Expression patterns of S100A7 (psoriasin) and S100A9 (calgranulin-B) in keratinocyte differentiation

Biomarkers in Cutaneous Keratinocyte Carcinomas

Skin cancer is the most common cancer type in the USA, with over five million annually treated cases and one in five Americans predicted to develop the disease by the age of 70. Skin cancer can be classified as melanoma or non-melanoma (NMSC), the latter including basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (SCC). Development of BCC and SCC is impacted by environmental, behavioral, and genetic risk factors and the incidence is on the rise, with the associated number of deaths surpassing those caused by melanoma, according to recent reports. Substantial morbidity is related to both BCC and SCC, including disfigurement, loss of function, and chronic pain, driving high treatment costs, and representing a heavy financial burden to patients and healthcare systems worldwide. Clinical presentations of BCC and SCC can be diverse, sometimes carrying considerable phenotypic similarities to benign lesions, and underscoring the need for the development of disease-specific biomarkers. Skin biomarker profiling plays an important role in deeper disease understanding, as well as in guiding clinical diagnosis and patient management, prompting the use of both invasive and non-invasive tools to evaluate specific biomarkers. In this work, we review the known and emerging biomarkers of BCC and SCC, with a focus on molecular and histologic biomarkers relevant for aspects of patient management, including prevention/risk assessments, tumor diagnosis, and therapy selection.

GLI Transcriptional Targets S100A7 and KRT16 Show Upregulated Expression Patterns in Epidermis Overlying the Tumor Mass in Melanoma Samples

Although not completely understood, the role of the Hedgehog-GLI (HH-GLI) signaling pathway in melanoma and epithelial skin tumors has been reported before. In this study, we confirmed in various melanoma cell line models that keratin 16 (KRT16) and S100 Calcium-Binding Protein A7 (S100A7) are transcriptional targets of GLI Family Zinc Finger (GLI) proteins. Besides their important role in protecting and maintaining the epidermal barrier, keratins are somehow tightly connected with the S100 family of proteins. We found that stronger expression of KRT16 indeed corresponds to stronger expression of S100A7 in our clinical melanoma samples. We also report a trend regarding staining of GLI1, which corresponds to stronger staining of GLI3, KRT16, and S100A7 proteins. The most interesting of our findings is that all the proteins are detected specifically in the epidermis overlying the tumor, but rarely in the tumor itself. The examined proteins were also not detected in the healthy epidermis at the edges of the sample, suggesting that the staining is specific to the epidermis overlaying the tumor mass. Of all proteins, only S100A7 demonstrated a statistically significant trend regarding tumor staging and staining intensity. Results from our clinical samples prove that immune infiltration is an important feature of melanoma. Pigmentophages and tumor-infiltrating lymphocytes (TIL) demonstrate a significant association with tumor stage, while mononuclear cells are equally present in all stages. For S100A7, we found an association between the number of TILs and staining intensity. Considering these new findings presented in our study, we suggest a more detailed examination of the possible role of the S100A7 protein as a biomarker in melanoma.

Nuclear proinflammatory cytokine S100A9 enhances expression of human papillomavirus oncogenes via transcription factor TEAD1

Transcription of the human papillomavirus (HPV) oncogenes, E6 and E7, is regulated by the long control region (LCR) of the viral genome. Although various transcription factors have been reported to bind to the LCR, little is known about the transcriptional cofactors that modulate HPV oncogene expression in association with these transcription factors. Here, we performed in vitro DNA-pulldown purification of nuclear proteins in cervical cancer cells, followed by proteomic analyses to identify transcriptional cofactors that bind to the HPV16 LCR via the transcription factor TEAD1. We detected the proinflammatory cytokine S100A9 that localized to the nucleus of cervical cancer cells and associated with the LCR via direct interaction with TEAD1. Nuclear S100A9 levels and its association with the LCR were increased in cervical cancer cells by treatment with a proinflammatory phorbol ester. Knockdown of S100A9 decreased HPV oncogene expression and reduced the growth of cervical cancer cells and their susceptibility to cisplatin, whereas forced nuclear expression of S100A9 using nuclear localization signals exerted opposite effects. Thus, we conclude that nuclear S100A9 binds to the HPV LCR via TEAD1 and enhances viral oncogene expression by acting as a transcriptional coactivator. IMPORTANCE Human papillomavirus (HPV) infection is the primary cause of cervical cancer, and the viral oncogenes E6 and E7 play crucial roles in carcinogenesis. Although cervical inflammation contributes to the development of cervical cancer, the molecular mechanisms underlying the role of these inflammatory responses in HPV carcinogenesis are not fully understood. Our study shows that S100A9, a proinflammatory cytokine, is induced in the nucleus of cervical cancer cells by inflammatory stimuli, and it enhances HPV oncogene expression by acting as a transcriptional coactivator of TEAD1. These findings provide new molecular insights into the relationship between inflammation and viral carcinogenesis.

Expression of S100A9 in adamantinomatous craniopharyngioma and its association with wet keratin formation

Wet keratin is a hallmark of adamantinomatous craniopharyngioma (ACP), which is frequently infiltrated by inflammatory cells. S100 calcium-binding protein A9 (S100A9) has been confirmed to play a decisive role in the development of inflammation. However, the relationship between wet keratin (keratin nodules) and S100A9 in ACP is poorly understood. The objective of the present study was to explore the expression of S100A9 in ACP and its association with wet keratin formation. Immunohistochemistry and immunofluorescence were used to detect the expression of S100A9, β-catenin and Ki67 in 46 cases of ACP. A total of three online databases were used to analyze S100A9 gene expression and protein data. The results revealed that S100A9 was primarily expressed in wet keratin and some intratumoral and peritumoral cells, and its expression in wet keratin was upregulated in the high inflammation group (P=1.800x10^-3). In addition, S100A9 was correlated with the degree of inflammation (r=0.6; P=7.412x10^-3) and the percentage of Ki67-positive cells (r=0.37; P=1.000x10^-2). In addition, a significant correlation was noted between the area of wet keratin and the degree of inflammation (r=0.51; P=2.500x10^-4). In conclusion, the present study showed that S100A9 was upregulated in ACP and may be closely associated with wet keratin formation and the infiltration of inflammatory cells in ACP.

Biomarkers found in the tumor interstitial fluid may help explain the differential behavior among keratinocyte carcinomas

Basal Cell Carcinomas (BCC) and cutaneous Squamous Cell Carcinomas (SCC) are the most frequent types of cancer, and both originate from the keratinocyte transformation, giving rise to the group of tumors called keratinocyte carcinomas (KC). The invasive behavior is different in each group of KC and may be influenced by their tumor microenvironment. The principal aim of the study is to characterize the protein profile of the Tumor Interstitial Fluid (TIF) of KC to evaluate changes in the microenvironment that could be associated with their different invasive and metastatic capabilities. We obtained TIF from 27 skin biopsies and conducted a label-free quantitative proteomic analysis comparing 7 BCCs, 16 SCCs, and 4 Normal Skins. A total of 2945 proteins were identified, 511 of them quantified in more than half of the samples of each tumoral type. The proteomic analysis revealed differentially expressed TIF-proteins that could explain the different metastatic behavior in both KC. In detail, the SCC samples disclosed an enrichment of proteins related to cytoskeleton, such as Stratafin and Ladinin1. Previous studies found their up-regulation positively correlated with tumor progression. Furthermore, the TIF of SCC samples was enriched with the cytokines S100A8/S100A9. These cytokines influence the metastatic output in other tumors through the activation of NF-kB signaling. According to this, we observed a significant increase in nuclear NF-kB subunit p65 in SCCs but not in BCCs. In addition, the TIF of both tumors was enriched with proteins involved in the immune response, highlighting the relevance of this process in the composition of the tumor environment. Thus, the comparison of the TIF composition of both KC provides the discovery of a new set of differential biomarkers. Among them, secreted cytokines such as S100A9 may help explain the higher aggressiveness of SCCs, while Cornulin is a specific biomarker for BCCs. Finally, the proteomic landscape of TIF provides key information on tumor growth and metastasis, which can contribute to the identification of clinically applicable biomarkers that may be used in the diagnosis of KC, as well as therapeutic targets.

