Human malignant melanoma. A genetic disease?

Loss of Heterozygosity on Chromosome 1 and 9 and Hormone Receptor Analysis of Metastatic Malignant Melanoma Presenting in Breast

Malignant melanoma (MM), the most common metastatic solid tumor to involve the breast, may present as a diagnostic problem, frequently requiring the use of ancillary studies for accurate diagnosis. The implication of hormonal interplay is strong since metastatic MM to the breast is seen nearly always in women. However, the role of hormonal status as a predisposing factor in the development of this entity is largely unresolved. A number of chromosomal loci, including ip36 and 9p2l-22, appear to harbor critical genes important to melanoma tumorigenesis, and additionally chromosome 9q22.3-31. We wanted to know if metastatic MM in breast showed chromosome lp and 9p genetic alterations (loss of heterozygosity) similar to those that occur in primary cutaneous MM, and whether additional 9q LOH changes are present. Hormonal receptor status of the metastatic MM was also determined. We identified 20 patients with known MM metastatic to the breast, which we analyzed with the following genetic markers: D9S12 (9q22.3), D9S171 (9p21), IFNA (9p22), and DlS450 (ip). Visually directed microdissection was performed on archival histologic slides containing both tumor and adjacent normal breast epithelium, followed by single-step DNA extraction and polymerase chain reaction (PCR) amplification for evaluation of loss of heterozygosity (LOH) for the above-listed markers. Immunohistochemical (IHC) stains for estrogen receptor (ER) and progesterone receptor (PR) was performed on 10 of the cases. Twelve of the 20 cases contained DNA suitable for PCR amplification following direct visualization microdissection. Four of 8 (50%) informative cases showed LOH at 9p21 with D9S171. Ten cases were heterozygous for IFNA, with 2 cases (20%) showing LOH at this locus. These particular cases also showed LOH at 9p21. One of 9 (11%) informative cases showed LOH for DlS450 (Ip36). Five cases were heterozygous for D9S12, and 2 1-22 (50%) and lp36 (11%), as previously described in primary cutaneous MM. Additional LOH was observed at the 9q22.3-31 locus (40%). We suggest this locus to be investigated for harboring potential genes important in the tumorigenesis of cutaneous MM.

Value of melanocytic-associated immunohistochemical markers in the diagnosis of malignant melanoma: a review and update

Since the identification of S100 protein as an immunohistochemical marker that could be useful in the diagnosis of melanoma in the early 1980s, a large number of other melanocytic-associated markers that could potentially be used to assist in the differential diagnosis of these tumors have also been investigated. A great variation exists, however, among these markers, not only in their expression in some subtypes of melanoma, particularly desmoplastic melanoma, but also in their specificity because some of them can also be expressed in nonmelanocytic neoplasms, including various types of soft tissue tumors and carcinomas. This article reviews the information that is currently available on the practical value of some of the markers that have more often been recommended for assisting in the diagnosis of melanomas, including those that have only recently become available.

Factors significantly increasing or inhibiting early stages of malignant melanoma (M.M.) and non-invasive evaluation of new treatment by ingestion and external application of optimal doses of the most effective anti-M.M. substances: haritaki, cilantro, vitamin D3, nori, EPA with DHA, & application of special (+) solar energy stored paper, which reduced the M.M. active area & asbestos rapidly

Sterilizing the pre-cancer skin of malignant melanoma (M.M.) with 70% Isopropyl alcohol intensified malignancy & the malignant response extended to surrounding normal looking skin, while sterilizing with 80% (vodka) or 12% (plum wine) ethyl alcohol completely inhibited M.M. in the area (both effects lasted for about 90 minutes initially). Burnt food (bread, vegetables, meat, and fish), a variety of smoked & non-smoked fish-skin, many animal's skin, pepper, Vitamin C over 75 mg, mango, pineapple, coconut, almond, sugars, Saccharine & Aspartame, garlic, onion, etc & Electromagnetic field from cellular phones worsened M.M. & induced abnormal M.M. response of surrounding skin. We found the following factors inhibit early stage of M.M. significantly: 1) Increasing normal cell telomere, by taking 500 mg Haritaki, often reached between 400-1150 ng& gradually diminished, but the M.M. response was completely inhibited until normal cell telomeres are reduced to 150 ng, which takes 6-8 hours. More than 70 mg Vitamin C, Orange Juice, & other high Vitamin C containing substances shouldn't be taken because they completely inhibit the effects of Haritaki. 2) We found Chrysotile asbestos & Tremolite asbestos (% of the Chrysotile amount) coexist. A special Cilantro tablet was used to remove asbestos & some toxic metals. 3) Vitamin D3 400 I.U. has a maximum inhibiting effect on M.M. but 800 I.U. or higher promotes malignancy. 4) Noricontaining Iodine, etc., was used. 5) EPA 180 mm with DHA 120 mg was most effectively used after metastasis to the surrounding skin was eliminated. When we combined 1 Cilantro tablet & Vitamin D3 400 I.U. withsmall Nori pieces & EPA with DHA, the effect of complete inhibition of M.M. lasted 9-11 hours. When these anti-M.M.substances (Haritaki, Vitamin D3, Cilantro, Nori, EPA. with DHA) were taken together, the effect lasted 12-14 hoursand M.M. involvement in surrounding normal-looking skin disappeared rapidly & original dark brown or black are as satisfying "ABCD" of M.M. completely fell off. Both oral & frequent external application of mixed solution of plum wine & the same combination of anti-M.M. substances can be used as very effective treatment by taking 2-3 times daily. Additional application of special (+) Solar Energy Stored Paper reduced asbestos & accelerated reduction of M.M. positive area rapidly. This method with individualized optimal doses has also been successfully applied to treat several other types of malignancies.

