摘要:

In human melanoma no complete information about the expression of the apoptosis-promoting and apoptosisinhibiting members of the Bcl-2 family has been available to date. In this study we have investigated by Western blotting the expression pattern of Bcl-2 and its homologues Bax, Bak, BCI-XL, Bcl-xs, Mcl-1 and Bad in 12 distant lymph node metastases from patients who have been treated by different regimes, in nine newly established cell lines of these metastases, in three cell lines obtained from other sources and in primary melanocytic cell lines from three neonatal and two adult subjects. Taken together, our data suggest that Bax, Bak, Bad, BclxLand Mcl-1 are expressed in addition to Bcl-2 in both normal melanocytes and in cell lines established from melanoma metastases. Regarding the role of Bcl-2 and its homologues, our data suggest that expression of this class of proteins is widespread and qualitatively similar in melanoma cell lines and normal human melanocytes. Although the expression of these proteins might affect growth behaviour and the progression of melanomas, our results are not compatible with the hypothesis that the Bcl-2 homologues investigated play a dominant role in the process of malignant transformation of melanocytes.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The effects of melatonin, its precursors and derivatives on the growth of cultured human uveal melanoma cells were studied. The melanoma cells were plated into 24-well plates. Melatonin, its 6-hydroxy or 6-chioro derivative, serotonin, tryptophan or kynurenine was added to the medium in concentrations of 0.001 to 1000 nM. After 5 days the cells were detached, counted, and compared with the controls. Melatonin inhibited the growth of uveal melanoma cell lines in a dose-dependent manner (0.1-10 nM). This growth inhibition occurred at concentrations of melatonin (2 nM) found in human aqueous humour. The melatonin derivatives also inhibited the growth of uveal melanoma cells; 6-chioromelatonin was more potent than melatonin and 6-hydromymelatonin was the least active (6-chioromelatonin > melatonin > 6-hydroxymelatonin). The precursors of melatonin (tryptophan and serotonin) and the abnormal metabolite of tryptophan (kynurenine) did not inhibit the growth of the melanoma cells, indicating that changes to the metabolic processes of melatonin may play a role in the pathogenesis of uveal melanoma.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Invasive growth and formation of metastases involve complex interactions between tumour cells, host cells and components of the extracellular matrix. Retinoids, a group of vitamin A derivatives, modulate cell growth and differentiation and have been found to suppress tumour cell invasion In vitro and formation of metastases in vivo. The aim of our study was to investigate changes in proliferation and invasion through membrane barriers in vitro of seven human melanoma cell lines, established from human primary melanomas or metastases, in response to treatment with retinoic acid (RA). These changes were compared with the expression and regulation of molecules that have been identified as targets of RA-mediated signal pathways. Invasiveness in vitro was correlated with the origin of the cell lines and was significantly higher in the lines derived from metastases. In all the cell lines proliferation and chemotaxis were inhibited by 10-5M RA, but the cell lines established from metastases were significantly more sensitive with respect to inhibition of invasion by RA. The specific expression patterns of MMP-1 and TIMP-2 were detected and regulated by RA in almost all cell lines, whereas expression of MMP-2 and TIMP-1 was not influenced by RA treatment. The most striking difference between the cell lines was a strong downregulation of transforming growth factor-β (TGF-β) expression in cell lines derived from metastases when treated with RA in contrast to cell lines from primary melanomas. These data provide evidence that RA modulates growth, chemotaxis and invasion in a broad panel of melanoma cell lines derived both from primary non-metastasized melanomas and metastases. However, distinct molecular mechanisms are involved in mediating these effects.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

