FK506 can activate transforming growth factor-beta signalling in vascular smooth muscle cells and promote proliferation.
OBJECTIVE
FK506-binding protein (FKBP) 12 is an inhibitor of transforming growth factor (TGF)-beta type I receptors. Several lines of evidence support the view that TGF-beta stimulates vascular smooth muscle cell (VSMC) proliferation and matrix accumulation. We investigated the effect of FK506, also known as tacrolimus, on cellular proliferation and on matrix protein production in human VSMCs.


RESULTS
We measured cell proliferation with flow cytometry using BrdU incorporation and fluorimetrically by measuring DNA concentration with Hoechst 33258. Western blot assay of whole-cell lysates was used to measure the levels of signalling proteins involved in proliferative pathways, in particular beta-catenin, pErk, pAkt, pmTOR, and cyclin D1. Collagen synthesis was also investigated by Western blotting. The TGF-beta signal was studied by both Western blotting and confocal microscopy. We used the SiRNA technique for FKBP12 gene silencing. Our results show that FK506 stimulates VSMC proliferation and collagen type I production. FK506 enhanced beta-catenin levels and activated the extracellular signal-regulated kinase, Akt, and mammalian target of rapamycin kinase, which are important effectors of proliferation. Accordingly, cyclin D1 expression was increased. We also demonstrate that FK506 activates the TGF-beta signal in VSMCs and that, through this mechanism, it stimulates cell proliferation.


CONCLUSIONS
FK506 can act as a growth factor for VSMCs.
Giordano
Arturo
A
Invasive Cardiology Unit, Clinica Pineta Grande, Castelvolturno, Italy.
Romano
Simona
S
Mallardo
Maria
M
D'Angelillo
Anna
A
Calì
Gaetano
G
Corcione
Nicola
N
Ferraro
Paolo
P
Romano
Maria Fiammetta
MF
D029404:Activin Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D002317:Cardiovascular Agents / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004149:Dioxoles / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases; D016559:Tacrolimus / Q000494:pharmacology*; D022061:Tacrolimus Binding Protein 1A / Q000378:metabolism; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; C495270:CTNNB1 protein, human; D002317:Cardiovascular Agents; D024042:Collagen Type I; D004149:Dioxoles; D047428:Protein Kinase Inhibitors; D053773:Transforming Growth Factor beta1; D051176:beta Catenin; D011494:Protein Kinases; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D029404:Activin Receptors; D022061:Tacrolimus Binding Protein 1A; D016559:Tacrolimus