Role and mechanism of insulin-like growth factor 2 on the proliferation of human trophoblasts in vitro

AimTo study the effect and relevant molecular mechanisms of insulin-like growth factor 2 (IGF2) on the proliferative activity of first trimester human trophoblasts in vitro. Materials and MethodsExtravillous cytotrophoblasts (EVCTs) were isolated and cultured. Cells were cultured with IGF2 at different concentrations and the proliferative activity was measured using methyl thiazolyl tretrazolium assay. LY294002, a specific inhibitor of the phosphatidylinositol 3-kinase (PI3K), was used as an indirect indicator of the possible involvement of the PI3K signal pathway. We tested the apoptosis rate using flow cytometry technology influenced by IGF2 with or without LY294002. The effects of IGF2 on phosphorylation of key cell signaling proteins (protein kinase B [AKT] and phosphorylated AKT) in EVCTs were examined by western blot analysis with or without LY294002. ResultsThere was a significant difference between the IGF2 group above 10nM and the control group (P<0.05). LY294002 (10M) not only inhibited the proliferative activity of EVCT, but also significantly restrained the effect on EVCTs (P<0.05). In vitro data proved that the apoptosis rate decreased when IGF2 was added (P<0.05), but increased when inhibited by LY294002 (P<0.05). After incubation with IGF2, AKT phosphorylation increased compared to incubation without IGF2 treatment (P<0.05). LY294002 activation reduced the IGF2-induced effects (P<0.05). ConclusionsOur data suggest that IGF2 enhances EVCT proliferation and inhibits apoptosis. The PI3K/AKT pathway is an important signaling pathway in the proliferative activity of EVCTs on early human pregnancy in vitro.