Alterations of beta-catenin pathway in non-melanoma skin tumors: loss of alpha-ABC nuclear reactivity correlates with the presence of beta-catenin gene mutation

Wnt/beta-catenin activated non pilomatrical carcinoma of the skin: a case series

Among skin epithelial tumors, recurrent mutations in the APC/CTNNB1 genes resulting in activation of the Wnt/β-catenin pathway have been reported predominantly in neoplasms with matrical differentiation. In the present study, we describe the morphologic, immunohistochemical, and genetic features of 16 primary cutaneous carcinomas harboring mutations activating the Wnt/β-catenin pathway without evidence of matrical differentiation, as well as four combined tumors in which a similar Wnt/β-catenin activated carcinoma component was associated with Merkel cell carcinoma or pilomatrical carcinoma. Among the pure tumor cases, 6/16 patients were female with a median age of 80 years (range: 58-98). Tumors were located on the head and neck (n=7, 44%), upper limb (n=4, 25%), trunk (n=3, 18%), and leg (n=2, 13%). Metastatic spread was observed in 4 cases resulting in death from disease in one patient. Microscopically, all cases were poorly differentiated neoplasms infiltrating the dermis and/or subcutaneous tissue. In 13 cases, solid "squamoid" areas were associated with a basophilic component characterized by rosette/pseudoglandular formation resulting in a biphasic appearance. Three specimens consisted only of poorly differentiated carcinoma lacking rosette formation. Immunohistochemical studies showed frequent expression of EMA (100%), BerEP4 (100%), cytokeratin 7 (94%), chromogranin A (44%), synaptophysin (82%) and cytokeratin 20 (69%). Complete loss of Rb expression was observed in all but one case. Nuclear β-catenin and CDX2 expressions were detected in all cases. Recurrent pathogenic somatic mutations were observed in APC (60%), CTNNB1 (40%) and RB1 (n=47%). Global methylation analysis confirmed that cases with rosette formation constituted a homogenous tumor group distinct from established skin tumor entities (pilomatrical carcinoma, Merkel cell carcinoma and squamous cell carcinoma) while the 3 other cases lacking such morphologic features did not. In addition, we identified four combined neoplasms in which there was a component showing a similar poorly differentiated rosette forming carcinoma demonstrating Rb loss and beta-catenin activation associated with either Merkel cell carcinoma (n=3) or pilomatrical carcinoma (n=1). In conclusion, we describe a distinctive neoplasm, for which we propose the term "Wnt/β-catenin activated rosette-forming carcinoma", morphologically characterized by the association of rosette formation, squamous and/or neuroendocrine differentiation, diffuse CDX2 expression, Rb loss, and mutations in CTNNB1/APC genes.

TCF7L1 regulates colorectal cancer cell migration by repressing GAS1 expression

Dysregulated Wnt/β-catenin signaling is a common feature of colorectal cancer (CRC). The T-cell factor/lymphoid enhancer factor (TCF/LEF; hereafter, TCF) family of transcription factors are critical regulators of Wnt/β-catenin target gene expression. Of the four TCF family members, TCF7L1 predominantly functions as a transcriptional repressor. Although TCF7L1 has been ascribed an oncogenic role in CRC, only a few target genes whose expression it regulates have been characterized in this cancer. Through transcriptome analyses of TCF7L1 regulated genes, we noted enrichment for those associated with cellular migration. By silencing and overexpressing TCF7L1 in CRC cell lines, we demonstrated that TCF7L1 promoted migration, invasion, and adhesion. We localized TCF7L1 binding across the CRC genome and overlapped enriched regions with transcriptome data to identify candidate target genes. The growth arrest-specific 1 (GAS1) gene was among these and we demonstrated that GAS1 is a critical mediator of TCF7L1-dependent CRC cell migratory phenotypes. Together, these findings uncover a novel role for TCF7L1 in repressing GAS1 expression to enhance migration and invasion of CRC cells.

Altered E-cadherin/β-catenin expression in feline cutaneous squamous cell carcinomas

Cutaneous squamous cell carcinoma (CSCC) is the most common malignant skin tumour in cats and the nature of the molecular mechanisms involved is poorly defined. Included among the molecular mechanisms in human and canine CSCCs is altered expression of E-cadherin/β-catenin. This study aimed to explore the immunohistochemical expression pattern of E-cadherin and β-catenin in 43 samples of feline CSCC by using a tissue microarray to elucidate whether expression of these molecules is dysregulated. Membrane expression of E-cadherin and membrane and cytoplasmic expression of β-catenin were significantly reduced in the CSCCs. Cytoplasmic expression of E-cadherin and nuclear expression of β-catenin were also found in some CSCCs. These findings indicate that altered expression of E-cadherin and β-catenin is a frequent event in feline CSCCs, suggesting that these molecules play an important role in acquisition of the malignant phenotype in feline patients with CSCC. The results also suggest the existence of a subpopulation of feline patients with CSCC in which the Wnt pathway may contribute to epidermal carcinogenesis.

High expression of NF-κB inducing kinase in the bulge region of hair follicle induces tumor

The bulge region, a reservoir of multipotent stem cells, is possibly responsible for tumorigenesis. NF-κB-inducing kinase (NIK) is a kinase involved in the activation of the noncanonical NF-κB pathway and exhibits positive staining in tumor cells. However, whether high expression of NIK can result in tumorigenesis has not been reported in published papers. By establishing Nik-coe (Nik-stopF/F crossed with Chat-cre) and Nik-soe (Nik-stopF/F crossed with Sox9-cre) mice, we found that overexpression of Nik in the bulge region of hair follicles induced hair follicle loss and tumorigenesis. Furthermore, RNA sequencing, proteomic and phosphopeptide analyses revealed that multiple cancer pathways are involved in tumor formation. Taken together, these findings indicate that constitutive activation of Nik in the bulge region induces tumorigenesis.

Wnt Signaling Pathways: From Inflammation to Non-Melanoma Skin Cancers

Canonical and non-canonical Wnt signaling pathways are involved in cell differentiation and homeostasis, but also in tumorigenesis. In fact, an exaggerated activation of Wnt signaling may promote tumor growth and invasion. We summarize the most intriguing evidence about the role of Wnt signaling in cutaneous carcinogenesis, in particular in the pathogenesis of non-melanoma skin cancer (NMSC). Wnt signaling is involved in several ways in the development of skin tumors: it may modulate the inflammatory tumor microenvironment, synergize with Sonic Hedgehog pathway in the onset of basal cell carcinoma, and contribute to the progression from precancerous to malignant lesions and promote the epithelial-mesenchymal transition in squamous cell carcinoma. Targeting Wnt pathways may represent an additional efficient approach in the management of patients with NMSC.

