3D human foreskin model for testing topical formulations of sildenafil citrate.

Sildenafil citrate is an approved drug used for the treatment of erectile dysfunction and premature ejaculation. Despite a widespread application, sildenafil citrate shows numerous adverse cardiovascular effects in high-risk patients. Local transdermal drug delivery of this drug is therefore being explored as an interesting and noninvasive alternative administration method that avoids adverse effects arised from peak plasma drug concentrations.

CD271 activation prevents low to high-risk progression of cutaneous squamous cell carcinoma and improves therapy outcomes.

Background: Cutaneous squamous cell carcinoma (cSCC) is the second most prevalent form of skin cancer, showing a rapid increasing incidence worldwide. Although most cSCC can be cured by surgery, a sizeable number of cases are diagnosed at advanced stages, with local invasion and distant metastatic lesions. In the skin, neurotrophins (NTs) and their receptors (CD271 and Trk) form a complex network regulating epidermal homeostasis.

Isolation of an "Early" Transit Amplifying Keratinocyte Population in Human Epidermis: A Role for the Low Affinity Neurotrophin Receptor CD271.

In the interfollicular epidermis (IFE), stem cells (KSC) generate transit amplifying (TA) cells that, after symmetric divisions, produce differentiating daughters. Here, we isolated and characterized the highly proliferative interfollicular epidermal basal cell population "early" TA (ETA) cells, based on their capacity to adhere to type IV collagen. Proliferation and colony-forming efficiency in ETA cells are lower than in KSC but higher than in "late" TA (LTA).

Investigating Cutaneous Squamous Cell Carcinoma and : Novel 3D Tools and Animal Models.

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients' care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion.

In Vivo Melanoma Cell Morphology Reflects Molecular Signature and Tumor Aggressiveness.

Melanoma is the deadliest type of skin cancer characterized by high cellular heterogeneity, which contributes to therapy resistance and unpredictable disease outcome. Recently, by correlating reflectance confocal microscopy morphology with histopathological type, we identified four distinct melanoma subtypes: dendritic cell, round cell, dermal nest, and combined-type melanomas. In this study, each reflectance confocal microscopy melanoma subtype expressed a specific biomolecular profile and biological behavior in vitro.

Activation of cGMP-Dependent Protein Kinase Restricts Melanoma Growth and Invasion by Interfering with the EGF/EGFR Pathway.

Drug resistance mechanisms still characterize metastatic melanoma, despite the new treatments that have been recently developed. Targeting of the cGMP/protein kinase G pathway is emerging as a therapeutic approach in cancer research. In this study, we evaluated the anticancer effects of two polymeric-linked dimeric cGMP analogs able to bind and activate protein kinase G, called protein kinase G activators (PAs) 4 and 5.

Loss of DLX3 tumor suppressive function promotes progression of SCC through EGFR-ERBB2 pathway.

Cutaneous squamous cell carcinoma (cSCC) ranks second in the frequency of all skin cancers. The balance between keratinocyte proliferation and differentiation is disrupted in the pathological development of cSCC. DLX3 is a homeobox transcription factor which plays pivotal roles in embryonic development and epidermal homeostasis.

Molecular Approach to Cutaneous Squamous Cell Carcinoma: From Pathways to Therapy.

Cutaneous squamous cell carcinoma (cSCC) represents the second most frequent skin cancer,recently showing a rapid increase in incidence worldwide, with around >1 million cases/year in theUnited States and 2500 deaths [1] [...

Do DLX3 and CD271 Protect Human Keratinocytes from Squamous Tumor Development?

Well-regulated epidermal homeostasis depends on the function of different classes of factors, such as transcription regulators and receptors. Alterations in this homeostatic balance may lead to the development of cutaneous squamous tumorigenesis. The homeobox transcription factor DLX3 is determinant for a p53-dependent regulation of epidermal differentiation and modulates skin carcinogenesis.

Soluble Fas Ligand Is Essential for Blister Formation in Pemphigus.

Pemphigus is a blistering disease characterized by pemphigus autoantibodies (PVIgG) directed mostly against desmogleins (Dsgs), resulting in the loss of keratinocyte adhesion (acantholysis). Yet, the mechanisms underlying blister formation remain to be clarified. We have shown previously that anti-Fas ligand (FasL) antibody (Ab) prevents PVIgG-induced caspase-8 activation and Dsg cleavage in human keratinocytes, and that sera from pemphigus patients contain abnormally increased levels of FasL.

Zebrafish as a Model Organism for the Development of Drugs for Skin Cancer.

