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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

Localization of GPR109A and GPR109B protein expression in cultured normal and malignant human skin cells.Panels A and B: Immunocytochemistry (ICC) analyses utilizing an antibody against GPR109A/B were performed on NHEK shown in red and merged with nuclear DAPI staining in blue. Panel A shows staining using the GPR109A/B antibody and Panel B shows staining in the presence of 1000 fold excess of peptides used to raise the antibody. Panel C: HaCaT, Panel D: Ras-transformed HaCaT, Panel E: A-431, Panel F: SCC-25. For all panels, magnification was 400× and size marker represents 10 microns.
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pone-0020487-g005: Localization of GPR109A and GPR109B protein expression in cultured normal and malignant human skin cells.Panels A and B: Immunocytochemistry (ICC) analyses utilizing an antibody against GPR109A/B were performed on NHEK shown in red and merged with nuclear DAPI staining in blue. Panel A shows staining using the GPR109A/B antibody and Panel B shows staining in the presence of 1000 fold excess of peptides used to raise the antibody. Panel C: HaCaT, Panel D: Ras-transformed HaCaT, Panel E: A-431, Panel F: SCC-25. For all panels, magnification was 400× and size marker represents 10 microns.

Mentions: NHEK cells were stained using the anti-peptide antibody (Fig. 5A) and peptide competition blocked the staining (Fig. 5B). Staining appears on the periphery of aggregates of cells forming “cobblestone structures” while isolated cells appear to have a more diffuse pattern of labeling (Fig. 5A). In HaCaT cells, GPR109A/B expression is mainly localized to the periphery (Fig. 5C). In contrast, in Ras-transformed HaCaT (Fig. 5D), A-431 (Fig. 5E), and SCC-25 (Fig. 5F) the plasma membrane localization is accompanied by labeling throughout the cytoplasm. Receptor expression in skin fibroblasts, CF3, is undetectable (data not shown).


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)

Localization of GPR109A and GPR109B protein expression in cultured normal and malignant human skin cells.Panels A and B: Immunocytochemistry (ICC) analyses utilizing an antibody against GPR109A/B were performed on NHEK shown in red and merged with nuclear DAPI staining in blue. Panel A shows staining using the GPR109A/B antibody and Panel B shows staining in the presence of 1000 fold excess of peptides used to raise the antibody. Panel C: HaCaT, Panel D: Ras-transformed HaCaT, Panel E: A-431, Panel F: SCC-25. For all panels, magnification was 400× and size marker represents 10 microns.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105069&req=5

pone-0020487-g005: Localization of GPR109A and GPR109B protein expression in cultured normal and malignant human skin cells.Panels A and B: Immunocytochemistry (ICC) analyses utilizing an antibody against GPR109A/B were performed on NHEK shown in red and merged with nuclear DAPI staining in blue. Panel A shows staining using the GPR109A/B antibody and Panel B shows staining in the presence of 1000 fold excess of peptides used to raise the antibody. Panel C: HaCaT, Panel D: Ras-transformed HaCaT, Panel E: A-431, Panel F: SCC-25. For all panels, magnification was 400× and size marker represents 10 microns.
Mentions: NHEK cells were stained using the anti-peptide antibody (Fig. 5A) and peptide competition blocked the staining (Fig. 5B). Staining appears on the periphery of aggregates of cells forming “cobblestone structures” while isolated cells appear to have a more diffuse pattern of labeling (Fig. 5A). In HaCaT cells, GPR109A/B expression is mainly localized to the periphery (Fig. 5C). In contrast, in Ras-transformed HaCaT (Fig. 5D), A-431 (Fig. 5E), and SCC-25 (Fig. 5F) the plasma membrane localization is accompanied by labeling throughout the cytoplasm. Receptor expression in skin fibroblasts, CF3, is undetectable (data not shown).

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