A new cellular pathway leads to destruction of a protein that promotes growth of breast, prostate and similar cancers and could provide a new avenue through which to pursue treatment of such diseases.

Bert O'Malley, at the Baylor College of Medicine, and his colleagues concentrated their efforts on a powerful oncogene or cancer-promoting gene called the steroid receptor coactivator ( SRC ) 3 which is also a powerful promoter of tumor growth.

" In high concentrations, it drives the cells to relentless replications," O'Malley said.

However, studies in the laboratory showed that another molecule called REG-GAMMA takes SRC3 to the proteasome where it is destroyed.

" Because REG-GAMMA does this to SRC3, it is a tumor suppressor," said O'Malley.

In breast cancer, when levels of REG-GAMMA are low, SRC3 levels can be high, resulting in tumor growth, said O'Malley.

" This is an important pathway for SRC3 degradation that has never been described," said O'Malley. Other modes of taking proteins to the proteasome for destruction involve adding a molecule called ubiquitin and using energy.

" This molecule does not require ubiquitin or an energy source," he said. " It's a really strange and different molecule for that reason."

Source: Baylor College of Medicine, 2006


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