Expression of insulin-like growth factor-II and insulin-like growth factor binding protein-1 in the placental basal plate from pre-eclamptic pregnancies

Abstract

Objectives: To determine whether expressions of insulin-like growth factor-II (IGF-II) and insulin-like growth factor binding protein-1 (IGFBP-1) are altered in pre-eclamptic placenta and to elucidate the possible relationship between their expressions and a mechanism for inadequate trophoblast invasion in pre-eclampsia. Methods: Placental tissues were obtained at cesarean delivery from five normotensive, nine mild pre-eclamptic and five severe pre-eclamptic women at 33–39 completed weeks of gestation. After total ribonucleic acid was extracted, reverse transcriptase-polymerase chain reaction was performed to determine IGF-II and IGFBP-1 mRNA expression. Product bands were quantitated by scanning densitometry and results were expressed as ratio of cytokines/β-actin. Western blot analysis was also done to determine IGF-II and IGFBP-1 protein expression. Statistical analysis was determined by Kruskal–Wallis analysis of variance with the Scheffe multiple post-hoc test. Results: The IGF-II mRNA levels of mild and severe pre-eclamptic placenta were significantly lower than that of uncomplicated placenta (P<0.005, P<0.001, respectively), with the level of severe pre-eclamptic placenta being significantly lower than that of mild pre-eclamptic placenta (P<0.05). As for the IGF-II protein expression, a significant decrease was found among the three groups (P<0.001), correlating with the IGF-II mRNA results. However, the mean IGFBP-1 mRNA levels of mild and severe pre-eclamptic placenta were significantly higher than that of uncomplicated placenta (P<0.05, P<0.005, respectively), with the level of severe pre-eclamptic placenta being significantly raised compared with that of mild pre-eclamptic placenta (P<0.05). Finally, a significant increase of IGFBP-1 protein expression was noted among the three groups (P<0.001), correlating with the IGFBP-1 mRNA results. Conclusions: This study suggests that IGF-II and IGFBP-1 might be associated with the impaired trophoblastic invasion that may lead to pathogenesis of pre-eclampsia.