Psoriasin (S100A7) associates with integrin β6 subunit and is required for αvβ6-dependent carcinoma cell invasion

Exploring the role of ITGB6: fibrosis, cancer, and other diseases

Integrin β6 (ITGB6), a member of the integrin family of proteins, is only present in epithelial tissues and frequently associates with integrin subunit αv to form transmembrane heterodimers named integrin αvβ6. Importantly, ITGB6 determines αvβ6 expression and availability. In addition to being engaged in organ fibrosis, ITGB6 is also directly linked to the emergence of cancer, periodontitis, and several potential genetic diseases. Therefore, it is of great significance to study the molecular-biological mechanism of ITGB6, which could provide novel insights for future clinical diagnosis and therapy. This review introduces the structure, distribution, and biological function of ITGB6. This review also expounds on ITGB6-related diseases, detailing the known biological effects of ITGB6.

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

Periodontal pathogens promote cancer aggressivity via TLR/MyD88 triggered activation of Integrin/FAK signaling that is therapeutically reversible by a probiotic bacteriocin

Epidemiological studies reveal significant associations between periodontitis and oral cancer. However, knowledge about the contribution of periodontal pathogens to oral cancer and potential regulatory mechanisms involved is limited. Previously, we showed that nisin, a bacteriocin and commonly used food preservative, reduced oral cancer tumorigenesis and extended the life expectancy in tumor-bearing mice. In addition, nisin has antimicrobial effects on key periodontal pathogens. Thus, the purpose of this study was to test the hypothesis that key periodontal pathogens (Porphyromonas gingivalis, Treponema denticola, and Fusobacterium nucleatum) promote oral cancer via specific host-bacterial interactions, and that bacteriocin/nisin therapy may modulate these responses. All three periodontal pathogens enhanced oral squamous cell carcinoma (OSCC) cell migration, invasion, tumorsphere formation, and tumorigenesis in vivo, without significantly affecting cell proliferation or apoptosis. In contrast, oral commensal bacteria did not affect OSCC cell migration. Pathogen-enhanced OSCC cell migration was mediated via integrin alpha V and FAK activation, since stably blocking alpha V or FAK expression abrogated these effects. Nisin inhibited these pathogen-mediated processes. Further, Treponema denticola induced TLR2 and 4 and MyD88 expression. Stable suppression of MyD88 significantly inhibited Treponema denticola-induced FAK activation and abrogated pathogen-induced migration. Together, these data demonstrate that periodontal pathogens contribute to a highly aggressive cancer phenotype via crosstalk between TLR/MyD88 and integrin/FAK signaling. Nisin can modulate these pathogen-mediated effects, and thus has therapeutic potential as an antimicrobial and anti-tumorigenic agent.

Increased expression of Psoriasin is correlated with poor prognosis of bladder transitional cell carcinoma by promoting invasion and proliferation

Psoriasin, otherwise known as S100A7, is a member of the S100 protein family. With the key function of binding calcium, it is able to regulate a range of cellular functions. Altered Psoriasin expression is associated with poor clinical outcomes in several solid cancers. The present study aimed to examine the implication of Psoriasin in bladder cancer (BC). Expression of Psoriasin was examined in BC cell lines using PCR. Immunohistochemical (IHC) staining of Psoriasin was performed on a bladder disease spectrum tissue array. Plasmids were constructed to effectively knockdown and overexpress Psoriasin in BC cells and further utilized for in vitro BC cellular function assays. Association between Psoriasin expression and survival of patients with BC was evaluated using Kaplan‑Meier survival analysis. Psoriasin was revealed to be expressed by both bladder epithelia and cancer cells as determined by IHC. Increased expression of Psoriasin was significantly correlated with a poor overall BC patient survival. Overexpression of Psoriasin in the EJ138 cell line increased cellular proliferation, adhesion and invasion, whereas knockdown exhibited the opposite effect on cellular functions in RT112 cells. Matrix metalloprotease (MMP)9 appeared to be the most affected of the three MMPs examined in these two BC cell lines. The analysis revealed a positive correlation in BC tumours between Psoriasin and MMP9. Overall, high Psoriasin expression was correlated with poor overall survival in BC patients and promoted invasiveness of BC cells via upregulation of MMPs. Psoriasin possesses certain prognostic and therapeutic potential in BC which requires further exploration.

