Cristina Vaschieri

Survivin Identifies Keratinocyte Stem Cells and Is Downregulated by Anti-β1 Integrin During Anoikis

Survivin belongs to the family of inhibitor of apoptosis proteins and is involved in regulation of cell death as well as cell division. Here, we show that wild‐type (WT) survivin is expressed in a subpopulation of basal keratinocytes in normal human skin at the cytoplasmic level. WT survivin is highly expressed in keratinocyte stem cells (KSCs), whereas its mRNA level decreases in transit amplifying (TA) cells and disappears in postmitotic (PM) cells. Likewise, WT survivin protein is expressed in KSCs, almost undetectable in TA cells, and absent in PM cells. Real time polymerase chain reaction demonstrates that the putative antiapoptotic isoforms survivin‐2B and survivin‐ΔEx3 are expressed at the highest levels in KSCs, whereas they tend to decrease in TA cells and disappear in PM cells. On the contrary, the putative proapoptotic variants of survivin, survivin‐3B, and survivin‐2α tend to be high in PM and TA cells and are almost absent in KSCs. By confocal microscopy, survivin is predominantly expressed at the nuclear level in KSCs, which proliferate significantly better than TA cells, which, in turn, express mostly cytosolic WT survivin. Blocking β1 integrin signal downregulates WT survivin mRNA and protein expression and induces apoptosis (anoikis) in KSCs. On the other hand, inhibition of β1 integrin upregulates mRNA expression of survivin‐2α. Taken together, these results indicate that survivin identifies human KSCs. Expression of nuclear survivin could reflect the different behavior between KSCs in vitro and in vivo, in terms of proliferation. Finally, survivin could be part of the “niche” protection by preventing anoikis in KSCs.

Functionalized gold nanoparticles for topical delivery of methotrexate for the possible treatment of psoriasis.

Gold nanoparticles (AuNPs) represent an effective choice for topical drug delivery systems thanks to their small size, general non-toxicity, ease of functionalization and high surface to volume ratio. Even if systemic, methotrexate still plays an important role in psoriasis treatment: its topical use shows insufficient percutaneus penetration owing to limited passive diffusion, high molecular weight and dissociation at physiological pH. The aim of our study was to design a new drug delivery nanocarrier for Methotrexate and to improve its solubility, stability and biodistribution. AuNPs were on purpose prepared with a hydrophilic stabilizing layer, in order to improve the colloidal stability in water. Water-soluble gold nanoparticles functionalized by sodium 3-mercapto-1-propansulfonate (Au-3MPS) were prepared and loaded with methotrexate (MTX). The loading efficiency of MTX on Au-3MPS was assessed in the range 70-80%, with a fast release (80% in one hour). The release was studied up to 24h reaching the value of 95%. The Au-3MPS@MTX conjugate was fully characterized by spectroscopic techniques (UV-vis, FTIR) and DLS. Preliminary toxicity tests in the presence of keratinocytes monolayers allowed to assess that the used Au-3MPS are not toxic. The conjugate was then topically used on C57BL/6 mouse normal skin in order to trace the absorption behavior. STEM images clearly revealed the distribution of gold nanoparticles inside the cells. In vitro studies showed that Methotrexate conjugated with Au-3MPS is much more efficient than Methotrexate alone. Moreover, DL50, based on MTT analysis, is 20 folds reduced at 48 h, by the presence of nanoparticles conjugation. UV-vis spectra for in vivo tracing of the conjugate on bare mouse skin after 24h of application, show increased delivery of Methotrexate in the epidermis and dermis using Au-3MPS@MTX conjugate, compared to MTX alone. Moreover we observed absence of the Au-3MPS in the dermis and in the epidermis, suggesting that these layers of the skin do not retain the nanoparticles. Based on our data, we found that the novel Au-3MPS@MTX conjugate is an effective non-toxic carrier for the satisfactory percutaneous absorption of Methotrexate and could help in possible topical treatment of psoriasis.

