similar to blood plasma [e.g., Plasmax, Human Plasma-Like Medium (HPLM)] alter cellular behaviors including responses to drugs. Similar effects have been observed with respect to O2 levels in cell culture. Given these observations, we investigated whether the effects of E2 and SERMs are also influenced by media composition and O2 level during cell culture experiments. We analyzed mitochondrial network characteristics, cellular oxidative metabolism, and H2O2 production in C2C12 myoblasts growing in physiological (5%) or standard cell culture (18%)O2 and in physiological (Plasmax) or standard cell culture [Dulbecco’s modified Eagle’s medium (DMEM)] media. Although E2 significantly lowered H2O2 production from cells growing in 18% O2/DMEM (standard cell culture), it had no effect on cells growing in Plasmax. Moreover, culture conditions significantly altered the effects of E2 and SERMs on mitochondrial abundance and network characteristics. These results indicate that the effects of E2 and SERMs on various aspects of cell physiology strongly depends on growth conditions, which in turn emphasizes the need to consider this carefully in cell culture experiments.