Occurrence of Human Defensins and S100 Proteins in Head and Neck Basal Cell Carcinoma (BCC) Entities: hBD3 and S100A4 as Potential Biomarkers to Evaluate Successful Surgical Therapy

Background: The goal of this study is the identification of potential marker molecules for characterizing different basal cell carcinoma entities, to help improve clinical decisions for surgical resection therapy. Methods: Three different entities, sclerodermiform, solid and superficial basal cell carcinomas, were subjected to immunohistochemical microscopy and histomorphometric analyses for human α- (DEFA1/3; DEFA4) and β-defensins (hBD1/2/3) and special S100 proteins (S100A4/7/8/9). Thirty specimens of the three entities were evaluated. Analyses were performed by comparing tissue and cellular localization and staining intensities of tumorous with non-tumorous areas. Staining intensities were semiquantitatively examined by using an RGB-based model. Results: Human defensins are present in all three entities of basal cell carcinomas. They all show cytoplasmic immunostaining in cells of the epithelium, stroma and tumor. Notably, human β-defensin3 is accumulated in the cell nuclei of sclerodermiform and superficial basal cell carcinomas. S100A4 and A7 are undetectable in tumor regions. However, S100A4 occurs in cancer-associated stroma cells with nuclear staining in superficial basal cell carcinomas. Conclusion: Two candidates, namely hBD3 and S100A4, might be used as potential clinical tools for evaluating successful surgical resection therapy to avoid aesthetic and functional facial deformation.

Antimicrobial Peptide Expression at the Ocular Surface and Their Therapeutic Use in the Treatment of Microbial Keratitis

Microbial keratitis is a common cause of ocular pain and visual impairment worldwide. The ocular surface has a relatively paucicellular microbial community, mostly found in the conjunctiva, while the cornea would be considered relatively sterile. However, in patients with microbial keratitis, the cornea can be infected with multiple pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, and Fusarium sp. Treatment with topical antimicrobials serves as the standard of care for microbial keratitis, however, due to high rates of pathogen resistance to current antimicrobial medications, alternative therapeutic strategies must be developed. Multiple studies have characterized the expression and activity of antimicrobial peptides (AMPs), endogenous peptides with key antimicrobial and wound healing properties, on the ocular surface. Recent studies and clinical trials provide promise for the use of AMPs as therapeutic agents. This article reviews the repertoire of AMPs expressed at the ocular surface, how expression of these AMPs can be modulated, and the potential for harnessing the AMPs as potential therapeutics for patients with microbial keratitis.

Novel archetype in psoriasis management bridging molecular dynamics in exploring novel therapies

Psoriasis is an autoimmune chronic inflammatory condition of skin affecting 125 million populaces around the globe. It is implicated as a result of multifaceted phenomena involving various cell and subcell activities with the aid of numerous cellular and molecular components including signaling aisle and regulatory proteins owing to the development of such hyperproliferative dermatological conditions. This involves a deeply complex and conflicting pathology owing to genetic and immunological deviations resulting from the unusual presentation of different signaling pathways and regulatory proteins. Explorations of these biomarkers and intervention of molecular and cellular processes in psoriasis are yet to be investigated and could be an exceptional aspect for understanding pathology with successful targeting of disease. In the presented study, we have integrated molecular insights, including signaling molecules, pathways, and proteins implicated in pathogenesis, and we have attempted to link this knowledge to the targeting of these phenomena in order to manage the conditions precisely. Further, therapeutic delivery approaches for targeting distinct layers of skin have also been investigated based on the application of different nanocarriers for successful psoriasis treatment.

Sustained Secretion of the Antimicrobial Peptide S100A7 Is Dependent on the Downregulation of Caspase-8

Antimicrobial peptides (AMPs) are the body's natural innate immune defense against a spectrum of pathogens and can also modulate cell proliferation, chemotaxis, angiogenesis, wound healing, and immune cell activity. Harnessing these diverse functions for prophylactic use is contingent upon understanding the regulatory mechanisms governing their unconventional secretion from cells. Analysis of the secretion of S100A7 (Psoriasin), an abundant AMP stored in differentiated keratinocytes of the skin, has revealed an unexpected biphasic secretory response to bacterial exposure. The core components regulating S100A7 secretion are NFκB/p38MAPK, caspase-1, and interleukin (IL)-1α. The initial activation of this core machinery is mediated by Toll-like receptor signaling, whereas the chronic response is mediated by Caspase-8 downregulation. Interestingly, there is a concomitant downregulation of Caspase-8 in inflammatory skin diseases wherein S100A7 is constitutively released. These results highlight the potential of targeting these components to control the release of AMPs from the skin in both homeostatic and disease conditions.

Novel epoxy-tiglianes stimulate skin keratinocyte wound healing responses and re-epithelialization via protein kinase C activation

Epoxy-tiglianes are a novel class of diterpene esters. The prototype epoxy-tigliane, EBC-46 (tigilanol tiglate), possesses potent anti-cancer properties and is currently in clinical development as a local treatment for human and veterinary cutaneous tumors. EBC-46 rapidly destroys treated tumors and consistently promotes wound re-epithelialization at sites of tumor destruction. However, the mechanisms underlying these keratinocyte wound healing responses are not completely understood. Here, we investigated the effects of EBC-46 and an analogue (EBC-211) at 1.51 nM-151 µM concentrations, on wound healing responses in immortalized human skin keratinocytes (HaCaTs). Both EBC-46 and EBC-211 (1.51 nM-15.1 µM) accelerated G0/G1-S and S-G2/M cell cycle transitions and HaCaT proliferation. EBC-46 (1.51-151 nM) and EBC-211 (1.51 nM-15.1 µM) further induced significant HaCaT migration and scratch wound repopulation. Stimulated migration/wound repopulation responses were even induced by EBC-46 (1.51 nM) and EBC-211 (1.51-151 nM) with proliferation inhibitor, mitomycin C (1 μM), suggesting that epoxy-tiglianes can promote migration and wound repopulation independently of proliferation. Expression profiling analyses showed that epoxy-tiglianes modulated keratin, DNA synthesis/replication, cell cycle/proliferation, motility/migration, differentiation, matrix metalloproteinase (MMP) and cytokine/chemokine gene expression, to facilitate enhanced responses. Although epoxy-tiglianes down-regulated established cytokine and chemokine agonists of keratinocyte proliferation and migration, enhanced HaCaT responses were demonstrated to be mediated via protein kinase C (PKC) phosphorylation and significantly abrogated by pan-PKC inhibitor, bisindolylmaleimide-1 (BIM-1, 1 μM). By identifying how epoxy-tiglianes stimulate keratinocyte healing responses and re-epithelialization in treated skin, our findings support the further development of this class of small molecules as potential therapeutics for other clinical situations associated with impaired re-epithelialization, such as non-healing skin wounds.

Loss of S100A14 expression at the tumor-invading front correlates with poor differentiation and worse prognosis in oral squamous cell carcinoma

BACKGROUND

We previously showed a tumor-suppressive function of S100A14 in oral squamous cell carcinoma (OSCC). This study aimed to examine the prognostic significance and differentiation-related function of S100A14 in OSCC.

METHODS

S100A14 expression was examined in 170 OSCCs from Norwegian and Nepalese populations using immunohistochemistry. Pro-differentiation function was investigated by overexpressing and silencing S100A14 expression in OSCC-derived cells. External transcriptomic datasets were used to validate association between S100A14 and differentiation markers in OSCC.

