The human FGF-8 gene localizes on chromosome 10q24 and is subjected to induction by androgen in breast cancer cells

Androgen-induced growth factor (AIGF or FGF-8) was originally isolated from the conditioned medium of an androgen-dependent Shionogi carcinoma, SC-3, cell line. It shares structural similarity with other members of the FGF family. The temporal and spatial expression patterns of the FGF-8 gene suggest its involvement in gastrulation, regionalization of the brain, and organogenesis of the limb and face as an embryonic epithelial factor. In the adult, expression of FGF-8 is restricted to gonads including testes and ovaries. Since FGF-8 is identified as a corroborating gene in MMTV-induced mammary tumors in Wnt-1 transgenic mice and because FGF-8 manifested its autocrine mitogenic activity in SC-3 cells, it is possible that aberrant expression of FGF-8 may be present in human cancers which are hormone dependent. However, very little is known about human FGF-8. To determine whether FGF-8 plays a role in human breast cancer, we have isolated the full-length cDNA from SK-BR-3 breast cancer cells. We have also isolated the corresponding genomic DNA in a P1 cloning vector. The FGF-8 gene has been mapped to chromosome 10q24 using both somatic cell hybrid genetic analysis and fluorescence in situ hybridization. Finally, we show that FGF-8 gene expression in a human breast cancer cell line, MDA-MB-231, is inducible by androgen. The findings presented here will facilitate our understanding of the molecular mechanism underlying hormone-responsive breast and prostate cancers.