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Wnt5a is strongly expressed at the leading edge in non-melanoma skin cancer, forming active gradients, while canonical Wnt signalling is repressed.

Pourreyron C, Reilly L, Proby C, Panteleyev A, Fleming C, McLean K, South AP, Foerster J - PLoS ONE (2012)

Bottom Line: Wnt5a is one of the so-called non-canonical Wnt ligands which do not act through β-catenin.In vitro migration assays show that Wnt5a concentration gradients determine its effect on keratinoctye migration: While chemotactic migration is inhibited by Wnt5a present in homogenous concentrations, it is enhanced in the presence of a Wnt5a gradient.This is confirmed by immunohistochemistry showing lack of nuclear β-catenin, as well as absent accumulation of Axin2.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Institute, College of Medicine, Dentistry, and Nursing, University of Dundee, Dundee, Scotland.

ABSTRACT
Wnt5a is one of the so-called non-canonical Wnt ligands which do not act through β-catenin. In normal development, Wnt5a is secreted and directs the migration of target cells along concentration gradients. The effect of Wnt5a on target cells is regulated by many factors, including the expression level of inhibitors and receptors. Dysregulated Wnt5a signalling facilitates invasion of multiple tumor types into adjacent tissue. However, the expression and distribution of Wnt5a in cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), as well as the effect of Wnt5a on keratinocyte migration has not been studied in detail to date. We here report that Wnt5a is upregulated in SCC and BCC and localised to the leading edge of tumors, as well as tumor-associated fibroblasts. The Wnt5a-triggered bundling of its receptor Fzd3 provides evidence of Wnt5a concentration gradients projecting into the tumor. In vitro migration assays show that Wnt5a concentration gradients determine its effect on keratinoctye migration: While chemotactic migration is inhibited by Wnt5a present in homogenous concentrations, it is enhanced in the presence of a Wnt5a gradient. Expression profiling of the Wnt pathway shows that the upregulation of Wnt5a in SCC is coupled to repression of canonical Wnt signalling. This is confirmed by immunohistochemistry showing lack of nuclear β-catenin, as well as absent accumulation of Axin2. Since both types of Wnt signalling act mutually antogonistically at multiple levels, the concurrent repression of canonical Wnt signalling suggests hyper-active Wnt5a signal transduction. Significantly, this combination of gene dysregulation is not observed in the benign hyperproliferative inflammatory skin disease psoriasis. Collectively, our data strongly suggest that Wnt5a signalling contributes to tissue invasion by non-melanoma skin cancer.

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Related in: MedlinePlus

Localization of Fzd3 in non-melanoma skin cancer.Immunohistochemistry performed as in figure 1 performed on SCC (a–d), or BCC (e–f) shown at 40× (a), 100× (b,d,e), or 400× (c,f) magnification, respectively. Black arrows indicate staining intensity of Fzd3 in the epidermis used to assess staining intensity in tumors (denoted by white arrows). Red arrows denote boundary of tumors, pointing toward stroma.
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pone-0031827-g002: Localization of Fzd3 in non-melanoma skin cancer.Immunohistochemistry performed as in figure 1 performed on SCC (a–d), or BCC (e–f) shown at 40× (a), 100× (b,d,e), or 400× (c,f) magnification, respectively. Black arrows indicate staining intensity of Fzd3 in the epidermis used to assess staining intensity in tumors (denoted by white arrows). Red arrows denote boundary of tumors, pointing toward stroma.

Mentions: Wnt5a concentration gradients cannot be directly detected in vivo. However, recently it was shown that, upon sensing a Wnt5a concentration gradient, target cells respond by bundling the Wnt5a receptor Fzd3 into focal aggregates in vitro [15]. Therefore, Fzd3 aggregates can be used as indirect marker to identify cells exposed to a Wnt5a gradients in primary tissue using immunohistochemistry. Indeed, we found that Fzd3 exhibited a strikingly polarised focal distribution both in epidermal keratinocytes as well as in the hair follicles (Fig. S1), suggesting that Wnt5a gradients are operative not only in development, but also in adult differentiated skin. Next, we investigated Fzd3 distribution in tumor sections. As with Wnt5a, we utilised the staining intensity of Fzd3 in the epidermis in each section to semiquantitatively assess the relative expression level (fig. 2a, black vs. white arrows). As shown in figure 2, Fzd3 was found in a zonal distribution, such that Fzd3-negative tumor areas alternate with Fzd3-positive areas (fig. 2b,e) within the tumors, while the invasive edges did not stain positive (fig. 2d). Tumor-infiltrating fibroblasts and endothelial cells were negative for Fzd3. In those tumor cells that did express Fzd3, Fzd3 exhibited a pronounced polarised focal intracellular aggregates, suggesting the existence of Wnt5a gradients. However, in contrast to normal epidermis, Fzd3-aggregates were not aligned along recogniseable planes, indicative of disorganised Wnt5a gradients. This overall Fzd3 expression pattern was quite comparable across all tumors studied (table 1).