RESULT

Loss of S100A14 expression at the invading tumor fronts significantly correlated with poor differentiation and reduced 10-years survival of OSCC-patients. Multivariate Cox analysis identified S100A14 to be an independent prognostic factor. Modulation of S100A14 expression in OSCC-derived cells positively correlated with the expression of differentiation markers. Analysis of external datasets supported the pro-differentiation function of S100A14.

CONCLUSION

These results indicate that S100A14 is a pro-differentiation protein and its expression might be useful as a prognostic marker in OSCC.

The expression of S100A8/S100A9 is inducible and regulated by the Hippo/YAP pathway in squamous cell carcinomas

Background

S100A8 and S100A9, two heterodimer-forming members of the S100 family, aberrantly express in a variety of cancer types. However, little is known about the mechanism that regulates S100A8/S100A9 co-expression in cancer cells.

Methods

The expression level of S100A8/S100A9 measured in three squamous cell carcinomas (SCC) cell lines and their corresponding xenografts, as well as in 257 SCC tissues. The correlation between S100A8/S100A9, Hippo pathway and F-actin cytoskeleton were evaluated using western blot, qPCR, ChIP and Immunofluorescence staining tests. IncuCyte ZOOM long time live cell image monitoring system, qPCR and Flow Cytometry measured the effects of S100A8/S100A9 and YAP on cell proliferation, cell differentiation and apoptosis.

Results

Here, we report that through activation of the Hippo pathway, suspension and dense culture significantly induce S100A8/S100A9 co-expression and co-localization in SCC cells. Furthermore, these expressional characteristics of S100A8/S100A9 also observed in the xenografts derived from the corresponding SCC cells. Importantly, Co-expression of S100A8/S100A9 detected in 257 SCC specimens derived from five types of SCC tissues. Activation of the Hippo pathway by overexpression of Lats1, knockdown of YAP, as well as disruption of F-actin indeed obviously results in S100A8/S100A9 co-expression in attached SCC cells. Conversely, inhibition of the Hippo pathway leads to S100A8/S100A9 co-expression in a manner opposite of cell suspension and dense. In addition, we found that TEAD1 is required for YAP-induced S100A8/S100A9-expressions. The functional studies provide evidence that knockdown of S100A8/S100A9 together significantly inhibit cell proliferation but promote squamous differentiation and apoptosis.

Conclusions

Our findings demonstrate for the first time that the expression of S100A8/S100A9 is inducible by changes of cell shape and density through activation of the Hippo pathway in SCC cells. Induced S100A8/S100A9 promoted cell proliferation, inhibit cell differentiation and apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5784-0) contains supplementary material, which is available to authorized users.

Expression profile and functional role of S100A14 in human cancer

S100A14 is one of the new members of the multi-functional S100 protein family. Expression of S100A14 is highly heterogeneous among normal human tissues, suggesting that the regulation of S100A14 expression and its function may be tissue- and context-specific. Compared to the normal counterparts, S100A14 mRNA and protein levels have been found to be deregulated in several cancer types, indicating a functional link between S100A14 and malignancies. Accordingly, S100A14 is functionally linked with a number of key signaling molecules such as p53, p21, MMP1, MMP9, MMP13, RAGE, NF-kB, JunB, actin and HER2. Of interest, S100A14 seems to have seemingly opposite functions in malignancies arising from the gastrointestional tract (tissues rich in epithelial components) compared to cancers in the other parts of the body (tissues rich in mesenchymal components). The underlying mechanism for these observations are currently unclear and may be related to the relative abundance and differences in the type of interaction partners (effector protein) in different cancer types and tissues. In addition, several studies indicate that the expression pattern of S100A14 has a potential to be clinically useful as prognostic biomarker in several cancer types. This review attempts to provide a comprehensive summary on the expression pattern and functional roles/related molecular pathways in different cancer types. Additionally, the prognostic potential of S100A14 in the management of human malignancies will be discussed.

Atopic dermatitis in African American patients is TH2/TH22-skewed with TH1/TH17 attenuation

BACKGROUND

African Americans (AA) are disproportionately impacted by atopic dermatitis (AD), with increased prevalence and therapeutic challenges unique to this population. Molecular profiling data informing development of targeted therapeutics for AD are derived primarily from European American (EA) patients. These studies are absent in AA, hindering development of effective treatments for this population.

OBJECTIVE

We sought to characterize the global molecular profile of AD in the skin of AA patients as compared with that of EA AD and healthy controls.

METHODS

We performed RNA-Seq with reverse transcription polymerase chain reaction validation and immunohistochemistry studies in lesional and nonlesional skin of AA and EA AD patients vs healthy controls.

RESULTS

African American AD lesions were characterized by greater infiltration of dendritic cells (DCs) marked by the high-affinity immunoglobulin E (IgE) receptor (FcεR1+) compared with EA AD (P < .05). Both AD cohorts showed similarly robust up-regulation of Th2-related (CCL17/18/26) and Th22-related markers (interleukin [IL]-22, S100A8/9/12), but AA AD featured decreased expression of innate immune (tumor necrosis factor [TNF], IL-1β), Th1-related (interferon gamma [IFN-γ], MX1, IL-12RB1), and Th17-related markers (IL-23p19, IL-36G, CXCL1) vs EA AD (P < .05). The Th2 (IL-13) and Th22-related products (IL-22, S100A8/9/12) and serum IgE were significantly correlated with clinical severity (Scoring of Atopic Dermatitis [SCORAD]) in AA. Fillagrin (FLG) was exclusively down-regulated in EA AD, whereas loricrin (LOR) was down-regulated in both AD cohorts and negatively correlated with SCORAD in AA.

CONCLUSION

The molecular phenotype of AA AD skin is characterized by attenuated Th1 and Th17 but similar Th2/Th22-skewing to EA AD. Our data encourages a personalized medicine approach accounting for phenotype-specific characteristics in future development of targeted therapeutics and clinical trial design for AD.

Evolution and Expression of S100A7 Gene in Vertebrates

The skin is the primary barrier between the internal organs of an organism and the environment, and it provides protection from ultraviolet (UV) radiation. According to the nocturnal bottleneck hypothesis, ungulates might have traversed to the grasslands and were exposed to UV radiation subsequent to the reduction in predation pressure. UV light exposure might have increased the S100A7 expression. In order to test whether the UV radiation is associated with the selection pressure on S100A7, we acquired the complete S100A7 DNA sequences from each of 42 vertebrate species. The results suggested that the evidence of diversifying selection in S100A7 occurred at the end of Mesozoic era, and the site of positive selection was observed in the branch of Artiodactyla (even-toed ungulates). In addition, we found that the transcription level of S100A7 in cashmere goat skin correlates with UV radiation. Our results indicated that S100A7 plays a role in the signaling between the skin genes and UV radiation during evolution.

Protein biomarker for psoriasis: A systematic review on their role in the pathomechanism, diagnosis, potential targets and treatment of psoriasis

Psoriasis is defined as a long-lasting multifactorial inflammatory autoimmune skin condition precisely characterized by delimited, erythematic papules with adherent shiny scales. The conditions are led by hyperproliferative responses of epidermis due to hyperactivation and immature keratinocytes production. The psoriatic skin consists of the thickened epidermal layer, in concurrence with inflammatory exudates in the dermis mainly of dendritic cells, neutrophils, T cells, and macrophages, contributing to the distinct manifestation of psoriatic lesions. It consents to multifaceted and discrete pathology due to the genetic and immunological alteration resulting from abnormal expression of various regulatory and structural proteins. These proteins are associated with various cellular and sub-cellular activities. Therefore, the presence of protein in a pathological cellular environment in the psoriatic lesions as well as in serum could be a great avenue for the insight of pathomechanism, anticipation and diagnosis of psoriasis. Research of protein biomarker in psoriasis is yet a developing realm to be explored by both fundamental and clinical researchers. This review is an attempt to assimilate the current discoveries and revelations of different proteins as a biomarker and their importance in pathogenesis, diagnosis, treatment, and anticipation of both the inflammatory and other dermatological aspects of psoriasis.

