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D Schadendorf

Publications and source records attributed to D Schadendorf.

At least 91 records · Page 5Linked to original sources
PubMed1996

Expression of CD44 splice variants in human skin and epidermal tumours.

Splice variants of the adhesion molecule CD44 (CD44v) are important in the lymphatic spread of rat carcinoma cells. In several human tumours expression of CD44v correlates with tumour progression. However, little is known about the physiological functions of distinct variant exons. Here we report on the immunohistological evaluation of CD44 expression in normal human skin and epidermal tumours which do not metastasise, or do so vary rarely. Frozen tissues were stained with a panel of monoclonal antibodies, recognizing epitopes of the CD44 standard isoform, as well as of variant exons v5, v6, v7, v7-v8 and v10. Stratum basale and spinosum as well as the root shaft of hairs reacted strongly with the whole panel of anti-CD44 antibodies. Stratum corneum, acinar cells of sebaceous and eccrine sweat glands stained with anti-CD44v5, anti-CD44v6 and anti-CD44v7, but not with anti-CD44v10, the latter recognizing the "epithelial isoform" (CD44v8-v10) of CD44. Ductal cells of glands and apocrine glands did not express CD44v. Compared with its expression in normal human skin, CD44v expression was reduced in basal cell carcinoma and squamous cell carcinoma of the skin. This was particularly true of CD44v10. The expression of CD44v in normal skin and dermal appendages indicates that not all combinations of variant exons are involved in tumour progression. Since the epithelial isoform is particularly downregulated in basal cell carcinoma and squamous cell carcinoma of the skin, it is unlikely that exons v8-v10 play a role in tumour progression. Rather, they may be of functional importance in maintenance of the epidermal structure.

Animals↗
PubMed1996

Metastatic potential of human melanoma cells in nude mice--characterisation of phenotype, cytokine secretion and tumour-associated antigens.

Incidence and mortality of human malignant melanoma has risen rapidly over recent decades. Although the notorious resistance to treatment is characteristic for metastatic malignant melanoma, only a few experimental models have been established to study the metastatic cascade or to test new alternative treatment modalities. Thus, new human models are wanted. Here, we describe the metastatic behaviour of seven human melanoma cell lines derived from two primary cutaneous melanomas (WM 98-1, WM 1341) and five metastases established from liver (UKRV-Mel-4), skin (M7, M13), pleural effusion (UKRV-Mel-2) and lymph node (MV3). All cell lines were analysed for their capacity to grow in nude mice after s.c. and i.v. administration. M13 cells developed liver metastases spontaneously after s.c. injection, and subsequent passages of M13 and M7 melanoma cells caused liver metastases after i.v. injection, whereas MV3 and WM98-1 gave rise to lung metastases, using the same inoculation route. In contrast, WM 1341, UKRV-Mel-2 and UKRV-Mel-4 grew only very slowly in nude mice after s.c. injection and did not cause any metastases after i.v. or s.c. administration. The pattern of metastases or growth kinetics did not correlate with the interleukin 8 or tumour necrosis factor secretion of cell lines. Adhesion molecules and growth factor receptor expression on the cell lines differed widely, as determined by flow cytometry, with the low metastatic cell lines (UKRV-Mel-2, UKRV-Mel-4 and WM 1341) demonstrating a marked reduction in VLA-1 and VLA-5 expression compared with the metastatic lines (M7, M13, MV3 and WM 98-1). Expression of pigment-related proteins such as tyrosinase, TRP-1, TRP-2, Melan-A/MART-1, gp100, MAGE1 or MAGE-3 was not associated with growth and metastatic characteristics of the melanoma cell lines analysed. In conclusion, the established human melanoma cell lines exhibited diverse growth behaviour in nude mice in congruence with some early established prognostic markers such as VLA-1 and VLA-5. The xenografts provide good models for further study of metastatic processes as well as for evaluation of alternative treatment modalities including new pharmaceutical drugs and gene therapeutic targeting using tissue-specific gene regulatory elements for gene targeting.

Animals↗
PubMed1996

Treatment of melanoma cells with the synthetic retinoid CD437 induces apoptosis via activation of AP-1 in vitro, and causes growth inhibition in xenografts in vivo.