Use of gene expression and pathway signatures to characterize the complexity of human melanoma

A defining characteristic of most human cancers is heterogeneity, resulting from the somatic acquisition of a complex array of genetic and genomic alterations. Dissecting this heterogeneity is critical to developing an understanding of the underlying mechanisms of disease and to paving the way toward personalized treatments of the disease. We used gene expression data sets from the analysis of primary and metastatic melanomas to develop a molecular description of the heterogeneity that characterizes this disease. Unsupervised hierarchical clustering, gene set enrichment analyses, and pathway activity analyses were used to describe the genetic heterogeneity of melanomas. Patterns of gene expression that revealed two distinct classes of primary melanoma, two distinct classes of in-transit melanoma, and at least three subgroups of metastatic melanoma were identified. Expression signatures developed to predict the status of oncogenic signaling pathways were used to explore the biological basis underlying these differential patterns of expression. This analysis of activities revealed unique pathways that distinguished the primary and metastatic subgroups of melanoma. Distinct patterns of gene expression across primary, in-transit, and metastatic melanomas underline the genetic heterogeneity of this disease. This heterogeneity can be described in terms of deregulation of signaling pathways, thus increasing the knowledge of the biological features underlying individual melanomas and potentially directing therapeutic opportunities to individual patients with melanoma.

Differential expression of S100 protein subtypes in malignant melanoma, and benign and malignant peripheral nerve sheath tumors

BACKGROUND

Desmoplastic melanoma (DM) may simulate various benign and malignant lesions, including benign peripheral nerve sheath tumors (BPNSTs) and malignant peripheral nerve sheath tumors (MPNSTs). The latter case is diagnostically challenging because DM generally show only S100 protein expression but no reaction to melanocytic markers. S100 family of proteins consists of over 20 members. We report on S100 subtypes in malignant melanomas (MMs), and BPNSTs and MPNSTs to investigate differential expression.

DESIGN

S100A1, S100A2, S100A4, S100A6 and S100B immunostains were performed on 80 MMs including conventional and desmoplastic types, 86 BPNSTs and 77 MPNSTs.

RESULTS

S100A1 expression was seen in > 91% of MMs in a diffuse reaction, whereas BPNSTs showed focal or no reaction. Sixteen percent of MPNSTs focally expressed S100A1 except for one case with diffuse reaction. S100A2 staining was negative or focal in all three groups whereas S100A4 reaction was variable in all three. S100A6 was diffusely expressed in MMs, BPNSTs and MPNSTs. S100B was stained diffusely in MMs and BPNSTs, but its reaction was observed in 30% of MPNSTs in a focal fashion.

CONCLUSION

S100A1 expression was diffuse in most of MMs but absent or focal in BPNSTs and MPNSTs. This may be helpful to distinguish between the two entities.

Identical twins with primary cutaneous melanoma presenting at the same time and location

Thus far there have been very few cases that document such a rarity as the same cancer occurring in monozygotic twins, at the same time, in the same location. We report this extraordinary phenomenon in our patients, 71-year-old identical female twins, presenting with melanoma at the same time (within 10 days of each other) and location (the right calf).

EGFR gene copy number alterations in primary cutaneous malignant melanomas are associated with poor prognosis

Copy number alterations of the epidermal growth factor receptor (EGFR) gene have been extensively analyzed in different cancers, but no data are available for primary malignant melanoma. The aim of the present study was to simultaneously investigate the EGFR gene and chromosome 7 copy number alterations in 81 cutaneous malignant melanomas by interphase FISH and correlate the data with clinicopathological parameters of patients. EGFR mRNA levels were detected by Affymetrix GeneChip Human Genome U133 Plus 2.0 expression arrays for 16 lesions. Both increased gene dosage and chromosome 7 alterations were found in 70% of tumors. Extra EGFR copies were detected in an additional 10% of samples. Polysomy 7 was associated with EGFR gene amplification. Significant correlation was found between EGFR alterations and histological subtypes, tumor thickness, ulceration and metastases formation. Amplification was significantly higher in lesions that developed metastases within 2 years after surgical excision of the primary tumor. Gene copy alterations were associated with elevated mRNA expression in 77% of lesions when compared to tumors with disomic EGFR status, the correlation was not directly proportional to gene copy number. Associations between protein expression and mRNA levels were even less prominent. In conclusion, our study indicates that amplification of the EGFR gene and polysomy 7 are frequent alterations in primary melanomas and are associated with bad prognosis. Further studies are required to clarify whether melanoma patients with EGFR alterations can benefit from anti-EGFR therapy.

Mosaic chromosome 6 trisomy in an epidermal nevus

We report a 2-year-old boy with a linear epidermal nevus. Mosaicism for chromosome 6 in skin fibroblasts of affected skin was discovered. Trisomy 6 has not been previously implicated as an isolated finding in epidermal nevi or cutaneous mosaicism.

