Androgen-induced growth factor (AIGF) has hormone-regulated properties in the mouse Shionogi carcinoma cell line. To investigate whether or not it is involved in growth of human hormone-responsive cancers, we isolated the human AIGF gene from a placental genomic library. Genomic analyses suggested that the AIGF gene was about 6.5 kilobases in length containing five exons. The deduced amino acid sequence of human AIGF was completely identical with that of the mouse. RT-PCR analyses showed that prostate and breast cancer cell lines, LNCaP, PC-3, and MCF-7, slightly expressed the AIGF gene. Recombinant AIGF enhanced the growth of the human prostate cancer LNCaP cells, and it also markedly stimulated the growth of fibroblasts. These in vitro findings suggest that AIGF might be a possible autocrine or paracrine factor in hormone-responsive cancers.