Calprotectin and the Initiation and Progression of Head and Neck Cancer

Calprotectin (S100A8/A9), a heterodimeric complex of calcium-binding proteins S100A8 and S100A9, is encoded by genes mapping to the chromosomal locus 1q21.3 of the epidermal differentiation complex. Whereas extracellular calprotectin shows proinflammatory and antimicrobial properties by signaling through RAGE and TLR4, intracytoplasmic S100A8/A9 appears to be important for cellular development, maintenance, and survival. S100A8/A9 is constitutively expressed in myeloid cells and the stratified mucosal epithelia lining the oropharyngeal and genitourinary mucosae. While upregulated in adenocarcinomas and other cancers, calprotectin mRNA and protein levels decline in head and neck squamous cell carcinoma (HNSCC). S100A8/A9 is also lost during head and neck preneoplasia (dysplasia). Calprotectin decrease does not correlate with the clinical stage (TNM) of HNSCC. When expressed in carcinoma cells, S100A8/A9 downregulates matrix metalloproteinase 2 expression and inhibits invasion and migration in vitro. S100A8/A9 regulates cell cycle progression and decelerates cancer cell proliferation by arresting at the G2/M checkpoint in a protein phosphatase 2α-dependent manner. In HNSCC, S100A8 and S100A9 coregulate with gene networks controlling cellular development and differentiation, cell-to-cell signaling, and cell morphology, while S100A8/A9 appears to downregulate expression of invasion- and tumorigenesis-associated genes. Indeed, tumor formation capacity is attenuated in S100A8/A9-expressing carcinoma cells in vivo. Hence, intracellular calprotectin appears to function as a tumor suppressor in head and neck carcinogenesis. When compared with S100A8/A9-low HNSCC based on analysis of TCGA, S100A8/A9-high HNSCC shows significant upregulation of apoptosis-related genes, including multiple caspases. Accordingly, S100A8/A9 facilitates DNA damage responses in HNSCC, promotes apoptotic cell death, and confers sensitivity to cisplatin and X-radiation in vitro. In the tumor milieu, loss of S100A8/A9 strongly associates with poor squamous differentiation and higher tumor grading, EGFR upregulation, increased DNA methylation, and, finally, poorer overall survival for patients with HNSCC. Hence, intracellular calprotectin shows a multifaceted protective role against the development of HNSCC.

Involvement of calprotectin (S100A8/A9) in molecular pathways associated with HNSCC

Calprotectin (S100A8/A9), a heterodimeric protein complex of calcium-binding proteins S100A8 and S100A9, plays key roles in cell cycle regulation and inflammation, with potential functions in squamous cell differentiation. While upregulated in many cancers, S100A8/A9 is downregulated in squamous cell carcinomas of the cervix, esophagus, and the head and neck (HNSCC). We previously reported that ectopic S100A8/A9 expression inhibits cell cycle progression in carcinoma cells. Here, we show that declining expression of S100A8/A9 in patients with HNSCC is associated with increased DNA methylation, less differentiated tumors, and reduced overall survival. Upon ectopic over-expression of S100A8/A9, the cancer phenotype of S100A8/A9-negative carcinoma cells was suppressed in vitro and tumor growth in vivo was significantly decreased. MMP1, INHBA, FST, LAMC2, CCL3, SULF1, and SLC16A1 were significantly upregulated in HNSCC but were downregulated by S100A8/A9 expression. Our findings strongly suggest that downregulation of S100A8/A9 through epigenetic mechanisms may contribute to increased proliferation, malignant transformation, and disease progression in HNSCC.

Derivation of marker gene signatures from human skin and their use in the interpretation of the transcriptional changes associated with dermatological disorders

Numerous studies have explored the altered transcriptional landscape associated with skin diseases to understand the nature of these disorders. However, data interpretation represents a significant challenge due to a lack of good maker sets for many of the specialized cell types that make up this tissue, whose composition may fundamentally alter during disease. Here we have sought to derive expression signatures that define the various cell types and structures that make up human skin, and demonstrate how they can be used to aid the interpretation of transcriptomic data derived from this organ. Two large normal skin transcriptomic datasets were identified, one RNA-seq (n = 578), the other microarray (n = 165), quality controlled and subjected separately to network-based analyses to identify clusters of robustly co-expressed genes. The biological significance of these clusters was then assigned using a combination of bioinformatics analyses, literature, and expert review. After cross comparison between analyses, 20 gene signatures were defined. These included expression signatures for hair follicles, glands (sebaceous, sweat, apocrine), keratinocytes, melanocytes, endothelia, muscle, adipocytes, immune cells, and a number of pathway systems. Collectively, we have named this resource SkinSig. SkinSig was then used in the analysis of transcriptomic datasets for 18 skin conditions, providing in-context interpretation of these data. For instance, conventional analysis has shown there to be a decrease in keratinization and fatty metabolism with age; we more accurately define these changes to be due to loss of hair follicles and sebaceous glands. SkinSig also highlighted the over-/under-representation of various cell types in skin diseases, reflecting an influx in immune cells in inflammatory disorders and a relative reduction in other cell types. Overall, our analyses demonstrate the value of this new resource in defining the functional profile of skin cell types and appendages, and in improving the interpretation of disease data. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The Characteristic of S100A7 Induction by the Hippo-YAP Pathway in Cervical and Glossopharyngeal Squamous Cell Carcinoma

S100A7 is expressed in many squamous cell carcinomas (SCCs). Our previous study revealed that S100A7 was dramatically induced in several SCC cells and activation of the Hippo pathway significantly promoted S100A7 in epidermoid carcinoma cells. However, whether the Hippo pathway regulates S100A7 expression in SCCs remains largely unknown. Here, we uncover that S100A7 induction by the Hippo-YAP pathway displays different characteristic in cervical and glossopharyngeal SCC. In well differentiated HCC94 cervical cells and FaDu pharyngeal cells, S100A7 is easily induced by both suspension and dense culture, which is accompanied by an increase in YAP phosphorylation and a decrease in nuclear YAP. Strikingly, these correlations of S100A7 and YAP reverse after recovery of cell attachment or relief from dense culture. Further examination finds that S100A7 induction is significantly repressed by nuclear YAP, which is validated by activation or inhibition of the Hippo pathway via loss- and/or gain-of- LATS1 and MST1 function. Subsequently, we prove that TEAD1 is required for YAP transcriptional repression of S100A7. However, S100A7 is hardly induced in poorly differentiated SiHa cervical cells and NCI-H226 pulmonary cells even in suspension or activation of the Hippo pathway. More importantly, cervical and lingual SCC tissues array analyses show that S100A7 expression displays the positive correlation with pYAP-S127 and the negative correlation with nuclear YAP in the majority of well differentiated but not in poorly differentiated tissues. Collectively, our findings demonstrate that the different induction of S100A7 toward activation of the Hippo pathway mainly depends on the degree of cell differentiation in cervical and glossopharyngeal SCC.

Psoriasin (S100A7) promotes stress-induced angiogenesis

BACKGROUND

Vascular modifications occur early in the development of psoriasis, and angiogenesis is one of the key features in the pathogenesis of the disease.

OBJECTIVES

To identify the role of the S100 protein psoriasin in psoriasis-associated angiogenesis.

METHODS

The role of psoriasin in mediating angiogenesis was investigated by silencing psoriasin with small interfering RNA (siRNA) and measuring psoriasis-associated angiogenic factors in human epidermal keratinocytes. The secretion of psoriasin and the effect of psoriasin on general regulators of angiogenesis in keratinocytes, and on endothelial cell migration, proliferation, tube formation and production of angiogenic mediators, was evaluated.