Human malignant melanoma is notoriously resistant to pharmacological modulation. We describe here for the first time that the synthetic retinoid CD437 has a strong dose-dependent antiproliferative effect on human melanoma cells (IC50: 5 x 10(-6) M) via the induction of programmed cell death, as judged by analysis of cell morphology, electron microscopical features, and DNA fragmentation. Programmed cell death was preceded by a strong activation of the AP-1 complex in CD437-treated cells as demonstrated by gel retardation and chloramphenicol transferase (CAT) assays. Northern blot analysis showed a time-dependent increase in the expression of c-fos and c-jun encoding components of AP-1, whereas bcl-2 and p53 mRNA levels remained constant. CD437 also exhibited a strong growth inhibitory effect on MeWo melanoma cells in a xenograft model. In tissue sections of CD437-treated MeWo tumors from these animals, apoptotic melanoma cells and c-fos overexpressing cells were colocalized by TdT-mediated deoxyuridine triphosphate-digoxigenin nick end labeling (TUNEL) staining and in situ hybridization. Taken together, this report identifies CD437 as a retinoid that activates and upregulates the transcription factor AP-1, leading eventually to programmed cell death of exposed human melanoma cells in vitro and in vivo. Further studies are needed to evaluate whether synthetic retinoids such as CD437 represent a new class of retinoids, which may open up new ways to a more effective therapy of malignant melanoma.

Animals↗
PubMed1996

Interleukin-7. Biology and implications for dermatology.

In recent years, it has become apparent that IL-7, originally characterized as a growth factor for pre-B lymphocytes, also has important implications for the skin. Keratinocytes have been shown to produce IL-7. which in turn can elicit a variety of biological responses on several cell types residing in the skin. IL-7 has been demonstrated to augment the cytolytic activity of cytotoxic T cells (CTL) and natural killer (NK) cells against various neoplastic targets including melanoma cells. Proliferation and long-term survival of murine dendritic epidermal T lymphocytes (DETC) in vitro is supported by IL-7. IL-7 also induces secretion of inflammatory cytokines by monocytes/macrophages and renders these cells to become tumoricidal against melanoma cells. Normal and malignant melanocytes respond to IL-7 with increased expression of intercellular adhesion molecule (ICAM-1). In addition, IL-7 has been shown to act as growth factor for Sezary cells, suggesting a role of keratinocyte-derived IL-7 in the pathogenesis of cutaneous T cell lymphoma. Because of the potent in vitro immunomodulatory effects of IL-7 which have been confirmed in mouse tumor models, IL-7 may become a valuable additional agent to immunotherapeutical regimens currently studied in patients with advanced melanoma. This review summarizes our present knowledge about the molecular and immunological properties of IL7 with emphasis on the effects of that cytokine within the cutaneous compartment and the potential clinical utility in dermatology.

Animals↗
PubMed1996

Quantitative detection of soluble adhesion molecules in sera of melanoma patients correlates with clinical stage.

BACKGROUND: Adhesion is crucial in the metastatic process of malignant tumours. Recently, the expression of certain selectins on intratumoral vessels has been shown to be associated with the clinical outcome of melanoma patients. OBJECTIVES AND METHODS: For the first time, this study examines the serum concentrations of circulating soluble vascular cellular adhesion molecule 1 (CD 106), endothelial leucocyte adhesion molecule (CD62E), sP-selectin (CD62P) and sCD44v5 in comparison to soluble intercellular adhesion molecule 1 (sICAM-1, CD54) in a series of 34 melanoma patients at different clinical stages and 11 normal donors using ELISA: RESULTS: sICAM-1 and sP-selectin levels were statistically elevated in all subgroups of melanoma patients compared to controls (p < 0.01). Circulating ICAM-1 as well as sP-selectin might be valuable additional serological tumour markers which correspond to tumour load and correlate with progression of malignant melanoma. CONCLUSION: Measurement of sICAM-1 and sP-selectin serum levels might therefore provide a sensitive tool for monitoring the clinical course of melanoma.

Adult↗
PubMed1996

Expression of CD44 variant isoforms in malignant melanoma.

