Abstract
Human tumors can constitutively express cytokines and growth factors, but the extent of this expression has not been investigated. Using 44 different probes to cytokines, growth factors, and their receptors, we tested 21 melanoma and 5 melanocyte cultures for RNA transcript expression by reverse transcriptase‐polymerase chain reaction. With 30 amplification cycles, expression of the cytokines interleukin (IL)‐1β, IL‐6, leukemia inhibitory factor (LIF), IL‐7, groα, IL‐8 and the p35 chain of IL‐12 was detected in more than 60% of melanomas. Concomitant receptors for IL‐6 and IL‐7 were also detected. IL‐1α, IL‐5, Rantes, IL‐10, interferon (IFN)‐β, tumor‐necrosis factor (TNF)‐α, G‐colony‐stimulating factor (CSF) and GM‐CSF were expressed at lower levels. Melanocytes showed greatly reduced cytokine RNA transcripts, and only groα was consistently detected. No expression of IL‐2, IL‐3, IL‐4, IL‐9, the p40 chain of IL‐12, IFN‐α or IFN‐γ RNA transcripts was detected in melanomas or melanocytes. The growth factors expressed by melanomas and, after further signal amplification, by melanocytes were transforming growth factor (TGF)‐α, epidermal growth factor (EGF), TGF‐β, endothelial‐cell growth factor (ECGF), basic‐fibroblast growth factor (bFGF), nerve growth factor (NGF) and steel. The receptors EGFR, FGFR, NGFRp70 and c‐kit were also expressed by melanomas and melanocytes. These results point to new possible autocrine and paracrine pathways in melanoma biology.