scholarly journals The Peroxisome Proliferator-Activated Receptor Gamma System Regulates Ultraviolet B-Induced ProstaglandinE2Production in Human Epidermal Keratinocytes

PPAR Research ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Raymond L. Konger ◽  
Kellie Clay Martel ◽  
Danielle Jernigan ◽  
Qiwei Zhang ◽  
Jeffrey B. Travers

Studies using PPARγagonists in mouse skin have suggested that peroxisome proliferator-activated receptor gamma (PPARγ) is irrelevant to cutaneous photobiology. However, in several epithelial cell lines, ultraviolet B (UVB) has been shown to induce the nonenzymatic production of oxidized phospholipids that act as PPARγagonists. UVB is also a potent inducer of prostaglandinE2  (PGE2)production and COX-2 expression in keratinocytes and PPARγis coupled to increasedPGE2production in other cell lines. In this current study, we demonstrate that PPARγagonists, but not PPARαor PPARβ/δagonists, inducePGE2production and COX-2 expression in primary human keratinocytes (PHKs). Importantly, PPARγagonist-induced COX-2 expression andPGE2production were partially inhibited by the PPARγantagonist, GW9662, indicating that both PPARγ-dependent and -independent pathways are likely involved. GW9662 also suppressed UVB andtert-butylhydroperoxide- (TBH-) inducedPGE2production in PHKs and intact human epidermis and partially inhibited UVB-induced COX-2 expression in PHKs. These findings provide evidence that PPARγis relevant to cutaneous photobiology in human epidermis.

Author(s):  
Rana A. Alaaeddine ◽  
Perihan A. Elzahhar ◽  
Ibrahim AlZaim ◽  
Wassim Abou-Kheir ◽  
Ahmed S.F. Belal ◽  
...  

: Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro-and anti-tumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarize the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.


2015 ◽  
Vol 91 (6) ◽  
pp. 1458-1468 ◽  
Author(s):  
Agilan Balupillai ◽  
Rajendra N. Prasad ◽  
Karthikeyan Ramasamy ◽  
Ganesan Muthusamy ◽  
Mohana Shanmugham ◽  
...  

Endocrinology ◽  
2004 ◽  
Vol 145 (7) ◽  
pp. 3353-3362 ◽  
Author(s):  
Fausto Bogazzi ◽  
Federica Ultimieri ◽  
Francesco Raggi ◽  
Dania Russo ◽  
Renato Vanacore ◽  
...  

Abstract GH has antiapoptotic effects on several cells. However, the antiapoptotic mechanisms of GH on colonic mucosa cells are not completely understood. Peroxisome proliferator activated receptor-γ (PPARγ) activation enhances apoptosis, and a link between GH and PPARγ in the colonic epithelium of acromegalic patients has been suggested. We investigated the effects of GH and of PPARγ ligands on apoptosis in colonic cancer cell lines. Colonic cells showed specific binding sites for GH, and after exposure to 0.05–50 nm GH, their apoptosis reduced by 45%. The antiapoptotic effect was due to either GH directly or GH-dependent local production of IGF-1. A 55–85% reduction of PPARγ expression was observed in GH-treated cells, compared with controls (P < 0.05). However, treatment of the cells with 1–50 μm ciglitazone (cig), induced apoptosis and reverted the antiapoptotic effects of GH by increasing the programmed cell death up to 3.5-fold at 30 min and up to 1.7-fold at 24 h. Expression of Bcl-2 and TNF-related apoptosis-induced ligand was not affected by either GH or cig treatment, whereas GH reduced the expression of Bax, which was increased by cig treatment. In addition, GH increased the expression of signal transducer and activator of transcription 5b, which might be involved in the down-regulation of PPARγ expression. In conclusion, GH may exert a direct antiapoptotic effect on colonic cells, through an increased expression of signal transducer and activator of transcription 5b and a reduction of Bax and PPARγ. The reduced GH-dependent apoptosis can be overcome by PPARγ ligands, which might be useful chemopreventive agents in acromegalic patients, who have an increased colonic polyps prevalence.


2002 ◽  
Vol 34 (4) ◽  
pp. 165-171 ◽  
Author(s):  
Kate M. Suchanek ◽  
Fiona J. May ◽  
Jodie A. Robinson ◽  
Won Jae Lee ◽  
Nicola A. Holman ◽  
...  

2001 ◽  
Vol 86 (5) ◽  
pp. 2170-2177 ◽  
Author(s):  
Kazuyasu Ohta ◽  
Toyoshi Endo ◽  
Kazutaka Haraguchi ◽  
Jerome M. Hershman ◽  
Toshimasa Onaya

Ligands for peroxisome proliferator-activated receptor γ (PPARγ) induce apoptosis and exert antiproliferative effects on several carcinoma cell lines. The present study investigates the expression of PPARγ and the possibility that agonists for PPARγ also inhibit the growth of human thyroid carcinoma cells. We examined this hypothesis using six cell lines, designated BHP thyroid carcinoma cells, which originated from patients with papillary thyroid carcinoma. RT-PCR analysis revealed that the thyroid carcinoma cell lines BHP2–7, 7–13, 10–3, and 18–21 express PPARγ. More PPARγ was expressed in carcinoma than in adjacent normal thyroid tissue in three of six samples of human papillary carcinoma of the thyroid. PPARγ-positive thyroid carcinoma cells were treated with agonists of PPARγ, troglitazone, BRL 49653, and 15-deoxy-Δ12,14-prostaglandin J2. Troglitazone (10μ mol/L), BRL 49653 (10 μmol/L), and 15-deoxy-Δ12,14-prostaglandin J2 (1 μg/mL) decreased[ 3H]thymidine incorporation and reduced cell number, respectively, in BHP carcinoma cell lines that expressed PPARγ. Under low serum conditions, ligands for PPARγ induced condensation of the nucleus and fragmentation of chromatin into nucleosome ladders. These findings indicate that the death of thyroid carcinoma cells is a form of apoptosis. To investigate the molecular mechanism of the apoptosis, we assessed expression of the apoptosis-regulatory genes bcl-2, bax, and c-myc. Troglitazone significantly increased the expression of c-myc messenger RNA but had no effect on the expression of bcl-2 and bax in thyroid carcinoma cells. These results suggest that, at least in part, the induction of apoptosis in human papillary thyroid carcinoma cells may be due to an increase of c-myc. Troglitazone (500 mg/kg·day) significantly inhibited tumor growth and prevented distant metastasis of BHP18–21 tumors in nude mice in vivo. Taken together, these results suggest that PPARγ agonist inhibit cell growth of some types of human thyroid cancer.


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