Apoptosis Induced by Serum Withdrawal in Human Mesangial Cells

Apoptosis has been reported to occur both during the course of kidney development and the progression of kidney injury to scarring. Insulin-like growth factor binding protein-3 (IGFBP-3), a component of the IGF system, has been shown to induce apoptosis in cancer cell lines. However, if IGFBP-3 has similar effects in human mesangial cells (HMC) remains unknown. The purpose of this study was to examine the expression of IGFBP-3 and its possible effect on the induction of apoptosis in HMC during serum deprivation. We have observed that IGFBP-3 accumulates progressively in HMC in which serum has been withdrawn. In these cells, an increase of IGFBP-3 is observed before the production of apoptosis suggesting a link between these phenomena. Furthermore, the addition of IGFBP-3 in physiological amounts (from 100 to 400 ng/ml) to culture medium devoid of growth factors accelerates and increases the apoptotic process with a dose-dependent effect. These findings suggest that IGFBP-3 is a mediator of cell death in human mesangial cells when the availability of growth factors is curtailed. These data also suggest that IGFBP-3 could contribute to apoptotic processes observed in human disease.