Immunohistochemical Localization of Phosphorylated and Unphosphorylated Form of β-catenin With Regard to Shadow Cell and Squamous Differentiation in Cutaneous Pilomatricoma

Pilomatricoma usually contains a mutation in CTNNB1 that encodes β-catenin (BC). It also shows nuclear accumulation of BC protein, which plays an important role in tumorigenesis of pilomatricoma. In vitro studies have indicated that mutant BC protein is unphosphorylated and shows nuclear accumulation, but this theory has not been confirmed in various tumors with CTNNB1 mutation. We examined immunohistochemical localization of phosphorylated BC (pBC) and unphosphorylated BC (npBC) with regard to the modes of cell death or differentiation in 25 cases of pilomatricoma. As for the component showing shadow cell differentiation, BC was detected in cytoplasm/nucleus and along cell membrane in basaloid cells, whereas only in the latter in transitional cells in all cases. Meanwhile, npBC was localized along cell membrane of transitional cells, but not in basaloid cells, nor in nucleus of any components. The components with squamous differentiation also revealed the staining patterns similar to those seen in shadow cell differentiation in some cases. pBC was found in some cell fragments in the amorphous debris containing apoptotic bodies among shadow cell nests. These results suggested that npBC plays an important role in cell adhesion during differentiation and that pBC expression is associated with apoptosis of basaloid cells in pilomatricoma. BC accumulated in the nucleus was not immunoreactive for npBC possibly due to post-translational modification or conformational changes that resulted in loss of or masked antigenicity when BC is assumed to be unphosphorylated.

Basal Cell Carcinoma: From Pathophysiology to Novel Therapeutic Approaches

Basal cell carcinoma (BCC) is the most common human cancer worldwide, and is a subtype of nonmelanoma skin cancer, characterized by a constantly increasing incidence due to an aging population and widespread sun exposure. Although the mortality from BCC is negligible, this tumor can be associated with significant morbidity and cost. This review presents a literature overview of BCC from pathophysiology to novel therapeutic approaches. Several histopathological BCC subtypes with different prognostic values have been described. Dermoscopy and, more recently, reflectance confocal microscopy have largely improved BCC diagnosis. Although surgery is the first-line treatment for localized BCC, other nonsurgical local treatment options are available. BCC pathogenesis depends on the interaction between environmental and genetic characteristics of the patient. Specifically, an aberrant activation of Hedgehog signaling pathway is implicated in its pathogenesis. Notably, Hedgehog signaling inhibitors, such as vismodegib and sonidegib, are successfully used as targeted treatment for advanced or metastatic BCC. Furthermore, the implementation of prevention measures has demonstrated to be useful in the patient management.

EGFR/c-Met and mTOR signaling are predictors of survival in non-small cell lung cancer

BACKGROUND

EGFR/c-Met activation/amplification and co-expression, mTOR upregulation/activation, and Akt/Wnt signaling upregulation have been individually associated with more aggressive disease and characterized as potential prognostic markers for lung cancer patients.

METHODS

Tumors obtained from 109 participants with stage I-IV non-small cell lung cancer (NSCLC) were studied for EGFR/c-Met co-localization as well as for total and active forms of EGFR, c-Met, mTOR, S6K, beta-catenin, and Axin2. Slides were graded by two independent blinded pathologists using a validated scoring system. Protein expression profile correlations were assessed using Pearson correlation and Spearman's rho. Prognosis was assessed using Kaplan-Meier analysis.

RESULTS

Protein expression profile analysis revealed significant correlations between EGFR/p-EGFR (p = 0.0412) and p-mTOR/S6K (p = 0.0044). Co-localization of p-EGFR/p-c-Met was associated with increased p-mTOR (p = 0.0006), S6K (p = 0.0018), and p-S6K (p < 0.0001) expression. In contrast, active beta-catenin was not positively correlated with EGFR/c-Met nor any activated proteins. Axin2, a negative regulator of the Wnt pathway, was correlated with EGFR, p-EGFR, p-mTOR, p-S6K, EGFR/c-Met co-localization, and p-EGFR/p-c-Met co-localization (all p-values <0.03). Kaplan-Meier analysis revealed shorter median survival in participants with high expression of Axin2, total beta-catenin, total/p-S6K, total/p-mTOR, EGFR, and EGFR/c-Met co-localization compared with low expression. After controlling for stage of disease at diagnosis, subjects with late-stage disease demonstrated shorter median survival when exhibiting high co-expression of EGFR/c-Met (8.1 month versus 22.3 month, p = 0.050), mTOR (6.7 month versus 22.3 month, p = 0.002), and p-mTOR (8.1 month versus 25.4 month, p = 0.004) compared with low levels.

CONCLUSIONS

These findings suggest that increased EGFR/c-Met signaling is correlated with upregulated mTOR/S6K signaling, which may in turn be associated with shorter median survival in late-stage NSCLC.

A, Bava SV, Sundaram S, Retnakumari AP, Chittalakkottu S, Anto RJ. Pre-clinical evidences for the efficacy of tryptanthrin as a potent suppressor of skin cancer

OBJECTIVE

Clinical trials have demonstrated the efficacy of indigo naturalis, a traditional Chinese medicine ingredient, against psoriasis, a skin disease characterized by keratinocyte hyperproliferation and inflammation. The present study investigates the efficacy of tryptanthrin, a bioactive compound in indigo naturalis, against non-melanoma skin cancer (NMSC) and the signalling events involved.

METHODS

Efficacy of tryptanthrin against NMSC was assessed using DMBA/PMA-induced skin carcinogenesis model in Swiss albino mice. Immunostaining for PCNA and ki-67 was used to mark proliferating cells in tissues. Haematoxylin and eosin staining and toluidine staining were employed to assess inflammation, and TUNEL assay was used to detect apoptosis in tissues. The signalling events were evaluated using Western blot, imunohistochemistry and immunofluorescence staining. MTT assay and clonogenic assay were performed to assess the viability and proliferation of cancer cells, in vitro.

RESULTS

In mice, topical application of tryptanthrin suppressed skin carcinogenesis. It attenuated inflammation, impeded the proliferation of hair follicle (HF) cells and suppressed the activation of β-catenin, a major driver of HF cell proliferation. Additionally tryptanthrin suppressed the activation of ERK1/2 and p38, both of which promote β-catenin activation and lowered the expression of c-Myc and cyclin-D1. Tryptanthrin suppressed the proliferation of the human NMSC cell line, A431 and abrogated EGF-induced activation of β-catenin and subsequent cytoskeletal rearrangement.

CONCLUSION

The study demonstrates with molecular evidence that tryptanthrin is an effective suppressor of NMSC.

Role of the Wnt signaling pathway in keratoacanthoma

BACKGROUND

Keratoacanthoma (KA) has a unique life cycle of rapid growth and spontaneous regression that shows similarities to the hair follicle cycle, which involves an active Wnt signaling during physiological regeneration. We analyzed the expression of the Wnt signaling proteins β-catenin, Lef1, Sox9, and Cyclin D1 in young and old human KAs to investigate a possible role for Wnt signaling in KAs.

AIM

To investigate the role of the Wnt/β-catenin signaling pathway in human KAs.

METHODS AND RESULTS

Formalin-fixed, paraffin-embedded tissue samples of 67 KAs were analyzed for protein expression using immunohistochemistry. The majority of KAs were positive for Sox9 and Cyclin D1 but not for nuclear-localized β-catenin or Lef-1. No significant differences in protein expressions were seen between young and old KAs. However, we found a significant association between Ki67 and Cyclin D1 proteins (P= .008).

CONCLUSIONS

The Wnt signaling pathway does not appear to play a significant role in the biogenesis of human KA. Sox9 overexpression may be indicative of inhibition of Wnt signaling. Sox-9 and Cyclin D1 are proliferation markers that are most likely transactivated by alternate signaling pathways.