New agents are required in the treatment of malignant melanoma, to be used alone or in combination with established therapies. Oncostatin M (OSM), a member of the gp130 family of cytokines, has previously been shown to inhibit the growth of melanoma cell lines. Tamoxifen (TAM) is widely used in the treatment of melanoma, typically in combination with chemo- and/or immunotherapy. A component of the antitumour activity of TAM is via modulation of transforming growth factor-β (TGFβ) which has previously been shown to be synergistic with OSM in vitro. To further investigate the clinical potential of OSM, alone and in combination with TAM, set concentrations of each were added to nine fresh and two well-established melanoma cell lines. The proliferation of seven of the 11 cell lines was inhibited by OSM, while two were unresponsive at the dose range tested. Of particular interest was the finding that the growth of two of the cell lines was significantly stimulated at low doses of OSM. The combination of OSM with TAM produced widely divergent results, most frequently resembling the effects of OSM alone. No synergism between the two was evident in any of the cell lines tested. Our results indicate that a combination of OSM and TAM in clinical trials needs further evaluation before it can be recommended. Furthermore, while OSM alone may be useful in the treatment of melanoma, this may be complicated by the possibility of stimulating tumour growth in some instances.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We evaluated the cytotoxic effects of a cell-permeable ceramide (Cer), N-hexanoyl-D-sphingosine (C6-Cer) and of two related sphingoid bases, sphingosine (So) and dihydrosphingosine (sphinganine; Sa) on human melanoma cell lines and on soft tissue sarcoma lines recently established from fresh surgical biopsy specimens. These cell lines ranged from high susceptibility (939 melanoma) to strong resistance (A2058 melanoma and all three sarcomas) to tumour necrosis factor (TNF), an inducer of elevated intracellular Cer levels. However, all the cell lines demonstrated a dose-dependent susceptibility to C6-Cer with protracted cytotoxic kinetics, with the C8161 melanoma being the most sensitive and A2058 the least. Protein kinase C (PKC) antagonizes Cer-dependent apoptosis, and chelerythrine chloride, So and Sa, which inhibit PKC, caused extremely rapid cytotoxicity of melanoma cell lines, irrespective of their relative sensitivity to C6-Cer. So-mediated cytotoxicity was extensive even after only 90 min of treatment, within the time frame of limb perfusion. So and Sa only slightly potentiated the cytotoxic responses to TNF, C6-Cer or melphalan. Sphingolipid-driven intracellular pathways may offer opportunities for therapy of these tumours.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Taxol, an antitumour alkaloid which stabilizes microtubules, demonstrates marked activity against several tumours. However, due to its low aqueous solubility, Cremophor EL (polyoxyethylated castor oil) is used as the excipient in pharmaceutical drug preparations of taxol. This has toxic side effects, thereby limiting the clinical use of taxol in cancer therapy. The aim of this study was to design a novel taxol formulation using thermosensitive liposomes in order to eliminate the Cremophor EL vehicle and improve the antitumour activity of taxol by site-specific drug delivery. Temperature-sensitive liposomes encapsulating taxol were prepared using the natural lipids egg phosphatidylcholine and cholesterol in combination with ethanol. The liposomes have a phase transition temperature (Tm) of 43°C. The in vivo efficacy of thermosensitive liposome encapsulated taxol was determined in B16F10 murine melanoma transplanted into C57BI/6 mice in combination with local hyperthermia. A significant reduction in tumour volume and an increase in survival time was observed in tumour-bearing mice treated with a combination of hyperthermia and thermosensitive liposome encapsulated taxol compared with animals treated with an equivalent dose of free taxol with or without hyperthermia. These results suggest that thermosensitive liposome encapsulated taxol in combination with hyperthermia may be useful in improving the therapeutic efficacy of taxol in the treatment of melanoma.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Granulocyte-macrophage colony stimulating factor (GMCSF) has been shown to inhibit the growth and progression of murine melanoma cells in syngeneic C57BL/6 (H-2b) recipient animals. We now demonstrate that this effect is not specific to melanomas derived from a single strain of mice by examining the subcutaneous growth of K1735 murine melanoma cells (H-2k) transfected with GM-CSF in a syngeneic mouse model. Non-GM-CSF-secreting melanoma cells (parental K1735 and K1735 cells transfected with the GM-CSF gene in the antisense orientation) generated tumours that reached a mean volume of 4000 mm3 after 30-40 days, with a mean survival of 40 days after tumour cell injection. In contrast, 90% of the mice injected with three different clones of GM-CSF-producing K1735 melanomas developed no measurable tumours and were healthy and tumour-free when followed for over 300 days post-inoculation. Additionally, mice injected with GM-CSF-secreting K1735 cells developed long-lasting immunity to the parental melanoma cell line challenge in vivo. A dense neutrophilic and lymphocytic inflammatory infiltrate as well as large numbers of dendritic cells were detected only at the inoculation sites of the GMCSF- producing melanoma cells. Thus, these studies demonstrate for the first time that GM-CSF inhibits melanoma growth in a second genetically distinct MHC tumour-host model system and further support the use of GM-CSF in clinical trials in the treatment of advanced malignant melanoma in humans.