The effects of hepatocyte growth factor and insulin-like growth factor-1 on the myogenic differentiation of satellite cells in human urethral rhabdosphincter

Abstract

Aims: To examine the effects of hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) on the myogenic differentiation of human urethral rhabdosphincter (RS) satellite cells.

Methods: Human RS was obtained from patients undergoing radical prostatectomy for prostate cancer. Selectively cultured RS satellite cells, transfected with temperature sensitive simian virus-40 T antigen (ts-SV40 Tag) to extend their lifespan, were cultured at 33 degrees C, and then incubated at 39 degrees C to induce myogenic differentiation. Varying concentrations of HGF and IGF-1 were added to the differentiation medium. Inactivation of SV40 Tag and evaluations of myogenic differentiation were examined by immunocytochemistry, western blotting and real-time RT-PCR.

Results: At 39 degrees C, ts-SV40 Tag-transfected RS satellite cells slowly proliferated, fused to form multinucleated myotubes, and expressed myosin heavy chain (MHC) in association with the temperature-dependent inactivation of SV40 Tag. IGF-1 significantly accelerated the MHC expression in a dose-dependent fashion through activation of the PI3-kinase pathway. Conversely, HGF did not promote MHC expression due a reduction in phosphorylation of both the MAP-kinase and the PI3-kinase pathways, a pattern of response different than the response of proliferating RS satellite cells to HGF.

Conclusions: HGF did not induce myogenic differentiation of RS satellite cells. Conversely, IGF-1 promoted myogenic differentiation of RS satellite cells via the PI3-K pathway likewise proliferating RS satellite cells. These findings may be useful for developing novel techniques for regenerating the human RS to treat urinary incontinence.