Integrin αvβ6: Structure, function and role in health and disease

Integrins are cell surface receptors that traditionally mediate cell-to-extracellular matrix and cell-to-cell adhesion. They can, however, also bind a large repertoire of other molecules. Integrin αvβ6 is exclusively expressed in epithelial cells where it can, for example, serve as a fibronectin receptor. However, its hallmark function is to activate transforming growth factor-β1 (TGF-β1) to modulate innate immune surveillance in lungs and skin and along the gastrointestinal tract, and to maintain epithelial stem cell quiescence. The loss of αvβ6 integrin function in mice and humans leads to an altered immune response in lungs and skin, amelogenesis imperfecta, periodontal disease and, in some cases, alopecia. Elevated αvβ6 integrin expression and aberrant TGF-β1 activation and function are associated with organ fibrosis and cancer. Therefore, αvβ6 integrin serves as an attractive target for cancer imaging and for fibrosis and cancer therapy.

Mechanism of prostaglandin E2-induced transcriptional up-regulation of Oncostatin-M by CREB and Sp1

Oncostatin-M (OSM) is a pleotropic cytokine belonging to the interleukin-6 family. Differential expression of OSM in response to varying stimuli and exhibiting repertoire of functions in different cells renders it challenging to study the mechanism of its expression. Prostaglandin E₂ (PGE₂) transcriptionally increased osm levels. In silico studies of ∼1 kb upstream of osm promoter region yielded the presence of CRE (cyclic AMP response element)-like sites at the distal end (CRE_osm). Deletion and point mutation of CRE_osm clearly indicated that this region imparted an important role in PGE₂-mediated transcription. Nuclear protein(s) from PGE₂-treated U937 cells, bound to this region, was identified as CRE-binding protein (CREB). CREB was phosphorylated on treatment and was found to be directly associated with CRE_osm The presence of cofactors p300 and CREB-binding protein in the complex was confirmed. A marked decrease in CREB phosphorylation, binding and transcriptional inhibition on treatment with PKA (protein kinase A) inhibitor, H89 (N-[2-[[3-(4-bromophenyl)-2-propenyl]amino]ethyl]-5-soquinolinesulfonamide), revealed the role of phosphorylated CREB in osm transcription. Additionally, other nuclear protein(s) were specifically associated with the proximal GC region (GC_osm) post PGE₂ treatment, later confirmed to be specificity protein 1 (Sp1). Interestingly, Sp1 bound to the proximal osm promoter was found to be associated with phospho-CREB-p300 complex bound to the distal osm promoter. Knockdown of Sp1 abrogated the expression and functionality of OSM. Thus, the present study conclusively proves that these transcription factors, bound at the distal and proximal promoter elements are found to associate with each other in a DNA-dependent manner and both are responsible for the PGE₂-mediated transcriptional up-regulation of Oncostatin-M.

Study of gene expression alteration in male androgenetic alopecia: evidence of predominant molecular signalling pathways

BACKGROUND

Male androgenetic alopecia (AGA) is the most common form of hair loss in men. It is characterized by a distinct pattern of progressive hair loss starting from the frontal area and the vertex of the scalp. Although several genetic risk loci have been identified, relevant genes for AGA remain to be defined.

OBJECTIVES

To identify biomarkers associated with AGA.

METHODS

Molecular biomarkers associated with premature AGA were identified through gene expression analysis using cDNA generated from scalp vertex biopsies of hairless or bald men with premature AGA, and healthy volunteers.

RESULTS

This monocentric study reveals that genes encoding mast cell granule enzymes, inflammatory mediators and immunoglobulin-associated immune mediators were significantly overexpressed in AGA. In contrast, underexpressed genes appear to be associated with the Wnt/β-catenin and bone morphogenic protein/transforming growth factor-β signalling pathways. Although involvement of these pathways in hair follicle regeneration is well described, functional interpretation of the transcriptomic data highlights different events that account for their inhibition. In particular, one of these events depends on the dysregulated expression of proopiomelanocortin, as confirmed by polymerase chain reaction and immunohistochemistry. In addition, lower expression of CYP27B1 in patients with AGA supports the notion that changes in vitamin D metabolism contributes to hair loss.

CONCLUSIONS

This study provides compelling evidence for distinct molecular events contributing to alopecia that may pave the way for new therapeutic approaches.

