K. Ogura et al., 8-bromo-cyclicAMP stimulates glucose transporter-1 expression in a human choriocarcinoma cell line, J ENDOCR, 164(2), 2000, pp. 171-178
Facilitative glucose transporter-1 (GLUT1) is abundant in trophoblast cells
and is responsible for glucose transport in the placenta. However, the cha
nge in GLUT expression in human placenta upon trophoblast differentiation r
emains to be clarified. Therefore, we first examined the localization of GL
UT1 and GLUT3 using human first-trimester chorionic villi. We found that GL
UT1 and GLUT3 were mainly localized to syncytiotrophoblast and cytotrophobl
ast cells respectively. We analyzed whether placental GLUT1 and GLUT3 expre
ssion changes during differentiation using a human choriocarcinoma (BeWo) c
ell line which is known to show functional and morphological differentiatio
n in response to cAMP in culture. Treatment of BeWo cells with 8-bromo-cycl
icAMP (8-bromo-cAMP) increased the level of hCG secretion and induced cell
fusion leading to the formation of large syncytia. Treatment of BeWo cells
with 8-bromo-cAMP also resulted in a significant increase in glucose uptake
on days 2-3 of culture. The stimulating effect of 8-bromo-cAMP on glucose
uptake was concentration dependent. Northern and immunoblot analyses reveal
ed that the levels of mRNA and protein of GLUT1, but not of GLUTS, were sig
nificantly increased by 8-bromo-cAMP. These findings suggest that 8-bromo-c
AMP stimulates GLUT1 expression with differentiation in BeWo cells.