Pten loss in Lgr5+ hair follicle stem cells promotes SCC development

Accumulating data support that tissue stem cells give rise to cancer cells. Hair follicle stem cells (HFSCs) undergo cyclic quiescence and activation and may sever as the origin of cutaneous squamous cell carcinoma (SCC). Pten is a tumor suppressor gene that is frequently mutated in hereditary cancer syndromes such as Cowden disease, which is featured with papillomatosis in cutaneous tissues and hyperkeratosis in the acral region of the skin. Additionally, mice with keratinocyte-specific Pten deficiency (k5-Pten^-/- mice) show epidermal hyperplasia and spontaneous tumor formation. However, the impact of Pten mutation in HFSCs, such as in Lgr5⁺ HFSCs, on SCC formation is unclear.

Methods: We established experiments with wildtype and Lgr5-CreER; Pten^flox/flox mice, and used DMBA/TPA two-stage skin carcinogenesis model to explore the effect of Pten loss in Lgr5⁺ HFSCs of 3 weeks old mice in skin carcinogenesis. In vitro experiments (cell culture and protein expression analysis) are employed to investigate molecular mechanisms involved.

Results: Pten loss in Lgr5⁺ HFSCs promoted SCC formation, which was attenuated in TNF^-/- mice. Notably, β-catenin loss in Lgr5⁺ HFSCs decreased the formation of SCC. In addition, Pten loss in cultured epidermal stem cells upregulated the levels of both phospho-Akt and β-catenin.

Conclusion: Pten loss in Lgr5⁺ cells induced Akt/β-catenin signaling, and SCCs can subsequently be raised as progeny from these primed Lgr5⁺ stem cells.

Wnt Signaling Pathways in Keratinocyte Carcinomas

The skin functions as a barrier between the organism and the surrounding environment. Direct exposure to external stimuli and the accumulation of genetic mutations may lead to abnormal cell growth, irreversible tissue damage and potentially favor skin malignancy. Skin homeostasis is coordinated by an intricate signaling network, and its dysregulation has been implicated in the development of skin cancers. Wnt signaling is one such regulatory pathway orchestrating skin development, homeostasis, and stem cell activation. Aberrant regulation of Wnt signaling cascades not only gives rise to tumor initiation, progression and invasion, but also maintains cancer stem cells which contribute to tumor recurrence. In this review, we summarize recent studies highlighting functional evidence of Wnt-related oncology in keratinocyte carcinomas, as well as discussing preclinical and clinical approaches that target oncogenic Wnt signaling to treat cancers. Our review provides valuable insight into the significance of Wnt signaling for future interventions against keratinocyte carcinomas.

Multiple oncogenic roles of nuclear beta-catenin

β-Catenin is essential for embryonic development and required for cell renewal/regeneration in adult life. Cellular β-catenin exists in three different pools: membranous, cytoplasmic and nuclear. In this review, we focus on functions of the nuclear pool in relation to tumorigenesis. In the nucleus, beta-catenin functions as both activator and repressor of transcription in a context-dependent manner. It promotes cell proliferation and supports tumour growth by enhancing angiogenesis. β-Catenin-mediated signalling regulates cancer cell metabolism and is associated with tumour-initiating cells in multiple malignancies. In addition, it functions as both pro- and anti-apoptotic factor besides acting to inhibit recruitment of inflammatory anti-tumour T-cells. Thus, β-catenin appears to possess a multifaceted nuclear function that may significantly impact tumour initiation and progression.

Cross-Talk between Wnt and Hh Signaling Pathways in the Pathology of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most frequently occurring form of all cancers. The cost of care for BCC is one of the highest for all cancers in the Medicare population in the United States. Activation of Hedgehog (Hh) signaling pathway appears to be a key driver of BCC development. Studies involving mouse models have provided evidence that activation of the glioma-associated oncogene (GLI) family of transcription factors is a key step in the initiation of the tumorigenic program leading to BCC. Activation of the Wnt pathway is also observed in BCCs. In addition, the Wnt signaling pathway has been shown to be required in Hh pathway-driven development of BCC in a mouse model. Cross-talks between Wnt and Hh pathways have been observed at different levels, yet the mechanisms of these cross-talks are not fully understood. In this review, we examine the mechanism of cross-talk between Wnt and Hh signaling in BCC development and its potential relevance for treatment. Recent studies have identified insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), a direct target of the Wnt/&beta;-catenin signaling, as the factor that binds to GLI1 mRNA and upregulates its levels and activities. This mode of regulation of GLI1 appears important in BCC tumorigenesis and could be explored in the treatment of BCCs.

Comparison of dysplastic fundic gland polyps in patients with and without familial adenomatous polyposis

AIMS

Dysplastic fundic gland polyps (d-FGPs) typically arise in patients with familial adenomatous polyposis (FAP) but may occur in non-syndromic patients. They rarely become malignant, but their significance is unclear, especially in non-syndromic patients. We aimed to compare d-FGPs in patients with and without FAP, using clinicopathologic findings and β-catenin immunohistochemistry (IHC).

METHODS AND RESULTS

We identified 124 fundic gland polyps with low-grade dysplasia (LGD) or high-grade dysplasia (HGD) or indefinite for dysplasia (IFD) from 66 patients (27 with FAP; 39 non-syndromic). We recorded patient sex, age at first d-FGP, time until subsequent d-FGP (if any), history of non-gastric cancer (no patients had gastric cancer), proton-pump inhibitor use, and the presence of Helicobacter pylori. β-Catenin IHC was performed on cases with available blocks. The mean age at d-FGP diagnosis was 31 years for FAP patients and 61 years for non-syndromic patients (P < 0.0001). Sixteen FAP patients (59%) developed at least one subsequent d-FGP, as compared with 10 (27%) non-syndromic patients (P = 0.0099). The median time between d-FGP detection was 11.5 months in FAP patients and 7 months in non-syndromic patients (P = 0.82). Six FAP patients (22%) and 17 non-syndromic patients (44%) had non-gastric malignancies (P = 0.11). β-Catenin IHC showed nuclear positivity in 14 of 112 (13%) d-FGPs: 12 of 94 with LGD, two of three with HGD, and none of 15 with IFD polyps.

CONCLUSIONS

Familial adenomatous polyposis patients develop d-FGPs earlier and more often develop additional ones than non-syndromic patients. d-FGPs in FAP and non-syndromic patients have similar low rates of β-catenin nuclear IHC positivity. FAP and non-syndromic patients developed non-gastric cancers at similar rates, suggesting that d-FGPs may portend a general increased risk of carcinogenesis in non-syndromic patients.

TCF7L1 recruits CtBP and HDAC1 to repress DICKKOPF4 gene expression in human colorectal cancer cells

The T-cell factor/Lymphoid enhancer factor (TCF/LEF; hereafter TCF) family of transcription factors are critical regulators of colorectal cancer (CRC) cell growth. Of the four TCF family members, TCF7L1 functions predominantly as a repressor of gene expression. Few studies have addressed the role of TCF7L1 in CRC and only a handful of target genes regulated by this repressor are known. By silencing TCF7L1 expression in HCT116 cells, we show that it promotes cell proliferation and tumorigenesis in vivo by driving cell cycle progression. Microarray analysis of transcripts differentially expressed in control and TCF7L1-silenced CRC cells identified genes that control cell cycle kinetics and cancer pathways. Among these, expression of the Wnt antagonist DICKKOPF4 (DKK4) was upregulated when TCF7L1 levels were reduced. We found that TCF7L1 recruits the C-terminal binding protein (CtBP) and histone deacetylase 1 (HDAC1) to the DKK4 promoter to repress DKK4 gene expression. In the absence of TCF7L1, TCF7L2 and β-catenin occupancy at the DKK4 promoter is stimulated and DKK4 expression is increased. These findings uncover a critical role for TCF7L1 in repressing DKK4 gene expression to promote the oncogenic potential of CRCs.

