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 serum (FCS)in 5% CO(2) incubator at 37&mgr; for 24h, and culture media were replaced to serum-free or different serum FCS levels (2.5%, 5%, 10%, 20% and 25%). Six h,12h,18h and 24h after the culture,the cells were incorporated &mgr;(3)H&mgr;-TdR for 4h. At last &mgr;(3)H&mgr;-TdR incorpor-ation was detected with liquid scintillation counting.RESULTS:DNA synthesis of SMMC-7721 cells could be sharply stimulated by short-time (6h) serum deprivation (the cpm value of (3)H-TdR incorporation of cells in serum-free was 39.32-fold higher than cells in 25% serum),and the incorporation of (3)H-TdR was negatively related to the serum levels.Longer-time serum starvation (12h, 18h and 24h) also greatly stimulated DNA synthesis, although the cpm value of (3)H-TdR incroporation was less than that in 6h serum deprivation. Morphology of cells cultured in different serum levels also showed significant difference.CONCLUSION: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.