Structurally diverse peroxisome proliferator-activated receptor agonists induce apoptosis in human uro-epithelial cells by a receptor-independent mechanism involving store-operated calcium channels

B. Chopra, N. T. Georgopoulos, A. Nicholl, J. Hinley, M. B. Oleksiewicz, J. Southgate

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Objectives: Peroxisome proliferator-activated receptors (PPARs) are implicated in epithelial cell proliferation and differentiation, but investigation has been confounded by potential off-target effects of some synthetic PPAR ligands. Our aim was to determine mechanisms underlying the pro-apoptotic effect of synthetic PPAR agonists in normal human bladder uro-epithelial (urothelial) cells and to reconcile this with the role of PPARs in urothelial cytodifferentiation. Materials and methods: Normal human urothelial (NHU) cells were grown as non-immortal lines in vitro and exposed to structurally diverse agonists ciglitazone, troglitazone, rosiglitazone (PPARγ), ragaglitazar (PPARα/γ), fenofibrate (PPARα) and L165041 (PPARβ/δ). Results: NHU cells underwent apoptosis following acute exposure to ciglitazone, troglitazone or ragaglitazar, but not fenofibrate, L165041 or rosiglitazone, and this was independent of ERK or p38 MAP-kinase activation. Pro-apoptotic agonists induced sustained increases in intracellular calcium, whereas removal of extracellular calcium altered the kinetics of ciglitazone-mediated calcium release from sustained to transient. Cell death was accompanied by plasma-membrane disruption, loss of mitochondrial membrane-potential and caspase-9/caspase-3 activation. PPARγ-mediated apoptosis was unaffected following pre-treatment with PPARγ antagonist T0070907 and was strongly attenuated by store-operated calcium channel (SOC) inhibitors 2-APB and SKF-96365. Conclusions: Our results provide a mechanistic basis for the ability of some PPAR agonists to induce death in NHU cells and demonstrate that apoptosis is mediated via PPAR-independent mechanisms, involving intracellular calcium changes, activation of SOCs and induction of the mitochondrial apoptotic pathway.

Original languageEnglish
Pages (from-to)688-700
Number of pages13
JournalCell Proliferation
Volume42
Issue number5
Early online date10 Jul 2009
DOIs
Publication statusPublished - 1 Oct 2009

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Peroxisome Proliferator-Activated Receptors
Calcium Channels
Epithelial Cells
Apoptosis
rosiglitazone
troglitazone
4-(3-(2-propyl-3-hydroxy-4-acetyl)phenoxy)propyloxyphenoxy acetic acid
Calcium
Fenofibrate
1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
Caspase 9
Mitochondrial Membrane Potential
p38 Mitogen-Activated Protein Kinases
Caspase 3
Cell Differentiation
Urinary Bladder
Cell Death

Cite this

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title = "Structurally diverse peroxisome proliferator-activated receptor agonists induce apoptosis in human uro-epithelial cells by a receptor-independent mechanism involving store-operated calcium channels",
abstract = "Objectives: Peroxisome proliferator-activated receptors (PPARs) are implicated in epithelial cell proliferation and differentiation, but investigation has been confounded by potential off-target effects of some synthetic PPAR ligands. Our aim was to determine mechanisms underlying the pro-apoptotic effect of synthetic PPAR agonists in normal human bladder uro-epithelial (urothelial) cells and to reconcile this with the role of PPARs in urothelial cytodifferentiation. Materials and methods: Normal human urothelial (NHU) cells were grown as non-immortal lines in vitro and exposed to structurally diverse agonists ciglitazone, troglitazone, rosiglitazone (PPARγ), ragaglitazar (PPARα/γ), fenofibrate (PPARα) and L165041 (PPARβ/δ). Results: NHU cells underwent apoptosis following acute exposure to ciglitazone, troglitazone or ragaglitazar, but not fenofibrate, L165041 or rosiglitazone, and this was independent of ERK or p38 MAP-kinase activation. Pro-apoptotic agonists induced sustained increases in intracellular calcium, whereas removal of extracellular calcium altered the kinetics of ciglitazone-mediated calcium release from sustained to transient. Cell death was accompanied by plasma-membrane disruption, loss of mitochondrial membrane-potential and caspase-9/caspase-3 activation. PPARγ-mediated apoptosis was unaffected following pre-treatment with PPARγ antagonist T0070907 and was strongly attenuated by store-operated calcium channel (SOC) inhibitors 2-APB and SKF-96365. Conclusions: Our results provide a mechanistic basis for the ability of some PPAR agonists to induce death in NHU cells and demonstrate that apoptosis is mediated via PPAR-independent mechanisms, involving intracellular calcium changes, activation of SOCs and induction of the mitochondrial apoptotic pathway.",
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Structurally diverse peroxisome proliferator-activated receptor agonists induce apoptosis in human uro-epithelial cells by a receptor-independent mechanism involving store-operated calcium channels. / Chopra, B.; Georgopoulos, N. T.; Nicholl, A.; Hinley, J.; Oleksiewicz, M. B.; Southgate, J.

