HOUSTON -- Scientists have identified two proteins in patients with ovarian cancer that, when prevalent, dramatically increase their chance for survival.

Led by researchers at the University of Texas M.D. Anderson Cancer Center, the discovery marks a significant advance for an emerging area of basic science called RNA interference, which one day may transform medicine.

After studying nearly 250 ovarian cancer patients, scientists found that woman with high levels of two proteins named Dicer and Drosha in their tumor cells had a median survival of 11 years. Patients with low levels of one or both proteins - about 40 percent of those studied - had a median survival of less than three years.

The results are reported in Thursday's issue of the New England Journal of Medicine.
``What's important is that Dicer and Drosha are critical to the process of RNA interference,'' said the study's senior author, Dr. Anil Sood, an M.D. Anderson professor.

Scientists have known about RNA interference, a biological mechanism used by cells to ``silence'' genes, only for about a decade. This discovery won Americans Andrew Fire and Craig Mello a Nobel Prize in 2006.

The mechanism has powerful therapeutic potential, because it affords scientists a new biological lever with which to stop genes from producing proteins inside cells. This is critical, because the cause of many diseases can be traced to the errant production of those proteins.

As part of the new study, Sood and his colleagues found that Dicer and Drosha play a critical part in the body's RNA interference processes and that they appear to help suppress tumors.

Low levels of the proteins likely permit genes to continue functioning when they should be silenced.
The information gained from the study helps scientists better understand the biological details of the RNA interference process. By understanding this, they can better tailor drugs to impair the ability of tumor cells to multiply.

``Not only does this work provide useful prognostic markers, but also, perhaps, these molecular mechanisms predicting outcome are the first steps  toward the goal of improving outcomes,'' wrote Yale biologists Frank Slack and Dr. Joanne Weidhaas in a commentary run by the journal alongside the Sood paper.

With the benefit of better understanding RNA interference in ovarian cancer, Sood and other scientists at M.D. Anderson have begun developing drugs to deliver the bits of genetic material needed to silence gene activity in cancer cells.

The researchers are working with M.D. Anderson to form a Houston-based company and anticipate beginning clinical trials of those drugs within a few years.

This story is brought to you through a partnership with the Houston Chronicle and Chron.com.