In a variety of human tumors, expression of splice variants of the adhesion molecule CD44 (CD44v) has been described as correlating with tumor progression. Here, we report on the expression of CD44v in melanocytes, nevi, primary melanomas, and cutaneous and lymph node metastases. Thirteen nevi, 65 primary melanomas of varying thickness, 39 cutaneous and 15 lymph node metastases, and melanocytes and a panel of melanoma lines were tested for surface expression of the standard form of CD44 and the variant exons v5, v6, v7, v7-v8, and v10 by immunohistology or fluorescence-activated cell sorting. Melanocytes did not express any variant isoform of CD44. However, nevi, as well as primary melanoma and melanoma metastases, stained to a varying degree with anti-CD44v5, anti-CD44v7-v8, and anti-CD44v10. Exons v6 and v7 were not detected on any of these tissue specimens. Compared with nevi, expression of exon v10 was up-regulated in thick primary tumors and skin metastases. Lymph node metastases displayed elevated levels of exon v5. Expression of CD44v in melanoma lines (n = 20) differed, inasmuch as many lines did not express variant isoforms; in particular, exon v10. Interestingly, however, the few CD44v5-positive melanoma lines metastasized in the nu/nu mouse. Because benign as well as malignant growth of melanocytes was accompanied by expression of CD44 variant isoforms, a linkage between expression of CD44 variant isoforms and malignant transformation or tumor progression was excluded. Considering the function of distinct isoforms, one might speculate that expression of exon CD44v5, which was up-regulated in lymph node metastases compared with nevi and primary melanoma, provided a growth stimulus. Exon v10 is present at high density in epidermal cells. The de novo expression of this exon in nevi and the increased expression in thick melanoma and skin metastases would be in line with the assumption of an anchoring advantage in the surrounding epidermal tissue.

Animals↗
PubMed1995

Human c-myb is expressed in cervical carcinomas and transactivates the HPV-16 promoter.

Human c-myb is normally involved in the regulation of proliferation and differentiation of hematopoietic cells. Until now, only a few reports have described elevated c-myb gene expression in epithelial tissue, suggesting that under certain circumstances, c-Myb protein might play a role during the process of malignant transformation of epithelial cells. To investigate a possible role of c-myb during papillomavirus-associated carcinogenesis, we investigated the c-myb mRNA expression in human papillomavirus (HPV)-associated tumors and tumor cell lines. Seven of nine cervical carcinomas and two of three carcinoma cell lines exhibited elevated c-myb transcriptional activity. In contrast to malignant cervical neoplasias, only 3 of 15 condylomata acuminata expressed a sparse signal for c-myb mRNA. Since the c-Myb protein has been described as a potent transcriptional regulator, we investigated the transactivating properties of c-Myb on the HPV-16 promoter/enhancer. Cotransfection of a chloramphenicol acetyltransferase-reporter plasmid containing the HPV-16 enhancer/promoter element with a full-length c-Myb-expressing plasmid resulted in a significant induction (4.3-fold) of the HPV-16 promoter, whereas expression of a carboxy-terminally deleted c-Myb protein led to no effects. Gel shift experiments showed a specific binding of recombinant c-Myb protein on the HPV-16 P97 enhancer. These data indicate that elevated c-myb expression occurs with HPV-associated cell transformation. Since c-Myb has been shown to stimulate the HPV-derived oncoprotein expression via transcriptional activation, it may play a role in the process of HPV-associated cervical carcinogenesis.

Base Sequence↗
PubMed1995

Characterization of gene regulatory elements for selective gene expression in human melanoma cells.

Since chemotherapy is not sufficiently effective, an alternative strategy for the treatment of advanced melanoma could be an in vivo gene therapy approach. For this purpose, a highly accurate delivery of the therapeutic gene and cell specific gene expression is essential. Since melanocytic cells are characterized by their pigmentation, and since tyrosinase is the key enzyme involved in melanogenesis, we studied the expression of a reporter gene which is under the control of the tyrosinase promoter or a combination of melanocyte-specific enhancer and tyrosinase promoter in ten human melanoma and four epithelial cell lines. Reporter gene expression was upregulated up to 21-fold using the tyrosinase promoter and up 154-fold using the enhancer/promoter construct compared to a control plasmid. Gene expression was strongly associated with capacity of cells for melanin synthesis. The results suggest that the use of tissue specific gene regulatory elements might provide a new opportunity for targeting therapeutic genes to melanoma cells.

Chloramphenicol O-Acetyltransferase↗
PubMed1995

Association with clinical outcome of expression of VLA-4 in primary cutaneous malignant melanoma as well as P-selectin and E-selectin on intratumoral vessels.

