Cytokine expression in human primary and metastatic melanoma cells: analysis in fresh bioptic specimens

In recent years, several studies have documented that melanoma cell lines produce various cytokine/growth factors and their receptors. Since cell lines can acquire altered properties, such as changes in growth requirements, we studied constitutive cytokine gene expression in melanoma cells from 20 fresh surgical specimens: seven primary melanomas and 13 metastases (12 lymph-node metastases and one subcutaneous metastasis). After tumour cell isolation by discontinuous gradient, we tested for mRNA expression by means of reverse-transcriptase polymerase chain reaction. Most melanoma cells tested expressed growth factors: basic fibroblast growth factor (bFGF), interleukin (IL)1 alpha, IL-1 beta, IL-6 and IL-8 and, in five cases out of 20, expressed granulocyte-macrophage colony-stimulating factor (GM-CSF) (two out of five were also positive for GM-CSF receptor). Our results do not point to a direct correlation between cytokine expression and clinical stage at the time when the bioptic specimen was obtained. However, they allow us to suggest a possible metastatic tumour cell phenotype, in which autogenous GM-CSF expression could modulate immune response against the tumour cell itself or could potentiate metastatic colonization properties.