osteoprotegerin and Melanoma

Melanoma represents one of the most aggressive forms of cancer. With the rapid increases in the incidence of melanoma in the United States, Australia and Europe over the last decades, melanoma has been considered an epidemic cancer in these areas. The aim of our study was to evaluate the utility of osteoprotegerin (OPG), osteopontin (OPN), epidermal growth factor (EGF) and vascular endothelial growth factor VEGF for the diagnosis and prognosis of melanoma.. Overall, 322 individuals were assessed: 183 melanoma patients and 139 healthy individuals. Melanoma patients were divided into four subgroups according to the Breslow score. OPN, OPG, EGF, and VEGF were determined in each plasma sample.. The serum levels of the following biomarkers were statistically significantly higher in the melanoma group compared to the control group: OPG and, OPN (p<0.0001), EGF (p=0.0379). In the first stage, OPG (p=0.0236) and OPN (p=0.0327) showed a statistically significant increase. Concerning positive and negative sentinel node metastases a statistically significant change was observed in: OPN (p<0.0001), EGF (p=0.0114), VEGF (p=0.0114).. OPG and OPN are promising biomarkers of early-stage melanoma. EGF and VEGF appear to be prognostic biomarkers.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Epidermal Growth Factor; Female; Humans; Lymphatic Metastasis; Male; Melanoma; Melanoma, Cutaneous Malignant; Middle Aged; Neoplasm Staging; Osteopontin; Osteoprotegerin; Prognosis; Skin Neoplasms; Vascular Endothelial Growth Factor A; Young Adult

Tumors escape host immune responses, in part, through the release of immunomodulatory factors and decoy receptors into their microenvironment. Several cancers express surface-bound and soluble members of the tumor necrosis factor (TNF) receptor superfamily, including TNFRSF11b/osteoprotegerin (OPG). In its physiologic role, OPG regulates bone remodeling through competition for osteoclast-activating cytokines and protects newly forming bone from T cell-mediated apoptosis. In multiple tumor types, OPG production is associated with an aggressive phenotype and increased metastasis to bone, but no study has examined OPG production in human metastatic melanoma. We demonstrate that a significant proportion of human metastatic melanomas constitutively produces OPG through a mechanism governed by membrane-bound TNF-α signaling through TNF receptor 1 (TNFR1). These observations both define a specific mechanism that regulates melanoma production of OPG and establish a new molecular target for the therapeutic regulation of OPG.

Topics: Apoptosis; Cell Line, Tumor; Cell Membrane; Cytokines; Gene Expression Regulation, Neoplastic; Humans; Immunotherapy; Melanoma; Neoplasm Metastasis; Osteoclasts; Osteoprotegerin; Phenotype; Prognosis; Signal Transduction; Time Factors; Tumor Necrosis Factor-alpha

The RANK/RANKL signalling mechanism is the final common pathway of osteoclast formation and activity. Inhibitors of RANK ligand (RANKL) that bind to RANK (for 'receptor activator of NF-kappaB'), such as osteoprotegerin (OPG), neutralizing antibodies against RANKL and soluble RANK antagonists, are well described inhibitors of bone metastasis in preclinical and clinical models, presumably because of their effects on osteoclasts. Jones et al. show that OPG inhibits bone metastasis after intracardiac injection of B16F10 murine melanoma cells, but claim that bone metastases are entirely independent of osteoclast formation and bone resorption: rather, they are caused by an effect on cell migration through RANK. However, we question whether these surprising conclusions are rigorously supported by their data.

Topics: Animals; Bone Neoplasms; Cell Line, Tumor; Cell Movement; Humans; Melanoma; Mice; Neoplasm Metastasis; Osteoclasts; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Reproducibility of Results

