Newly Cloned Gene Studied for Possible Role in Breast Cancer

A team of researchers at Ohio State University's ComprehensiveCancer Center have isolated and cloned a gene that may play arole in breast cancer.

The gene is the human fibroblast growth factor-8 (FGF-8) gene.The researchers also tracked the gene's location to a region ofchromosome 10. That area of the chromosome is also associatedwith prostate cancer and glioblastoma.

The scientists believe that the gene may have a role in breastcancer because other research has linked the FGF-8 gene to mammarycancer in mice. Mammary cancer in mice is equivalent to breastcancer in humans.

The FGF-8 gene is also of interest because it is activated byandrogens. Androgens, which stimulate the development of hairgrowth and other male characteristics, also occur in women butonly in minute amounts.

Gene Activated By Androgens

"FGF-8 is the only growth factor gene that is activated byandrogens," said Ing-Ming Chiu, professor of internal medicineand the researcher who led the study.

"It's a good candidate for study as an oncogene because ofits role in mouse mammary tumors. We thought the same gene inhumans might be involved in hormone-dependent cancers like breastcancer and prostate cancer."

The research, published in the July issue of Oncogene,also showed that the androgen dihydrotestosterone (DHT) activatesthe human FGF-8 gene in laboratory cells.

"We have found that DHT activates the FGF-8 gene in laboratory-grownbreast cancer cells," said Chiu, "but that alone isnot evidence of a connection between the FGF-8 gene and breastcancer."

The researchers are now studying human breast tumor tissue providedby breast surgeon Michael Walker at the Arthur G. James CancerHospital and Research Institute for the expression of the FGF-8gene.

"We also want to learn if this gene plays a role in malebreast cancer and in prostate cancer," said Chiu. Breastcancer is rare in men, with an estimated 1,400 new cases and about260 deaths occurring annually. Breast cancer in women has an estimated184,300 new cases and 44,300 deaths.

Chiu's laboratory was the first to clone the gene from fibroblastgrowth factor-1 (FGF-1), which is important for cells that formconnective tissue. The protein produced by the FGF-1 gene is presentin glioblastoma.

"Our research on the FGF-8 gene is a natural extension ofour work on FGF-1," he said. Normally, the FGF-8 gene isimportant during embryonic development. In adults, it is alsoactive in the ovaries and testes, although its role in these tissuesis unknown.

If Chiu and his colleagues do find a link between cancer and theFGF-8 gene, it might mean that the gene could serve as a markerfor breast cancer. It might also provide a new target for drugsdesigned to inhibit tumor development.