Genética molecular aplicada ao câncer cutâneo não melanoma

Os cânceres cutâneos não melanoma são as neoplasias malignas mais comuns em humanos. O carcinoma basocelular e o carcinoma espinocelular representam cerca de 95% dos cânceres cutâneos não melanoma, o que os torna um crescente problema para a saúde pública mundial devido a suas prevalências cada vez maiores. As alterações genéticas que ocorrem no desenvolvimento dessas malignidades cutâneas são apenas parcialmente compreendidas, havendo muito interesse no conhecimento e determinação das bases genéticas dos cânceres cutâneos não melanoma que expliquem seus fenótipos, comportamentos biológicos e potenciais metastáticos distintos. Apresenta-se uma revisão atualizada da genética molecular aplicada aos cânceres cutâneos não melanoma, em especial ao carcinoma basocelular e carcinoma espinocelular, enfatizando os mais freqüentes genes e os principais mecanismos de instabilidade genômica envolvidos no desenvolvimento dessas malignidades cutâneas.

Preponderance of the oncogenic V599E and V599K mutations in the B-raf kinase domain is enhanced in melanoma lymph node metastases

Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, amongst other carcinomas, in a substantial subset of primary melanomas, with a preponderance of mutations within the kinase domain, including the activating V599E and V599K transitions. We investigated a representative series of 54 resection specimens of melanoma lymph node metastases for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain by polymerase chain reaction (PCR) and single-strand conformational polymorphism (SSCP) gel electrophoresis. Sequencing of cloned PCR-SSCP amplicons resulted in 24 (44%) samples harbouring somatic mutations, which is not significantly different from the mutation frequency found in recently investigated primary cutaneous melanomas (Deichmann M, Thome M, Benner A, Näher H. B-raf exon 15 mutations are common in primary melanoma resection specimens but not associated with clinical outcome. Oncology 2004; 66:411-419). The activating mutation T1796A was present in 20 (83%) of these resection specimens, followed in frequency by the oncogenic g1795A mutation in five (21%) cases. With regard to the B-raf protein sequence, the acidic amino acid transitions V599E and V599K were predicted in 15 (62%) and five (21%) of the 24 positive metastases, respectively. The detection of mutations at this hot spot codon was significantly associated with subsequent visceral metastasis (P=0.03; Fisher's exact test). During the transition from primary melanomas (see reference above) to lymph node metastases, the spectrum of B-raf mutations narrows significantly (P=0.00047). The oncogenic B-raf mutations V599E and V599K, as early events in melanocyte transformation, persist throughout metastasis with important prognostic implications.

Preponderance of the oncogenic V599E and V599K mutations in B-raf kinase domain is enhanced in melanoma cutaneous/subcutaneous metastases

BACKGROUND

Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other carcinomas, in a substantial subset of primary melanomas with a preponderance of mutations within the kinase domain including the activating V599E and V599K transitions.

METHODS

We here investigated a representative series of 60 resection specimens of cutaneous and subcutaneous melanoma metastases for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) gel electrophoresis.

RESULTS

Sequencing of cloned PCR-SSCP amplicons resulted in 24 (40%) samples harbouring somatic mutations which is not exceeding the mutation frequency in recently investigated primary melanomas. The activating mutation T1796A was present in 24/60 (40%) resection specimens, followed in frequency by the oncogenic g1795A mutation in 8/60 (13%) cases. As to the B-raf protein sequence, the acidic amino acid transitions V599E and V599K were predicted in 19/60 (32%) and 6/60 (10%) cases, respectively, but were not associated with enhanced risk for subsequent metastasis in patients' follow up. In comparison to the primary melanomas that we recently investigated, the spectrum of predicted B-raf protein mutations narrowed significantly in the cutaneous/subcutaneous metastases. Unexpectedly, V599 and V599E mutations were absent in cutaneous/subcutaneous metastases derived from acrolentiginous melanomas as preceding primary tumours.

CONCLUSION

During transition from primary melanomas towards cutaneous/subcutaneous metastases, the spectrum of predicted B-raf mutations narrows significantly. Focusing on the V599E and V599K, these oncogenic mutations are likely to affect melanocyte-specific pathways controlling proliferation and differentiation.

Decreased levels of (6-4) photoproduct excision repair in hybrid fish of the genus Xiphophorus

Selected hybridization in the fish genus Xiphophorus has been used for many years to study the genetics of malignant melanoma. Because DNA damage caused by ultraviolet radiation is implicated in the etiology of sunlight-induced melanoma, the heritability of mechanisms that mitigate DNA damage is a matter of some interest. We examined nucleotide excision repair of the two major types of DNA-damage induced by sunlight; the cyclobutane pyrimidine dimer (CPD) and the pyrimidine(6-4)pyrimidone dimer [(6-4)PD]. In most cases, removal of the (6-4)PD was more rapid than the CPD, and in many cases, the F1 hybrid showed reduced repair efficiency compared with the parental species. These data demonstrate reduced function in multienzyme hybrid systems and provide molecular support for potential reduced fitness in hybrid fish under conditions of environmental stress.

Analysis of protein tyrosine kinase expression in melanocytic lesions by tissue array

BACKGROUND

It has been proposed that melanoma progression involves a multistep process from benign nevi (BN), dysplastic nevi (DN), radial and vertical growth phase melanoma (MM) to metastatic melanoma (MMM). Protein tyrosine kinases (PTKs) may participate in this progression.

METHODS

Tissue microarray blocks of 89 melanocytic lesions were evaluated by immunohistochemistry for the expression of selected PTKs: c-kit, c-abl, abl-related gene (ARG), platelet-derived growth factor receptors alpha (PDGFR-alpha) and beta (PDGFR-beta).