In: Cell Proliferation, Vol. 42, No. 5, 01.10.2009, p. 688-700.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Structurally diverse peroxisome proliferator-activated receptor agonists induce apoptosis in human uro-epithelial cells by a receptor-independent mechanism involving store-operated calcium channels

AU - Chopra, B.

AU - Georgopoulos, N. T.

AU - Nicholl, A.

AU - Hinley, J.

AU - Oleksiewicz, M. B.

AU - Southgate, J.

PY - 2009/10/1

Y1 - 2009/10/1

N2 - Objectives: Peroxisome proliferator-activated receptors (PPARs) are implicated in epithelial cell proliferation and differentiation, but investigation has been confounded by potential off-target effects of some synthetic PPAR ligands. Our aim was to determine mechanisms underlying the pro-apoptotic effect of synthetic PPAR agonists in normal human bladder uro-epithelial (urothelial) cells and to reconcile this with the role of PPARs in urothelial cytodifferentiation. Materials and methods: Normal human urothelial (NHU) cells were grown as non-immortal lines in vitro and exposed to structurally diverse agonists ciglitazone, troglitazone, rosiglitazone (PPARγ), ragaglitazar (PPARα/γ), fenofibrate (PPARα) and L165041 (PPARβ/δ). Results: NHU cells underwent apoptosis following acute exposure to ciglitazone, troglitazone or ragaglitazar, but not fenofibrate, L165041 or rosiglitazone, and this was independent of ERK or p38 MAP-kinase activation. Pro-apoptotic agonists induced sustained increases in intracellular calcium, whereas removal of extracellular calcium altered the kinetics of ciglitazone-mediated calcium release from sustained to transient. Cell death was accompanied by plasma-membrane disruption, loss of mitochondrial membrane-potential and caspase-9/caspase-3 activation. PPARγ-mediated apoptosis was unaffected following pre-treatment with PPARγ antagonist T0070907 and was strongly attenuated by store-operated calcium channel (SOC) inhibitors 2-APB and SKF-96365. Conclusions: Our results provide a mechanistic basis for the ability of some PPAR agonists to induce death in NHU cells and demonstrate that apoptosis is mediated via PPAR-independent mechanisms, involving intracellular calcium changes, activation of SOCs and induction of the mitochondrial apoptotic pathway.

AB - Objectives: Peroxisome proliferator-activated receptors (PPARs) are implicated in epithelial cell proliferation and differentiation, but investigation has been confounded by potential off-target effects of some synthetic PPAR ligands. Our aim was to determine mechanisms underlying the pro-apoptotic effect of synthetic PPAR agonists in normal human bladder uro-epithelial (urothelial) cells and to reconcile this with the role of PPARs in urothelial cytodifferentiation. Materials and methods: Normal human urothelial (NHU) cells were grown as non-immortal lines in vitro and exposed to structurally diverse agonists ciglitazone, troglitazone, rosiglitazone (PPARγ), ragaglitazar (PPARα/γ), fenofibrate (PPARα) and L165041 (PPARβ/δ). Results: NHU cells underwent apoptosis following acute exposure to ciglitazone, troglitazone or ragaglitazar, but not fenofibrate, L165041 or rosiglitazone, and this was independent of ERK or p38 MAP-kinase activation. Pro-apoptotic agonists induced sustained increases in intracellular calcium, whereas removal of extracellular calcium altered the kinetics of ciglitazone-mediated calcium release from sustained to transient. Cell death was accompanied by plasma-membrane disruption, loss of mitochondrial membrane-potential and caspase-9/caspase-3 activation. PPARγ-mediated apoptosis was unaffected following pre-treatment with PPARγ antagonist T0070907 and was strongly attenuated by store-operated calcium channel (SOC) inhibitors 2-APB and SKF-96365. Conclusions: Our results provide a mechanistic basis for the ability of some PPAR agonists to induce death in NHU cells and demonstrate that apoptosis is mediated via PPAR-independent mechanisms, involving intracellular calcium changes, activation of SOCs and induction of the mitochondrial apoptotic pathway.

KW - apoptosis

KW - bladder epithelium

KW - calcium cell level

KW - calcium transport

KW - cell differentiation

KW - cell membrane

KW - controlled study

KW - drug effect

KW - drug mechanism

KW - epithelium cell

KW - human cell

KW - mitochondrial membrane potential

KW - Caspase 3

KW - Caspase 9

KW - Cell Division

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DO - 10.1111/j.1365-2184.2009.00628.x

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VL - 42

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JO - Cell Proliferation

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SN - 0960-7722

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