Psoriasin promotes invasion, aggregation and survival of pancreatic cancer cells; association with disease progression

Psoriasin (S100A7) is an 11-kDa small calcium binding protein initially isolated from psoriatic skin lesions. It belongs to the S100 family of proteins which play an important role in a range of cell functions including proliferation, differentiation, migration and apoptosis. Aberrant Psoriasin expression has been implicated in a range of cancers and is often associated with poor prognosis. This study examined the role of Psoriasin on pancreatic cancer cell functions and the implication in progression of the disease. Expression of Psoriasin was determined in a cohort of pancreatic tissues comprised of 126 pancreatic tumours and 114 adjacent non-tumour pancreatic tissues. Knockdown and overexpression of Psoriasin in pancreatic cancer cells was performed using specifically constructed plasmids, which either had anti-Psoriasin ribozyme transgene or the full length human Psoriasin coding sequence. Psoriasin knockdown and overexpression was verified using conventional RT-PCR and qPCR. The effect of manipulating Psoriasin expression on pancreatic cancer cell functions was assessed using several in vitro cell function assays. Local invasive pancreatic cancers extended beyond the pancreas expressed higher levels of Psoriasin transcripts compared with the cancers confined to the pancreas. Primary tumours with distant metastases exhibited a reduced expression of Psoriasin. Psoriasin overexpression cell lines exhibited significantly increased growth and migration compared to control cells. In addition, Psoriasin overexpression resulted in increased pancreatic cancer cell invasion which was associated with upregulation of matrix metalloproteinase-2 (MMP-2) and MMP-9. Overexpression of Psoriasin also promoted aggregation and survival of pancreatic cancer cells when they lost anchorage. Taken together, higher expression of Psoriasin was associated with local invasion in pancreatic cancers. Psoriasin expression is associated with pancreatic cancer cell growth, migration, cell-matrix adhesion, and invasion via regulation of MMPs. As such, the proposed implications of Psoriasin in invasion, disease progression and as a potential therapeutic target warrant further investigation.

Screening out irrelevant cell-based models of disease

The common and persistent failures to translate promising preclinical drug candidates into clinical success highlight the limited effectiveness of disease models currently used in drug discovery. An apparent reluctance to explore and adopt alternative cell- and tissue-based model systems, coupled with a detachment from clinical practice during assay validation, contributes to ineffective translational research. To help address these issues and stimulate debate, here we propose a set of principles to facilitate the definition and development of disease-relevant assays, and we discuss new opportunities for exploiting the latest advances in cell-based assay technologies in drug discovery, including induced pluripotent stem cells, three-dimensional (3D) co-culture and organ-on-a-chip systems, complemented by advances in single-cell imaging and gene editing technologies. Funding to support precompetitive, multidisciplinary collaborations to develop novel preclinical models and cell-based screening technologies could have a key role in improving their clinical relevance, and ultimately increase clinical success rates.

S100P interacts with integrin α7 and increases cancer cell migration and invasion in lung cancer

S100P, a Ca2⁺ binding protein, has been shown to be overexpressed in various cancers. However, its functional character in lung cancer remains largely unknown. In this study, we show that S100P increases cancer migration, invasion and metastasis in lung cancer cells. Ectopic expression of S100P increases migration, invasion and EMT in less invasive CL1-0 lung cancer cells. Conversely, knockdown of S100P suppressed migration and invasion, and caused a reversion of EMT in highly invasive lung cancer cells. These effects were transduced by increasing the interaction of S100P with integrin α7, which activated focal adhesion kinase (FAK) and AKT. Blocking FAK significantly decreased S100P-induced migration by decreasing Src and AKT activation, whereas inhibiting AKT reduced S100P upregulation on ZEB1 expression. Further study has indicated that S100P knockdown prevents the spread of highly metastatic human lung cancer in animal models. This study therefore suggests that S100P represents a critical activator of lung cancer metastasis. Detection and targeted treatment of S100P-expressing cancer is an attractive therapeutic strategy in treating lung cancer.

Mechanisms of Invasion in Head and Neck Cancer

CONTEXT

The highly invasive properties demonstrated by head and neck squamous cell carcinoma (HNSCC) are often associated with locoregional recurrence and lymph node metastasis in patients and is a key factor leading to an expected 5-year survival rate of approximately 50% for patients with advanced disease. It is important to understand the features and mediators of HNSCC invasion so that new treatment approaches can be developed.

OBJECTIVES

To provide an overview of the characteristics, mediators, and mechanisms of HNSCC invasion.

DATA SOURCES

A literature review of peer-reviewed articles in PubMed on HNSCC invasion.

