Inhibitor of DNA Binding Protein 2 (ID2) Mediates the Anti-Proliferative and Pro-Differentiation Effects of Insulin-like Growth Factor-1 (IGF-1).

In preeclampsia (PE), impaired trophoblast proliferation and differentiation are thought to cause abnormal placentation and subsequent clinical manifestations of the disease, i.e., hypertension, proteinuria, and end-organ damage. Insulin-like growth factor-1 (IGF-1) influences trophoblast cell function; however, the mechanism of IGF-1's action on trophoblasts is not understood well. Inhibitor of DNA binding protein 2 (ID2) is involved in trophoblast differentiation and implicated in many processes disrupted in PE, including placental development, vascular differentiation, and angiogenesis. We hypothesized that IGF-1 regulates trophoblast proliferation and differentiation via ID2. Immortalized human first trimester trophoblast cells (HTR-8/SVneo) were treated with IGF-1 for 24 h after serum starvation. ID2 mRNA and protein were measured, as well as trophoblast cell viability, proliferation, tube formation, and migration. IGF-1 decreased ID2 expression in a dose-dependent manner. IGF-1 decreased trophoblast proliferation but increased cell viability, differentiation, and migration. ID2 overexpression mitigated the effects of IGF-1 on trophoblast cells. These data suggest that IGF-1 could regulate trophoblast proliferation and differentiation through ID2. The dysregulation of ID2-mediated IGF-1 signaling in trophoblast cells could be involved in the pathogenesis of pregnancy disorders like uterine growth restriction and PE.