Role for p27
            <sup>Kip1</sup>
            in Vascular Smooth Muscle Cell Migration

Cytochrome P450-derived epoxyeicosatrienoic acids (EETs) stimulate endothelial cell proliferation and angiogenesis. In this study, we investigated the involvement of the forkhead box, class O (FOXO) family of transcription factors and their downstream target p27Kip1 in EET-induced endothelial cell proliferation. Incubation of human umbilical vein endothelial cells with 11,12-EET induced a time-and dose-dependent decrease in p27Kip1 protein expression, whereas p21 Cip1 was not significantly affected. This effect on p27Kip1 protein was associated with decreased mRNA levels as well as p27Kip1 promoter activity. 11,12-EET also stimulated the time-dependent phosphorylation of Akt and of the forkhead factors FOXO1 and FOXO3a, effects prevented by the phosphatidylinositol 3-kinase inhibitor LY 294002. Transfection of endothelial cells with either a dominantnegative or an "Akt-resistant"/constitutively active FOXO3a mutant reversed the 11,12-EET-induced downregulation of p27Kip1 , whereas transfection of a constitutive active Akt decreased p27Kip1 expression independently of the presence or absence of 11,12-EET. To determine whether these effects are involved in EETinduced proliferation, endothelial cells were transfected with the 11,12-EET-generating epoxygenase CYP2C9. Transfection of CYP2C9 elicited endothelial cell proliferation and this effect was inhibited in cells co-transfected with CYP2C9 and either a dominant-negative Akt or constitutively active FOXO3a. Reducing FOXO expression using RNA interference, on the other hand, attenuated p27Kip1 expression and stimulated endothelial cell proliferation. These results indicate that EET-induced endothelial cell proliferation is associated with the phosphatidylinositol 3-kinase/Akt-dependent phosphorylation and inactivation of FOXO factors and the subsequent decrease in expression of the cyclin-dependent kinase inhibitor p27Kip1 .The epoxyeicosatrienoic acids (EETs) 1 are biologically active eicosanoids generated by cytochrome P450 epoxygenases (1, 2). Epoxygenases of the CYP2B, -2C, and -2J subfamilies are expressed in vascular endothelial cells and metabolize arachidonic acid into a series of regio-and stereo-selective EETs (5,8,11,and 14, that are potent vasodilators and have been identified as endothelium-derived hyperpolarizing factors (3-5).Recent reports have shown that EETs exert multiple effects on the vascular wall that are not directly related to changes in membrane potential or vascular tone. Indeed, EETs seem to act as second messengers in numerous signaling pathways (6, 7) and are involved in the regulation of inflammation, migration, apoptosis, hypoxia-reoxygenation injury, and platelet aggregation (8 -13). Moreover, we and others have recently been able to demonstrate that EETs stimulate endothelial cell proliferation and elicit an angiogenic response (14 -16).Progression through the mammalian cell cycle requires the activation of cyclin-dependent kinases (CDKs) through association with regulatory subunits (cyclins) that phosphorylate the retinoblastoma ...

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“…Kip1 is a likely candidate to couple cell cycle progression with migration and angiogenesis (47)(48)(49). Kip1 levels.…”

Section: Kip1mentioning

confidence: 99%

11,12-Epoxyeicosatrienoic Acid-induced Inhibition of FOXO Factors Promotes Endothelial Proliferation by Down-Regulating p27

Potente

Fißlthaler

Busse

et al. 2003

Journal of Biological Chemistry

156

149

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“…Recently, inhibition of motility or invasion by rapamycin has been described in porcine, murine and human aortic smooth muscle cells (Poon et al, 1996;Sun et al, 2001;Sakakibara et al, 2005), canine kidney epithelial cells (MDCKT23) and human colorectal cells (HCT-8/ S11) (Attoub et al, 2000), Swiss 3T3 fibroblasts (Berven et al, 2004), trophoblast (SGHPL-4) (Cartwright et al, 2002), neutrophils (Gomez-Cambronero, 2003), ovarian cells (Wong et al, 2004), and human umbilical vein endothelial cells (Kwon et al, 2005) in culture. In vivo, rapamycin also potently inhibits metastases of transplanted tumors derived from murine adenocarcinoma cells (CT-26) (Guba et al, 2002), human renal cancer cells (RCC 786-O) (Luan et al, 2003), murine nonsmall-cell lung cancer cells (KLN-205) (Boffa et al, 2004) and osteosarcoma (K7M2) (Wan et al, 2005) in mice.…”