RESULTS

Seventeen of 31 (55%) MMM lacked expression of c-kit versus 100% expression (18/18) in DN and 96% expression (22/23) in MM; similarly, only 59% (10/17) of BN showed expression of c-kit. PDGFR-beta expression levels were similar in BN, DN, and MM, but lower in MMM. There was a trend toward lower expression of abl and ARG from BN to MMM. There was a marked decrease in staining intensity of ARG from BN to DN, MM, and MMM.

CONCLUSION

Our results support that BN is different from DN and MM and that these two are different from MMM. Metastasis appears to be associated with loss of c-kit and PDGFR-beta expression. Since malignant melanoma expresses PTK, it may be a candidate for treatment with anti-PTK, such as STI-571 (Gleevec).

Expression of c-myc and bcl-2 in primary and advanced cutaneous melanoma

Apoptosis is an important co-factor in the pathogenesis of a plethora of malignancies. Enhanced c-myc activation can result either in proliferation or apoptosis. Coexpression with antiapoptotic bcl-2, which abrogates the apoptotic function of c-myc might lead to an enormous growth advantage of cells. In order to elucidate the role of c-myc and bcl-2 as well as the coexpression of both genes in human melanoma, their expression was studied in four samples of normal skin (SK), 15 surgical margins (SM), 20 benign melanocytic nevi (MN), 20 primary melanomas (MM), and 30 melanoma metastases (MMET) by RT-PCR. These results were compared with immunohistochemistry (IH) in 7 SK, 7 SM, 26 MN, 50 MM, and 34 MMET. Similar results were found with both methods. However, MMET expressed c-myc (PCR 28/30, IH 23/34) as well as bcl-2 (PCR 27/30, IH 24/34) more frequently. Primary melanomas showed a similar expression pattern as SM and nevi. Moreover, in contrast to SK, SM, MN, and MM coexpression of bcl-2 and c-myc was found more frequently in MMET (PCR 25/30, p < 0.01, IH 19/34, p < 0.01). These results indicate that coexpression of c-myc and bcl-2 appears to be associated with advanced melanoma and contributes to the malignant phenotype.

Nuclear to cytoplasmic compartment shift of the p33ING1b tumour suppressor protein is associated with malignancy in melanocytic lesions

AIMS

Cutaneous malignant melanoma is an unpredictable neoplasm. Studies of cell cycle and proliferation-associated proteins may help in the understanding of the genesis of melanomas. The tumour suppressor gene TP53 has been shown to be involved in melanomas. However, the incidence of TP53 malfunction in cutaneous melanoma is unclear, and other regulators of cell cycle control are likely to be involved in both the development and progression of melanocytic neoplasia. A candidate is the ING1 gene, which co-operates with TP53 in growth suppression and apoptosis. Thus loss of ING1 function may have similar consequences to loss of TP53 function and may contribute to tumorigenesis. Therefore we have studied the expression of p33ING1b protein in cutaneous melanocytic neoplasia.

METHODS AND RESULTS

Sixty-seven melanocytic lesions were studied by immunohistochemistry for the expression of p33ING1b. In our series there was loss of nuclear p33ING1b expression in invasive malignant melanoma compared with normal cutaneous melanocytes or the melanocytes of benign melanocytic naevi. This was associated with an enhancement of cytoplasmic p33ING1b expression which was particularly prominent in invasive malignant melanoma.

CONCLUSIONS

Cytoplasmic immunostaining for p33ING1b using MAb GN2 is strongly associated with 'activated' melanocytic lesions; therefore it is possible that this MAb could be of value in diagnostic practice. Furthermore, the reduction in p33ING1b expression and perhaps translocation from the nucleus to the cytoplasm may play a central role in the development and progression of melanomas.

Xiphophorus interspecies hybrids as genetic models of induced neoplasia

Fishes of the genus Xiphophorus (platyfishes and swordtails) are small, internally fertilizing, livebearing, and derived from freshwater habitats in Mexico, Guatemala, Belize, and Honduras. Scientists have used these fishes in cancer research studies for more than 70 yr. The genus is presently composed of 22 species that are quite divergent in their external morphology. Most cancer studies using Xiphophorus use hybrids, which can be easily produced by artificial insemination. Phenotypic traits, such as macromelanophore pigment patterns, are often drastically altered as a result of lack of gene regulation within hybrid fishes. These fish can develop large exophytic melanomas as a result of upregulated expression of these pigment patterns. Because backcross hybrid fish are susceptible to the development of melanoma and other neoplasms, they can be subjected to potentially deleterious chemical and physical agents. It is thus possible to use gene mapping and cloning methodologies to identify and characterize oncogenes and tumor suppressors implicated in spontaneous or induced neoplasia. This article reviews the history of cancer research using Xiphophorus and recent developments regarding DNA repair capabilities, mapping, and cloning of candidate genes involved in neoplastic phenotypes. The particular genetic complexity of melanoma in these fishes is analyzed and reviewed.

