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Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

Bermudez Y, Benavente CA, Meyer RG, Coyle WR, Jacobson MK, Jacobson EL - PLoS ONE (2011)

Bottom Line: Receptor transcripts are greatly over-expressed in squamous cell cancers.In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling.The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Arizona Cancer Center and Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, United States of America.

ABSTRACT

Background: Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i)-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells.

Results: Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional.

Conclusions: The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

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Related in: MedlinePlus

GPR109A and GPR109B are expressed in human tissues and cells including skin.Panel A: RT-PCR was performed on total RNA from adipose tissue, placenta, lung, and skin tissues and cells using primers specific for GPR109A (top row) and GPR109B (bottom row) as described in Materials and Methods. Panel B: qRT-PCR was performed on total RNA from six different normal human skin tissues using probes specific for GPR109A (dark grey column) and GPR109B (light grey column) receptors as described in Material and Methods. Students t-test was used to compare GPR109A to GPR109B, * p≤0.05. Panel C: qRT-PCR analyses were performed on total RNA from ten human squamous cell carcinoma tissues using probes specific for GPR109A (dark grey columns) and GPR109B (light grey columns) receptors. Results represent the mean ± SEM. Students t-test was used to compare to normal human skin, * p≤0.05.
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pone-0020487-g002: GPR109A and GPR109B are expressed in human tissues and cells including skin.Panel A: RT-PCR was performed on total RNA from adipose tissue, placenta, lung, and skin tissues and cells using primers specific for GPR109A (top row) and GPR109B (bottom row) as described in Materials and Methods. Panel B: qRT-PCR was performed on total RNA from six different normal human skin tissues using probes specific for GPR109A (dark grey column) and GPR109B (light grey column) receptors as described in Material and Methods. Students t-test was used to compare GPR109A to GPR109B, * p≤0.05. Panel C: qRT-PCR analyses were performed on total RNA from ten human squamous cell carcinoma tissues using probes specific for GPR109A (dark grey columns) and GPR109B (light grey columns) receptors. Results represent the mean ± SEM. Students t-test was used to compare to normal human skin, * p≤0.05.

Mentions: The promotion of epidermal differentiation by nicotinic acid led us to characterize the nicotinic acid receptors in human skin as a putative nicotinic acid target. Genes encoding both high affinity (GPR109A) and low affinity (GPR109B) forms of the nicotinic acid receptor have been described previously and the expression of these genes has been reported in skin [6], [12], [21] but very minimal characterization has been reported. PCR analysis revealed expression of genes encoding nicotinic acid receptors in adipose tissue, placenta, and lung (Fig. 2A), tissues previously shown to express both receptor forms [6], [7], [8], [10], [12]. Fig. 2A also shows that transcripts for both high and low affinity forms of the receptor were readily detected in human skin and HaCaT cells. Very little signal was detected in CF3 dermal skin fibroblasts (the bright partial signal shown for GPR109A likely represents contamination from the HaCaT lane as it was not observed in repeat experiments). The relative levels of expression in human skin examined by qRT-PCR show that the gene encoding the high affinity form of the receptor is expressed at approximately 2.2 fold higher level than the low affinity form (Fig. 2B).


Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

Bermudez Y, Benavente CA, Meyer RG, Coyle WR, Jacobson MK, Jacobson EL - PLoS ONE (2011)

GPR109A and GPR109B are expressed in human tissues and cells including skin.Panel A: RT-PCR was performed on total RNA from adipose tissue, placenta, lung, and skin tissues and cells using primers specific for GPR109A (top row) and GPR109B (bottom row) as described in Materials and Methods. Panel B: qRT-PCR was performed on total RNA from six different normal human skin tissues using probes specific for GPR109A (dark grey column) and GPR109B (light grey column) receptors as described in Material and Methods. Students t-test was used to compare GPR109A to GPR109B, * p≤0.05. Panel C: qRT-PCR analyses were performed on total RNA from ten human squamous cell carcinoma tissues using probes specific for GPR109A (dark grey columns) and GPR109B (light grey columns) receptors. Results represent the mean ± SEM. Students t-test was used to compare to normal human skin, * p≤0.05.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3105069&req=5

pone-0020487-g002: GPR109A and GPR109B are expressed in human tissues and cells including skin.Panel A: RT-PCR was performed on total RNA from adipose tissue, placenta, lung, and skin tissues and cells using primers specific for GPR109A (top row) and GPR109B (bottom row) as described in Materials and Methods. Panel B: qRT-PCR was performed on total RNA from six different normal human skin tissues using probes specific for GPR109A (dark grey column) and GPR109B (light grey column) receptors as described in Material and Methods. Students t-test was used to compare GPR109A to GPR109B, * p≤0.05. Panel C: qRT-PCR analyses were performed on total RNA from ten human squamous cell carcinoma tissues using probes specific for GPR109A (dark grey columns) and GPR109B (light grey columns) receptors. Results represent the mean ± SEM. Students t-test was used to compare to normal human skin, * p≤0.05.
Mentions: The promotion of epidermal differentiation by nicotinic acid led us to characterize the nicotinic acid receptors in human skin as a putative nicotinic acid target. Genes encoding both high affinity (GPR109A) and low affinity (GPR109B) forms of the nicotinic acid receptor have been described previously and the expression of these genes has been reported in skin [6], [12], [21] but very minimal characterization has been reported. PCR analysis revealed expression of genes encoding nicotinic acid receptors in adipose tissue, placenta, and lung (Fig. 2A), tissues previously shown to express both receptor forms [6], [7], [8], [10], [12]. Fig. 2A also shows that transcripts for both high and low affinity forms of the receptor were readily detected in human skin and HaCaT cells. Very little signal was detected in CF3 dermal skin fibroblasts (the bright partial signal shown for GPR109A likely represents contamination from the HaCaT lane as it was not observed in repeat experiments). The relative levels of expression in human skin examined by qRT-PCR show that the gene encoding the high affinity form of the receptor is expressed at approximately 2.2 fold higher level than the low affinity form (Fig. 2B).

Bottom Line: Receptor transcripts are greatly over-expressed in squamous cell cancers.In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling.The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Arizona Cancer Center and Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, United States of America.

ABSTRACT

Background: Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i)-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells.

Results: Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional.

Conclusions: The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

Show MeSH
Related in: MedlinePlus