Vasoactive intestinal peptide induces neuroendocrine differentiation in the LNCaP prostate cancer cell line through PKA, ERK, and PI3K.
BACKGROUND
Neuroendocrine (NE) differentiation in prostate cancer has been correlated with unfavorable clinical outcome. The mechanisms by which prostate cancer acquires NE properties are poorly understood, but several signaling pathways have been proposed. We have previously observed that vasoactive intestinal peptide (VIP) stimulates cAMP production mainly through VPAC(1) receptor, inducing NE differentiation in LNCaP cells. The aim of this study was to analyze the mechanisms involved in this process.


METHODS
Reverse transcriptase (RT)-polymerase chain reaction (PCR), quantitative real-time RT-PCR, Western blotting, and immunocytochemistry were performed.


RESULTS
LNCaP cells produce VIP, as demonstrated by RT-PCR and immunocytochemistry. VIP induced NE differentiation of LNCaP cells at a time as short as 1 hr of treatment, and the same occurred with the expression and secretion of neuronal-specific enolase (NSE, a NE differentiation marker). These effects were faster than those exerted by serum-deprivation. VIP induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation and NE differentiation by PKA-dependent and independent pathways, since the PKA inhibitor H89 partially blocked VIP-induced NE differentiation and did not affect ERK1/2 phosphorylation. mitogen-activated protein kinase kinase (MEK) and phosphoinositide 3-kinase (PI3K) appear to be also involved since the inhibitors PD98059 and wortmannin abolished ERK1/2 phosphorylation and decreased NE differentiation induced by VIP. Moreover, VIP activated Ras suggesting the involvement of a Ras-dependent pathway.


CONCLUSIONS
VIP behaves as autocrine/paracrine factor in LNCaP cells by inducing NE differentiation through PKA, ERK1/2, and PI3K.
Unidad de Neuroendocrinología Molecular, Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
Irene
I
Gutiérrez-Cañas
María G
MG
Juarranz
Beatriz
B
Collado
Nieves
N
Rodríguez-Henche
Antonio
A
Chiloeches
Juan C
JC
Prieto
María J
MJ
Carmena
D018278:Carcinoma, Neuroendocrine; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011471:Prostatic Neoplasms; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D018696:Neuroprotective Agents; D014660:Vasoactive Intestinal Peptide; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3