p40 in Conjunction With CK20 and E-Cadherin Distinguishes Primary Adnexal Neoplasms of the Skin

Although basal cell carcinomas (BCC) show typical histomorphologic features, they sometimes remain difficult in distinction from benign adnexal skin tumors of follicular origin like trichoepithelioma (TE) or trichoblastoma (TB). Consequently, an immunohistochemical marker panel separating described entities would be helpful in clinical routine. Thus, we stained 22 skin lesions (BCC, TE, and TB) against β-catenin, CK20, E-cadherin, p40, and p63. The staining pattern was described and quantified using an immunohistochemical score. Although p40 and p63 revealed a strong staining intensity of all skin lesions without distinction between BCC and benign lesions (P=1.000), established Merkel cell marker CK20 illustrated a loss of staining in BCC compared with TE and TB (P=0.007). In contrast, BCC exhibited an increased expression of E-cadherin in relation to TE and TB (P=0.009). Single application of CK20 or E-cadherin could predict diagnosis of BCC in 81.8% or 72.7%, respectively. Combining consecutive staining of E-cadherin and CK20 could even enhance specificity toward diagnosis of TE or TB. Hence, findings of our study imply that sequential staining of CK20 and E-cadherin prevents false-positive classification of BCC. Furthermore, our study demonstrated that p40 exhibits the same staining pattern in BCC, TE, and TB. Therefore, p40 might replace p63 equivalently establishing diagnosis of primary adnexal neoplasms of the skin in the form of BCC as well as benign adnexal tumors. As a result, the depicted immunohistochemical marker panel may be applied for adnexal skin neoplasms as a diagnostic adjunct especially in surgically challenging body regions.

WNT Signaling in Cutaneous Squamous Cell Carcinoma: A Future Treatment Strategy?

The molecular mechanisms underlying cutaneous squamous cell carcinoma are less well established than those for other common skin cancers, but recent evidence has highlighted a potentially critical role for WNT signaling in both the development and progression of cutaneous squamous cell carcinoma. WNT pathways are aberrantly regulated in multiple tumor types (albeit in a context-dependent manner), and this has stimulated the development of WNT inhibitory compounds for cancer treatment. In this review, we examine existing evidence for a role of WNT signaling in cutaneous squamous cell carcinoma and discuss if WNT inhibition represents a realistic therapeutic strategy for the future.

Sox9 is a β-catenin-regulated transcription factor that enhances the colony-forming activity of squamous cell carcinoma cells

Squamous cell carcinoma (SCC) is a common skin cancer, of which the incidence is relatively high, ranking second among the non‑melanoma skin cancers. It is known that numerous intracellular signal regulators are involved in the pathogenesis of SCC. The Wnt/β-catenin signaling pathway serves an important role in cancer development. However, the downstream effectors of β‑catenin remain to be clearly elucidated yet. The present study investigated the functional importance of Wnt/β‑catenin signaling in cutaneous SCC. β‑catenin expression was reduced using recombinant adenovirus expressing specific microRNA (miR). Knockdown of β‑catenin resulted in a marked reduction of the colony-forming activity of the SCC cells, SCC12. In an attempt to identify the β‑catenin downstream genes, it was found that Sox9 was regulated by β‑catenin in SCC12 cells. Overexpression of a constitutively active form of β‑catenin led to the induction of Sox9, while knockdown of β‑catenin resulted in downregulation of Sox9. When the expression of Sox9 was reduced using specific miR, colony-forming activity of the SCC12 cells was significantly reduced. When Sox9 was overexpressed in cells where β‑catenin was knocked down, it partially restored the colony‑forming potential. Taken together, the present results suggested that Sox9 is a β-catenin downstream transcription factor and is positively involved in SCC development.

Expression of retinoic acid-binding proteins and retinoic acid receptors in sebaceous cell carcinoma of the eyelids

Background

Sebaceous cell carcinoma of the eyelid is a malignant tumor. However, the pathoetiology of sebaceous cell carcinoma is not clear. Retinoic acid (RA) signaling is essential for skin epidermal differentiation including the eyelids. In this study, we investigate the expression of β-catenin, RA-binding proteins and RA receptors in sebaceous cell carcinoma of the eyelid and try to estimate their influence on its pathoetiology.

Methods

Retrospective, noncomparative, consecutive interventional case series. Sixteen cases of eyelid sebaceous gland carcinoma who received tumor excision at our hospital between 2001 and 2011 were included. Immunohistochemical staining for β-catenin, cellular retinoic acid binding protein 1 (CRABP1), cellular retinoic acid binding protein 2 (CRABP2), fatty acid-binding protein 5 (FABP5), retinoic acid receptors (RAR-α, −β, −γ), and retinoid X receptors (RXR-α, −β, −γ) was performed on tissue samples obtained from tumor excision.

Results

Of the 16 sebaceous cell carcinoma cases reviewed, six were male and 10 female. The mean follow-up period was 6.7 ± 3.66 years (range, 0.3–13 years). Of these 16 cases, the expression of β-catenin was significantly increased in sebaceous cell carcinoma cases. CRABP1 was similarly expressed in the sebaceous cell carcinoma and control groups. CRABP2 and FABP5 were expressed in hair follicles of lid skin in both groups, whereas the CRABP2 and FABP5 were aberrantly expressed in the tumor cells of the sebaceous glands. Notably, the expression of retinoic acid receptor (RAR-β) and retinoid X receptors (RXR-β, −γ) was significantly upregulated in sebaceous cell carcinoma of the eyelids.

Conclusions

Our findings indicate that retinoic acid signaling is related to the pathogenesis of sebaceous cell carcinoma of the eyelids.

Frequent activation of the β-catenin gene in sporadic colorectal carcinomas: A mutational & expression analysis

β-catenin (CTNNB1), an oncogene/onco-protein and an adhesion molecule is a key effector in colorectal cancer (CRC). Its activation, and subsequent up-regulation of Wnt-signaling, is an important event in the development of certain human cancers including CRC. Mutations in the β-catenin gene in the region of serine-threonine glycogen kinase (GSK)-3β phosphorylation target sites have been identified in colorectal cancer in humans. In the current study, we investigated 60 sporadic colorectal adenocarcinomas along with adjoining and normal mucosa cases in humans for β-catenin mutations. Thirteen of sixty colorectal tumors from humans had point mutations with a frequency of 21.66% at codons 24, 26, 27, 32, 34, 35, 41, 42,43, 46, 49, 54, 55, or 67 sites which are mutated in colorectal cancer and some of these sites in other cancers. Thus, there appears to be a key involvement of β-catenin activation in human colorectal carcinogenesis. mRNA expression analysis using q-Real Time PCR showed 21.5-fold up-regulation of β-catenin mRNA in tumor tissue compared to normal and adjoining mucosa. Protein expression analysis using immunohistochemistry, confocal microscopy, and Western blot confirmed aberrant accumulation of β-catenin protein along the nucleus and cytoplasm following mutation. The observed mutations and up-regulation of mRNA in tumors, and the increased expression of β-catenin protein in CRC suggest that these alterations are early and prognostic events in sporadic colorectal carcinogenesis in humans. © 2015 Wiley Periodicals, Inc.