CONCLUSIONS

Histologic features of HNSCC tumors can help predict prognosis and influence clinical treatment decisions. Cell surface receptors, signaling pathways, proteases, invadopodia function, epithelial-mesenchymal transition, microRNAs, and tumor microenvironment are all involved in the regulation of the invasive behavior of HNSCC cells. Identifying effective HNSCC invasion inhibitors has the potential to improve outcomes for patients by reducing the rate of spread and increasing responsiveness to chemoradiation.

Joining S100 proteins and migration: for better or for worse, in sickness and in health

The vast diversity of S100 proteins has demonstrated a multitude of biological correlations with cell growth, cell differentiation and cell survival in numerous physiological and pathological conditions in all cells of the body. This review summarises some of the reported regulatory functions of S100 proteins (namely S100A1, S100A2, S100A4, S100A6, S100A7, S100A8/S100A9, S100A10, S100A11, S100A12, S100B and S100P) on cellular migration and invasion, established in both culture and animal model systems and the possible mechanisms that have been proposed to be responsible. These mechanisms involve intracellular events and components of the cytoskeletal organisation (actin/myosin filaments, intermediate filaments and microtubules) as well as extracellular signalling at different cell surface receptors (RAGE and integrins). Finally, we shall attempt to demonstrate how aberrant expression of the S100 proteins may lead to pathological events and human disorders and furthermore provide a rationale to possibly explain why the expression of some of the S100 proteins (mainly S100A4 and S100P) has led to conflicting results on motility, depending on the cells used.

S100A7 overexpression is a predictive marker for high risk of malignant transformation in oral dysplasia

Early detection of oral lesions (OLs) at high risk of cancer development is of utmost importance for intervention. There is an urgent unmet clinical need for biomarkers that allow identification of high-risk OLs. Recently, we identified and verified a panel of five candidate protein biomarkers namely S100A7, prothymosin alpha, 14-3-3ζ, 14-3-3σ and heterogeneous nuclear ribonucleoprotein K using proteomics to distinguish OLs with dysplasia and oral cancers from normal oral tissues. The objective of our study was to evaluate the potential of these candidate protein biomarkers for identification of oral dysplastic lesions at high risk of cancer development. Using immunohistochemistry, we analyzed expressions of these five candidate protein biomarkers in 110 patients with biopsy-proven oral dysplasia and known clinical outcome and determined their correlations with p16 expression and HPV 16/18 status. Kaplan-Meier survival analysis showed reduced oral cancer-free survival (OCFS) of 68.6 months (p = 0.007) in patients showing cytoplasmic S100A7 overexpression when compared to patients with weak or no S100A7 immunostaining in cytoplasm (mean OCFS = 122.8 months). Multivariate Cox regression analysis revealed cytoplasmic S100A7 overexpression as the most significant candidate marker associated with cancer development in dysplastic lesions (p = 0.041, hazard ratio = 2.36). In conclusion, our study suggested the potential of S100A7 overexpression in identifying OLs with dysplasia at high risk of cancer development.

Desmoglein 3 promotes cancer cell migration and invasion by regulating activator protein 1 and protein kinase C-dependent-Ezrin activation

Desmoglein 3 (Dsg3), the pemphigus vulgaris antigen, has recently been shown to be upregulated in squamous cell carcinoma (SCC) and has been identified as a good tumor-specific marker for clinical staging of cervical sentinel lymph nodes in head and neck SCC. However, little is known about its biological function in cancer. The actin-binding protein Ezrin and the activator protein 1 (AP-1) transcription factor are implicated in cancer progression and metastasis. Here, we report that Dsg3 regulates the activity of c-Jun/AP-1 as well as protein kinase C (PKC)-mediated phosphorylation of Ezrin-Thr567, which contributes to the accelerated motility of cancer cells. Ectopic expression of Dsg3 in cancer cell lines caused enhanced phosphorylation at Ezrin-Thr567 with concomitant augmented membrane protrusions, cell spreading and invasive phenotype. We showed that Dsg3 formed a complex with Ezrin at the plasma membrane that was required for its proper function of interacting with F-actin and CD44 as Dsg3 knockdown impaired these associations. The increased Ezrin phosphorylation in Dsg3-overexpressing cells could be abrogated substantially by various pharmacological inhibitors for Ser/Thr kinases, including PKC and Rho kinase that are known to activate Ezrin. Furthermore, a marked increase in c-Jun S63 phosphorylation, among others, was found in Dsg3-overexpressing cells and the activation of c-Jun/AP-1 was further supported by a luciferase reporter assay. Taken together, our study identifies a novel Dsg3-mediated c-Jun/AP-1 regulatory mechanism and PKC-dependent Ezrin phosphorylation that could be responsible for Dsg3-associated cancer metastasis.

