Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When human melanoma cells are lysed in a neutral buffer they release from the chromosomes double-stranded DNA replication intermediates. We have now examined the effect of a bifunctional alkylator (melphalan) on the formation of these intermediates. After treatment for 25 min there is little or no release of double-stranded DNA intermediates from the chromosomes. When the cells are washed free of the drug and cultivated further there is a resumed formation of the DNA intermediates. This is paralleled by the finding that the cells, when the drug is removed, after a time-lag, regain the capacity to proliferate.
Carcinogenesis 1981
PMID:Melphalan prevents the formation of double-stranded DNA replication intermediates in human malignant melanoma cells. 732 32

The polymorphic CYP2D6 gene encoding debrisoquine hydroxylase has attracted much interest for its possible role in human pulmonary carcinogenesis. The purpose of this work was to determine the frequency of poor metabolizers (PM) and extensive metabolizers (EM) of debrisoquine in Slovene population of healthy individuals (n = 107), lung cancer patients (200) and melanoma patients (121). Polymorphism of CYP2D6 gene was studied by genotyping based on PCR analysis of the intron 3 exon 4 junction containing G to A mutation and one base pair deletion in exon 5, which are responsible for approximately 95% of poor metabolizer phenotype in Caucasians. In the healthy Slovene population 62.5% of individuals were identified as extensive metabolizers, 31% as extensive-heterozygous metabolizers and 6.5% as poor metabolizers of debrisoquine. The frequency of EM individuals was 70.5% in lung cancer patients and 64% in melanoma patients, the frequency of extensive-heterozygous subjects was 27% in lung cancer patients and 31% in melanoma patients. The frequency of PM individuals in the lung cancer patients was 2.5% and in melanoma patients 5%. The decrease in PM genotype in the group of Slovene lung cancer patients is similar to the decrease published for some other ethnic groups. Our results support the hypothesis that polymorphic CYP2D6 gene probably plays some, though not a prevalent role in chemical carcinogenesis. Poor metabolizer individuals appear to be less susceptible to lung cancer than EM individuals.
Carcinogenesis 1995 Nov
PMID:Human CYP2D6 gene polymorphism in Slovene cancer patients and healthy controls. 758 85

Aberrant proliferation of tumor cells characterizes cancer growth. Investigations of cellular growth control mechanisms have contributed to our understanding of carcinogenesis and to the identification of compounds with specific antitumor activity. Many cytokines have been found to act on melanoma tumors, either produced by the tumor cells themselves or by infiltrating host cells. Purified cytokines allowed direct comparison of the growth response between normal human melanocytes and malignant melanoma cells. The present paper summarizes results of a series of our own experiments not yet published and data from a review of the recent literature. Proliferation of normal human melanocytes is enhanced by several cytokines, including basic fibroblast growth factor (bFGF), melanoma growth stimulatory activity (MGSA), hepatocyte growth factor (HGF), and mast cell growth factor (MGF). Melanoma cells are additionally stimulated by epidermal growth factor (EGF)/transforming growth factor alpha (TGF-alpha) and nerve growth factor (NGF). Tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and interleukin (IL)-6 are all potent inhibitors of melanocyte growth, but they are less effective on melanoma cells or even stimulate their growth. Interferon (IFN)-alpha and IFN-gamma inhibited proliferation of melanoma cells but not of melanocytes, whereas IFN-beta showed antiproliferative effects in both cell types. These findings suggest an alteration in growth control mechanisms during melanocyte transformation and possibly play a role in melanoma pathogenesis.
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PMID:Growth control of melanoma cells and melanocytes by cytokines. 759 88

