High concentration of insulin promotes apoptosis of primary cultured rat ovarian granulosa cells via its increase in extracellular HMGB1.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting women of reproductive age. Insulin resistance/hyperinsulinemia is a prevalent finding in women with PCOS, which indicates that insulin resistance/hyperinsulinemia may be an important player in the pathogenesis of the PCOS. However, the underlying mechanism of insulin resistance/hyperinsulinemia on the pathogenesis of the PCOS remains elusive. In this study, we found an increased high-mobility group box 1 (HMGB1) in the serum from women with PCOS having insulin resistance/hyperinsulinemia. Furthermore, we discovered that high concentration of insulin, which mimics insulin resistance model, promoted apoptosis in primary cultured rat ovarian granulosa cells (GCs) via its effect on the increase in extracellular HMGB1. Our data presented the first evidence that increased HMGB1 induced by insulin resistance/hyperinsulinemia promoted apoptosis of ovarian GCs, which provided new molecular basis for the PCOS pathogenesis.