Differential occurrence of S100A7 in breast cancer tissues: a proteomic-based investigation

PURPOSE

The present study reports for the first time a large-scale proteomic screening of the occurrence, subcellular localization and relative quantification of the S100A7 protein among a group of 100 patients, clinically grouped for the diagnosis of infiltrating ductal carcinoma (IDC).

EXPERIMENTAL DESIGN

To this purpose, the methods of differential proteomics, Western blotting, and immunohistochemistry were used.

RESULTS

The identity of two isoforms of the protein was assessed by mass spectrometry and immunologically confirmed. Moreover, we proved by immunocytochemical applications the exclusive localization of the protein within the neoplastic cells. The correlation of S100A7 expression levels with the collective profile of cancer patients' proteomics predicted functional interactions, distinct for the two isoforms. The S100A7b isoform was significantly correlated with specific protein clusters (calcium binding, signaling and cell motion, heat shock and folding) and intercrossing pathways (antioxidant, metabolic and apoptotic pathways), while the more acidic isoform was correlated with a narrow number of proteins mainly unrelated to the b isoform.

CONCLUSIONS AND CLINICAL RELEVANCE

This study is the first proteomic-based report on S100A7 in a large series of IDC patients. The correlation with in silico data may significantly contribute the knowledge of possible pathways for S100A7, providing novel insights into the mechanism of action of this protein. We suggest that each S100A7 isoform is involved in critical phases of the breast cancer growth and progression, probably through interaction with different partner proteins.

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 antimicrobial peptides is significantly altered in cutaneous squamous cell carcinoma and precursor lesions

BACKGROUND

Antimicrobial peptides and proteins are not only effectors of the immune system but are also attributed important roles in tumour progression or tumour suppression in several malignancies such as oral squamous cell carcinoma (SCC).

OBJECTIVES

These reports encouraged us to systematically investigate the expression of different classes of antimicrobial peptides and proteins in tissue samples of cutaneous SCC and its precursor lesions.

METHODS

The protein expression of human beta-defensin (hBD)-1, -2, and -3, ribonuclease (RNase)-7 and the S100 protein psoriasin were analysed in 25 patients with actinic keratosis (AK), 30 with SCC in situ (SCCis), 23 with SCC, nine healthy skin controls and 10 healthy, chronically ultraviolet (UV)-exposed controls, by means of immunohistochemistry.

RESULTS

Expression of hBD-1 was significantly reduced in SCC compared with UV-exposed healthy skin, AK and SCCis. RNase-7 expression was reduced gradually parallel to every step of malignant transformation, with the highest expression in healthy skin and the lowest expression in SCC. hBD-2 and psoriasin were significantly overexpressed in SCC and SCCis, compared with healthy controls. hBD-3 showed significantly more frequent expression in AK than in healthy controls, and in patients with SCCis and SCC.

CONCLUSIONS

It is tempting to speculate that hBD-1 and RNase-7 might act as tumour suppressors while hBD-2 and psoriasin might act in the opposite way as promoters of tumour progression. Further investigations should clarify whether hBD-2 and hBD-3 could be potential targets for the development of pharmacological therapy.

The clinical significance of Psoriasin for non-small cell lung cancer patients and its biological impact on lung cancer cell functions

BACKGROUND

Psoriasin (S100A7) is a member of the S100 gene family. Alteration of Psoriasin expression has previously been reported to play an important role in cancer aggressive behaviour. The current study sought to investigate the level of Psoriasin expression at the mRNA level in a cohort of patients with non-small cell lung cancer (NSCLC), the association with clinical implication and outcomes, and the molecular and cellular impact of the protein on lung cancer cells.

METHODS

Fresh frozen NSCLC cell carcinoma tissues, along with matched normal tissues were obtained from 83 NSCLC patients who received curative resection from January 2003 to December 2011. The expression of Psoriasin in the NSCLC specimens was assessed using both quantitative real time PCR (QPCR) and immunochemical staining. Knockdown and forced expression of Psoriasin in NSCLC cell lines were carried out using constructed plasmid vectors carrying either ribozyme transgenes targeting human Psoriasin or full-length coding sequence, respectively. The effect of Psoriasin on the functions of NSCLC cells was determined using a variety of in vitro cell function assays.

