Abstracts: E.P.G and R T.C. Belgtum 1995
EFFECT OF RETINOIC ACID ON CULTURED HUMAN TROPHOBLAST CELLS. A. Malek, A Zakher and H. Schneider Department of Obstetrics and Gynaecology, University of Berne, Switzerland. Vitamin A and ItS structurally related retinoids have been reported to enhance cell proliferation and to either enhance or suppress differentiation. Retinoic acid (RA) is a physiological metabolite of vitamin A and has been shown as both a morphogen and a teratogen. We have previously demonstrated the inhibitory effect of acitretin (a synthetic retinoid) on the release of HCG only. Such an effect could not be shown on other placental proteins (I-IPL, SP 1 and PAPP-A) using cultured trophoblast cells. We have isolated cytotrophoblast cells at different stages of development from human term placenta (n=2) using percoll density (D) gradient (1.033-1 075g/mL) Cells isolated at D=1.063 winch have prewously been shown to be at an early stage of development, were cultured for 5 days in the presence of RA (50, 200 and 1600 ng/mL) or vehicle control (0.16% acetone). Four placental proteins (HCG, HPL, SP 1 and PAPP-A) were measured. The quantity of protein released by the cultured cells under control conditions during day 1 and 2 amounts to 10-30% for HCG, PAPP-A, SP 1 and 50% for I-IPL release during the total culture period of 5 days. There seems to be more protein release into the culture media between day 2 and 5, with a lag phase of release during the first two days of culture. In this study the effect of RA on the mean release observed between day 2 and 5 was compared to the values obtained m the control experiments. There was a dose dependent stimulatory effect of ILk on HCG, PAPP-A and SP1, but not on HPL. Culture with 1600 ng/mL RA showed 125-140% of the control release for HCG, PAPP-A and SP 1, while with 50 ng/mL RA SP 1 reached 115% while no effect on HCG and PAPP-A was observed. The effect on HPL release showed an opposite trend. The higher concentration of RA (1600 ng/mL) was without effect while with the lower concentration (200 and 50 ng/mL R.A) there was inhibition (16%, 28% respectively). These results demonstrate that the action of RA on cultured trophoblast cells is both dose dependent and protein specific
EXPRESSION OF AMPHIREGULIN AND TRANSFORMING GROWTH FACTOR ALPHA mRNA IN GESTATIONAL TISSUE AT TERM. U. Manuelpillai, M. Bhave, B. Fairclough and M. Towstoless, Centre for Bioprocessmg and Food Technology, Victoria University, Werribee, Victoria, Australia. Human gestauonal tissue is known to express Epidermal Growth Factor (EGF) and its receptor the Epidermal Growth Factor Receptor (EGFR). However, the m.RNA expression and roles of other members of the EGF family such as Amphlreguhn (Ar) and Transforrmng Growth Factor Alpha (TGFa) in gestational tissue is still uncertain. Previous studies have shown that Ar and TGFa bind to the EGFR and have been detected m carcinomas where these peptides have been implicated in cellular transformation. This study was undertaken to determine the levels of mRNA expression for Ar and TGFa in antalon, chonon and placental tissue obtained from caesarean section and spontaneous delivery at term. Total RNA was extracted from tissue collected in liquid nitrogen between 38-40 weeks of gestauon. Northern blots containing total RNA were probed with 3~p labelled human cDNA TGF~ probe or an oligonucleotlde probe complementary to human Ar. Messenger RNA transcripts of 1.4 and 4 4kb of Ar and TGFa respectively were found to be expressed in the amnion, chorion and placenta from spontaneously delivered and caesarean section tissue. Total RNA was also subjected to reverse transcription PCR using primers complementary to human Ar and fragments obtained from gel electrophoresls of these RT-PCR products were found to be the expected size. Laser densttometnc scanning of autoradiographs indicated simdar relative levels of TGFo~ or Ar in the ammon, chonon and placenta. The presence of mRNA transcripts indicate that Ar and TGFot may play a role in parturition and or fetoplacental development.