The protein phosphatase 2A subunit Bgamma gene is identified to be differentially expressed in malignant melanomas by subtractive suppression hybridization

Several genes implicated in the development of various malignancies appear to be of minor relevance in melanoma. We therefore aimed to find a tumour suppressor candidate involved in this malignancy by comparing gene expression in uncultured primary melanoma specimens with those in acquired melanocytic naevi, from which quite often melanomas are known to arise. Applying the subtractive suppression hybridization technique, we generated a subtracted library of candidate genes downregulated in melanoma. Among the cDNA fragments identical to known genes, this library included a cDNA fragment 630 bp in length that is identical to the gene for the human protein phosphatase 2A (PP2A) regulatory subunit B (B56) gamma isoform (PP2A-Bgamma, PPP2R5C). On further evaluation of 15 primary melanoma and 16 acquired melanocytic naevus tissue specimens from independent patients using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis, expression of this gene was found to be suppressed in melanomas compared with naevi; the difference was statistically significant. As PP2A is known to be a major cellular serine-threonine phosphatase, and has been implicated not only in the regulation of cell growth and division but also in the control of gene transcription and growth factor signal transduction, alterations in the pattern of the regulatory subunits may affect substrate specificity and subcellular localization of the PP2A holoenzyme in melanoma cells.

Application of molecular cytogenetic techniques in a case study of human cutaneous metastatic melanoma

Consistent structural chromosome rearrangements have rarely been identified in adult solid tumors. The introduction of advanced molecular cytogenetic techniques has provided new ways of analyzing highly complex karyotypes commonly encountered in these malignancies. This study describes a detailed molecular cytogenetic analysis of a sporadic human cutaneous melanoma biopsy, M92-047, using a combination of G-banding, fluorescence in situ hybridization (FISH), chromosome microdissection, and comparative genomic hybridization (CGH). G-banding revealed that this tumor was composed primarily of closely related near-diploid and near-tetraploid cell subpopulations containing several clonal numerical and structural chromosome alterations. Fluorescence in situ hybridization using whole chromosome painting probes and chromosome arm painting probes, was employed to verify the rearranged chromosomes; dic(1;4), der(8)t(1;8), and der(15)t(6;15), whereas marker chromosomes dic(8;1;16), der(12)t(9;12), and der(17)t(13;17) were discerned by chromosome microdissection and subsequent reverse in situ hybridization (rev ish) analysis. Comparative genomic hybridization illustrated DNA copy number changes in good agreement with the karyotypic analysis. Although this line exhibits recurrent alterations representative of melanoma, two unique breakpoints--1p13 and 8p21--were identified in two different rearranged chromosomes, suggesting potentially important regions for further dissection by molecular genetic techniques. This report demonstrates the advantages of combining multiple techniques in order to obtain a detailed description of cytogenetic changes in melanoma.

Outdoor activities in childhood: a protective factor for cutaneous melanoma? Results of a case-control study in 271 matched pairs

BACKGROUND

A matched case-control study was performed in Munich, Germany, in 1996-97 to evaluate the risk of cutaneous melanoma due to ultraviolet (UV) exposure behaviour in Southern Bavaria, Germany.

OBJECTIVES

Patients with cutaneous melanoma and controls were investigated by two physicians using a standardized questionnaire to identify risk factors for the development of melanoma, such as professional and leisure sun exposure behaviour. In each person, a total body examination was performed to detect benign skin alterations, phenotypic characteristics and precursor lesions for skin cancer.

PATIENTS/METHODS

A total of 271 melanoma patients and 271 controls were individually matched for residence, age and gender. A multiple conditional logistic regression analysis was performed.

RESULTS

Of 56 factors, those risk factors with a strong effect on the development of melanoma were: the existence of melanoma in first degree relatives, solar lentigo, actinic keratosis, actinic cheilitis, skin phototype, immediate skin reaction to UV light at the start of the outdoor season, sunburn in childhood and sun exposure during holidays in sunny areas 20 years before melanoma was diagnosed; outdoor activities in childhood were found to be protective.

CONCLUSIONS

Sunburn in childhood and increased sun exposure during annual holidays in sunny areas should be avoided. In contrast, outdoor activities in childhood, including soccer and gardening, should be encouraged because they are associated with a lower risk of melanoma formation.

Chromosome 7 aneusomy. A marker for metastatic melanoma? Expression of the epidermal growth factor receptor gene and chromosome 7 aneusomy in nevi, primary malignant melanomas and metastases

Receptor tyrosine kinases such as the epidermal growth factor receptor (EGFR) play an important role in a variety of malignant neoplasias, making the search for aberrations in the relevant chromosomes an important issue. Differential expression of the EGFR gene was investigated by reverse transcriptase (RT)-PCR on tissue samples of normal skin, nevi, primary melanomas, and melanoma metastases. The EGFR gene is located on chromosome 7p12.3-p12.1. To determine the number of chromosomes 7 in cell nuclei of the mentioned tissue samples we performed fluorescence in situ hybridization (FISH) on touch preparations, using a DNA probe that hybridizes specifically to the centromeric region of chromosome 7. Additionally, chromosome 7 number in interphase nuclei was determined in short-term primary cell cultures of nevi, primary melanomas, and metastases. The highest EGFR gene expression frequency was found in melanoma metastases. By FISH we detected the highest fraction of cell nuclei with more than two chromosomes 7 in the group of metastases. Our results suggest that overexpression of the EGFR gene might play an important role in metastasis of malignant melanoma. This is well reflected by polysomy 7, possibly accounting for an increased EGFR gene copy number.

c-MYC and nodular malignant melanoma. A case report

BACKGROUND

The incidence of skin cancer has been rising since the 1950s. About 75% of skin cancer-associated deaths are caused by malignant melanoma. Nodular malignant melanoma accounts for 20% of melanocytic malignant tumors and is associated with a relatively poor prognosis. Extensive research has been undertaken, but a molecular marker that can predict a more aggressive course of melanoma still has not been found.