RESULTS

Higher mRNA levels of Psoriasin were observed in tumour tissues when compared to both the paired normal background tissues and none paired normal tissues (p = 0.0251 and 0.0195). The mRNA level of Psoriasin was found to be higher in the squamous carcinoma (P=0.035). Higher Psoriasin expression is associated with poor prognosis. The cell function tests had supportive results to the clinical findings. Over-expression of Posriasin in lung cancer cells (SK-MES-1) resulted in an increase in in vitro growth and invasiveness. In contrast, Psoriasin knockdown suppressed cell growth and invasion (P<0.05), but increased cell adhesion (P<0.05).

CONCLUSIONS

Psoriasin expression is increased in lung cancer, more specifically in lung squamous carcinoma compared with adenocarcinoma, and is associated with poor prognosis. Psoriasin plays crucial roles in regulating the growth and invasion of lung cancer cells.

Circulating tumour cells and cancer stem cells: a role for proteomics in defining the interrelationships between function, phenotype and differentiation with potential clinical applications

Research on the discovery and implementation of valid cancer biomarkers is one of the most challenging fields in oncology and oncoproteomics in particular. Moreover, it is generally accepted that an evaluation of cancer biomarkers from the blood could significantly enable biomarker assessments by providing a relatively non-invasive source of representative tumour material. In this regard, circulating tumour cells (CTCs) isolated from the blood of metastatic cancer patients have significant promise. It has been demonstrated that localised and metastatic cancers may give rise to CTCs, which are detectable in the bloodstream. Despite technical difficulties, recent studies have highlighted the prognostic significance of the presence and number of CTCs in the blood. Future studies are necessary not only to detect CTCs but also to characterise them. Furthermore, another pathogenically significant type of cancer cells, known as cancer stem cells (CSCs) or more recently termed circulating tumour stem cells (CTSCs), appears to have a significant role as a subpopulation of CTCs. This review discusses the potential application of proteomic methodologies to improve the isolation and characterisation of CTCs and to distinguish between CTCs with a poor clinical significance and those with important biological and clinical implications.

A human monoclonal antibody 264RAD targeting αvβ6 integrin reduces tumour growth and metastasis, and modulates key biomarkers in vivo

αvβ6 integrin expression is upregulated on a wide range of epithelial tumours, and is thought to play a role in modulating tumour growth. Here we describe a human therapeutic antibody 264RAD, which binds and inhibits αvβ6 integrin function. 264RAD cross-reacts with human, mouse and cynomolgus monkey αvβ6, and inhibits binding to all ligands including the latency-associated peptide of TGF-β. Screening across a range of integrins revealed that 264RAD also binds and inhibits the related integrin αvβ8, but not the integrins α5β1, αvβ3, αvβ5 and α4β1. In vitro 264RAD inhibited invasion of VB6 and Detroit 562 cells in a Matrigel invasion assay and αvβ6 mediated production of matrix metalloproteinase-9 in Calu-3 cells. It inhibited TGF-β-mediated activation of dermal skin fibroblasts by preventing local activation of TGF-β by NCI-H358 tumour cells in a tumour cell-fibroblast co-culture assay. In vivo 264RAD showed dose-dependent inhibition of Detroit 562 tumour growth, regressing established tumours when dosed at 20 mg/kg once weekly. The reduction in growth associated with 264RAD was related to a dose-dependent inhibition of Ki67 and phospho-ERK and a reduction of αvβ6 expression in the tumour cells, coupled to a reduction in fibronectin and alpha smooth muscle actin expression in stromal fibroblasts. 264RAD also reduced the growth and metastasis of orthotopic 4T1 tumours. At 20 mg/kg growth of both the primary tumour and the number of metastatic deposits in lung were reduced. The data support the conclusion that 264RAD is a potent inhibitor of αvβ6 integrin, with some activity against αvβ8 integrin, that reduces both tumour growth and metastasis.