We have analysed, by in situ hybridization, mRNA expression of TGF-beta 1, TGF-beta 2, TGF-beta 3, and of TGF-beta type II receptor in benign melanocytic naevi, primary melanomas, and in skin metastases of malignant melanomas. Our results show that melanoma progression correlates with overexpression of TGF-beta. All skin metastases and most primary melanomas invasive to Clark's level IV-V revealed specific TGF-beta 2 mRNA and protein expression. However, expression of this cytokine was not observed in benign melanocytic lesions and was detected only in one of five early primary melanomas investigated. Some primary melanomas and skin metastases also revealed specific TGF-beta 1 mRNA signals although expression of this isoform was not found in benign naevi. TGF-beta 3 expression, which was only barely detectable in benign melanocytic lesions, was enhanced in some skin metastases. Interestingly, the epidermis overlaying melanomas revealed lower levels of TGF-beta 3 mRNA expression than epidermis of healthy skin or epidermis adjacent to benign naevi, thereby suggesting that paracrine mechanisms between tumour cells and keratinocytes may influence melanoma development. In primary melanomas TGF-beta type II receptor mRNA signals were much more heterogeneously distributed when compared to benign melanocytic naevi, suggesting variable degrees of TGF-beta resistance among melanoma cells within individual lesions. However, melanoma progression appeared not to be correlated with a complete loss of TGF-beta type II receptor gene expression, since all skin metastases revealed clearly detectable although heterogeneous levels of TGF-beta type II receptor mRNA expression.
Carcinogenesis 1995 Jul
PMID:In situ analysis of transforming growth factor-beta s (TGF-beta 1, TGF-beta 2, TGF-beta 3), and TGF-beta type II receptor expression in malignant melanoma. 761 83

The GSTM1 gene on chromosome 1p encodes the carcinogen-detoxification enzyme, glutathione S-transferase (mu subclass). The homozygous null genotype at this locus has been associated with increased susceptibility to malignancy, including some skin cancers. One hundred and twenty-four Australian patients with sporadic melanoma and 62 with familial basal cell carcinomas (a feature of nevoid basal cell carcinoma syndrome, NBCCS) were examined for germline homozygous deletions of GSTM1 using multiplex polymerase chain reactions. The homozygous null genotype was not overrepresented in either those with a single melanoma or in the NBCCS cases. Nor did it significantly accelerate tumorigenesis in either group. Analyses of much larger sample sizes will be required to investigate the representation of the null genotype in patients with multiple melanoma primaries and in those with melanoma co-existing with other non-cutaneous malignancies.
Carcinogenesis 1995 Aug
PMID:Glutathione S-transferase GSTM1 null genotype is not overrepresented in Australian patients with nevoid basal cell carcinoma syndrome or sporadic melanoma. 763 33

P44 Ro (Mel) is a human malignant melanoma cell line derived from a testicular metastasis in a DNA repair deficient, xeroderma pigmentosum patient. This line harbors a N-ras gene mutated in codon 61. To investigate other cellular genes possibly contributing to the expression of its transformed phenotype, four XP44 revertant cell lines were isolated by different selection procedures and the association of the level of expression of various oncogenes (including N-ras) and tumor suppressor genes with the selection for the revertant phenotype was determined. The revertants exhibited a significant but variable degree of phenotypic reversion, according to the selective pressure to which they were submitted, and a phenotypic stability dependent on their constant maintenance in selective medium. Back-revertant lines were isolated by culturing revertant lines in control medium for several weeks. The comparison between parental, revertant and back-revertant cells has revealed that, beyond the mutation in codon 61 of N-ras, two groups of genes appear to be also implicated in the transformation process of XP44 RO (Mel) cells: one group, comprising pim A, trk, Rb and p53, whose expression is independent of the cell selection conditions; the other group, comprising Ha-ras, N-ras, neu 1, fos and met H, whose expression is more or less dependent upon such conditions. The myc gene is apparently not involved in this phenomenon. These results, besides strengthening the concept that carcinogenesis is a multigenic process, suggest that diverse mechanisms can lead to the transformed phenotype, but that these mechanisms might have some pathway(s) in common.
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PMID:Cellular genes possibly involved in the transformation process of the human melanoma cell line XP44 RO (Mel). 765