p75 neurotrophin receptor mediates apoptosis in transit amplifying cells and its overexpression restores cell death in psoriatic keratinocytes

p75 neurotrophin receptor (p75NTR) belongs to the TNF-receptor superfamily and signals apoptosis in many cell settings. In human epidermis, p75NTR is mostly confined to the transit-amplifying (TA) sub-population of basal keratinocytes. Brain-derived neurotrophic factor (BDNF) or neurotrophin-4 (NT-4), which signals through p75NTR, induces keratinocyte apoptosis, whereas β-amyloid, a ligand for p75NTR, triggers caspase-3 activation to a greater extent in p75NTR transfected cells. Moreover, p75NTR co-immunoprecipitates with NRAGE, induces the phosphorylation of c-Jun N-terminal kinase (JNK) and reduces nuclear factor kappa B (NF-κB) DNA-binding activity. p75NTR also mediates pro-NGF-induced keratinocyte apoptosis through its co-receptor sortilin. Furthermore, BDNF or β-amyloid cause cell death in TA, but not in keratinocyte stem cells (KSCs) or in p75NTR silenced TA cells. p75NTR is absent in lesional psoriatic skin and p75NTR levels are significantly lower in psoriatic than in normal TA keratinocytes. The rate of apoptosis in psoriatic TA cells is significantly lower than in normal TA cells. BDNF or β-amyloid fail to induce apoptosis in psoriatic TA cells, and p75NTR retroviral infection restores BDNF- or β-amyloid-induced apoptosis in psoriatic keratinocytes. These results demonstrate that p75NTR has a pro-apoptotic role in keratinocytes and is involved in the maintenance of epidermal homeostasis.

Pathologic Changes After Photodynamic Therapy for Basal Cell Carcinoma and Bowen Disease A Histologic and Immunohistochemical Investigation

OBJECTIVE To investigate the in vivo reactions and the mechanisms of cell death after photodynamic therapy (PDT) for cutaneous carcinomas. Photodynamic therapy is a new treatment modality for nonmelanoma skin cancers. Its effects on target tissue have been well investigated in vitro, where apoptosis appears to be the main effector mechanism, but its effects remain undefined in vivo. DESIGN Skin biopsy specimens were obtained sequentially after PDT for basal cell carcinoma and in situ squamous cell carcinoma (Bowen disease). Evidence from routine histologic evaluation was compared with a panel of apoptosis-related (TUNEL [terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling], caspase-3, and Bcl-2) and inflammatory (CD4, CD8, CD20, CD68, and CD56) markers. We used electron microscopy to evaluate cell damage at the ultrastructural level. MAIN OUTCOME MEASURES Evidence of the mechanisms of tumor cell damage after PDT, detection of histologic and/or immunohistochemical signs of apoptosis, and time course of the tumor destruction and inflammatory reaction. RESULTS Early epidermal damage and an acute dermal inflammatory response were detected 15 minutes after PDT. In basal cell carcinoma, nodule damage progressed from scant apoptotic cells seen at the dermal-epithelial junction to massive destruction seen after 1 and 2 days. The periphery of the basaloid nodules consistently showed earlier and predominant damage, as demonstrated by the perfect coincidence of histologic and immunohistochemical evidence with apoptotic markers (TUNEL and caspase-3 staining). Fibrosis and lentigolike changes were seen in late biopsy specimens. CONCLUSIONS This study defines the time course and characteristics of the skin tumor response to PDT. Taken together, our observations suggest that direct damage to cancer cells is the main effector mechanism leading to PDT response. The involvement of apoptosis is demonstrated by the simultaneous appearance of histologic, immunohistochemical, and ultrastructural markers that occur in the early phases of the cutaneous reaction to PDT. These observations could help to develop future refinements of the PDT technique.

Stem cell properties in cell cultures from different stage of melanoma progression.

Cutaneous melanoma is an extremely heterogenous human cancer. The most aggressive melanoma may contain deregulated cells with undifferentiated/stem cell-like phenotype. A critical mechanism by which melanoma cells enhance their invasive capacity is the dissolution of the intercellular adhesion and the acquisition of mesenchymal features as a part of an epithelial-to-mesenchymal transition. The aim of this study was to clarify the role of a stem cell-like population in human melanomas by means of melanocytic cell culture analysis obtained from distinct histotypes of primary and metastatic malignant melanoma. Patients with advanced melanoma >2 cm in diameter and/or >300 mm2 surface were enrolled. The melanoma cells were isolated from skin biopsies of lentigo maligna melanoma, superficial spreading melanoma, nodular melanoma, and metastatic melanoma. The colony forming unit assay and alkaline phosphatase stain were evaluated. Cells were subsequently cultured and maintained in different media to evaluate their ability to differentiate into osteogenic and adipogenic lineages. Immunohistochemistry and flow cytometry analysis were performed to evaluate antigenic markers CD90, CD73, CD105, CD146, CD20, CD166, and Nestin. This study confirms that melanoma can include heterogenous cell populations with the ability both to self-renew and to a give rise to differentiated progeny. Melanoma cells displayed intratumoral heterogeneity and dynamic antigen phenotypes. Histologically, transitions from normal skin to melanoma were associated with a gradual increase in the expression of CD146, CD20, CD133, Nestin, and CD73. These molecular profiles could be further analyzed and, in the future, used for the development of novel biomolecular targeted-therapy approaches.

