neuropeptide-y and Cell-Transformation--Neoplastic

In prostate cancer (PCa), neuroendocrine differentiation (NED) is commonly observed in relapsing, hormone therapy-resistant tumours after androgen deprivation. However, the molecular mechanisms involved in the NED of PCa cells remain poorly understood. In this study, we investigated the expression of the neuroendocrine secretory protein secretogranin II (SgII) in PCa, and its potential involvement in the progression of this cancer as a granulogenic factor promoting NED.. We have examined SgII immunoreactivity in 25 benign prostate hyperplasia and 32 PCa biopsies. In vitro experiments were performed to investigate the involvement of SgII in the neuroendocrine differentiation and the proliferation of PCa cell lines.. We showed that immunoreactive SgII intensity correlates with tumour grade in PCa patients. Using the androgen-dependent lymph node cancer prostate cells (LNCaP) cells, we found that NED triggered by androgen deprivation is associated with the induction of SgII expression. In addition, forced expression of SgII in LNCaP cells implemented a regulated secretory pathway by triggering the formation of secretory granule-like structures competent for hormone storage and regulated release. Finally, we found that SgII promotes prostate cancer (CaP) cell proliferation.. The present data show that SgII is highly expressed in advanced PCa and may contribute to the neuroendocrine differentiation by promoting the formation of secretory granules and the proliferation of PCa cells.

Topics: Androgen Antagonists; Androgens; Cell Line, Tumor; Cell Transformation, Neoplastic; Culture Media; Disease Progression; Humans; Male; Neuropeptide Y; Prostate-Specific Antigen; Prostatic Neoplasms; Secretogranin II; Steroids

Von Hippel-Lindau (VHL) tumor suppressor protein is expressed in neurons of the central nervous system and plays an important role during the neuronal differentiation of central nervous system progenitor cells. To elucidate the neuronal differentiating potential of VHL protein in neuroblastoma cells, we overexpressed or inhibited VHL protein in human neuroblastoma cells (SY-SH5Y), and examined the morphological change, expressions of neuronal markers, and electrophysiological functions. Here we show that with VHL gene transduction SY-SH5Y cells stably expressing the VHL protein had neurite-like processes with varicosities, showed the distinct expression of the neuronal markers neuropeptide Y and neurofilament 200, acquired regulated neurosecretion competence in response to depolarizing and cholinergic stimuli, and had large voltage-gated fast sodium currents and delayed rectifier potassium (Kv) currents compatible with those of functional neurons. In addition, they displayed inactivated ether-á-go-go potassium channels related to the promotion of the cell cycle and to the termination of differentiation. Also, by treatment with retinoic acid, they rapidly underwent cell death related to apoptosis. These findings suggest that the induction of neuronal function by VHL protein is associated with down-regulation of the cell cycle. In contrast, the inhibition of endogenous expression of VHL protein with antisense-orientated VHL gene transduction reduced such neuronal properties inherent to these cells, including the capacity for activation of ether-á-go-go channels. In conclusion, VHL protein has a neuronal differentiating potential to transform neuroblastoma cells into functional neuron-like cells. Our finding of the neuronal differentiation of neuroblastoma cells under the control of the VHL gene may contribute to the development of clinical techniques for neuronal regeneration in the case of intractable neuronal diseases and for differentiation therapy against neuroblastomas.

Topics: Apoptosis; Cell Differentiation; Cell Transformation, Neoplastic; Down-Regulation; Ether-A-Go-Go Potassium Channels; Genetic Therapy; Humans; Ion Channel Gating; Ligases; Neuroblastoma; Neurofilament Proteins; Neurons; Neuropeptide Y; Potassium Channels; RNA, Messenger; Sodium Channels; Transfection; Tretinoin; Tumor Cells, Cultured; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Von Hippel-Lindau Tumor Suppressor Protein

Neuropeptide Y (NPY) acts through specific receptors to inhibit adenyl cyclase and may have a role in neuroblastomas and neuroepitheliomas (NE) as a regulator of cell growth and differentiation. The authors have examined the status of NPY receptors in the NE cell line SK-N-MC and the effect of retinoic acid (RA), a known differentiating agent, on their expression and function.. Competitive NPY binding studies were performed on normal and RA-treated cells, followed by Scatchard analysis. NPY receptor function in the absence of or following RA treatment was determined by the ability of various concentrations of NPY to attenuate the forskolin-stimulated accumulation of intracellular cAMP. The mitogenic effect of NPY was evaluated by growing normal or RA-treated cell in the presence of various concentrations of NPY.. Scatchard analysis showed a Kd of 2.3 nmol/L and a Bmax of 91,000 receptors per cell for untreated cells. RA treatment decreased receptor expression to 11,700 per cell without a significant change in receptor affinity (3.6 nmol/L). The effect of forskolin was inhibited by NPY in a dose-dependent fashion in both untreated and treated cells indicating functional receptors in both NPY stimulates the growth of normal SK-N-MC cells. NPY stimulated growth was significantly attenuated after RA treatment, possibly as a result of decreased NPY receptor expression.. Treatment of SK-N-MC cells with RA, a known differentiating agent, leads to decreased expression of functional NPY receptors and a concomitant decrease in the mitogenic effect of NPY. This supports the role for NPY in the pathogenesis of NE.

Topics: Cell Division; Cell Transformation, Neoplastic; Down-Regulation; Humans; Mitogens; Neuroectodermal Tumors, Primitive, Peripheral; Neuropeptide Y; Receptors, Neuropeptide Y; Tretinoin; Tumor Cells, Cultured