Researches identify unique sperm gene
Finding may open new avenues for cancer research

Rebecca Arrington

Anne Westbrook is part of the Center for Research in Reproductive Health team that identified SPAN-X, a gene found in sperm and also some cancers.

By Suzanne Morris

Cell biologists at the U.Va. Health System have identified a new gene, called SPAN-X, that could eventually lead to better diagnosis and treatment for certain cancers.

At first it was believed that SPAN-X is only found in normal testes. Recently, the researchers found that SPAN-X is also present in some tumors, including skin, breast, prostate and ovarian. Their findings are reported in this month's issue of Biology of Reproduction.

"In the testis, SPAN-X is found in the nuclear membrane of developing sperm, which suggests it may play an important role in the maturation of the sperm nucleus. This is a highly specific function, and we were surprised to find that this gene is also present in certain cancer cells," said Anne Westbrook, a research associate at U.Va. and leader of the team that discovered the new gene.

Blue= Sperm nucleus Green= X chromosome Red= SPAN-X protein

Previous research has shown that certain proteins are found only in the testis and are introduced for the first time during puberty. To protect them from being attacked as a foreign invader, the male body has adapted to hide these proteins from the immune system. However, since these proteins are not protected from the immune system when they are produced by cancer cells, researchers believe they will be good targets for anti-tumor therapy.

"We aren't sure yet what role SPAN-X might play in diagnosing or treating these cancers, but the finding raises interesting questions about the role of SPAN-X in tumor progression," Westbrook said.

"Based on our findings, it seems possible that as some tumors become cancerous and develop irregularly, they may begin to mimic the way genes are expressed during sperm formation," said John Herr, director for the Center for Research in Reproductive Health in whose laboratory the research was performed.

This finding is likely to open several new avenues of research. The researchers will explore several possibilities in hope of identifying treatment targets for specific cancers.

Currently, they are looking at a large number of stored tissue samples to see how frequently SPAN-X is present in different cancers. If particular levels of SPAN-X are associated with a specific type of cancer, it could eventually lead to a test that would allow for earlier diagnosis of that cancer, Herr explained.

In addition, Herr said that greater understanding of how SPAN-X functions in both normal and cancer cells could help determine if it may be a useful component of a cancer vaccine or if blocking its function could slow down or stop cancer.