Alterations in antigenic properties of normal epidermis adjacent to basal cell carcinomas

Contribution of Keratinocytes in Skin Cancer Initiation and Progression

Keratinocytes are major cellular components of the skin and are strongly involved in its homeostasis. Oncogenic events, starting mainly from excessive sun exposure, lead to the dysregulation of their proliferation and differentiation programs and promote the initiation and progression of non-melanoma skin cancers (NMSCs). Primary melanomas, which originate from melanocytes, initiate and develop in close interaction with keratinocytes, whose role in melanoma initiation, progression, and immune escape is currently being explored. Recent studies highlighted, in particular, unexpected modes of communication between melanocytic cells and keratinocytes, which may be of interest as sources of new biomarkers in melanomagenesis or potential therapeutic targets. This review aims at reporting the various contributions of keratinocytes in skin basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and melanoma, with a greater focus on the latter in order to highlight some recent breakthrough findings. The readers are referred to recent reviews when contextual information is needed.

In situ hybridization analysis of the expression of human telomerase RNA in normal and pathologic conditions of the skin

Human telomerase RNA (hTER) expression in skin was examined by in situ hybridization analysis. All newborn foreskins examined (n = 5) expressed hTER in epidermal basal cells at moderate levels. Telomerase RNA was not detectable in most adult specimens from sun protected areas (six of seven), whereas all samples obtained from sun exposed areas (n = 8) showed moderate hTER signals in epidermal basal cells. Telomerase RNA was also detected at moderate to strong levels in basal cells of psoriasis, contact dermatitis, and the proliferative cells of the anagen hair bulb. Basal cell carcinoma samples (14 of 15) had moderate to high hTER expression throughout the entire tumor, whereas squamous cell carcinomas (seven of eight) showed variable intensities of hTER expression but only in the cells at the periphery of tumor nests. All melanomas examined (n = 5) had moderate hTER expression in all tumor cells. The hTER signal intensities in skin tumors did not correlate with the age or sex of the donors, the clinical history of the lesions, or the histologic subtypes. To address whether hTER expression correlated with the proliferative state, sequential sections were stained with anti-Ki-67 antibody, a proliferation marker. In newborn foreskins, squamous cell carcinomas, and basal cell carcinomas, the distributions of hTER and Ki-67 were similar but not always identical. Telomerase RNA was more abundant than Ki-67 in the basal and suprabasal layer of newborn foreskins, suggesting that hTER expression is present both in actively cycling and in resting cells.

Differential patterns of placental and epithelial cadherin expression in basal cell carcinoma and in the epidermis overlying tumours

P-cadherin (P-CD) and E-cadherin (E-CD) are expressed by keratinocytes and play an important role in skin morphogenesis. P-CD expression is restricted to the basal layer of normal epidermis, whereas E-CD is expressed in all the living layers. We have previously reported a reduced expression of E-CD in most cases of infiltrative basal cell carcinoma (BCC). In the present work we have investigated by immunohistochemistry the expression of both P-CD and E-CD in a new series of 32 patients with BCC. Most cases of superficial multicentric BCC and some nodular tumours had preserved expression of both cadherins in all tumour cells. The majority of nodular BCCs had partially reduced expression of one or both cadherins with an ordered distribution of cells showing different cadherin staining throughout the tumour mass. A severe reduction of E-CD expression with a disordered distribution of cells with different immunostaining intensity was observed in most specimens of infiltrative BCC. In contrast, P-CD expression was preserved in all cases of infiltrative BCC. These results suggest that P-CD and E-CD play different roles in the growth pattern of BCC. In addition, both anomalous P-CD expression and reduced E-CD expression were frequently observed in the spinous layer of epidermis overlying tumours. This phenomenon was significantly associated with the presence of keratinocytic atypia, which suggests that disturbed cadherin expression could be a marker of premalignant changes and/or hyperproliferative activity in human epidermis.

Ehlers-Danlos syndrome type VIII: biochemical, stereological and immunocytochemical studies on dermis from a child with clinical signs of Ehlers-Danlos syndrome and a family history of premature loss of permanent teeth

We studied collagen expressed by skin fibroblasts in culture, and performed immunocytochemical, ultrastructural and stereological analysis of dermis from a child with signs reminiscent of a mild Ehlers-Danlos syndrome (EDS) type IV and severe periodontitis. No alterations in types I and III [corrected] collagen synthesis and secretion, or serum levels of type III procollagen aminoterminal propeptide were found, and morphological studies revealed non-specific alterations of collagen and elastic components observed in many connective tissue disorders.