Wnt/β-Catenin Signaling Pathway in Skin Carcinogenesis and Therapy

Cooperating with other signaling pathways, Wnt signaling controls cell proliferation, morphology, motility, and embryonic development destination and maintains the homeostasis of tissues including skin, blood, intestine, and brain by regulating somatic stem cells and their niches throughout adult life. Abnormal regulation of Wnt pathways leads to neoplastic proliferation in these tissues. Recent research shows that Wnt signaling is also associated with the regulation of cancer stem cells (CSCs) through a similar mechanism to that observed in normal adult stem cells. Thus, the Wnt/β-catenin signaling pathway has been intensively studied and characterized. For this review, we will focus on the regulation of the Wnt/β-catenin signaling pathway in skin cancer. With the important role in stemness and skin CSC proliferation, the Wnt/β-catenin signaling pathway and its elements have the potential to be targets for skin cancer therapy.

Beta-catenin expression in psoriasis

BACKGROUND

Psoriasis is a common inflammatory skin disease characterized by abnormal keratinocyte proliferation and differentiation. Beta-catenin participates in intercellular adhesion. Catenins are proteins found in complexes with cadherin cell adhesion molecules of cells. The role of catenin in regulating keratinocyte stem cell differentiation and hair follicle morphogenesis has been extensively reported.

AIMS AND OBJECTIVES

is to study β-catenin expression in lesional and non-lesional psoriatic skin to throw light upon its possible role in the pathogenesis of psoriasis.

MATERIALS AND METHODS

Biopsies were taken from 20 patients with psoriasis vulgaris and from 10 normal controls. The distribution of Beta catenin was investigated using polycolonal rabbits B-catenin antibody-1 by immunohistochemical method.

RESULTS

In this study membranous β-catenin expression was significantly demonstrated in the control group then the non-lesional areas in comparison to the lesional areas (P < 0.001). Nuclear β-catenin staining expression was significantly more demonstrated in lesional and non-lesional areas in comparison to the control cases (P < 0.001).

CONCLUSIONS

The down regulation of membranous β-catenin expression in lesional psoriatic skin might reflect a useful phenotypic marker of hyperprolifration of keratinocytes in psoriasis. Moreover, the mild down regulation of membranous β-catenin expression in non lesional psoriatic skin may provide clues about incipient structural abnormalities in the pathogenesis of psoriasis, providing an early diagnostic indicator for evolution to a generalized form of the disease. Nuclear β-catenin expression was not found in the control group but was demonstrated in lesional and moderately in non-lesional reflecting its role in kerationcyte proliferation.

Wnt-3a-activated human fibroblasts promote human keratinocyte proliferation and matrix destruction

Aberrant Wnt regulation, detectable by nuclear translocation of beta-catenin, is a hallmark of many cancers including skin squamous cell carcinomas (SCCs). By analyzing primary human skin SCCs, we demonstrate that nuclear beta-catenin is not restricted to SCC cells but also detected in stromal fibroblasts, suggesting an important role for aberrant Wnt regulation also in the tumor microenvironment. When human keratinocytes and fibroblasts were treated with Wnt-3a, fibroblasts proved to be more responsive. Accordingly, Wnt-3a did not alter HaCaT cell functions in a cell-autonomous manner. However, when organotypic cultures (OTCs) were treated with Wnt-3a, HaCaT keratinocytes responded with increased proliferation. As nuclear beta-catenin was induced only in the fibroblasts, this argued for a Wnt-dependent, paracrine keratinocyte stimulation. Global gene expression analysis of Wnt-3a-stimulated fibroblasts identified genes encoding interleukin-8 (IL-8) and C-C motif chemokine 2 (CCL-2) as well as matrix metalloproteinase-1 (MMP-1) as Wnt-3a targets. In agreement, we show that IL-8 and CCL-2 were secreted in high amounts by Wnt-3a-stimulated fibroblasts also in OTCs. The functional role of IL-8 and CCL-2 as keratinocyte growth regulators was confirmed by directly stimulating HaCaT cell proliferation in conventional cultures. Most important, neutralizing antibodies against IL-8 and CCL-2 abolished the Wnt-dependent HaCaT cell hyperproliferation in OTCs. Additionally, MMP-1 was expressed in high amounts in Wnt-3a-stimulated OTCs and degraded the stromal matrix. Thus, our data show that Wnt-3a stimulates fibroblasts to secrete both keratinocyte proliferation-inducing cytokines and stroma-degrading metalloproteinases, thereby providing evidence for a novel Wnt deregulation in the tumor-stroma directly contributing to skin cancer progression.

Nanoparticle-formulated siRNA targeting integrins inhibits hepatocellular carcinoma progression in mice

Integrins play an important role during development, regulating cell differentiation, proliferation and survival. Here we show that knockdown of integrin subunits slows down the progression of hepatocellular carcinoma (HCC). Using nanoparticulate delivery of short interfering RNAs targeting β1 and αv integrin subunits we downregulate all integrin receptors in hepatocytes. Short-term integrin knockdown (two weeks) does not cause apparent structural or functional perturbations of normal liver tissue. Alterations in liver morphology accumulate upon sustained integrin downregulation (seven weeks). The integrin knockdown leads to significant retardation of HCC progression, reducing proliferation and increasing tumour cell death. This tumour retardation is accompanied by reduced activation of MET oncogene as well as expression of its mature form on the cell surface. Our data suggest that transformed proliferating cells from HCC are more sensitive to knockdown of integrins than normal quiescent hepatocytes, highlighting the potential of siRNA-mediated inhibition of integrins as an anti-cancer therapeutic approach.

Role of CRD-BP in the growth of human basal cell carcinoma cells

Although the number of new cases of Basal Cell Carcinoma (BCC) has increased rapidly in the last few decades, the molecular basis of its pathogenesis is not completely understood. Activation of Hedgehog (Hh) signaling pathway has been shown to be a key factor driving the development of BCC. The Wnt/β-catenin signaling pathway was also shown to be activated in BCCs and to perhaps modulate the activity of Hh pathway. We have previously identified a novel mechanism by which Wnt signaling regulates the transcriptional outcome of Hh signaling pathway. We demonstrated that CRD-BP, a direct target of the Wnt/β-catenin signaling, binds to GLI1 mRNA, stabilizes it, and consequently upregulates its levels (mRNA and protein) and activities. We hypothesized that Wnt-induced and CRD-BP-dependent regulation of GLI1 expression and activities is important to the development of BCC. In this study, we show that CRD-BP is over-expressed in BCC and that its expression positively correlates with the activation of both Wnt and Hh signaling pathways. We also describe the generation and characterization of a human BCC cell line. This cell line was utilized to demonstrate the importance of CRD-BP-dependent regulation of GLI1 expression and activities in the development of BCC.

Flurbiprofen benzyl nitrate (NBS-242) inhibits the growth of A-431 human epidermoid carcinoma cells and targets β-catenin

Background

The Wnt/β-catenin/T cell factor (TCF) signaling pathway is important in the development of nonmelanoma skin cancers (NMSCs). Nitric-oxide-releasing nonsteroidal anti-inflammatory drugs (NO-NSAIDs) are chemopreventive agents consisting of a traditional NSAID attached to an NO-releasing moiety through a chemical spacer. Previously we showed that an aromatic spacer enhanced the potency of a particular NO-NSAID compared to an aliphatic spacer.

Methods

We synthesized an NO-releasing NSAID with an aromatic spacer (flurbiprofen benzyl nitrate, NBS-242), and using the human skin cancer cell line A-431, we evaluated its effects on cell kinetics, Wnt/β-catenin, cyclin D1, and caspase-3.

