The Xenobiotic Transporter ABCG2 Plays a Novel Role in Differentiation of Trophoblast-like BeWo Cells

Trophoblast cells undergo loss of plasma membrane lipid asymmetry during cell fusion without further progression to terminal phases of apoptosis. The nature of the anti-apoptotic mechanisms providing cell survival during this process is unknown. Using a BeWo cell model, we explored the role of the xenobiotic/lipid transporter ABCG2 in promoting cell survival during forskolin-induced differentiation. Suppression of ABCG2 expression by siRNA led to a marked increase in phosphatidylserine externalisation followed by accumulation of ceramides and increased apoptosis. Expression of markers of syncytial formation (β-hCG and HERV-W) was decreased by ABCG2 silencing, although fusion was unaffected. These findings suggest that ABCG2 protects cells during the period of transient membrane instability associated with cell differentiation and fusion, highlighting a novel, previously unrecognised role of ABCG2 as a survival factor during the formation of the placental syncytium.