RESULTS

Reactive oxygen species (ROS) and hypoxia induced the expression of psoriasin. Downregulation of psoriasin in keratinocytes using siRNA altered the ROS-induced expression of the psoriasis-associated angiogenic factors vascular endothelial growth factor (VEGF), heparin-binding epidermal growth factor-like growth factor, matrix metalloproteinase 1 and thrombospondin 1. Overexpression of psoriasin altered several regulators of angiogenesis and led to the secretion of psoriasin. Treatment with extracellular psoriasin induced proliferation, migration and tube formation in dermal-derived endothelial cells to a similar extent as VEGF and interleukin-17, and induced the expression and release of proangiogenic mediators. These effects were suggested to be mediated by the PI3K and nuclear factor kappa B pathways.

CONCLUSIONS

These findings suggest that psoriasin expression is promoted by oxidative stress in keratinocytes and amplifies the ROS-induced expression of angiogenic factors relevant to psoriasis. Moreover, extracellularly secreted psoriasin may act on dermal endothelial cells to contribute to key features angiogenesis.

Low vitamin D-modulated calcium-regulating proteins in psoriasis vulgaris plaques: S100A7 overexpression depends on joint involvement

Psoriasis is an inflammatory skin disease with or without joint involvement. In this disease, the thickened epidermis and impaired barrier are associated with altered calcium gradients. Calcium and vitamin D are known to play important roles in keratinocyte differentiation and bone metabolism. Intracellular calcium is regulated by calcium-sensing receptor (CASR), calcium release-activated calcium modulator (ORAI) and stromal interaction molecule (STIM). Other proteins modulated by vitamin D play important roles in calcium regulation e.g., calbindin 1 (CALB1) and transient receptor potential cation channel 6 (TRPV6). In this study, we aimed to investigate the expression of calcium-regulating proteins in the plaques of patients with psoriasis vulgaris with or without joint inflammation. We confirmed low calcium levels, keratinocyte hyperproliferation and an altered epidermal barrier. The CASR, ORAI1, ORAI3, STIM1, CALB1 and TRPV6 mRNA, as well as the sterol 27-hydroxylase (CYP27A1), 25-hydroxyvitamin D3 1-α-hydroxylase (CYP27B1) and 1,25-dihydroxyvitamin D3 24-hydroxylase (CYP24A1) protein levels were low in the plaques of patients with psoriasis. We demonstrated S100 calcium-binding protein A7 (S100A7) overexpression in the plaques of patients with psoriasis vulgaris with joint inflammation, compared with those without joint involvement. We suggest an altered capacity to regulate the intracellular Ca2+ concentration ([Ca2+]i), characterized by a reduced expression of CASR, ORAI1, ORAI3, STIM1, CALB1 and TRPV6 associated with diminished levels of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], which may be associated with an altered balance between keratinocyte proliferation and differentiation in the psoriatic epidermis. Additionally, differences in S100A7 expression depend on the presence of joint involvement.

S100A7 (psoriasin) inhibits human epidermal differentiation by enhanced IL-6 secretion through IκB/NF-κB signalling

Psoriasin (S100A7), a member of the S100 protein family, is a well-known antimicrobial peptide and a signalling molecule which regulates cellular function and is highly expressed in hyperproliferative skin conditions such as atopic dermatitis (AD) and psoriasis with disrupted skin barrier function. However, its role in epidermal differentiation remains unknown. We examined the effect of S100A7 on epidermal differentiation in normal human keratinocytes (NHKs) and on a reconstituted human epidermis model. When NHKs were exposed to disruptive stimuli such as Staphylococcus aureus, ultraviolet irradiation and retinoic acid, the secretion of S100A7 into the culture medium increased and the expression of epidermal differentiation markers decreased. Treatment of NHKs with S100A7 significantly inhibited epidermal differentiation by reducing the expression of keratin 1, keratin 10, involucrin and loricrin and by increasing the expression of abnormal differentiation markers (keratin 6 and keratin 16). We verified that the MyD88-IκB/NF-κB signal cascade was activated via RAGE after S100A7 treatment, resulting in the upregulation of interleukin-6. Finally, we confirmed that S100A7 is a negative regulator of epidermal differentiation using a reconstituted human epidermis model. This study suggests that S100A7-related signalling molecules could be potent targets for recovering skin barrier function in AD and psoriasis where S100A7 is accumulated excessively.

Phenotypic Plasticity Determines Cancer Stem Cell Therapeutic Resistance in Oral Squamous Cell Carcinoma

Cancer stem cells (CSCs) drive tumour spread and therapeutic resistance, and can undergo epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) to switch between epithelial and post-EMT sub-populations. Examining oral squamous cell carcinoma (OSCC), we now show that increased phenotypic plasticity, the ability to undergo EMT/MET, underlies increased CSC therapeutic resistance within both the epithelial and post-EMT sub-populations. The post-EMT CSCs that possess plasticity exhibit particularly enhanced therapeutic resistance and are defined by a CD44(high)EpCAM(low/-) CD24(+) cell surface marker profile. Treatment with TGFβ and retinoic acid (RA) enabled enrichment of this sub-population for therapeutic testing, through which the endoplasmic reticulum (ER) stressor and autophagy inhibitor Thapsigargin was shown to selectively target these cells. Demonstration of the link between phenotypic plasticity and therapeutic resistance, and development of an in vitro method for enrichment of a highly resistant CSC sub-population, provides an opportunity for the development of improved chemotherapeutic agents that can eliminate CSCs.

Th2 cytokines differentially regulate psoriasin expression in human nasal epithelia

BACKGROUND

Psoriasin is known to be expressed in diverse organs, where it exerts antimicrobial activity. Psoriasin is also involved in the local host defense mechanism against pathogens. We hypothesized that allergy-related T-helper cell type 2 (Th2) cytokines may regulate the expression of psoriasin.

METHODS

We treated normal human nasal epithelial (NHNE) cells with IL-4 or IL-13. Using human nasal tissues, we compared the expression level of psoriasin. We performed real-time polymerase chain reaction and Western blot assays using NHNE cells. Immunohistochemical staining and Western blot assays were performed with human nasal tissues. Furthermore, we studied the antimicrobial activity of nasal secretions from normal and allergic rhinitis patients.

RESULTS

IL-13 markedly down-regulated psoriasin expression at the gene and protein levels in NHNE cells, and it also decreased the amount of psoriasin protein that was secreted into the extracellular compartment in NHNE cells. IL-4 had no statistically significant effect. Results from immunohistochemical staining and Western blot assays showed that psoriasin expression was decreased in allergic rhinitis patients compared with control subjects. Nasal secretions of allergic rhinitis patients exhibited decreased antimicrobial activity compared with control subjects.

CONCLUSION

We found that Th2 cytokines regulated psoriasin expression in NHNE cells, and psoriasin expression was decreased in allergic rhinitis patients compared with control subjects. The decreased expression of psoriasin may be related to the reduction in antimicrobial capacity of nasal secretions under allergic conditions, resulting in an increase in susceptibility to viruses or bacterial infections.

The S100 proteins in epidermis: Topology and function

BACKGROUND

S100 proteins are small calcium binding proteins encoded by genes located in the epidermal differentiation complex (EDC). Differently to other proteins encoded by EDC genes, which are indispensable for normal epidermal differentiation, the role of S100 proteins in the epidermis remains largely unknown.

SCOPE OF REVIEW

Particular S100 proteins differ in their distribution in epidermal layers, skin appendages, melanocytes and Langerhans cells. Taking into account that each epidermal component consists of specialized cells with well-defined functions, such differential distribution may be indicative of the function of a given S100 protein. We used this criterion together with the survey of the current experimental data pertinent to epidermis to provide a fairly comprehensive view on the possible function of individual S100 proteins in this tissue.

MAJOR CONCLUSIONS

S100 proteins are differently expressed and, despite extensive structural homology, perform diverse functions in the epidermis. Certain S100 proteins probably ensure constant epidermal renewal and support wound healing while others act in epidermal differentiation or have a protective role. As their expression is differently affected in various skin pathologies, particular S100 proteins could be valuable diagnostic markers.