Pemphigus with features of both vulgaris and foliaceus variants localized to the nose

We report the case of a 74‐year‐old man affected by an unusual variant of pemphigus. He presented with a crusty and scaly lesion of the nose. We performed reflectance confocal microscopy and optical coherence tomography on the lesion, which suggested an unexpected diagnosis of pemphigus. Therefore, to confirm our diagnostic suspicions, we executed indirect immunofluorescence and two biopsies, one for histopathological examination and one for direct immunofluorescence. Histopathological evaluation showed acantholysis with formation of clefts in the granular and spinous layers of the epidermis. Direct immunofluorescence revealed immunoglobulin G and C3 deposit to the full thickness of the epidermis. Indirect immunofluorescence showed intercellular antibodies at a titer of 1:40 in the suprabasal epidermis. The immunoblot analysis using epidermal extract revealed the presence of circulating antibodies directed to 130‐ and 160‐kDa antigens in the patients serum. These two antigens were evidenced from nitrocellulose membrane with colorimetric AP systems, which highlighted the presence of autoantibodies against desmoglein (Dsg)1 and Dsg3 (sodium dodecylsulfate polyacrylamide gel electrophoresis). We also performed an enzyme‐linked immunoassay. All these findings suggested that this patients pemphigus had features of both vulgaris and foliaceus variants.

Electrochemotherapy induces apoptotic death in melanoma metastases: a histologic and immunohistochemical investigation.

Background Electrochemotherapy (ECT) is increasingly used in the treatment of primary and secondary skin tumors, but little is known about the pathologic mechanism responsible for tumor cell destruction in humans. Knowledge of detailed mechanism of host response after ECT may improve the treatment efficacy related to patient selection and technique refinements. Aim The aim of the study was to investigate the histopathology and mechanism of cell death after ECT in cutaneous melanoma metastases. Methods Skin biopsy specimens were sequentially obtained after ECT of cutaneous melanoma metastases, during a follow-up period of 2 months. Results from histologic evaluation and immunohistochemical characterization of the inflammatory infiltrate (CD3, CD4, CD8, CD56, Granzyme-B) were compared with a panel of apoptosis-related markers. Main outcome measures Evidence of the mechanism of tumor cell damage, identification of histological and immunohistochemical signs of apoptosis and/or necrosis underlining a possible time course of tumor destruction and inflammatory reaction after ECT. Results Early signs of epidermal degeneration, an increase of the inflammatory infiltrate, and initial tumor cell morphological changes were already detected 10 min after ECT. The cell damage progression, as demonstrated by histological and immunohistochemical evidence using apoptotic markers (TUNEL and caspase-3 staining), reached a climax 3 days after treatment, to continue until 10 days after. Scarring fibrosis and complete absence of tumor cells were observed in the late biopsy specimens. A rich inflammatory infiltrate with a prevalence of T-cytotoxic CD3/CD8-positive cells was detected 3 h after ECT and was still appreciable 3 months later. Conclusion This study attempts to define the time course and characteristics of tumor response to ECT. The observations suggest both a direct necrotic cell damage and a rapid activation of apoptotic mechanisms that occur in the early phases of the cutaneous reaction to ECT. A persistent immune response of T-cytotoxic lymphocytes could possibly explain the long-term local tumor control.

Structure–Activity Relationships within a Series of σ1 and σ2 Receptor Ligands: Identification of a σ2 Receptor Agonist (BS148) with Selective Toxicity against Metastatic Melanoma

A new series of spirocyclic σ receptor (σR) ligands were prepared and studied. Most were found to have a high affinity and selectivity for σ1R; three compounds were shown to be σ1R agonists, while another proved to be the only σ1R antagonist. Only one of the σ1R agonists (BS148) also exhibited σ2R selectivity and was able to inhibit the growth of metastatic malignant melanoma cell lines without affecting normal human melanocytes. The antiproliferative activity of this compound suggested an σ2R agonist profile. Further, preliminary investigations indicated that the mechanism of metastatic malignant melanoma cell death induced by BS148 is due, at least in part, to apoptosis.