METHODS

The authors applied cytogenetic and molecular genetic techniques to a case of nodular malignant melanoma. They used comparative genomic hybridization (CGH) to identify chromosomal regions affected by genomic changes and interphase fluorescence in situ hybridization (FISH) on touch preparations of the tissue to elucidate the CGH findings further. To investigate the functionality of the affected c-MYC gene, the authors detected its transcript via reverse transcription and polymerase chain reaction.

RESULTS

CGH revealed a copy number gain in the 6p and 8q24-8qter region. FISH with c-MYC and centromere eight specific probes revealed that the tumor, in contrast to unaffected skin, was characterized by a gain in copy numbers of the c-MYC gene. The c-MYC gene transcript was detected at higher levels in the tumor than in the tissue taken from the safety margin.

CONCLUSIONS

The WAF1 gene located on chromosome 6p, which in this case had a copy number gain, might be involved in melanoma pathogenesis. The authors suggest that the c-MYC gene plays an important role in melanoma development and progression. The c-MYC gene seems to be affected by gaining functional copies, leading to a change in the normally regulated gene-dose effect.

Awareness and early detection of cutaneous melanoma: an analysis of factors related to delay in treatment

Factors associated with the detection of cutaneous melanomas and reasons for delay in diagnosis were investigated in 429 patients with histologically proven melanoma operated on between January 1993 and June 1996. Patients were interviewed using a standardized questionnaire. In 25% of patients, treatment was delayed for more than 1 year from the time they first noticed a suspicious pigmented lesion. Melanoma was detected by the patients themselves in 67% of women and 45% of men. The three predominant clinical symptoms of melanoma were change in colour (darker), increase in size and increase in elevation of a pigmented lesion. The role of sun exposure and of naevi as risk factors for melanoma, as well as the potential benefit of early treatment, were known by 87%, 66% and 82% of the patients, respectively. However, melanoma awareness had no impact on the time period between first observation of skin changes and treatment. Among the factors associated with delay in melanoma diagnosis, an initial incorrect diagnosis as a benign lesion by the physician first visited (in 18% of all cases) had the highest significance. Patients detecting their lesions themselves were treated significantly later than patients in whom others had remarked on changes in a naevus. Furthermore, melanomas of the head and neck were treated later than melanomas at other body sites. Further efforts to educate both the public and the medical profession are essential to ensure earlier treatment for cutaneous melanomas.

Cytogenetic analysis of three oropharyngeal malignant melanomas in dogs

Three cases of histologically confirmed oropharyngeal malignant melanomas in dogs are presented including clinical examinations and cytogenetic analysis. Case one showed a hyperdiploid karyotype. Case two, a recurrent tumour, had a highly hypodiploid karyotype with supernumerary meta- and submetacentric chromosomes in all metaphases analysed. In the third case, a clonal fusion of chromosome 1 and 25 was observed. Comparing these results with another case of canine cutaneous melanoma as well as with human malignant melanomas reported in the literature, these tumours obviously often show cytogenetic aberrations like aneuploidy and centric fusions.

Comparative structure and characterization of a CDKN2 gene in a Xiphophorus fish melanoma model

We have cloned, sequenced, and characterized the RNA expression properties of a fish CDKN2 gene from Xiphophorus helleri and X. maculatus. This gene, termed CDKN2X, shows a high degree of amino acid sequence similarity to members of the mammalian CDKN2 gene family, which includes the tumor suppressor loci CDKN2A (P16) and CDKN2B (P15). Comparative sequence analysis suggests that fish CDKN2X is similarly related to all four mammalian gene family members, and may represent a descendant of an ancestral prototypic CDKN2 gene. CDKN2X was mapped to a region on autosomal Xiphophorus linkage group V (LG V) known to contain the DIFF gene that acts as a tumor suppressor of melanoma formation in X. helleri/X. maculatus backcross hybrids. Thus, CDKN2X may be a candidate for the tumor suppressor DIFF gene. Here we have sequenced CDKN2X in both Xiphophorus species and have characterized its expression in normal and melanotic tissues within control and backcross hybrid fish. A simultaneous expressional analysis of the Xmrk-2 tyrosine kinase receptor gene, which is strongly implicated in melanomagenesis in this system, was also performed. RT - PCR analyses revealed that both genes were highly expressed in melanomas. For CDKN2X, this result contrasts numerous findings in human tumors including human melanoma in which either CDKN2A (P16) deactivation or LOH was observed.

Involvement of chromosome losses in the progression and metastasis formation of a human malignant melanoma

To characterize the possible cytogenetic link between a primary tumor and its metastasis, interphase cytogenetic analysis was performed on tumor cells and cutaneous metastasis from a male patient with malignant melanoma by using fluorescence in situ hybridization. The numbers of distinct hybridization domains specific for ten different pericentromeric sequences were used as indicators of copy numbers of these chromosomes. In the primary tumor, the majority of cells had two copies of these chromosomes, but significant numbers of nuclei also were present with one and three copies. In addition, in almost all cells, both sex chromosomes were abnormal; nullisomy of the Y chromosome was associated with X disomy. The corresponding metastatic tumor cells were predominantly monosomic; only the distribution of chromosomes 11 and 7 was similar to the primary tumor. In the metastatic tumor, the sex chromosomes had a normal copy number; that is, one Y and one X were detected. These data indicate that both the initiation and the progression of this melanoma are associated with chromosome losses.