GENERAL SIGNIFICANCE

S100 proteins seem to be important although not yet fully recognized epidermal constituents. Better understanding of their role in the epidermis might be helpful in designing therapies to various skin diseases.

S100A16 promotes differentiation and contributes to a less aggressive tumor phenotype in oral squamous cell carcinoma

Background

Altered expression of S100A16 has been reported in human cancers, but its biological role in tumorigenesis is not fully understood. This study aimed to investigate the clinical significance and functional role of S100A16 in oral squamous cell carcinoma (OSCC) suppression.

Methods

S100A16 mRNA and/or protein levels were examined by quantitative RT-PCR and immunohistochemistry in whole- and laser microdissected-specimens of normal human oral mucosa (NHOM, n = 65), oral dysplastic lesions (ODL, n = 21), OSCCs (n = 132) and positive cervical nodes (n = 17). S100A16 protein expression in OSCC was examined for correlations with clinicopathological variables and patient survival. S100A16 was over-expressed and knocked-down in OSCC-derived (CaLH3 and H357) cells by employing retroviral constructs to investigate its effects on cell proliferation, sphere formation and three dimensional (3D)-organotypic invasive abilities in vitro and tumorigenesis in a mouse xenograft model.

Results

Both S100A16 mRNA and protein levels were found to be progressively down-regulated from NHOM to ODL and OSCC. Low S100A16 protein levels in OSCC significantly correlated with reduced 10-year overall survival and poor tumor differentiation. Analysis of two external OSCC microarray datasets showed a positive correlation between the mRNA expression levels of S100A16 and keratinocyte differentiation markers. CaLH3 and H357 cell fractions enriched for differentiated cells either by lack of adherence to collagen IV or FACS sorting for low p75NTR expression expressed significantly higher S100A16 mRNA levels than the subpopulations enriched for less differentiated cells. Corroborating these findings, retroviral mediated S100A16 over-expression and knock-down in CaLH3 and H357 cells led to respective up- and down-regulation of differentiation markers. In vitro functional studies showed significant reduction in cell proliferation, sphere formation and 3D-invasive abilities of CaLH3 and H357 cells upon S100A16 over-expression. These functional effects were associated with concomitant down-regulation of self-renewal (Bmi-1 and Oct 4A) and invasion related (MMP1 and MMP9) molecules. S100A16 over-expression also suppressed tumorigenesis of H357 cells in a mouse xenograft model and the resulting tumor xenografts displayed features/expression of increased differentiation and reduced proliferation/self-renewal.

Conclusions

These results indicate that S100A16 is a differentiation promoting protein and might function as a tumor suppressor in OSCC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1622-1) contains supplementary material, which is available to authorized users.

Regulation of Dendritic Cell Function in Inflammation

Dendritic cells (DC) are professional antigen presenting cells and link the innate and adaptive immune system. During steady state immune surveillance in skin, DC act as sentinels against commensals and invading pathogens. Under pathological skin conditions, inflammatory cytokines, secreted by surrounding keratinocytes, dermal fibroblasts, and immune cells, influence the activation and maturation of different DC populations including Langerhans cells (LC) and dermal DC. In this review we address critical differences in human DC subtypes during inflammatory settings compared to steady state. We also highlight the functional characteristics of human DC subsets in inflammatory skin environments and skin diseases including psoriasis and atopic dermatitis. Understanding the complex immunoregulatory role of distinct DC subsets in inflamed human skin will be a key element in developing novel strategies in anti-inflammatory therapy.

The Characteristics and Function of S100A7 Induction in Squamous Cell Carcinoma: Heterogeneity, Promotion of Cell Proliferation and Suppression of Differentiation

S100A7 is highly expressed in squamous cell carcinomas (SCC) and is related to the terminal differentiation of keratinocytes. However, its characteristic and function in SCC is not very known. In this present study, we used immunohistochemistry to examine the expression of S100A7 in 452 SCC specimens, including the lung, esophagus, oral cavity, skin, cervix, bladder, and three SCC cell lines. We found that S100A7-positive staining showed significant heterogeneity in six types of SCC specimen and three SCC cell lines. Further examination found that S100A7-positive cells and its expression at mRNA and protein levels could be induced in HCC94, FaDu, and A-431 cells both in vitro and in vivo using immunohistochemistry, real-time PCR, and Western blotting. Notably, the upregulation of squamous differentiation markers, including keratin-4, keratin-13, TG-1, and involucrin, also accompanied S100A7 induction, and a similar staining pattern of S100A7 and keratin-13 was found in HCC94 cells both in vitro and in vivo. Further study revealed that the overexpression of S100A7 significantly increased proliferation and inhibited squamous differentiation in A-431 cells both in vitro and in vivo. Conversely, silencing S100A7 inhibited cell growth and survival and increased the expression of keratin-4, keratin-13, TG-1, and involucrin in HCC94 cells. Therefore, these results demonstrate that S100A7 displays heterogeneous and inducible characteristic in SCC and also provide novel evidence that S100A7 acts as a dual regulator in promoting proliferation and suppressing squamous differentiation of SCC.

S100A7 acts as a dual regulator in promoting proliferation and suppressing squamous differentiation through GATA-3/caspase-14 pathway in A431 cells

S100A7 is expressed in many squamous cell carcinomas (SCCs), such as SCC of the skin, and well-differentiated SCC always displays stronger staining of this protein. A431 cells, an epidermal cancer cell line, were selected as a cell model to investigate the roles and mechanism of S100A7 in SCC of the skin. In this study, we demonstrated that the overexpression of S100A7 in A431 cells significantly promoted cell proliferation in vitro and tumor growth in vivo, whereas it suppressed the expression of GATA-3, caspase-14 and three squamous differentiation markers, keratin-1, TG-1 and involucrin. Conversely, the overexpression of caspase-14 not only significantly decreased cell proliferation and delayed tumor growth but also markedly induced the expression of three squamous differentiation markers, whereas S100A7 and GATA-3 were not influenced. Further evidence showed that silencing GATA-3 greatly inhibited the expression of caspase-14 and three differentiation markers, while the expression of S100A7 was not changed; contrary results were obtained when overexpressing GATA-3. Importantly, restoring the expression of GATA-3 and caspase-14 in A431-S100A7 cells could bypass the ability of S100A7 to increase cell viability and repress squamous differentiation. These data suggested that S100A7 expression in SCC may play an important role in the maintenance of SCC cell dedifferentiation, at least in SCC of the skin.

Downregulation of S100 Calcium Binding Protein A9 in Esophageal Squamous Cell Carcinoma

The development of esophageal squamous cell carcinoma (ESCC) is poorly understood and the major regulatory molecules involved in the process of tumorigenesis have not yet been identified. We had previously employed a quantitative proteomic approach to identify differentially expressed proteins in ESCC tumors. A total of 238 differentially expressed proteins were identified in that study including S100 calcium binding protein A9 (S100A9) as one of the major downregulated proteins. In the present study, we carried out immunohistochemical validation of S100A9 in a large cohort of ESCC patients to determine the expression and subcellular localization of S100A9 in tumors and adjacent normal esophageal epithelia. Downregulation of S100A9 was observed in 67% (n = 192) of 288 different ESCC tumors, with the most dramatic downregulation observed in the poorly differentiated tumors (99/111). Expression of S100A9 was restricted to the prickle and functional layers of normal esophageal mucosa and localized predominantly in the cytoplasm and nucleus whereas virtually no expression was observed in the tumor and stromal cells. This suggests the important role that S100A9 plays in maintaining the differentiated state of epithelium and suggests that its downregulation may be associated with increased susceptibility to tumor formation.

The antimicrobial protein S100A7/psoriasin enhances the expression of keratinocyte differentiation markers and strengthens the skin's tight junction barrier

BACKGROUND

S100A7/psoriasin is a member of the S100 protein family and is encoded in the epidermal differentiation complex, which contains genes for markers of epidermal differentiation. S100A7/psoriasin is overexpressed in hyperproliferative skin diseases, where it is believed not only to exhibit antimicrobial functions, but also to induce immunomodulatory activities, including chemotaxis and cytokine/chemokine production.

