Serum deprivation enhances DNA synthesis of human hepatoma SMMC-7721 cells

AIM To determine the relationship between serum deprivation or serum levels and cell proliferation of human hepatoma SMMC-7721 cells. METHODS Human hepatoma SMMC-7721 cells were grown in RPMI 1640 supplemented with 10% fetal calf (FCS) in 5% CO2 incubator at 37 degrees C for 24 h, and culture media were replaced to serum-free or different serum FCS levels (2.5%, 5%, 10%, 20% and 25%). Six h, 12 h, 18 h and 24 h after the culture, the cells were incorporated [H-3]-TdR for 4 h. At last [3H]-TdR incorporation was detected with liquid scintillation counting. RESULTS DNA synthesis of SMMC-7721 cells could be sharply stimulated by short-time (6 h) serum deprivation (the cpm value of H-3-TdR incorporation of cells in serum-free was 39.32-fold higher than cells in 25% serum), and the incorporation of H-3-TdR was negatively related to the serum levels. Longer-time serum starvation (12 h, 18 h and 24 h) also greatly stimulated DNA synthesis, although the cpm value of H-3-TdR incroporation was less than that in 6 h serum deprivation. Morphology of cells cultured in different serum levels also showed significant difference. CONCLUSIONS Compared with other cell lines such as BEL7404 and Swiss 3T3, human hepatoma SMMC-7721 cells had different response to the serum deprivation. Short-time serum deprivation could greatly stimulate DNA synthesis of human hepatoma SMMC-7721 cells. Precautions must be given to the changes of serum levels for the detection of growth factors and drugs using SMMC-7721 cells as a model.