The cellular and humoral mechanisms accounting for osteolysis in skeletal metastases of malignant melanoma are uncertain. Osteoclasts, the specialised multinucleated cells that carry out bone resorption, are derived from monocyte/macrophage precursors. We isolated tumour-associated macrophages (TAMs) from metastatic (lymph node/skin) melanomas and cultured them in the presence and absence of osteoclastogenic cytokines and growth factors. The effect of tumour-derived fibroblasts and melanoma cells on osteoclast formation and resorption was also analysed. Melanoma TAMs (CD14+/CD51-) differentiated into osteoclasts (CD14-/CD51+) in the presence of receptor activator for nuclear factor kappaB ligand (RANKL) and macrophage-colony stimulating factor. Tumour-associated macrophage-osteoclast differentiation also occurred via a RANKL-independent pathway when TAMs were cultured with tumour necrosis factor-alpha and interleukin (IL)-1alpha. RT-PCR showed that fibroblasts isolated from metastatic melanomas expressed RANKL messenger RNA and the conditioned medium of cultured melanoma fibroblasts was found to be capable of inducing osteoclast formation in the absence of RANKL; this effect was inhibited by the addition of osteoprotegerin (OPG). We also found that cultured human SK-Mel-29 melanoma cells produce a soluble factor that induces osteoclast differentiation; this effect was not inhibited by OPG. Our findings indicate that TAMs in metastatic melanomas can differentiate into osteoclasts and that melanoma fibroblasts and melanoma tumour cells can induce osteoclast formation by RANKL-dependent and RANKL-independent mechanisms, respectively.

Topics: Aged; Aged, 80 and over; Antineoplastic Agents; Bone Resorption; Carrier Proteins; Cell Differentiation; Cells, Cultured; Culture Media, Conditioned; Female; Fibroblasts; Glycoproteins; Humans; Interleukin-1; Lymphatic Metastasis; Macrophages; Male; Melanoma; Membrane Glycoproteins; Middle Aged; Osteoclasts; Osteolysis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reverse Transcriptase Polymerase Chain Reaction; Skin Neoplasms; Tumor Necrosis Factor-alpha

Past studies have shown that apoptosis mediated by TNF-related apoptosis-inducing ligand (TRAIL) is regulated by the expression of two death receptors [TRAIL receptor 1 (TRAIL-R1) and TRAIL-R2] and two decoy receptors (TRAIL-R3 and TRAIL-R4) that inhibit apoptosis. In previous studies, we have shown that TRAIL but not other members of the tumor necrosis factor family induce apoptosis in approximately two-thirds of melanoma cell lines. Here, we examined whether the expression of TRAIL-R at the mRNA and protein level in a panel of 28 melanoma cell lines and melanocytes correlated with their sensitivity to TRAIL-induced apoptosis. We report that at least three factors appear to underlie the variability in TRAIL-induced apoptosis. (a) Four of nine cell lines that were insensitive to TRAIL-induced apoptosis failed to express death receptors, and in two instances, lines were devoid of all TRAIL-Rs. Southern analysis suggested this was due to loss of the genes for the death receptors. (b) Despite the presence of mRNA for the TRAIL-R, some of the lines failed to express TRAIL-R protein on their surface. This was evident for TRAIL-R1 and more so for the TRAIL decoy receptors TRAIL-R3 and -R4. Studies on permeabilized cells revealed that the receptors were located within the cytoplasm and redistribution from the cytoplasm may represent a posttranslational control mechanism. (c) Surface expression of TRAIL-R1 and -R2 (but not TRAIL-R3 and -R4) showed an overall correlation with TRAIL-induced apoptosis. However, certain melanoma cell lines and clones were relatively resistant to TRAIL-induced apoptosis despite the absence of decoy receptors and moderate levels of TRAIL-R1 and -R2 expression. This may indicate the presence of inhibitors within the cells, but resistance to apoptosis could not be correlated with expression of the caspase inhibitor FLICE-inhibitory protein. mRNA for another TRAIL receptor, osteoprotegerin, was expressed in 22 of the melanoma lines but not on melanocytes. Its role in induction of apoptosis remains to be studied. These results appear to have important implications for future clinical studies on TRAIL.

Topics: Apoptosis; Blotting, Southern; Carrier Proteins; CASP8 and FADD-Like Apoptosis Regulating Protein; Flow Cytometry; Glycoproteins; GPI-Linked Proteins; Humans; Intracellular Signaling Peptides and Proteins; Melanoma; Neoplasm Proteins; Osteoprotegerin; Polymerase Chain Reaction; Receptors, Cytoplasmic and Nuclear; Receptors, TNF-Related Apoptosis-Inducing Ligand; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Member 10c; Regression Analysis; RNA, Messenger; Tumor Cells, Cultured; Tumor Necrosis Factor Decoy Receptors