110. EFFECTS OF cAMP AND SERUM ON HUMAN TROPHOBLAST CELL VIABILITY AND DIFFERENTIATION

The formation of syncytium is a pivotal event for trophoblast cells to interact with the placental bed. While cAMP is regarded as an inducer of syncytialisation, the affect of different culture conditions on this cAMP effect has not been explored. Therefore, the effects of cAMP on cell differentiation and viability in the presence or absence of serum were investigated in the human choriocarcinoma cell lines, BeWo and JEG-3. We observed that in the absence of cAMP, BeWo cells grew best in media containing 10% FCS, followed by media containing charcoal-stripped 10% FCS (10%CCS), and less well in serum-free media. In the presence of cAMP ( 0.25~1.5 mM ), our observations suggest different cellular programmes may be in play. Treatment of BeWo cells with 0.75 mM cAMP for 24h and 48h, in the absence of serum, increased cell viability (MTT assay) by 25.1% and 46.1% respectively, compared to the control cells. Interestingly, this cAMP effect on cell viability was not observed in the JEG-3 cell line. In contrast, BeWo cell viability was decreased by 49.5% and 25.2%, and by 27.5% and 31.1% in JEG-3 cells, when the cAMP stimulated cells were cultured for 48h in 10% CCS and 10% FCS media, respectively. In addition, we observed a change in BeWo, but not JEG-3, cell morphology to a spindle-like shape with pseudopodia when cAMP stimulated cells were cultured in media containing 10% CCS or 10% FCS for greater than 24h. Since the process of syncytialisation may involve apoptotic events, we speculate that the different effects of cAMP on cell viability in trophoblast cells may be related to syncytialising factors contained in serum media. Further study will clarify whether serum promotes syncytium formation, while the lack of serum based factors could switch the cellular programme from one of syncytialisation toward a more proliferative type.