The tyrosinase promoter has been used to target expression of the mutated human T24 Ha-ras oncogene in pigment-producing cells of transgenic mice. Two independent founder mice carrying the transgene survived and showed the same distinct phenotype of mutated coat color, deeply pigmented skin with multiple nevi, and twirling behavior. The offspring of one of these founders were developed into a line that stably expressed the same phenotype. Histopathological analysis of the tissues revealed hyperpigmentation and/or melanocytic hyperplasia in the skin, eyes, inner ear, and meningeal membranes in the brain. Reverse transcriptase-polymerase chain reaction analysis revealed expression of the transgene in skin, brain, and spleen. We propose that these transgenic mice will be a model for studying the process of multistage melanoma carcinogenesis and a system for evaluating potential chemopreventive agents.
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PMID:Hyperpigmentation and melanocytic hyperplasia in transgenic mice expressing the human T24 Ha-ras gene regulated by a mouse tyrosinase promoter. 766 20

It is often stated that persons of Celtic origin have an increased risk of skin cancer, but the evidence for this is almost exclusively anecdotal. We believe that the possibility of the Celts being at greater risk of skin cancer has important implications with regard to management in particular and in assisting our understanding of carcinogenesis in general. For these reasons we have reviewed all those studies implicating Celtic ancestry in the development of both malignant melanoma and nonmelanoma skin cancer.
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PMID:Increased risk of skin cancer: another Celtic myth? A review of Celtic ancestry and other risk factors for malignant melanoma and nonmelanoma skin cancer. 767

According to the current concept of carcinogenesis, the alterations of p53 tumor suppressor gene have been the most frequently detected in both human cancer cell lines and cancer tissues freshly isolated. This study was conducted to investigate the p53 gene alteration in malignant melanoma. Nineteen tumor tissues were obtained from 19 patients with malignant melanoma and examined for the expression of p53 protein by immunohistochemical staining with mouse monoclonal anti-p53 antibody, NCL-p53-DO-7. Twelve out of 19 cases (63%) showed positive reactions for p53 protein: 26, 21 and 16% of which had low, intermediate and high reactivity, respectively. p53 alteration more frequently expressed in female (10/12) than male patients (2/7) with malignant melanoma (p < 0.05). The incidence of expression of p53 protein was compared according to the stages and the sites of tissue obtained. The positive rate for p53 protein was not significantly different between the stages. The positive rates for p53 protein were five out of five (100%), one out of two (50%) and six out of twelve (50%) in tissues obtained from the metastatic, lymph node, and primary sites, respectively. The difference in the positive rates, however, is not statistically significant. These results suggest that p53 gene is a frequent target for mutation in the development of malignant melanoma.
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PMID:Aberrant expression of p53 gene product in malignant melanoma. 770 85

We have investigated UV-B-induced skin tumors of hairless SKH-HRA mice for alterations in the p53 gene and for mutations in either of the three ras genes. Out of 32 tumors screened, only one contained a ras mutation, i.e. in codon 12 of the K-ras gene. Alterations in the p53 gene were much more abundant, as illustrated immunohistochemically by the accumulation of p53 protein in 75% of the tumor sections examined. Immunoreactivity was observed primarily in the proliferative cell compartment, but no clear correlation between p53 staining in tumor cells and histological parameters for malignancy was observed. Subsequent sequence analysis showed that point mutations in the p53 gene are detectable in 30% (nine out of 30) of the skin tumors examined. The majority of the mutations are located in codons 267 and 272, most likely originating from UV-B-induced photo-adducts at dipyrimidine sites in the non-transcribed strand. Codon 272 corresponds to the human codon 278, which is also a hotspot for p53 mutations in human non-melanoma skin cancers. Codon 267 matches the human codon 273, which does not contain a dipyrimidine site, but represents a CpG hotspot for p53 mutations in internal malignancies. Our results demonstrate that this hairless mouse model for UV-induced skin cancer corresponds closely to human non-melanoma skin cancers with respect to mutations in the p53 gene.
Carcinogenesis 1995 May
PMID:Frequent p53 alterations but low incidence of ras mutations in UV-B-induced skin tumors of hairless mice. 776 77


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