New potential target for cancer therapy.

• Position: Tumors - Alternative splicing

Alternative splicing--a process that allows a single gene to code for multiple proteins--appears to be a new potential target for anti-telomerase cancer therapy, researchers at the University of Texas Southwestern Medical Center, Dallas, have found.

The enzyme telomerase is overexpressed in almost all cancer cells, and previous research efforts have failed to identify good telomerase inhibitors. The study, by Woodring Wright, professor of cell biology and internal medicine, identifies a new approach for inhibiting telomerase, which is an enzyme that drives uncontrolled division and replication of cancer cells.

Telomeres are specialized structures at the ends of each chromosome. As DNA replicates, telomeres shorten each time a cell divides. Telomerase in human cancer cells is 10 to 20 times more active than in normal body cells. The increase provides a selective growth advantage to many types of tumors. If telomerase activity was to be turned off, then telomeres in cancer cells would shorten like they do in normal body cells.

"The oft-used analogy is that telomeres are like the plastic ends of shoelaces that protect them from fraying," Wright explains. "Once the plastic becomes damaged and falls off, the shoelace can no longer be threaded effectively. The only solution at that point is to throw the shoelace away."

In most tissues, telomerase turns off during...