Gene expression in uninvolved oral mucosa of OSCC patients facilitates identification of markers predictive of OSCC outcomes

Oral and oropharyngeal squamous cell carcinomas (OSCC) are among the most common cancers worldwide, with approximately 60% 5-yr survival rate. To identify potential markers for disease progression, we used Affymetrix U133 plus 2.0 arrays to examine the gene expression profiles of 167 primary tumor samples from OSCC patients, 58 uninvolved oral mucosae from OSCC patients and 45 normal oral mucosae from patients without oral cancer, all enrolled at one of the three University of Washington-affiliated medical centers between 2003 to 2008. We found 2,596 probe sets differentially expressed between 167 tumor samples and 45 normal samples. Among 2,596 probe sets, 71 were significantly and consistently up- or down-regulated in the comparison between normal samples and uninvolved oral samples and between uninvolved oral samples and tumor samples. Cox regression analyses showed that 20 of the 71 probe sets were significantly associated with progression-free survival. The risk score for each patient was calculated from coefficients of a Cox model incorporating these 20 probe sets. The hazard ratio (HR) associated with each unit change in the risk score adjusting for age, gender, tumor stage, and high-risk HPV status was 2.7 (95% CI: 2.0–3.8, p = 8.8E-10). The risk scores in an independent dataset of 74 OSCC patients from the MD Anderson Cancer Center was also significantly associated with progression-free survival independent of age, gender, and tumor stage (HR 1.6, 95% CI: 1.1–2.2, p = 0.008). Gene Set Enrichment Analysis showed that the most prominent biological pathway represented by the 71 probe sets was the Integrin cell surface interactions pathway. In conclusion, we identified 71 probe sets in which dysregulation occurred in both uninvolved oral mucosal and cancer samples. Dysregulation of 20 of the 71 probe sets was associated with progression-free survival and was validated in an independent dataset.

Distinct innate immune gene expression profiles in non-melanoma skin cancer of immunocompetent and immunosuppressed patients

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) are the most frequent skin cancers in humans. An intact immune system is critical for protection against SCC since organ transplant recipients (OTR) have a 60- to 100-fold higher risk for developing these tumors. The role of the innate immune system in tumor immunosurveillance is unclear. Our aim was to determine the expression of selected innate immune genes in BCC and SCC arising in immunocompetent and OTR patients. Lesional and peri-lesional skin from 28 SCC and 19 BCC were evaluated for mRNA expression of toll-like receptors (TLR) 1-9, downstream TLR signaling molecules, and antimicrobial peptides. 11 SCC occurring in OTR patients were included in the analysis. We found that SCC but not BCC showed significantly elevated expression of TLRs 1-3, 5-8, TRIF and TRAF1. TNF was increased in SCC compared to normal skin. BCC showed increased IFNγ. hBD1, hBD2 and psoriasin mRNA and protein expression were significantly higher in SCC than in normal skin and higher than in BCC. SCC from OTR showed only an increase in hBD2 but no increase in hBD1 or psoriasin. We conclude that innate immune gene expression in SCC is distinct from normal skin and BCC. BCC shows lesser induction of innate immune genes. SCC from OTR patients have depressed expression of hBD1 and psoriasin compared to SCC from immunocompetent patients.

Psoriasin (S100A7) is a positive regulator of survival and invasion of prostate cancer cells

OBJECTIVES

Psoriasin, also known as S100A7 and first identified as a protein highly expressed in psoriatic lesions, is a calcium binding protein that has been indicated in various malignancies. The current study aimed to examine the implication of psoriasin in prostate cancer (CaP), particularly its impact on functions of CaP cells.

MATERIALS AND METHODS

Expression of psoriasin was examined in a variety of prostatic cell lines and human CaP tissues using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. Knockdown and overexpression of psoriasin in CaP cells was performed using specifically constructed plasmids, which either had an anti-psoriasin ribozyme transgene or the full-length human S100A7 coding sequence. The effects of manipulating psoriasin expression on cellular functions of CaP cells were assessed using in vitro assays.

RESULTS

Psoriasin was expressed in prostate epithelia and cancer cells. Elevated expression of psoriasin was evident in CaP from its IHC staining in CaP frozen specimens. Psoriasin promoted cell survival under serum starvation. Its expression was inversely correlated with cell-matrix adhesion. Psoriasin increased invasiveness of PC-3 cells via a regulation of matrix metalproteinases (MMPs).

CONCLUSIONS

Aberrant expression of psoriasin is implicated in CaP. Its expression in CaP cells is associated with cell survival, adhesion, and in vitro invasion, which is via the regulation of MMPs.