Sunlight and carcinogenesis: expression of p53 and pyrimidine dimers in human skin following UVA I, UVA I + II and solar simulating radiations

DNA damage by UV radiation plays an essential role in skin cancer induction. We report that even sub-erythemal doses of solar simulating radiation, are capable of inducing substantial nuclear damage, namely pyrimidine dimers and p53 induction in human skin in situ. The quantity and distribution of p53 induced in human skin by UV radiation depended highly on the waveband and dose of UV used. Solar simulating radiation induced very high levels of p53 throughout all layers in epidermal keratinocytes 24 hr following an erythemal dose (230+/-15.9/1000 cells), and the induction followed a dose response. Following UVA I + II and UVA I radiations, p53 expression was approximately half of that seen with equivalent biological doses of solar simulating radiation (63.5+/-28.5 and 103+/-15.9, respectively). Expression of p53 was seen in basal cell keratinocytes at lower doses of UVA, but all layers of the epidermis were affected at higher doses. Pyrimidine dimer induction, however, was seen to be the same for equivalent biological doses of UVA I, UVA I + II and solar simulating radiations, which coincides with previous findings that pyrimidine dimers initiate the erythemal response and are implicated in skin carcinogenesis. When equivalent biological doses of pure UVA are used with no UVB contamination, significant nuclear alterations occur in human skin in situ, which can approach those seen with UVB radiation. Our results suggest that DNA damage assessed in vivo by immunohistochemistry could provide a very sensitive endpoint for determining the efficacy of protective measures, such as sunscreens or protective clothing, against both UVB- and UVA-induced damage in human skin.

Genetic alterations of p16INK4a and p53 genes in sporadic dysplastic nevus

It is still unclear whether the sporadic form of dysplastic nevi (SDN) represents a premalignant lesion of malignant melanoma and whether genetic alterations are involved in the development of SDN. To determine whether p16INK4a and p53 genetic abnormalities could be associated with development of SDN, nevus cell nests were procured selectively from H & E-stained slide sections by using a modified microdissection technique and were screened for the presence of mutations and loss of heterozygosity (LOH) of p16INK4a and p53 genes using a polymerase chain reaction-based LOH, single-strand conformation polymorphism, and direct DNA sequencing analyses. Hemizygous deletion was detected in 9 of 12 informative cases (75%) for 9p21-22 (p16INK4a) at one or more loci and 60% (6/10) for 17p13 (p53). As for mutation, we found 3 missense mutations and 1 mutation in the first intron in p16INK4a and 2 missense mutations in p53. Among these mutations in p16INK4a and p53, 5 of 6 mutations were of the C:G to T:A transitional type; this is known to be related to ultraviolet radiation as previously confirmed in other skin cancers. This indicates that p16INK4a and p53 genetic alterations may play an important role in the evolution of SDN and may represent an early event in the development of malignant melanoma. Furthermore, ultraviolet radiation might be the predominant etiologic agent in the development of SDN.

Loss of expression of receptor tyrosine kinase family genes PTK7 and SEK in metastatic melanoma

Protein tyrosine kinases (PTKs) have been implicated in the development of many common human tumours including melanoma. Previously we isolated PTK gene sequences expressed in normal melanocytes. Here we examined expression of 9 of these genes in cell lines derived from defined stages of melanoma progression, by Northern blotting and in some cases immunoblotting. We also tested cells from 2 animal models of particular stages in progression, as well as uncultured biopsies of metastatic melanoma. The expression of 2 receptor kinase family members found in melanocytes, PTK7/CCK-4 and SEK/TYRO1, was decreased or lost in advanced melanomas. PTK7 mRNA was found in only 54% of melanoma cell lines and 20% of melanoma biopsies. Similarly, expression was lost in 2 advanced cell lines selected from an early melanoma line that did express PTK7 mRNA. SEK/TYRO1 expression was observed in 75% and 17% of cell lines from primary and metastastic melanomas, respectively. Conversely, mRNA for the non-receptor kinase PTK6/BRK was not detected in normal melanocytes or primary melanoma lines, but was found in 9% of metastatic melanoma cell lines.

Translation initiation factor eIF-4A1 mRNA is consistently overexpressed in human melanoma cells in vitro

The oncogenic potential of translation initiation factors (eIF-4E and eIF-2alpha) has been described in previous studies leading to the definition of translational oncogenes. Two previously isolated cDNA clones, expressed differently in human melanoma cells and normal human melanocytes, were identified in this study as coding for the translation initiation factor eIF-4A1. Northern-blot analysis revealed consistent overexpression of eIF-4A1 mRNA in a panel of 14 melanoma cell lines (on an average 5.6 times higher than in cultures of normal human melanocytes). In contrast, the mRNAs of the other group-4 translation initiation factors (eIF-4A2, eIF-4B, eIF-4E and eIF-4gamma) were less and not consistently elevated. Cultures of congenital melanocytic nevi exhibited intermediate expression of eIF-4A1. Thus, eIF-4A1 overexpression seems to be an important feature of melanoma cells and might contribute to their malignant transformation.