Results

NBS-242 inhibited the growth of A-431 cancer cells, being ~15-fold more potent than flurbiprofen and up to 5-fold more potent than NO-flurbiprofen with an aliphatic spacer, the half maximal inhibitory concentrations (IC₅₀) for growth inhibition being 60 ± 4 μM, 320 ± 20 μM, and 880 ± 65 μM for NBS-242, NO-flurbiprofen, and flurbiprofen, respectively. This effect was associated with inhibition of proliferation, accumulation of cells in the G₀/G₁ phase of the cell cycle, and an increase in apoptotic cell population. NBS-242 cleaved β-catenin both in the cytoplasm and the nucleus of A-431 cells. NBS-242 activated caspase-3 whose activation was reflected in the cleavage of procaspase-3. To test the functional consequence of β-catenin cleavage, we determined the expression of cyclin D1, a Wnt-response gene. NBS-242 reduced cyclin D1 levels in a concentration dependent manner.

Conclusion

These findings establish a strong inhibitory effect of NBS-242 in A-431 human epidermoid carcinoma cells. NBS-242 modulates parameters that are important in determining cellular mass.

Patched knockout mouse models of Basal cell carcinoma

Basal cell carcinoma (BCC) is the most common human tumor. Mutations in the hedgehog (HH) receptor Patched (PTCH) are the main cause of BCC. Due to their high and increasing incidence, BCC are becoming all the more important for the health care system. Adequate animal models are required for the improvement of current treatment strategies. A good model should reflect the situation in humans (i.e., BCC initiation due to Ptch mutations on an immunocompetent background) and should allow for (i) BCC induction at a defined time point, (ii) analysis of defined BCC stages, and (iii) induction of BCC in 100% of animals. In addition, it should be easy to handle. Here, we compare several currently existing conventional and conditional Ptch knockout mouse models for BCC and their potential use in preclinical research. In addition, we provide new data using conditional Ptch^flox/flox mice and the K5-Cre-ER^T+/− driver.

E2F1 loss induces spontaneous tumour development in Rb-deficient epidermis

The specific ablation of Rb1 gene in epidermis (Rb(F/F);K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (Rb(F/F);K14creER(TM)). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (Rb(F/F);K14cre). In an E2F1-null background (Rb(F/F);K14creER(TM); and E2F1(-/-) mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, Rb(F/F);K14creER(TM);E2F1(-/-) mice develop spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19(arf)/p53 axis, also show aberrant activation of β-catenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homoeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs.

Canonical Wnt/β-catenin signaling in epicardial fibrosis of failed pediatric heart allografts with diastolic dysfunction

BACKGROUND

Failed pediatric heart allografts with diastolic dysfunction exhibit severe epicardial fibrosis. The molecular mechanism underlying this process is poorly understood. Canonical Wnt/β-catenin signaling plays an important role in epithelial-mesenchymal transition and is implicated in fibrosing diseases. In this study, we tested the hypothesis that canonical Wnt/β-catenin signaling is activated in epicardial fibrosis of end-stage dysfunctional pediatric allografts.

METHODS

Fourteen explanted heart grafts of 12 patients who had undergone 14 heart transplantations were used for immunohistochemical staining of β-catenin and its nuclear binding partners, T-cell factor/lymphoid enhancer factor family transcriptional factors. Fourteen age-matched native hearts from patients who had undergone first heart transplantation without evidence of epicardial fibrosis were used as controls.

RESULTS AND CONCLUSIONS

Epicardial fibroblasts from explanted allografts demonstrated nuclear accumulation of β-catenin. These cells also showed nuclear positivity for T-cell factor 4. No T-cell factor 3 expression was present in the epicardium. T-cell factor 1 and lymphoid enhancer factor 1 were observed in lymphocytes, but not in other cell types of the epicardium. These findings suggest an association between canonical Wnt/beta-catenin signaling and epicardial fibrosis of failed pediatric heart allografts. Should activation of this pathway be shown to be causal to epicardial fibrosis in this setting, then inhibition of this pathway may help to prevent this devastating process.

Epithelial to mesenchymal transition in cutaneous squamous cell carcinoma is correlated with COX-2 expression but not with the presence of stromal macrophages or CD10-expressing cells

Epithelial to mesenchymal transition (EMT) is an intricate process by which epithelial cells loose epithelial characteristics and acquire a mesenchymal-like phenotype. EMT and cyclooxygenase 2 (COX-2) expression are related to tumor invasion and metastasis. The tumor microenvironment plays a major role in tumor progression and the induction of EMT. Here, we investigated the relationship between EMT and COX-2 expression as well as tumor-associated macrophages (TAM) and CD10-positive stromal cells during the development of cutaneous squamous neoplastic lesion. We performed immunohistochemical staining for vimentin, E-cadherin, β-catenin, COX-2, CD68, and CD10 in 41 cases of squamous cell cancers (SCC), 20 of Bowen's disease, 30 of actinic keratosis, and 30 samples of normal skin. SCC cells showed significantly increased vimentin expression and reduced expression of membranous E-cadherin and β-catenin compared with cells in precursor lesions and in normal skin. COX-2 expression was also markedly increased in SCC cells. E-cadherin expression was positively correlated with β-catenin expression and inversely correlated with COX-2 expression in SCC cells. The number of TAM and CD10-positive stromal cells increased from the normal skin to precursor lesions and SCC cells. The number of TAM and of CD10-positive stromal cells did not correlate with the expression of E-cadherin, β-catenin, COX-2, and vimentin in SCC cells. We suggest that cutaneous SCC cells show EMT, which appears to be correlated with COX-2 expression but not with stromal CD10 expression and TAM.

Regulation of the DLG tumor suppressor by β-catenin

The discs-large (DLG) tumor suppressor plays essential roles in regulating cell polarity and proliferation. It localizes at sites of cell-cell contact where it acts as a scaffold for multiple protein interactions, including with the adenomatous polyposis coli (APC) tumor suppressor, which in turn regulates β-catenin. Furthermore, many tumor types including breast and colon have increased levels of β-catenin activity with correspondingly low levels of DLG expression. Here we provide evidence of a direct functional link between these apparently separate phenomena. We show that overexpressed β-catenin can enhance the turnover of DLG in a proteosome dependent manner. This effect is specific to DLG and is not seen with two other PDZ domain-containing targets of β-catenin, MAGI-1 and Scribble. Furthermore, siRNA-mediated ablation of endogenous β-catenin expression also enhances DLG stability. β-catenin-induced degradation of DLG appears to be a consequence of a direct association between the two proteins and requires β-catenin PDZ binding potential. In contrast, the enhanced turnover of DLG requires the unique N-terminal sequences and its PDZ domains. Finally, we also show that the capacity of DLG to inhibit transformed cell growth in an oncogene cooperation assay is inhibited by β-catenin. Taken together these studies suggest that one mechanism by which deregulated β-catenin can contribute to tumorigenesis is through enhancing DLG degradation.

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

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.