BACKGROUND: The process of tumor growth and metastasis is a complex multistep cascade. The ability of tumor cells to adhere to and detach from extracellular matrix and endothelial cells may be crucial in the metastatic process and may dramatically alter the clinical prognosis and outcome for patients with certain cancers. A number of adhesion molecules have been detected on human melanoma cells and have been associated with various properties in vitro including invasiveness. Recent findings from our laboratory have indicated an ordered change in integrin expression during the process of tumor progression. PURPOSE: This study was designed to identify molecular markers present on human melanoma cells and in intratumoral vessels that have prognostic significance regarding disease-free interval and survival time. METHODS: Specimens of primary cutaneous malignant melanoma were obtained from 60 patients who had been followed for at least 36 months, with development of metastases in 29 patients during that period of time, and were analyzed for their expression of VLA-4, VLA-6, ICAM-1, ELAM-1 (E-selectin), CD62 (P-selectin), and CD44v6 molecules on tumor and endothelial cells by immunostaining. Light microscopy was used to evaluate and categorize the number of positively stained cells. Statistical analyses were done to determine the relationship of the expression of individual adhesion molecules with time to disease progression (i.e., disease-free interval) and overall survival time. RESULTS: In each case, positive staining for ELAM-1 and CD62 on intratumoral vessels and for VLA-4 on human melanoma cells was negatively associated with disease-free interval (P < .01) and overall survival time (P < .01). The presence of VLA-6, CD44v6, and ICAM-1 on melanoma cells was not associated with clinical outcome. CONCLUSIONS: Immunohistochemical screening and detection of ELAM-1, CD62, and VLA-4 may help to define a subgroup of melanoma patients at risk of developing metastases.

Adult↗
PubMed1995

Dendritic cells generated from peripheral blood transfected with human tyrosinase induce specific T cell activation.

Peptides of melanosomal proteins have recently been shown to be recognized in an HLA-restricted mode by specific cytolytic T lymphocytes in melanoma patients. Dendritic antigen-presenting cells (DC) are considered to be the most effective stimulators of T cell responses, and the use of these cells has therefore been proposed to generate therapeutic responses to tumor antigens in cancer patients. We, therefore, generated DC from peripheral blood of normal donors in the presence of granulocyte/macrophage colony-stimulating factor and interleukin-4. Flow cytometric analysis of the cells during a 2-week culture revealed a loss of CD14 and CD34 expression, a concomittent increase of CD1a, CD11a,b and c, CD44, CD45, CD54, HLA-class I and II, and intermediate levels of CD26, CD80 and CD86. Cultured DC stimulated proliferation of allogeneic T cells and induced a marked, up to 20-fold, stimulation of T cell proliferation after pulsing with tetanus toxoid. To achieve independence of already-identified antigenic peptides presented in HLA class I-restricted fashion, which limits the general applicability of such peptides for vaccination of melanoma patients, we tested whether DC are transfectable with eukaryotic expression plasmids. DC transfected with two reporter genes (CAT, beta-galactosidase) using a liposome-based transfection technique, exhibited only low levels of enzymatically active proteins, but were able to degrade rapidly intracellular proteins and to process peptides efficiently. Chloramphenicol acetyltransferase as well as tyrosinase mRNA were detectable after transfection by reverse-transcriptase-polymerase chain reaction, and enzyme activities became measurable. Furthermore, DC transfected with the tyrosinase gene were able to induce specific T cell activation in vitro, indicating appropriate peptide processing and presentation in DC after transfection. These data suggest new approaches to future tumor vaccination strategies.

Amino Acid Sequence↗
PubMed1995

Effects of various synthetic retinoids on proliferation and immunophenotype of human melanoma cells in vitro.