Skin cancer, which includes melanoma and squamous cell carcinoma, represents the most common type of cutaneous malignancy worldwide, and its incidence is expected to rise in the near future. This condition derives from acquired genetic dysregulation of signaling pathways involved in the proliferation and apoptosis of skin cells. The development of animal models has allowed a better understanding of these pathomechanisms, with the possibility of carrying out toxicological screening and drug development.

A novel DLX3-PKC integrated signaling network drives keratinocyte differentiation.

Epidermal homeostasis relies on a well-defined transcriptional control of keratinocyte proliferation and differentiation, which is critical to prevent skin diseases such as atopic dermatitis, psoriasis or cancer. We have recently shown that the homeobox transcription factor DLX3 and the tumor suppressor p53 co-regulate cell cycle-related signaling and that this mechanism is functionally involved in cutaneous squamous cell carcinoma development. Here we show that DLX3 expression and its downstream signaling depend on protein kinase C α (PKCα) activity in skin.

CD271 Down-Regulation Promotes Melanoma Progression and Invasion in Three-Dimensional Models and in Zebrafish.

CD271 is a neurotrophin receptor variably expressed in melanoma. Although contradictory data are reported on its role as a marker of tumor-initiating cells, little is known about its function in tumor progression. CD271 expression was higher in spheroids derived from freshly isolated cells of primary melanomas and in primary WM115 and WM793-B cell lines, and it decreased during progression to advanced stages in cells isolated from metastatic melanomas and in metastatic WM266-4 and 1205Lu cell lines.

Survivin Modulates Squamous Cell Carcinoma-Derived Stem-Like Cell Proliferation, Viability and Tumor Formation in Vivo.

Squamous Cell Carcinoma-derived Stem-like Cells (SCC-SC) originate from alterations in keratinocyte stem cells (KSC) gene expression and sustain tumor development, invasion and recurrence. Since survivin, a KSC marker, is highly expressed in SCC-SC, we evaluate its role in SCC-SC cell growth and SCC models. Survivin silencing by siRNA decreases clonal growth of SCC keratinocytes and viability of total, rapidly adhering (RAD) and non-RAD (NRAD) cells from primary SCC.

CD271 mediates stem cells to early progeny transition in human epidermis.

CD271 is the low-affinity neurotrophin (p75NTR) receptor that belongs to the tumor necrosis factor receptor superfamily. Because in human epidermis, CD271 is predominantly expressed in transit-amplifying (TA) cells, we evaluated the role of this receptor in keratinocyte differentiation and in the transition from keratinocyte stem cells (KSCs) to progeny. Calcium induced an upregulation of CD271 in subconfluent keratinocytes, which was prevented by CD271 small interfering RNA.

E-FABP induces differentiation in normal human keratinocytes and modulates the differentiation process in psoriatic keratinocytes in vitro.

Epidermal fatty acid-binding protein (E-FABP) is a lipid carrier, originally discovered in human epidermis. We show that E-FABP is almost exclusively expressed in postmitotic (PM) keratinocytes, corresponding to its localization in the highest suprabasal layers, while it is barely expressed in keratinocyte stem cells (KSC) and transit amplifying (TA) keratinocytes. Transfection of normal human keratinocytes with recombinant (r) E-FABP induces overexpression of K10 and involucrin.

Role of neurotrophins on dermal fibroblast survival and differentiation.

Neurotrophins (NTs) belong to a family of growth factors that play a critical role in the control of skin homeostasis. NTs act through the low-affinity receptor p75NTR and the high-affinity receptors TrkA, TrkB, and TrkC. Here we show that dermal fibroblasts (DF) and myofibroblasts (DM) synthesize and secrete all NTs and express NT receptors.

A previously unreported function of β(1)B integrin isoform in caspase-8-dependent integrin-mediated keratinocyte death.

Integrins regulate adhesive cell-matrix interactions and mediate survival signals. On the other hand, unligated or free cytoplasmic fragments of integrins induce apoptosis in many cell types (integrin-mediated death). We have previously shown that β(1) integrin expression protects keratinocyte stem cells from anoikis, whereas the role of the β(1)B integrin isoform has not been clarified.

Endogenous survivin modulates survival and proliferation in UVB-treated human keratinocytes.

Survivin is a bi-functional member of inhibitor of apoptosis protein family, as it is able to both inhibit apoptosis and to regulate cell cycle. We investigated the role of survivin in human keratinocytes under normal conditions and during UVB irradiation. Survivin siRNA decreases proliferation and induces apoptosis in human keratinocytes, in a mode consistent with the mitotic catastrophe.