Background: Neuroendocrine (NE) differentiation in prostate tumors has been correlated with androgen independent disease and increased risk of death. In vitro, IL-6 initiates NE differentiation utilizing the signal transduction initiated by the interaction with IL-6R alpha and gp130. In this study we analysed the NE differentiation process in vitro and in vivo using the LNCaP androgen dependent cell line via ligand independent induction of NE differentiation.
Methods: LNCaP cells were transfected with a constitutively active gp130 subunit, gp130act. Cell proliferation rate was determined and clones were examined for neuroendocrine differentiation by morphological change, upregulation of CgA and serotonin and formation of dense core vesicles with LNCaP parental cells as the control. Xenograft formation was examined and compared in immunocompromised mice.
Results: Gp130act expression promoted significant neuroendocrine differentiation in vitro as determined by a NE like morphology change (increased neurite like extension formation), elevated CgA expression and the formation of dense core vesicles (DCV). These measures concurred with those examined in LNCaP cells following 100 ng/ml IL-6 treatment. Further investigation of the LNCaP gp130act cells in vivo, in immunocompromised androgen intact mice, confirmed that the NE like morphology, as determined by histological and high resolution transmission electron microscopy, was maintained.
Conclusions: NE differentiation was initiated by the expression of gp130act in a ligand independent manner, highlighting the importance of gp130 in the neuroendocrine differentiation process. Further investigation of upregulated/downregulated gene expression in these cells may provide valuable insight into the NE differentiation process.
2004 Wiley-Liss, Inc.