Cutaneous melanoma in patients with sarcoma

BACKGROUND

The authors became interested in an association between cutaneous melanoma and sarcoma when they reviewed their experience with other malignancies occurring in patients with a diagnosis of sarcoma.

METHODS

The authors identified 48 patients with both melanoma and bone or soft tissue sarcoma (STS) by a computer search of all sarcoma patients entered into their institution's cancer registry between 1943 and 1996 who had an additional diagnosis of melanoma. The medical records were reviewed and clinical and pathologic data collected.

RESULTS

The median age at diagnosis was 46 years for patients with melanoma and 50 years for patients with sarcoma, which was consistent with population-based data. Among patients with STS (n = 41), malignant peripheral nerve sheath tumors (MPNT) were more common in patients with both diagnoses (5 of 41; 13%) when compared with all adults with STS admitted to the study center between 1982 to date (125 of 2901; 4%; P < 0.05). Liposarcoma occurred in only 1 patient with both melanoma and STS (1 of 41; 2%), despite the fact that it was the most common histologic diagnosis in all adults with STS (625 of 2901; 22%; P < 0.001). The anatomic site of STS was more commonly visceral (11 of 41; 27%) when compared with all adults with STS (424 of 2901; 15%; P < 0.05). A positive family history of cancer was noted in 50% of the patients, and 25% of patients had a third primary tumor.

CONCLUSIONS

Although a distinct "melanoma/sarcoma" syndrome was not identified, MPNT as well as visceral sarcomas were more common than expected in this study. The authors also noted strong family histories of cancer as well as additional primary malignancies in patients with melanoma and sarcoma, suggesting a predisposition toward cancer.

Signal transduction by the oncogenic receptor tyrosine kinase Xmrk in melanoma formation of Xiphophorus

Melanoma formation in Xiphophorus is initiated by overexpression of an oncogenic version of the EGFR-related receptor tyrosine kinase Xmrk (Xiphophorus melanoma receptor kinase). High steady-state levels of Xmrk oncogene mRNA are found in malignant melanoma; however, this overabundance of transcripts appears to be not sufficient for manifestation of the full oncogenic potential of Xmrk. In addition, several amino acid exchanges cause the oncogenic receptor to be highly active, resulting in a strong tyrosine phosphorylation even without growth factor stimulation. Besides the receptor itself a Xmrk-specific signal transduction seems to be a critical part of the transformation machinery. Expression experiments in transgenic fish indicate that the Xmrk-mediated intracellular signalling is contributing to the cell-type specificity in development of hereditary melanoma in Xiphophorus.

Melanoma as a second malignant neoplasm after childhood cancer

BACKGROUND

As more children survive childhood cancers, the population at risk for second malignant tumors increases. The development of melanoma as a second malignant tumor is not well described.

METHODS

The M.D. Anderson Cancer Center's 50-year experience with patients who developed melanoma after treatment of a childhood cancer was retrospectively reviewed.

RESULTS

One hundred seventy-two patients with a second malignancy were identified; 11 patients had melanoma as a second malignancy. The most common first malignancies were Hodgkin's disease, brain tumors, and retinoblastomas. Melanoma developed in an irradiated field in 4 patients. Six patients had lymphatic or distant metastasis at diagnosis. Five of 11 patients died of melanoma.

CONCLUSIONS

Factors contributing to melanoma as a second malignancy may include genetic factors and the effects of chemotherapy and radiation. Survivors of childhood malignancy should be considered at risk for developing melanoma, and suspicious pigmented lesions should be carefully evaluated.

Overexpression and mutations of p53 in metastatic malignant melanomas

Alterations of the p53 tumor suppressor gene are the most frequent genetic abnormalities in human malignancies, but the role of p53 in the etiology of malignant melanomas is unclear. Fifty unselected malignant melanomas were analyzed for p53 overexpression by immunohistochemistry using 3 monoclonal antibodies (MAbs). Fifteen tumors (29.4%) showed positive staining with at least 2 different antibodies. In the first 20 consecutive tumors exons 5-9 and adjacent splice sites of the p53 gene were analyzed by genomic sequencing. There were 4 mutations in 20 metastatic melanomas. Three of 4 mutations were C:G-->T:A transitions. A search of our database of p53 mutations revealed that out of 8 p53 mutations reported by others, 4 are C:G-->T:A transitions at dipyrimidine sites, and one is a tandem CC-->TT mutation. This mutational pattern is comparable with the pattern of p53 mutations in squamous cell and basal cell carcinomas of the skin and is related to exposure to ultraviolet B (UV-B) wavelength radiation. Taken together with a predominance of UV-induced mutations in the CDKN2/ p16 gene demonstrated in melanoma cell lines, our data support a role of sunlight exposure in the etiology of malignant melanoma. The low frequency of p53 mutants in melanomas compared with other types of skin cancers suggests that although mutations in this gene are likely to be involved in the development of some malignant melanomas, they do not play as large a role as in squamous and basal cell carcinomas of the skin.

Genetics of Cutaneous Malignant Melanoma

An increase in the clinical significance of cutaneous malignant melanoma has paralleled a dramatic increase in the rate of death from this disease. The critical genetic changes associated with the genesis and progression of this disease are only beginning to be identified. This review highlights genetic changes in cutaneous melanoma and discusses the genetics of predisposition, cytogenetics, changes in proto-oncogenes and oncogenes, and evidence for the role of tumor suppressor genes in this malignancy. The viewpoint of this article is that malignant melanoma is a genetic disease.