Tissue Culture Media Supplemented With 10% Fetal Calf Serum Contains a Castrate Level of Testosterone

BACKGROUND. Human prostate cancer cells are routinely maintained in media supplemented with 10% Fetal Calf Serum (FCS) to provide androgen. In the present study, total and free testosterone levels in 10%FCS supplemented tissue culture media were determined and compared to levels in intact and castrated human males. Dextran-coated charcoal stripped FCS (i.e., DC-FCS) is often used instead of FCS to minimize the level of androgen provided in 10% serum supplemented media. Therefore, total and free testosterone levels in 10%DC-FCS containing media were likewise determined. METHODS. Total testosterone, free testosterone, and total dihydrotestosterone (DHT) were determined on RPMI-1640 media supplemented with either 10%FCS or 10%DC-FCS by ELISA assays before and after exposure to LNCaP human prostate cancer cells in culture. The growth and PSA secretion by these cells was also determined. RESULTS. Ten percentage FCS supplemented media contains a castrate level of testosterone. However, even with this castrate starting level of testosterone, LNCaP cells concentrate and metabolize the testosterone to produce a physiologic (i.e., 10 nM) level of intracellular DHT which optimally stimulates the growth of these cells in vitro. CONCLUSIONS. The present studies document that prostate cancer cells auto-regulate their androgen metabolism so that an optimal level of DHT for growth is maintained during both up and down fluctuations in the supply of testosterone. These results have significant implications for whether exogenous androgen should be added to the 10%FCS supplemented media to grow prostate cancer cells from intact versus castrated patients. Prostate 69: 1724-1729, 2009. (C) 2009 Wiley-Liss, Inc.