β-catenin in canine skin: immunohistochemical pattern of expression in normal skin and cutaneous epithelial tumours

In normal adult skin, β-catenin is a structural component of the intercellular junction and the Wnt/β-catenin pathway plays a key role in the regulation of cutaneous homeostasis, particularly in the maintenance of hair follicle stem cells. No data are available on the expression pattern of β-catenin in normal canine skin and in canine cutaneous epidermal and follicular tumours. The present study used immunohistochemistry to determine β-catenin expression in four samples of normal canine skin and 62 cutaneous epithelial tumours (14 epidermal, 30 follicular and 18 glandular). β-catenin expression was localized to the nucleus of matrical and dermal papilla cells in anagen hair follicles and was also found in scattered cells of the outer root sheath, suggesting that these follicular epithelial cells may have a high proliferative potential. Nuclear labelling, considered a hallmark of activation of the Wnt/β-catenin signalling pathway, was observed in canine follicular tumours with matrical differentiation (100% of cases of trichoepithelioma and pilomatricoma), suggesting that a possible mutation of the canine CTNBB1 gene may underlie these tumours. In contrast, malignant tumours (squamous cell carcinoma, basal cell carcinoma, sebaceous and apocrine gland carcinoma and epithelioma) were characterized by reduction/loss of β-catenin membrane labelling compared with normal cutaneous epithelial cells and benign tumours, suggesting that reduction/loss of β-catenin expression is important in the acquisition of the malignant phenotype and may have a role in the infiltration and metastasis of these tumours.

Tumor stroma-derived Wnt5a induces differentiation of basal cell carcinoma of Ptch-mutant mice via CaMKII

Basal cell carcinoma (BCC) is the most common skin tumor in humans. Although BCCs rarely metastasize, they can cause significant morbidity due to local aggressiveness. Approximately 20% of BCCs show signs of spontaneous regression. The understanding of molecular events mediating spontaneous regression has the potential to reduce morbidity of BCC and, potentially, other tumors, if translated into tumor therapies. We show that BCCs induced in conditional Ptch(flox/flox)ERT2(+/-) knockout mice regress with time and show a more differentiated phenotype. Differentiation is accompanied by Wnt5a expression in the tumor stroma, which is first detectable at the fully developed tumor stage. Coculture experiments revealed that Wnt5a is upregulated in tumor-adjacent macrophages by soluble signals derived from BCC cells. In turn, Wnt5a induces the expression of the differentiation marker K10 in tumor cells, which is mediated by Wnt/Ca(2+) signaling in a CaMKII-dependent manner. These data support a role of stromal Wnt5a in BCC differentiation and regression, which may have important implications for development of new treatment strategies for this tumor. Taken together, our results establish BCC as an easily accessible model of tumor regression. The regression of BCC despite sustained Hedgehog signaling activity seems to be mediated by tumor-stromal interactions via Wnt5a signaling.

Beta-catenin mutation does not seem to have an effect on the tumorigenesis of pediatric rhabdomyosarcomas

Involvement of the Wnt signal transduction pathway has been shown in different pediatric embryonal tumors, such as hepatoblastoma, nephroblastoma, pancreatoblastoma, and medulloblastoma. There are few data available on the status of beta-catenin in rhabdomyosarcoma (RMS), another pediatric embryonal tumor. The aims of this study were 1st to verify the status of the exon 3 of CTNNB1 and 2nd to assess the usefulness of beta-catenin immunostaining in a small series of 8 embryonal RMS, 3 alveolar RMS, and 1 sclerosing RMS (SRMS). Sequence analysis revealed no mutations in the exon 3 of CTNNB1 in all the tumors studied. All RMS showed a cytoplasmic beta-catenin staining with cytoplasmic membrane reinforcement and no nuclear delocalization. We conclude that there is no evidence of beta-catenin mutation in the genesis of rhabdomyosarcoma and that beta-catenin does not represent a useful immunomarker to help distinguish between embryonal RMS and alveolar RMS.

BAMBI gene is epigenetically silenced in subset of high-grade bladder cancer

The bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI) is a transmembrane TGFRI/BMPRI-related pseudoreceptor, antagonizes transforming growth factor (TGF)-beta/BMP signaling by inhibiting the formation of functional authentic receptor complexes (TGFRI/BMPRI and TGFRII/BMPRII). On the assumption that BAMBI gene expression is epigenetically altered during human bladder cancer progression, we screened the expression of BAMBI protein by immunohistochemistry and the methylation status of the BAMBI promoter. In the normal or reactive urothelium, BAMBI expression was mostly overlapped with that of BMPRI, and a similar colocalization pattern was noted in low-grade papillary cancers. In high-grade and invasive cancers, however, mainly two reciprocal immunohistochemical expression patterns were observed: BAMBI-low/BMPRI-high, and BAMBI-high/BMPRI-low, indicating that BAMBI expression is controlled such that it does not interfere with the responsiveness of high-grade cancer cells to TGF-beta/BMP signaling. Moreover, methylation of the BAMBI gene correlated significantly with negative BAMBI expression in bladder tumors. Although BAMBI overexpression significantly increased the number of apoptotic cells in T24 line, knock-down small interfering RNA showed no remarkable change. Cell motility assay revealed that on treatment with either TGF-beta1 or BMP2, T24 and HTB9 lines showed a marked increase in the number of migrated cells which, however, decreased significantly through the forced expression of BAMBI. Since certain subsets of aggressive tumors often promote cell motility, invasion and survival by inducing epithelial-to-mesenchymal transition through TGF-beta/BMP in an autocrine and paracrine manner, hypermethylation of the BAMBI gene promoter that leads to BAMBI gene suppression may be one of the epigenetic events affecting the invasiveness or aggressiveness of bladder cancers.

The novel protein PTPIP51 is expressed in human keratinocyte carcinomas and their surrounding stroma

Background: The novel protein PTPIP51 (SwissProt accession code Q96SD6) is known to interact with two non-transmembrane protein-tyrosine phosphatases, PTP1B and TCPTP in vitro. Overexpression of the full-length protein induces apoptosis in HeLa and HEK293T cells (Lv et al. 2006). PTPIP51 shows a tissue-specific expression pattern and is associated with cellular differentiation and apoptosis in some mammalian tissues, especially in human follicular and interfollicular epidermis. PTPIP51 protein is expressed in all suprabasal layers of normal epidermis, whereas the basal layer contains PTPIP51 mRNA only but lacks the protein. Objectives: The expression of PTPIP51 was investigated in keratinocyte carcinomas, that is human basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) as well as Bowen's disease (BD) and keratoacanthomas (KAs) on a transcriptional (mRNA) and translational (immunohistochemical) level. Methods: Formalin-fixed, paraffin-embedded sections of BCCs, SCCs, KAs and BD, respectively, were analysed by RT-PCR, as well as immunohistochemistry and subsequent fluorescence microscopy. PTPIP51-positive cells of the tumour and the surrounding stroma were identified on the basis of specific morphological features by means of H & E staining. To obtain further information about a putative function of PTPIP51, a possible association of PTPIP51 with apoptotic cells, as well as an assumed negative correlation with proliferating cells was investigated by means of an in-situ TUNEL assay and Ki67/MIB-1 antigen staining, respectively. Co-immunostainings with PTPIP51 were performed for the following antigens: TCPTP, PTP1B and β-catenin. Results: PTPIP51-expression was detected in BCCs and SCCs of the skin, as well as in KAs and BD. Both types of keratinocyte carcinoma revealed a specific localization pattern of PTPIP51 in malignant keratinocytes. Whereas PTPIP51 -positive cells of BCC were found to form two cluster types with a different subcellular localization of the protein, i.e. cytoplasmic and nuclear or predominantly membranous, investigation of SCC revealed a meshwork-like appearance of PTPIP51-positive malignant keratinocytes, created by a mainly membranous localization. BD and KA resembled the findings of PTPIP51-expression in SCC. Furthermore, we observed a partial co-localization of PTP1B and PTPIP51 in BCC. SCC and BCC showed a co-expression and partial co-localization of PTPIP51 with β-catenin. Some PTPIP51-positive cells were found to undergo apoptosis. PTPIP51 was also expressed in cells comprising the surrounding stromal microenvironment. This was particularly noticed for endothelial cells lining peritumoural vessels as well as for infiltrating cells of both, the innate and the adaptive immune system. Conclusions: The results showed a distinct mainly membranous expression pattern of PTPIP51 in BCCs and SCCs. Since PTPIP51 was also detected in the peritumoural tissue, the protein may play a crucial role in keratinocyte tumour development.