Biology of basal cell carcinoma (Part I)

Basal cell carcinoma is the most common malignancy in humans. Although rarely metastatic, it is capable of significant local destruction and disfigurement. This two-part article reviews the current understanding of basal cell carcinoma biology. Part I examines significant clinical, histologic, and ultrastructural features that relate to invasive potential. Genetic characteristics, including tumor growth rate, chromosomal abnormalities, and oncogene presence, are discussed, and expression of important cell and matrix proteins, including keratin, fibronectin, and HLA antigens, are reviewed. Further topics to be explored in Part II include host immunologic responses, theories of pathogenesis, and valuable second-line therapeutic regimens for treatment of multiple cancers.

Advances in the immunobiology of the skin. Implications for cutaneous malignancies

Recent advances in cutaneous immunobiology have led to the realization that skin is an important and unique immunologic organ. Studies on the immunobiology of skin cancers induced by ultraviolet radiation indicate that immune mechanisms can play a crucial role in the development of cutaneous tumors. This paper summarizes the evidence linking skin and the immune system and discusses current hypotheses concerning the mechanisms by which UV radiation interferes with cutaneous immunity. The significance of these findings for cutaneous carcinogenesis is discussed.

The use of monoclonal antibody to keratin in human epidermal disease: alterations in immunohistochemical staining pattern

A monoclonal antikeratin antibody, designated AEl, was used to stain frozen sections of normal and abnormal human skin by the immunofluorescence and peroxidase-antiperoxidase techniques. In normal human epidermis and ichthyosis vulgaris, a nonproliferative epidermal disease, this antibody selectively stained epidermal basal cells. Very different staining patterns were observed in various other epidermal diseases. A suprabasal staining pattern was observed in psoriasis (16 cases), verruca (9), seborrheic keratosis (5), actinic keratosis (2), as well as the epidermis adjacent to certain epidermal neoplasms (4). Basal cell carcinoma (7) showed weak, homogeneous staining. In contrast, a disorganized pattern consisting of cells with various staining intensities was observed in Bowen's disease (2) and squamous cell carcinoma (4). Although the biochemical basis for these altered staining patterns remains to be elucidated, these results provide further evidence that epidermal keratin expression can be affected by various disease states. Moreover, our data suggest that a common alteration in keratin expression, as defined by the suprabasal AEl staining pattern, exists in psoriasis and a number of other benign hyperproliferative epidermal diseases.

Local immune response in basal cell carcinoma: characterization by transmission electron microscopy and monoclonal anti-T6 antibody

We examined lesional and perilesional skin from nine basal cell carcinomas occurring in six patients to determine the role of local immunity in the pathogenesis of these neoplasms. Marked hyperplasia of Langerhans cells and indeterminate cells as defined by monoclonal anti-T6 antibody was observed in lesional and perilesional skin of most specimens. Ultrastructurally, Langerhans cells were observed in the dermis and above the basement membrane zone where mitotic activity was documented. Apposition of Langerhans cells and indeterminate cells with degenerating and necrotic neoplastic keratinocytes and with exocytotic lymphocytes was frequently encountered. Zonal necrosis of carcinoma cells was often immediately peripheral to exocytotic lymphoid cells. These observations support the contention that an active local immunologic response is related to the biologic behavior of some basal cell carcinomas.

Significant progress in dermatologic research since 1977

Some active fields of experiment dermatology have been selected to demonstrate the interaction between basic research and clinical dermatology. The identification of the Langerhans cell, the typing of mononuclear cells, and the identification of T cell growth factors have significant implication in contact dermatitis, lymphomas, etc. The group of papovaviruses is better defined in relationship to the type of disease that they produce and its oncogenic potential. Various types of vasculitis are better understood, thanks to research in humoral immunity and complement activation. Melanogenesis and its control by peptides is progressing. New specific proteins have been identified in the connective tissues, and their role has been clarified. Identification of specific proteins of keratinocytes and study of differentiation of these cells have provided useful information and some skin disorders. The control of epidermal cell proliferation and differentiation, through membrane receptors, growth factors, and intracellular enzymes, is progressively giving clues to the understanding of genetic disorders, cancers, the effect of retinoids and phototherapy.