Since response rates in human melanoma are low with currently available therapeutic modalities, we have reevaluated the potential usefulness of retinoids as new alternatives for therapy of metastatic melanoma. Nine synthetic retinoids with high affinity and/or selectivity for the retinoic acid receptors (RAR) alpha, beta, and gamma were studied in comparison to all-trans retinoic acid (RA) for their in vitro effects on melanoma cell proliferation and for their immunomodulating capacities using four human melanoma cell lines. Eight out of ten retinoids tested had no effect on melanoma cell growth, whereas the remaining two compounds with high RAR-gamma selectivity (CD437 and CD2325) showed a dose-dependent antiproliferative effect on all melanoma cell lines with IC50 (concentration inhibiting response by 50%) values between 10(-6) and 10(-7)M. Further analyses showed that paracrine-mediated tumor cell growth inhibition such as induction of transforming growth factor (TGF)-beta described as one mechanism of retinoid action and enzyme systems such as tyrosinase and monoamine oxidase were not involved in mediating the antiproliferative effects exerted by the two retinoids. Four of nine retinoids modulated HLA-DR expression on human melanoma cells, and expression levels of intercellular adhesion molecule 1 (ICAM-1) was increased by another subset of compounds. These effects were, however, not correlated to the receptor selectivity of the retinoids. The potent growth inhibitory effect of the RAR-gamma-selective retinoids and the immunomodulating capacities of the retinoids open an interesting alternative for new antiproliferative and immunomodulatory strategies in the treatment of metastatic melanoma.

Antigens, CD↗
PubMed1995

Mast cells in melanocytic tumours.

The importance of mast cells in local homeostasis, inflammation and tumour surveillance is supported by many studies, and the association of mast cells with various neoplasms has been known for a long time. The functional significance of mast cells surrounding tumours is currently unclear. In the present histopathological study, 16 naevi and 44 primary malignant melanomas were analysed. The follow-up time after primary surgery of malignant melanoma patients was almost 10 years, during which time half of the tumours had metastasized. The numbers of mast cells surrounding pigmented lesions were determined. The mast cells were visualized using a modified toluidine blue staining (pH 0.5; 24 h). Significantly different numbers of mast cells were found in naevi compared to melanomas (P = 0.0013), but no significant correlation could be identified regarding prognostic parameters including tumour thickness and clinical outcome.

Adult↗
PubMed1995

[Interleukin 7 in dermatology. Molecular, immunologic and preclinical aspects].

The vast body of knowledge on interleukin-7 (IL-7) that has accumulated over the last few years, i.e. since its discovery in 1988, is of increasing relevance for dermatologists. Because of its particular immunological effects, IL-7 is of particular interest in two areas of dermatology. First, IL-7 can be a valuable addition to immunotherapeutic approaches to the treatment of malignant melanoma. A first pilot study of IL-7 gene-modified autologous tumour cells in the treatment of metastatic melanoma is therefore currently being initiated by the authors. Then, keratinocytes are efficient IL-7-secreting cells and there is evidence that IL-7 can modulate the presence and proliferation of normal and malignant lymphopoietic cells in the dermis. In addition, IL-7 is presently the most potent growth factor for in vitro cultivation of Sézary cells and for the establishment of Sézary cell lines. This report reviews molecular, immunological and preclinical properties of IL-7, with special reference to the possible therapeutic efficacy of this cytokine in dermatology.

Genetic Therapy↗
PubMed1995

Nuclear proto-oncogene products transactivate the human papillomavirus type 16 promoter.

Human papillomavirus (HPV) type 16 and 18 viral genomes are frequently detected in cervical and penile cancer biopsies. Although this strongly suggests a prominent role for HPV infection in the development of genital cancer, other genetic or environmental factors are also involved. Genital cancer is postulated to result from loss of cellular control functions, which leads to an unregulated expression of HPV oncogenic proteins. In our study, we determined the trans-activating properties of nuclear proto-oncogene proteins c-Fos, c-Jun and c-Myc on P97 enhancer/promoter activity of HPV16. Using a CAT-reporter construct containing the HPV16 enhancer/promoter element, we investigated the trans-activating effects of c-Fos, c-Jun, c-Myc, and E2 in cervical HT-3 cells. c-Fos and c-Jun overexpression resulted in a 3.3- and 3.1-fold up-regulation of CAT activity. Only 2-fold induction was determined by co-transfection with c-myc and the viral transcription factor E2. Based on these findings, we investigated the expression of HPV DNA (16 and 18) as well as nuclear proto-oncogenes (c-fos, c-jun and c-myc) in nine cervical cancers by in situ hybridisation. In six out of nine carcinomas, HPV16 and/or HPV18 DNA was detectable. All tumours showed an intense and homogeneous expression of c-fos and c-jun mRNA, while the signal for c-myc was detectable only in four specimens. These data suggest that deregulation of nuclear proto-oncogene expression may contribute to an overexpression of HPV-derived oncogenic proteins (E6 and E7), which is generally hypothesised to be an important step in the malignant transformation of HPV-associated tumours.

Base Sequence↗