Human β-defensins and psoriasin/S100A7 expression in salivary glands: anti-oncogenic molecules for potential therapeutic approaches

BACKGROUND

Host defence peptides (HDPs), including human β-defensins (hBDs) and psoriasin/S100A7, exert antimicrobial and immunoregulatory functions of the innate defense system. In addition to these functions, the search for cancer biomarkers has identified HDPs as playing a potential role in both tumor suppression and oncogenesis. Although HDPs are highly expressed in salivary glands, their role as molecules for potential diagnostic and therapeutic approaches has not yet been analyzed.

OBJECTIVE

The aim of the present study was to investigate whether expression levels of putative pro- or anti-oncogenic hBDs, including hBD-1, -2, -3, and psoriasin/S100A7, are altered in salivary gland tumor tissue as potential targets for molecular-based therapeutic approaches.

METHODS

We analyzed the expression levels of hBD-1, -2, -3, and psoriasin/S100A7 by quantitative real-time polymerase chain reaction (qrt-PCR) and immunohistochemistry in a case control study by comparing salivary gland tumor samples relative to healthy control specimens from 58 patients. Expression level analysis of hBD-1, -2, -3, and psoriasin/S100A7 by qrt-PCR was normalized to the endogenous 18S rRNA expression levels.

RESULTS

The results demonstrate the significant downregulation of hBD-1 (p < 0.001), hBD-2 (p = 0.003), hBD-3 (p = 0.002), and psoriasin/S100A7 (p = 0.003) mRNA in human salivary gland tumors compared with healthy control specimens. Protein expression levels of hBD-1, -2, -3, and psoriasin/S100A7 in salivary gland tumor tissue were strongly reduced compared with healthy control specimens.

CONCLUSION

The data indicates a putative role of the innate defense system in salivary gland tumor formation. The identification of immunoregulatory molecules as diagnostic biomarkers or therapeutic targets could provide new approaches for molecular-based diagnostic and therapeutic support to treat salivary gland tumors as well as other malignancies. We suggest that HDPs should be taken into consideration for use in molecular-based therapeutic approaches.

Multiple roles of integrin-linked kinase in epidermal development, maturation and pigmentation revealed by molecular profiling

Integrin-linked kinase (ILK) is an important scaffold protein that mediates a variety of cellular responses to integrin stimulation by extracellular matrix proteins. Mice with epidermis-restricted inactivation of the Ilk gene exhibit pleiotropic phenotypic defects, including impaired hair follicle morphogenesis, reduced epidermal adhesion to the basement membrane, compromised epidermal integrity, as well as wasting and failure to thrive leading to perinatal death. To better understand the underlying molecular mechanisms that cause such a broad range of alterations, we investigated the impact of Ilk gene inactivation on the epidermis transcriptome. Microarray analysis showed over 700 differentially regulated mRNAs encoding proteins involved in multiple aspects of epidermal function, including keratinocyte differentiation and barrier formation, inflammation, regeneration after injury, and fundamental epidermal developmental pathways. These studies also revealed potential effects on genes not previously implicated in ILK functions, including those important for melanocyte and melanoblast development and function, regulation of cytoskeletal dynamics, and homeobox genes. This study shows that ILK is a critical regulator of multiple aspects of epidermal function and homeostasis, and reveals the previously unreported involvement of ILK not only in epidermal differentiation and barrier formation, but also in melanocyte genesis and function.

Selection and characterization of human antibody fragments specific for psoriasin - a cancer associated protein

S100A7 (psoriasin) is a calcium-binding protein that is upregulated in many types of cancer and often associated with poor prognosis. Its role in carcinogenesis has been associated with the stimulation of VEGF and EGF activity. The recent research showed that psoriasin directly interacts with αvβ6 integrin, a protein related to the invasive phenotype of cancer. Moreover, this interaction promotes the αvβ6-dependent invasive activity. The important function of S100A7 in carcinoma development determines a great need for valuable tools enabling its detection, quantification and also activity inhibition. Here, we show the selection of S100A7 specific antibody fragments from the human scFv phage library ETH-2 Gold. We have selected antibody fragments specific for psoriasin, purified them and analyzed by BIAcore affinity measurements. The best clone was subjected to affinity maturation procedure yielding molecule with a subnanomolar affinity towards human S100A7 protein. Selected clone was expressed in a bivalent format and applied for immunostaining analysis, which confirmed the ability of the antigen recognition in physiological conditions. We therefore propose that obtained antibody, that is the first phage display-derived human antibody against psoriasin, can serve as a useful psoriasin binding platform in research, diagnostics and therapy of cancer.