Bazex-Dupré-Christol syndrome: an ectodermal dysplasia with skin appendage neoplasms

Bazex-Dupré-Christol syndrome is a rare X-linked genodermatosis characterized by early-onset nonmelanoma skin cancers, atrophoderma follicularis, hypotrichosis, hypohidrosis, and multiple milia. Its molecular basis remains unknown and nosologic classification is debated. We report a 5-year-old child presenting sparse hair, reduced sweating, ice-pick skin depressions of the dorsum of hands, facial and limb milia, perianal skin hyperpigmentation, and hyperpigmented papules of the axillae and neck. His mother showed similar features but lacked hair involvement. Histologic examination of a skin papule obtained from the index case revealed features consistent with trichoepithelioma. Our findings indicate that trichoepitheliomas are an early sign of Bazex-Dupré-Christol syndrome and may guide the diagnosis even before the development of basal cell carcinomas. The high frequency of hypotrichosis, hypohidrosis and dry skin in Bazex-Dupré-Christol syndrome indicates that it may be better classified as an ectodermal dysplasia. Comparison with other conditions combining features of ectodermal dysplasia and proneness to skin tumors suggests the involvement of a common pathogenic pathway implicated in both skin development and cancer.

Immunohistochemical assessment of E-cadherin and beta-catenin in trichofolliculomas and trichoepitheliomas

BACKGROUND

Trichofolliculomas and trichoepitheliomas are benign skin neoplasms originating from hair follicle cells. They result from defects in the signaling pathways that regulate hair follicle morphogenesis and regeneration. Thus they seem to be an excellent model of these processes. It is known that the E-cadherin/beta-catenin system of adhesion molecules plays a crucial role in the maintenance of tissue architecture.

AIM

The aim of the present study was to investigate their involvement in benign hair follicle tumor development.

METHODS

Semiquantitative intensity of expression were examined in formalin-fixed and paraffin-embedded tissue sections of 53 trichoepitheliomas, 15 trichofolliculomas and 19 normal skin samples by indirect immunohistochemistry.

RESULTS

The intensity of E-cadherin/beta-catenin expression in tumor cells did not differ from controls. However, normal hair follicles cells exhibited membranous E-cadherin/beta-catenin expression, whereas both types of tumors, particularly trichoepitheliomas, showed E-cadherin/beta-catenin expression with a predominantly cytoplasmic localization.

CONCLUSIONS

We suggest that this dystopic distribution of the E-cadherin/beta-catenin complex in hair follicle tumor cells may be a marker of cell-cell adhesion disruption which may contribute to the tumor formation.

Cutaneous cancer stem cell maintenance is dependent on beta-catenin signalling

Continuous turnover of epithelia is ensured by the extensive self-renewal capacity of tissue-specific stem cells. Similarly, epithelial tumour maintenance relies on cancer stem cells (CSCs), which co-opt stem cell properties. For most tumours, the cellular origin of these CSCs and regulatory pathways essential for sustaining stemness have not been identified. In murine skin, follicular morphogenesis is driven by bulge stem cells that specifically express CD34. Here we identify a population of cells in early epidermal tumours characterized by phenotypic and functional similarities to normal bulge skin stem cells. This population contains CSCs, which are the only cells with tumour initiation properties. Transplants derived from these CSCs preserve the hierarchical organization of the primary tumour. We describe beta-catenin signalling as being essential in sustaining the CSC phenotype. Ablation of the beta-catenin gene results in the loss of CSCs and complete tumour regression. In addition, we provide evidence for the involvement of increased beta-catenin signalling in malignant human squamous cell carcinomas. Because Wnt/beta-catenin signalling is not essential for normal epidermal homeostasis, such a mechanistic difference may thus be targeted to eliminate CSCs and consequently eradicate squamous cell carcinomas.

Expression of Cadherin/Catenin Cell—Cell Adhesion Molecules in a Onychomatricoma

Onychomatricoma is a rare nail tumor with a distinctive architecture. Proximally, there are serum-filled invaginations of nail matrix epithelium into the stroma, and distally, dermal protrusions perforate the nail plate. Because other matrical tumors of follicular and odontogenic origin express nuclear β-catenin, we examined the expression of cadherin/catenin proteins in this onychomatricoma case. The patient presented with a toenail yellow streak, and the biopsy revealed an onychomatricoma. E-cadherin and β-catenin were at the cell membrane in the epithelial invaginations. P-cadherin was restricted to basal cells. In contrast to other matrical tumors, nuclear β-catenin was not present. These results suggest that onychomatricoma may lack the transcriptional activating role of β-catenin that characterizes follicular and odontogenic matrical tumors. This is the first report on the expression of cadherin/ catenin cell—cell adhesion proteins in this rare nail tumor.

Increased nuclear beta-catenin in suprabasal involved psoriatic epidermis

BACKGROUND

Psoriasis is a common inflammatory skin disease characterized by abnormal keratinocyte proliferation and differentiation, increased angiogenesis and inflammation. There is evidence that some keratinocyte differentiation events are controlled by changes in cell-cell adhesion. beta-catenin is a 94-kDa protein which has a dual function as a component of intercellular adherens junctions and also as a transcription factor as part of the Wnt signalling pathway. beta-catenin is not required for keratinocyte proliferation but has been shown to regulate keratinocyte stem cells and hair follicle morphogenesis.

OBJECTIVES

To investigate the distribution and function of beta-catenin in involved psoriatic epidermis and in epidermal keratinocytes.

METHODS

Biopsies were obtained from patients with psoriasis and from normal controls. The distribution of beta-catenin was investigated using antibodies to both total and unphosphorylated active beta-catenin. Luciferase assays were used to measure transcriptional activation of transglutaminase 1 (TGase 1) and involucrin and to investigate the functional role of beta-catenin in interfollicular keratinocytes.

RESULTS

Increased nuclear beta-catenin was seen in lesional suprabasal psoriatic epidermis compared with uninvolved or normal skin. Increased active unphosphorylated beta-catenin was also detected within the differentiating compartment of involved psoriatic epidermis. Expression of TGase 1 overlapped with beta-catenin in suprabasal lesional psoriasis. The TGase 1 promoter was positively regulated by activated beta-catenin and by the glycogen synthase kinase binding protein, suggesting that beta-catenin and glycogen synthase kinase 3beta may regulate TGase 1 expression.

CONCLUSIONS

This is the first report to convincingly demonstrate increased beta-catenin in involved psoriasis and to implicate beta-catenin in the regulation of TGase 1. This evidence suggests a role for beta-catenin signalling in regulating keratinocyte differentiation in interfollicular skin in addition to previously reported functions in stem cell fate determination, hair follicle regulation and skin tumorigenesis.