Effects of insulin-like growth factor-I and Progranulin on a human trophoblast model

Abstract

Gestational diabetes and obesity are associated with increased placental weight and fetal birth weight. Placental development is mainly promoted by trophoblast proliferation and various humoral factors. Insulin-like growth factor-1 (IGFI) levels are increased in mothers with gestational diabetes, and trophoblast proliferation is promoted in a dose-dependent manner. In addition, progranulin (PGRN), an adipokine involved in obesity, plays an important role in the proliferation of trophoblast cell lines. IGF-I and PGRN independently affect placental development, but there are many unknowns regarding their interaction. In this study, we investigated the combined effects of IGF-I and PGRN on trophoblast proliferation using the human choriocarcinoma cell line JEG-3. Cell proliferation was evaluated using a cell counting method and a water-soluble tetrazolium-1 assay. Furthermore, the effect of PGRN on the intracellular signaling pathways of IGFI, particularly the phosphorylation of Akt and Erk1/2, was evaluated using western blotting. IGF-I significantly increased cell proliferation in JEG-3 cells. However, the proliferative effect of a low concentration of IGF-I (100 ng/mL) was inhibited by simultaneous treatment with PGRN. Pretreatment with PGRN significantly suppressed phosphorylation of Erk1 at a low concentration of IGF-I (P < 0.01) but had no effect on phosphorylation of Akt. PGRN may suppress IGF-I-induced trophoblast proliferation by regulating the phosphorylation of Erk1/2, especially at low concentrations of IGFI. PGRN modulates the proliferative effects of IGF-I in a complex manner, dependent on the concentration and timing of exposure. These findings indicate that the placental growth factor IGF-I may be regulated by PGRN.

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