IL-12-dependent innate immunity arrests endothelial cells in G0-G1 phase by a p21(Cip1/Waf1)-mediated mechanism.
Innate immunity may activate paracrine circuits able to entail vascular system in the onset and progression of several chronic degenerative diseases. In particular, interleukin (IL)-12 triggers a genetic program in lymphomononuclear cells characterized by the production of interferon-γ and specific chemokines resulting in an angiostatic activity. The aim of this study is to identify molecules involved in the regulation of cell cycle in endothelial cells co-cultured with IL-12-stimulated lymphomonuclear cells. By using a transwell mediated co-culture system we demonstrated that IL-12-stimulated lymphomonuclear cells induce an arrest of endothelial cells cycle in G1, which is mainly mediated by the up-regulation of p21(Cip1/Waf1), an inhibitor of cyclin kinases. This effect requires the activation of STAT1, PKCδ and p38 MAPK, while p53 is ineffective. In accordance, siRNA-dependent silencing of these molecules in endothelial cells inhibited the increase of p21(Cip1/Waf1) and the modification in cell cycle promoted by IL-12-stimulated lymphomonuclear cells. These results indicate that the angiostatic action of IL-12-stimulated lymphomononuclear cells may lie in the capability to arrest endothelial cells in G1 phase through a mechanisms mainly based on the specific up-regulation of p21(Cip1/Waf1) induced by the combined activity of STAT1, PKCδ and p38 MAPK.
Department of Oncological Sciences, Institute for Cancer Research and Treatment, University of Torino, 10060, Candiolo, Torino, Italy. lucia.napione@ircc.it
Lucia
L
Napione
Marina
M
Strasly
Claudia
C
Meda
Stefania
S
Mitola
Maria
M
Alvaro
Gabriella
G
Doronzo
Serena
S
Marchiò
Enrico
E
Giraudo
Luca
L
Primo
Marco
M
Arese
Federico
F
Bussolino
D018920:Coculture Techniques; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D016193:G1 Phase; D006801:Humans; D007113:Immunity, Innate; D018664:Interleukin-12 / Q000502:physiology*; D034741:RNA, Small Interfering; D016192:Resting Phase, Cell Cycle
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D034741:RNA, Small Interfering; D018664:Interleukin-12