OBJECTIVES

To evaluate the effect of S100A7/psoriasin on keratinocyte differentiation and regulation of the tight junction (TJ) barrier.

METHODS

Expression of differentiation markers and TJ proteins in human keratinocytes was determined by real-time polymerase chain reaction and Western blot. The changes in TJ barrier function were assessed by transepithelial electrical resistance and paracellular permeability assays. Glycogen synthase kinase-3 (GSK-3) and mitogen-activated protein kinase (MAPK) activation was analysed by Western blot, whereas β-catenin and E-cadherin activation was evaluated by Western blot and immunofluorescence.

RESULTS

S100A7/psoriasin enhanced the expression of several differentiation markers and selectively increased the expression of TJ proteins (e.g. claudins and occludin), which are known to strengthen the TJ barrier. Furthermore, S100A7/psoriasin increased β-catenin and E-cadherin accumulation at cell-cell contact, and enhanced transepithelial electrical resistance while reducing the paracellular permeability of keratinocyte layers. The data suggest that S100A7/psoriasin-mediated regulation of the TJ barrier was via both the GSK-3 and MAPK pathways, as evidenced by the inhibitory effects of inhibitors for GSK-3 and MAPKs.

CONCLUSIONS

Our finding that S100A7/psoriasin regulates differentiation and strengthens TJ barrier function provides novel evidence that, in addition to antimicrobial and immunoregulatory activities, S100A7/psoriasin is involved in skin innate immunity.

Expression of human solute carrier family transporters in skin: possible contributor to drug-induced skin disorders

Solute carrier (SLC) transporters play important roles in absorption and disposition of drugs in cells; however, the expression pattern of human SLC transporters in the skin has not been determined. In the present study, the expression patterns of 28 human SLC transporters were determined in the human skin. Most of the SLC transporter family members were either highly or moderately expressed in the liver, while their expression was limited in the skin and small intestine. Treatment of human keratinocytes with a reactive metabolite of ibuprofen significantly reduced cell viability. Expression array analysis revealed that S100 calcium binding protein A7A (S100A7A) was induced nearly 50-fold in dermal cells treated with ibuprofen acyl-glucuronide. Determination of the expression of drug-metabolizing enzymes as well as drug transporters prior to the administration of drugs would make it possible to avoid the development of idiosyncratic skin diseases in individuals.

S100A9 has a protective role in inflammation-induced skin carcinogenesis

The S100A8/A9 heterodimer is expressed by myeloid cells where its function has been extensively investigated. Immune cell S100A8/A9 promotes proinflammatory effects, and its absence is often associated with lack of leukocyte recruitment resulting in protection in terms of disease progression. S100A8/A9 is also expressed by certain epithelia, either constitutively as in mucosal epithelia or following stimulation as in skin keratinocytes. The role of the heterodimer in this context has not been as frequently explored. In this study, the incidence of skin papillomas induced by 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) in S100a9(-/-) mice has been investigated. Unlike the immune disorders and certain models of cancer, absence of S100A8/A9 caused an increased incidence in skin of papillomas and, subsequently, squamous cell carcinomas. Although associated in S100a9(-/-) mice with increased recruitment of neutrophils and T cells, a bone marrow chimera experiment revealed the major defect to be primarily due to the absence of S100A8/A9 in the skin keratinocytes. S100a9(-/-) skin displayed enhanced Ki-67 expression over the time period of appearance of the papillomas suggesting an effect of S100A8/A9 in regulating proliferation in the epidermal layer. Thus, despite immune cell recruitment in S100a9(-/-) mouse skin that might have been predicted to promote tumor growth, it was the absence of S100A8/A9 in skin keratinocytes that dominated in terms of papilloma formation. The study highlights the importance of the S100A8/A9-expressing skin epidermal layer in controlling skin tumor formation and suggests that the influence of the heterodimer is dependent on the tissue context in which it is expressed.

Aberrant expression of S100A6 and matrix metalloproteinase 9, but not S100A2, S100A4, and S100A7, is associated with epidermal carcinogenesis

BACKGROUND

S100 proteins belong to a family of calcium-binding proteins that regulate cell proliferation and differentiation. Despite our growing knowledge about the biology of S100 proteins in some human cancers, little is known about the expression of S100 family members in epidermal tumors and their clinical significance.

OBJECTIVE

To determine the expression of S100A2, S100A4, S100A6, S100A7, as well as matrix metalloproteinases 9 (MMP9) in a spectrum of epidermal tumors with benign and malignant characteristics.

METHODS

Immunohistological staining was performed for S100A2, S100A4, S100A6, S100A7, and MMP9 in 101 cases of various types of epidermal tumors, viz., squamous cell carcinoma (SCC), Bowen's disease (BD), actinic keratosis (AK), basal cell carcinoma (BCC), keratoacanthoma (KA), and seborrheic keratosis (SK). Thirteen specimens of normal skin (NS) served as control.

RESULTS

S100A2, S100A6, and S100A7 positive immunostaining was variably observed in different epidermal tumors. S100A4 staining was not observed in any epidermal tumors, but was clearly visible in dendritic cells. MMP9 immunostaining was positive only in 22/26 (84.62%) of SCC and 2/15 (13.33%) of BD cases. Expression of S100A2, S100A6, and S100A7 was increased in tumor cells compared to NS. However, only S100A6 expression was significantly associated with malignant transformation of epidermal tumors. Moreover, S100A6 expression was correlated with MMP9 expression in metastatic SCC.

CONCLUSIONS

Epidermal tumors show increased expression of S100A2 and S100A7 proteins. S100A4 may be a useful and distinct marker for epidermal dendritic cells. Expression of S100A6 and MMP9 in combination is associated with the development of SCC.

Opposing functions of psoriasin (S100A7) and koebnerisin (S100A15) in epithelial carcinogenesis

The S100 protein family is involved in epithelial cell maturation and inflammation. Some S100 members are dysregulated during carcinogenesis and have been established as tumor markers. Psoriasin (S100A7) and koebnerisin (S100A15) are highly homologous proteins that have been first described in psoriasis, which is characterized by disturbed epidermal maturation and chronic inflammation. Despite their homology, both S100 proteins are distinct in expression and function through different receptors but synergize as chemoattractants and pro-inflammatory 'alarmins' to promote inflammation. Psoriasin and koebnerisin are further regulated with tumor progression in epithelial cancers. In tumor cells, high cytoplasmic expression of psoriasin and koebnerisin may prevent oncogenic activity, whereas their nuclear translocation and extracellular secretion are associated with tumor progression and poor prognosis. The present review outlines these opposing effects of psoriasin and koebnerisin in multifunctional pathways and mechanisms that are known to affect tumor cells ('seeds'), tumor environment ('soil') and tumor cell metastasis ('seeding') thereby influencing epithelial carcinogenesis.

