Gene May Provide Specific Target For Attacking Prostate Cancer

A gene discovered by researchers at UCLA’s Jonsson Cancer Center may provide a target on prostate cancer cells for antibodies to attack, allowing the antibodies to destroy those cells while ignoring all others.

A paper in a recent issue of the Proceedings of the National Academy of Sciences describes the gene and its potential value.

 First author of the paper--Dr. Robert Reiter of UCLA’s Jonsson Cancer Center and an assistant professor in the Department of Urology at UCLA’s School of Medicine--observes that identification of genes such as the one he discovered "is critical to the development" of new diagnostic and therapeutic methods for combating prostate cancer.

New Gene Has Interesting Features

"The importance of this gene is that it links the development of a special set of cells in the prostate to the creation of prostate cancer," said Dr. Owen Witte, co-author of the paper, professor of microbiology in the Department of Microbiology and Molecular Genetics at UCLA, and an investigator at the Howard Hughes Medical Institute.

The prostate stem-cell antigen gene (PSCA), and the protein it expresses, have many interesting features:

• The protein exists predominantly on the surface of prostate cells, and, therefore, antibodies designed to kill prostate cancer cells can potentially be engineered to seek out cells that express PSCA while ignoring cells that do not make PSCA.

• The protein appears to be more prevalent on prostate cancer cells than on normal prostate cells. As a result, antibodies can seek out high concentrations of PSCA, thereby specifically targeting cancerous prostate cells.

• It is possible that the PSCA protein may be secreted into the bloodstream in significant amounts. Reiter is studying that possibility. If the hypothesis is correct, PSCA will be a good marker (along with the existing prostate-specific antigen) to indicate the presence of prostate cancer.

• Because the PSCA gene closely resembles stem cells, PSCA may have a function in the development of prostate cancer cells.

"We think that PSCA provides the target I’ve described, and it may also be a good marker for the presence of prostate cancer. We’re very excited about our discovery," Reiter said.

In collaboration with pathologist Max Loda of Harvard Medical School and Beth Israel Deaconess Medical Center in Boston, Reiter has found that more than 80% of prostate cancers produce high levels of PSCA.