Wnt5a is strongly expressed at the leading edge in non-melanoma skin cancer, forming active gradients, while canonical Wnt signalling is repressed.

Pourreyron C, Reilly L, Proby C, Panteleyev A, Fleming C, McLean K, South AP, Foerster J - PLoS ONE (2012)

Localization of Fzd3 in non-melanoma skin cancer.Immunohistochemistry performed as in figure 1 performed on SCC (a–d), or BCC (e–f) shown at 40× (a), 100× (b,d,e), or 400× (c,f) magnification, respectively. Black arrows indicate staining intensity of Fzd3 in the epidermis used to assess staining intensity in tumors (denoted by white arrows). Red arrows denote boundary of tumors, pointing toward stroma.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285195&req=5

pone-0031827-g002: Localization of Fzd3 in non-melanoma skin cancer.Immunohistochemistry performed as in figure 1 performed on SCC (a–d), or BCC (e–f) shown at 40× (a), 100× (b,d,e), or 400× (c,f) magnification, respectively. Black arrows indicate staining intensity of Fzd3 in the epidermis used to assess staining intensity in tumors (denoted by white arrows). Red arrows denote boundary of tumors, pointing toward stroma.
Mentions: Wnt5a concentration gradients cannot be directly detected in vivo. However, recently it was shown that, upon sensing a Wnt5a concentration gradient, target cells respond by bundling the Wnt5a receptor Fzd3 into focal aggregates in vitro [15]. Therefore, Fzd3 aggregates can be used as indirect marker to identify cells exposed to a Wnt5a gradients in primary tissue using immunohistochemistry. Indeed, we found that Fzd3 exhibited a strikingly polarised focal distribution both in epidermal keratinocytes as well as in the hair follicles (Fig. S1), suggesting that Wnt5a gradients are operative not only in development, but also in adult differentiated skin. Next, we investigated Fzd3 distribution in tumor sections. As with Wnt5a, we utilised the staining intensity of Fzd3 in the epidermis in each section to semiquantitatively assess the relative expression level (fig. 2a, black vs. white arrows). As shown in figure 2, Fzd3 was found in a zonal distribution, such that Fzd3-negative tumor areas alternate with Fzd3-positive areas (fig. 2b,e) within the tumors, while the invasive edges did not stain positive (fig. 2d). Tumor-infiltrating fibroblasts and endothelial cells were negative for Fzd3. In those tumor cells that did express Fzd3, Fzd3 exhibited a pronounced polarised focal intracellular aggregates, suggesting the existence of Wnt5a gradients. However, in contrast to normal epidermis, Fzd3-aggregates were not aligned along recogniseable planes, indicative of disorganised Wnt5a gradients. This overall Fzd3 expression pattern was quite comparable across all tumors studied (table 1).

Bottom Line: Wnt5a is one of the so-called non-canonical Wnt ligands which do not act through β-catenin.In vitro migration assays show that Wnt5a concentration gradients determine its effect on keratinoctye migration: While chemotactic migration is inhibited by Wnt5a present in homogenous concentrations, it is enhanced in the presence of a Wnt5a gradient.This is confirmed by immunohistochemistry showing lack of nuclear β-catenin, as well as absent accumulation of Axin2.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Institute, College of Medicine, Dentistry, and Nursing, University of Dundee, Dundee, Scotland.

ABSTRACT
Wnt5a is one of the so-called non-canonical Wnt ligands which do not act through β-catenin. In normal development, Wnt5a is secreted and directs the migration of target cells along concentration gradients. The effect of Wnt5a on target cells is regulated by many factors, including the expression level of inhibitors and receptors. Dysregulated Wnt5a signalling facilitates invasion of multiple tumor types into adjacent tissue. However, the expression and distribution of Wnt5a in cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), as well as the effect of Wnt5a on keratinocyte migration has not been studied in detail to date. We here report that Wnt5a is upregulated in SCC and BCC and localised to the leading edge of tumors, as well as tumor-associated fibroblasts. The Wnt5a-triggered bundling of its receptor Fzd3 provides evidence of Wnt5a concentration gradients projecting into the tumor. In vitro migration assays show that Wnt5a concentration gradients determine its effect on keratinoctye migration: While chemotactic migration is inhibited by Wnt5a present in homogenous concentrations, it is enhanced in the presence of a Wnt5a gradient. Expression profiling of the Wnt pathway shows that the upregulation of Wnt5a in SCC is coupled to repression of canonical Wnt signalling. This is confirmed by immunohistochemistry showing lack of nuclear β-catenin, as well as absent accumulation of Axin2. Since both types of Wnt signalling act mutually antogonistically at multiple levels, the concurrent repression of canonical Wnt signalling suggests hyper-active Wnt5a signal transduction. Significantly, this combination of gene dysregulation is not observed in the benign hyperproliferative inflammatory skin disease psoriasis. Collectively, our data strongly suggest that Wnt5a signalling contributes to tissue invasion by non-melanoma skin cancer.

Show MeSH
Related in: MedlinePlus