Thrombin-activated platelets induce proliferation of human skin fibroblasts by stimulating autocrine production of insulin-like growth factor-1.
Platelet components have found successful clinical utilization to initiate or to accelerate tissue-repair mechanisms. However, the molecular pathways by which platelet factors contribute to tissue regeneration have not been fully elucidated. We have studied the effect of thrombin-activated platelets (TAPs) on cell growth in vivo and in cultured cell systems. Application of TAPs to ulcerative skin lesions of diabetic patients induced local activation of ERK1/2 and Akt/PKB. Moreover, when applied to cultured human skin fibroblasts, TAPs promoted cell growth and DNA synthesis and activated platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF)-1 receptor tyrosine kinases. PDGF was released by TAPs and rapidly achieved a plateau. At variance, the release of IGF-1 was mainly provided by the TAPs-stimulated fibroblasts and progressively increased up to 48 h. The PDGF-R blocker Ag1296 reduced the activation of Akt/PKB and, at a lesser extent, of ERK1/2. Conversely, inhibition of IGF-1 signaling by Ag1024 and expression of a dominant-negative IGF-1R mutant selectively reduced the stimulation of ERK1/2 by TAPs and fibroblast-released factors, with minor changes of Akt/PKB activity. Thus, platelet factors promote fibroblast growth by acutely activating Akt/PKB and ERK1/2. Sustained activation of ERK1/2, however, requires autocrine production of IGF-1 by TAPs-stimulated fibroblasts.
Giacco
Ferdinando
F
Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Via Pansini 5, 80131 Napoli, Italy.
Perruolo
Giuseppe
G
D'Agostino
Elio
E
Fratellanza
Giorgio
G
Perna
Enzo
E
Misso
Saverio
S
Saldalamacchia
Gennaro
G
Oriente
Francesco
F
Fiory
Francesca
F
Miele
Claudia
C
Formisano
Salvatore
S
Beguinot
Francesco
F
Formisano
Pietro
P
D001792:Blood Platelets / Q000166:cytology / Q000502:physiology*; D018929:Cell Culture Techniques; D002455:Cell Division; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D015539:Platelet Activation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012867:Skin / Q000166:cytology; D012879:Skin Physiological Phenomena; D013917:Thrombin / Q000502:physiology*
D007334:Insulin-Like Growth Factor I; D051057:Proto-Oncogene Proteins c-akt; D013917:Thrombin