Section: Introductionmentioning

confidence: 99%

Rapamycin inhibits cell motility by suppression of mTOR-mediated S6K1 and 4E-BP1 pathways

et al. 2006

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Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), inhibits tumor cell motility. However, the underlying mechanism is poorly understood. Here, we show that rapamycin inhibited type I insulin-like growth factor (IGF-I)-stimulated motility of a panel of cell lines. Expression of a rapamycin-resistant mutant of mTOR (mTORrr) prevented rapamycin inhibition of cell motility. However, cells expressing a kinase-dead mTORrr remained sensitive to rapamycin. Downregulation of raptor or rictor by RNA interference (RNAi) decreased cell motility. However, only downregulation of raptor mimicked the effect of rapamycin, inhibiting phosphorylation of S6 kinase 1 (S6K1) and 4E-BP1. Cells infected with an adenovirus expressing constitutively active and rapamycin-resistant mutant of p70 S6K1, but not with an adenovirus expressing wild-type S6K1, or a control virus, conferred to resistance to rapamycin. Further, IGF-I failed to stimulate motility of the cells, in which S6K1 was downregulated by RNAi. Moreover, downregulation of eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) by RNAi-attenuated rapamycin inhibition of cell motility. In contrast, expression of constitutively active 4E-BP1 dramatically inhibited IGF-I-stimulated cell motility. The results indicate that both S6K1 and 4E-BP1 pathways, regulated by TORC1, are required for cell motility. Rapamycin inhibits IGF-I-stimulated cell motility, through suppression of both S6K1 and 4E-BP1/eIF4E-signaling pathways, as a consequence of inhibition of mTOR kinase activity.

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“…This blocks the cell cycle in the G1 (growth) phase, where RNA and proteins are synthesized. The cell is then unable to enter the S (synthesis) phase, thus preventing replication (20,21).…”

Section: Discussionmentioning

confidence: 99%

Comparative effects of sirolimus-eluting versus bare metal stents on neointimal hyperplasia in balloon-injured external iliac artery of rabbits

Patel¹,

Parikh²,

Patil³

et al. 2015

Turk J Vet Anim Sci

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The aim of this study was to check effectiveness of drug-eluting stents for prevention of restenosis resulting from neointimal hyperplasia. Twenty-one sirolimus-eluting stents (SESs) and bare metal stents (BMSs; control) were compared by implantation into left and right balloon-injured external iliac arteries of New Zealand White rabbits, respectively. Under general anesthesia and angiography, using 3-mm coronary balloon catheters, stents were successfully deployed. Anticoagulant therapy was not given to any animal. Rabbits were allotted into three groups at 7, 14, and 21 days (7 rabbits in each group). Each stented vessel of sacrificed rabbits was subjected to a resin-embedding technique and methyl methacrylate sections were obtained using a tungsten carbide knife for staining. In histological examination, SESs showed marked reductions in almost all parameters. Morphometric results showed that arteries with SESs had a larger luminal area (P < 0.0001), lower intimal (P < 0.001) and medial (P < 0.001) thickness, and lower intimal index (P < 0.003) as opposed to arteries stented with BMSs. Luminal narrowing in SESs was 0% and reendothelialization was similar in both stented groups (90.48%). SESs showed marked reduction in nonocclusive peristrut fibrin deposition versus BMSs. Thus, the SES was more effective for prevention of restenosis than the BMS in rabbit.

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Role for p27 ^Kip1 in Vascular Smooth Muscle Cell Migration

Abstract: Lack of p27(Kip1) reduces rapamycin-mediated inhibition of SMC migration. These novel findings suggest a role for p27(Kip1) in the signaling pathway(s) that regulates SMC migration.

Cited by 160 publications

References 30 publications

11,12-Epoxyeicosatrienoic Acid-induced Inhibition of FOXO Factors Promotes Endothelial Proliferation by Down-Regulating p27

11,12-Epoxyeicosatrienoic Acid-induced Inhibition of FOXO Factors Promotes Endothelial Proliferation by Down-Regulating p27

Rapamycin inhibits cell motility by suppression of mTOR-mediated S6K1 and 4E-BP1 pathways

Comparative effects of sirolimus-eluting versus bare metal stents on neointimal hyperplasia in balloon-injured external iliac artery of rabbits

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Role for p27 Kip1 in Vascular Smooth Muscle Cell Migration

Abstract: Lack of p27(Kip1) reduces rapamycin-mediated inhibition of SMC migration. These novel findings suggest a role for p27(Kip1) in the signaling pathway(s) that regulates SMC migration.

Cited by 160 publications

References 30 publications

11,12-Epoxyeicosatrienoic Acid-induced Inhibition of FOXO Factors Promotes Endothelial Proliferation by Down-Regulating p27

11,12-Epoxyeicosatrienoic Acid-induced Inhibition of FOXO Factors Promotes Endothelial Proliferation by Down-Regulating p27

Rapamycin inhibits cell motility by suppression of mTOR-mediated S6K1 and 4E-BP1 pathways

Comparative effects of sirolimus-eluting versus bare metal stents on neointimal hyperplasia in balloon-injured external iliac artery of rabbits

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Role for p27 ^Kip1 in Vascular Smooth Muscle Cell Migration