Nerve growth factor (NGF) stimulates growth and differentiation of sensory and sympathetic neurons. It is not known what role NGF plays in melanoma development, but nevus and malignant melanoma cells express NGF-receptor (NGF-R). We counted nerve fibers within melanocytic nevi, primary cutaneous melanomas, and cutaneous melanoma metastases using a monoclonal antibody (MoAb) as marker against a 200-kD glycoprotein that is expressed on human nerves. The expression of NGF-R was studied in serial cryostat sections using a MoAb against the NGF-R. Compared to normal skin, increased numbers of nerve fibers were found in 72 melanocytic nevi. In congenital nevi their number significantly increased with age. In 47 primary cutaneous melanomas the number of nerve fibers decreased in proportion to tumor thickness. In 33 cutaneous melanoma metastases no accumulation of nerve fibers was found. NGF-R was not expressed in normal skin melanocytes and in the majority of nevus cells in melanocytic nevi. Considerable numbers of NGF-R-positive nervus cells were found only in some congenital nevi and few acquired nevi with dysplastic features. By contrast, in primary and metastatic melanomas higher expression of NGF-R was observed. The increased number of nerve fibers in melanocytic nevi suggests that neurite-promoting factors are produced in situ. Production of such factors appears to be lost in malignant melanoma cells. The finding of an inverse correlation between an abundance of nerve fibers in NGF-R-poor nevi and a high expression of NGF-R in melanomas that show no evidence of nerve growth suggest a role of NGF and its receptor in malignant melanocytic tumors.
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"Binding of NGF, the prototypic NT, has been associated with an uncharacterized survival advantage [Fabricant et al., 1977] with p75 NTR frequently overexpressed by aggressive malignant melanoma cells [Brocker et al., 1991; Herrmann et al., 1993; Mattei et al., 1994]. We have previously observed that NT responsiveness , regulation of extracellular matrix (ECM) degradative enzymes, i.e., heparanase, and cell invasion correlated with augmented p75 NTR levels in brain-colonizing melanoma cells [Marchetti et al., 1993; Marchetti and Nicolson, 2001]. "
[Show abstract][Hide abstract] ABSTRACT: The p75 neurotrophin receptor (p75(NTR)), a common receptor for members of the neurotrophins (NT) family, was previously identified as a molecular determinant of brain metastasis. We have also reported that NT treatment of murine and human brain-metastatic melanoma cells affects their invasive capacities and increases the production of heparanase, an important and unique extracellular matrix (ECM) degradative enzyme. Neurotrophism can be a survival-support mechanism for brain-metastatic cells and a survival assay was devised to mimic the growth limiting conditions of rapidly expanding metastatic tumors prior to neoangiogenesis. We report that p75(NTR) promoted the survival of brain-metastatic melanoma cells but not melanocytes in stress cultures conditions. Secondly, melanoma cells fluorescently sorted for high p75(NTR) expression (p75(NTR-H) cells) had an up to a 15-fold greater survival than those sorted for low p75(NTR) expression (p75(NTR-L) cells). Thirdly, cells overexpressing p75(NTR) associated with the growth fraction and provided these cells with an inherent growth advantage. Finally, we observed an increased survival of sorted p75(NTR-L) cells, dependent upon treatment of NT members whose functional receptors are present on these cells. Together, these results delineate that p75(NTR)-mediated trophic support profoundly affects competitive melanoma-cell survival when the tumor cell microenvironment becomes growth limiting.
Full-text · Article · Jan 2004 · Journal of Cellular Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Thirteen specimens of metastatic malignant melanoma resected from eight patients undergoing craniotomy were analyzed cytogenetically from short-term cultures. All patients had chromosome 1 aberrations, as did three of four patients with metastases only to extracranial sites. Both groups had variable involvement of chromosomes 3, 6, 7, and 8. Only those with brain metastases had 11q and/or 17q involvement in six of eight patients. In reported cases of nonbrain metastases, when chromosome 11 was involved, the short arm was usually deleted or replaced through translocation; on the contrary, in reports on patients with brain metastases, the long arm of chromosome 11 was deleted at q23 or was the recipient of a translocation at q23, and/or 17q was present as an isochromosome. These aberrations were similar to those found in the patients with brain metastases in this report. Two patients undergoing brain resections did not show 11q or 17q aberrations, one near diploid with t(10;19) and the other near hexaploid with few structural rearrangements. The neural cell adhesion molecule gene is located near 11q23, and the neural growth factor receptor is located near 17q21-q22. The relevance of these genes to brain metastases in melanoma is under investigation.
No preview · Article · Jan 1993 · Cancer Genetics and Cytogenetics