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Epiluminescence microscopy (ELM) is a useful method for improved diagnostic accuracy in early cutaneous melanoma. Conventional photographs of ELM images are commonly used for clinical research and documentation. Electronic images have advantages compared with photographs and are essential for medical informatics, computerized learning and telemedicine. Compression of electronic images allows a reduction in the volume of data, but significant image deterioration may occur at high compression rates. We sought to study the diagnostic informativeness of compressed digital ELM images compared with conventional photographs. Fifty photographs of pigmented skin lesions, including 23 melanomas, were presented to eight dermatologists as photographic slides and as digital images with 30:1 Joint Photographic Experts Group (JPEG) compression. The diagnostic performance of the media and the readers was described in terms of sensitivity, specificity and areas under receiver operating characteristic curves (AUC). Agreement between the readings of the two types of media regarding the presence or absence of ELM criteria was assessed using kappa (K) statistics. The mean AUC was 0.81 (95% confidence interval [Cl]=0.73-0.90) for slides and 0.81 (95% Cl=0.72 0.90; P=0.89) for digital images. Agreement between the readings of the two types of media regarding the presence or absence of ELM criteria ranged from K=0.55 (95% Cl=0.22-0.88) for grey-blue area to K=0.89 (95% Cl=0.74-1.00) for radial streaming. In conclusion, digital ELM images with 30:1 JPEG compression appear to be as informative as photographic slides when used to differentiate between melanoma and nonmelanoma.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Epiluminescence microscopy (ELM) is a non-invasive technique for in vivo examination which can provide additional criteria for the clinical diagnosis of pigmented skin lesions (PSLs). In the present study we attempt to determine whether PSLs can be automatically diagnosed by an integrated computerized system. This system should recognize the PSL, automatically extract features and use these features in training an artificial neural network, which should - if sufficiently trained - be capable of recognizing and classifying a new PSL without human aid. One hundred and twenty images of randomly selected histologically proven PSLs (33 common naevi, 48 dysplastic naevi and 39 malignant melanomas) were used in this study. The images were digitally obtained and the morphological features of the PSLs were extracted electronically without human assistance. The numerical data were then divided into learning and testing cases and linked to an artificial neural network for training and for further classification of lesions that the system had not been trained on. Our results show that the computerized system was able to automatically identify 95% of the PSLs presented. The sensitivity and specificity of the computerized system were 90% and 74%, respectively. In contrast, when differentiating between individual types of lesions, the system performed at true positive rates of only 38% for malignant melanoma, 62% for dysplastic naevi and 33% for common naevi. Our data indicate that (1) ELM images of PSLs provide an excellent source for digital image analysis; (2) the vast majority of PSLs can be correctly identified by a relatively simple (and thus not 'intelligent') application of digital image analysis; (3) automatic feature extraction based mainly on ABCD rules provides reliable data on the distinction between benign and malignant PSLs; and (4) there is evidence that artificial neural networks can be trained to adequately discriminate between benign and malignant PSLs.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Inactivation of the p16 tumour suppressor gene has been reported frequently in melanoma cell lines, and mutations have been detected in familial melanoma kindreds. The aim of this study was to assess the role of p16 inactivation in melanocytic progression by measuring the level of p16 protein in a range of sporadic, benign and malignant melanocytic lesions. Using dual parameter flow cytometry, p16 protein expression was measured in 30 benign melanocytic naevi, 38 primary and 51 metastatic melanomas. A high level of p16 expression was demonstrated in benign melanocytic naevi (96% median nuclear positivity), with a significant reduction in primary melanomas (69%, P< 0.001). The median nuclear positivity of primary melanomas was significantly higher (P<0.03) than the level of expression in metastatic lesions (median positivity 37%). A progressive loss of p16 expression was demonstrated from benign melanocytic naevi through to primary and metastatic lesions. These data suggest that loss of p16 protein expression is not only associated with the early transformation of benign lesions, but also with the later stages of malignant progression.

ISSN:0960-8931    

出版商:OVID    

年代:1998

数据来源: OVID