The expression of Psoriasin (S100A7) and CD24 is linked and related to the differentiation of mammary epithelial cells

Psoriasin (S100A7), a member of the S100 family of calcium-binding proteins, is highly expressed in high-grade ductal carcinoma in situ (DCIS) and in the benign hyperproliferative skin disorder psoriasis. The gene that encodes psoriasin and many other S100 genes are located within a gene cluster on chromosome region 1q21, known as the epidermal differentiation complex. This cluster contains genes for several differentiation markers that play important roles in the terminal differentiation of the epidermis. The purpose of the present study was to evaluate the role of psoriasin in the differentiation process of mammary epithelial cells. Normal mammary epithelial cells (MCF10A) cultured in confluence and suspension, conditions known to induce psoriasin expression, demonstrated a shift towards a more differentiated phenotype indicated by an increase in the expression of the luminal differentiation markers CD24 and MUC1 and the reduced expression of the breast stem cell marker CD44. The expression of psoriasin and MUC1 was most pronounced in the CD24⁺-enriched fraction of confluent MCF10A cells. The shift towards a more differentiated phenotype was abolished upon the downregulation of psoriasin using short hairpin RNA (shRNA) and small interfering RNA (siRNA). Using specific inhibitors, we showed that psoriasin and CD24 expression was regulated by reactive oxygen species (ROS) and the nuclear factor (NF)-κB signaling pathways. While immunohistochemical analyses of DCIS showed heterogeneity, the expression of psoriasin and CD24 showed a similar staining pattern. Our findings suggest that the expression of psoriasin is linked to the luminal differentiation marker CD24 in mammary epithelial cells. Psoriasin demonstrated an essential role in the shift towards a more differentiated CD24⁺ phenotype, supporting the hypothesis that psoriasin plays a role in the differentiation of luminal mammary epithelial cells.

Progressive activation of T(H)2/T(H)22 cytokines and selective epidermal proteins characterizes acute and chronic atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common disease with an increasing prevalence. The primary pathogenesis of the disease is still elusive, resulting in the lack of specific treatments. AD is currently considered a biphasic disease, with T(H)2 predominating in acute disease and a switch to T(H)1 characterizing chronic disease. Elucidation of the molecular factors that participate in the onset of new lesions and maintenance of chronic disease is critical for the development of targeted therapeutics.

OBJECTIVES

We sought to characterize the mechanisms underlying the onset and maintenance of AD.

METHODS

We investigated intrapersonal sets of transcriptomes from nonlesional skin and acute and chronic lesions of 10 patients with AD through genomic, molecular, and cellular profiling.

RESULTS

Our study associated the onset of acute lesions with a striking increase in a subset of terminal differentiation proteins, specifically the cytokine-modulated S100A7, S100A8, and S100A9. Acute disease was also associated with significant increases in gene expression levels of major T(H)22 and T(H)2 cytokines and smaller increases in IL-17 levels. A lesser induction of T(H)1-associated genes was detected in acute disease, although some were significantly upregulated in chronic disease. Further significant intensification of major T(H)22 and T(H)2 cytokines was observed between acute and chronic lesions.

CONCLUSIONS

Our data identified increased S100A7, S100A8, and S100A9 gene expression with AD initiation and concomitant activation of T(H)2 and T(H)22 cytokines. Our findings support a model of progressive activation of T(H)2 and T(H)22 immune axes from the acute to chronic phases, expanding the prevailing view of pathogenesis with important therapeutic implications.

Novel insights into the role of S100A8/A9 in skin biology

S100A8 and S100A9 belong to the damage-associated molecular pattern molecules. They are upregulated in a number of inflammatory skin disorders. Owing to their abundance in myeloid cells, the main function of S100A8/A9 has been attributed to their role in inflammatory cells. However, it is becoming increasingly clear that they also exert important roles in epithelial cells. In this review, we discuss the context-dependent function of S100A8/A9 in epithelial cells and their impact on wound healing, psoriasis and other skin diseases.

Novel S100A7 (psoriasin)/S100A15 (koebnerisin) subfamily: highly homologous but distinct in regulation and function

S100A7 (psoriasin) and S100A15 (koebnerisin) were first identified in inflamed psoriatic skin. They are of major interest because of their putative functional roles in innate immunity, epidermal cell maturation, and epithelial tumorigenesis. Human S100A7 and S100A15 have lately evolved by gene duplications within the epidermal differentiation complex (chromosome 1q21) during primate evolution forming a novel S100 subfamily. Therefore, S100A7 and S100A15 are almost identical in sequence (>90%) and are difficult to discriminate. Despite their high homology, S100A7 and S100A15 are distinct in tissue distribution, regulation, and function, and thus, exemplary for the diversity within the S100 family. Their different properties are compelling reasons to discriminate S100A7 (psoriasin) and S100A15 (koebnerisin) in epithelial homeostasis, inflammation, and cancer.

Expression of antimicrobial peptides and proteins in etanercept-treated psoriasis patients

Recent papers highlight the role of dysregulated expression of antimicrobial peptides and proteins (AMPs) in the pathogenesis of psoriasis. Etanercept, a blocker of the pro-inflammatory cytokine tumour necrosis factor-α (TNF-α), is effective in the treatment of psoriasis. We aimed to evaluate the expression profiles of AMPs in psoriatic skin before and after a 6-week course of etanercept therapy. We included 12 psoriasis patients who underwent medium-dose etanercept treatment for 6weeks. At baseline and at the end of therapy immunohistochemistry from lesional skin was performed for psoriasin, LL-37, and human ß-defensin 2 (hBD-2). After 6-week treatment, the modified psoriasis area and severity index significantly decreased from 37.5±5.9 to 14±13.4. Lesional immunoreactivity scores of psoriasin, LL-37, and hBD-2 also significantly decreased after a 6-week course of etanercept. We have demonstrated that etanercept-induced improvement of psoriasic lesions is associated with a significant decline of AMP protein expression.

The p63 target HBP1 is required for skin differentiation and stratification

Genetic experiments established that p63 is crucial for the development and maintenance of pluristratified epithelia. In the RNA interference (RNAi) screening for targets of p63 in keratinocytes, we identified the transcription factor, High Mobility Group (HMG) box protein 1 (HBP1). HBP1 is an HMG-containing repressor transiently induced during differentiation of several cell lineages. We investigated the relationship between the two factors: using RNAi, overexpression, chromatin immunoprecipitations and transient transfections with reporter constructs, we established that HBP1 is directly repressed by p63. This was further confirmed in vivo by evaluating expression in p63 knockout mice and in transgenics expressing p63 in basal keratinocytes. Consistent with these findings, expression of HBP1 increases upon differentiation of primary keratinocytes and HaCaT cells in culture, and it is higher in the upper layers of human skin. Inactivation of HBP1 by RNAi prevents differentiation of keratinocytes and stratification of organotypic skin cultures. Finally, we analyzed the keratinocyte transcriptomes after HBP1 RNAi; in addition to repression of growth-promoting genes, unexpected activation of differentiation genes was uncovered, coexisting with repression of other genes involved in epithelial cornification. Our data indicate that suppression of HBP1 is part of the growth-promoting strategy of p63 in the lower layers of epidermis and that HBP1 temporally coordinates expression of genes involved in stratification, leading to the formation of the skin barrier.

Expression patterns of S100 proteins in melanocytes and melanocytic lesions

S100 proteins are differentially expressed in tumours of epithelial origin. Little is known about their expression in melanocyte-derived tumours of neuroectodermal origin. We have analysed the expression of some S100 proteins in this line of lesions using SAGE Genie informatics, cell culture and human tumour tissue. The pattern of expression of six S100 proteins was investigated at both the mRNA and protein levels, using quantitative real-time PCR, western blotting and immunohistochemical analysis. No differential expression was observed with respect to S100A4, S100A7, S100A8, S100A9 and S100A11. In contrast, S100A10 was downregulated in three melanoma cell lines compared with normal melanocytes. Using SAGE informatics, two-dimensional displays of microarray expression data from the NCI60_Novartis cell lines displayed a positive correlation between the expression of S100A10 and the expression of the proliferation marker, Ki67. Our data suggest that S100A10, like its binding partners S100A7 and annexin A2, is an oxidant-sensitive protein. In addition, higher expression of S100A10 was detected in melanocyte cell lines with long projections compared with melanoma cell lines with small ripples. In a panel of 47 melanocyte-derived lesions comprising melanocytic naevi and melanomas, S100A10 was expressed to varying degrees in the melanocytic lesions. The antigen was primarily expressed in regions with a strong proliferating or differentiating capacity, especially in regions in or near the epidermis. We suggest that S100A10 may play a role in the regulation of the proliferation or early maturation sequence of melanocytic lesions, and that it merits further study as a potential biomarker of activity.