The vitamin D receptor agonist elocalcitol inhibits IL-8-dependent benign prostatic hyperplasia stromal cell proliferation and inflammatory response by targeting the RhoA/Rho kinase and NF-kappaB pathways.
BACKGROUND
Benign prostatic hyperplasia (BPH) is characterized by an important inflammatory component. Stimulation of human prostate stromal cells from BPH tissues with proinflammatory cytokines leads to secretion of IL-8, a chemokine involved in BPH pathogenesis. The vitamin D receptor (VDR) agonist elocalcitol can arrest prostate growth in BPH patients, but its mechanism of action in this pathology is still incompletely understood.


METHODS
IL-8 levels were measured by real-time RT-PCR and ELISA. NF-kappaB translocation and COX-2 expression were evaluated by confocal microscopy. RhoA and Rho-kinase (ROCK) gene expression and functional activity were studied by real-time RT-PCR, immuno-kinase assays, Western blot analysis, confocal microscopy, and cell invasion.


RESULTS
Stimulation of BPH cells with IL-8 activates the calcium-sensitizing RhoA/ROCK pathway, as demonstrated by the increased membrane translocation of RhoA and by phosphorylation of the ROCK substrate myosin phosphatase target subunit 1 (MYPT-1). In agreement with these data, C3 exoenzyme, a selective RhoA inhibitor, inhibits IL-8-induced invasion of BPH cells. The VDR agonist elocalcitol significantly inhibits IL-8 production by BPH cells stimulated with inflammatory cytokines, and IL-8-induced proliferation of BPH cells. In addition, elocalcitol inhibits IL-8-induced membrane translocation of RhoA and MYPT-1 phosphorylation in BPH cells, and inhibits dose-dependently their IL-8-dependent invasion. The inhibition induced by elocalcitol of IL-8 production by BPH cells is accompanied by decreased COX-2 expression and PGE(2) production and by arrest of NF-kappaB p65 nuclear translocation, associated with inhibition of the RhoA/ROCK pathway.


CONCLUSIONS
These data provide a mechanistic explanation for the anti-proliferative and anti-inflammatory properties of elocalcitol in BPH cells.
Penna
Giuseppe
G
BioXell, Milan, Italy.
Fibbi
Benedetta
B
Amuchastegui
Susana
S
Corsiero
Elisa
E
Laverny
Gilles
G
Silvestrini
Enrico
E
Chavalmane
Aravinda
A
Morelli
Annamaria
A
Sarchielli
Erica
E
Vannelli
Gabriella Barbara
GB
Gacci
Mauro
M
Colli
Enrico
E
Maggi
Mario
M
Adorini
Luciano
L
D002117:Calcitriol / Q000031:analogs & derivatives* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D007371:Interferon-gamma / Q000494:pharmacology; D020381:Interleukin-17 / Q000494:pharmacology; D016209:Interleukin-8 / Q000378:metabolism*; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D011470:Prostatic Hyperplasia / Q000378:metabolism / Q000473:pathology*; D018167:Receptors, Calcitriol / Q000819:agonists; D015398:Signal Transduction / Q000187:drug effects; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
C487049:BXL628; D020381:Interleukin-17; D016209:Interleukin-8; D016328:NF-kappa B; D018167:Receptors, Calcitriol; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D051546:Cyclooxygenase 2; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D002117:Calcitriol; D015232:Dinoprostone