Different KGF expression in squamous cell carcinomas of the head and neck and in normal mucosa

Fibroblast growth factors (FGFs) are major factors mediating epithelial-mesenchymal interactions in the epidermis and mucosa. In this study the expression of the FGFs keratinocyte growth factor (KGF), acidic FGF (aFGF) and basic FGF (bFGF) was examined in tumour tissue specimens from 14 patients with advanced-stage squamous cell carcinoma of the head and neck (SCCHN) and 3 SCC cell lines by reverse-transcribed polymerase chain reaction (RT-PCR) and immunohistochemistry. None of the SCC cell lines was positive for KGF mRNA, whereas all cell lines were highly positive for aFGF and bFGF. In SCCHN tissue samples the level of KGF mRNA expression was significantly lower than in normal mucosa. Tumour stroma and the submucosal areas of normal mucosa stained intensely with anti-KGF antibody in immunohistochemical slides, whereas tumour cell nests were negative. Exposure of SCC cells to KGF thus differs from normal mucosa both quantitatively and regarding spatial distribution. This fact and the overexpression of aFGF and bFGF by tumour cells potentially promote tumour growth, invasion and metastasis. Since these growth factors and their receptors are well characterized, these observations could lead to new therapeutic strategies in SCCHN, for instance by blocking their receptors or antisense targeting.