Increased expression of fibroblast growth factor 8 in human breast cancer

Fibroblast growth factor 8 (FGF8) is an important developmental protein whi ch is oncogenic and able to cooperate with wnt-1 to produce mouse mammary c arcinoma. The level of expression of FGF8 mRNA was measured in 68 breast ca ncers and 24 non-malignant breast tissues. Elevated levels of FGF8 mRNA wer e found in malignant compared to non-malignant breast tissues with signific antly more malignant tissues expressing FGF8 (P = 0.019) at significantly h igher levels (P = 0.031), In situ hybridization of breast cancer tissues an d analysis of purified populations of normal epithelial cells and breast ca ncer cell lines showed that malignant epithelial cells expressed FGF8 mRNA at high levels compared to non-malignant epithelial and myoepithelial cells and fibroblasts. Although two of the receptors which FGF8 binds to (FGFR2- IIIc, FGFR3-IIIc) are not expressed in breast cancer cells, an autocrine ac tivation loop is possible since expression of fibroblast growth factor rece ptor (FGFR) 4 and FGFR1 are retained in malignant epithelial cells. This is the first member of the FGF family to have increased expression in breast cancer and a potential autocrine role in its progression.