Many breast cancer cells facing potentially lethal antiestrogen therapy recycle to survive, researchers say.
About 70 percent of breast cancer cells have receptors for the hormone estrogen, which acts as a nutrient and stimulates their growth. Patients typically get an antiestrogen such as tamoxifen for five years to try to starve them to death, says Dr. Patricia V. Schoenlein, cancer researcher in the Medical College of Georgia Schools of Medicine and Graduate Studies.
"About 50 to 60 percent of these women really benefit from hormonal therapy," says Dr. Schoenlein. Why others don't has been asked for at least two decades.
One reason may be breast cancer cells switch into a survival mode that normal cells also use when faced with starvation, according to research published in the September issue of Molecular Cancer Therapeutics. Dr. Schoenlein also is reporting on the research during the 2nd World Conference on Magic Bullets (Ehrlich II) Oct. 3-5 in Nrenberg, Germany.
It's called macroautophagy autophagy means "self eating" and within a week, breast cancer cells can reorganize component parts, degrade non-essentials and live in this state until antiestrogen therapy is stopped or the cells mutate and resume proliferation in the presence of tamoxifen. "It's like taking your foot off of the gas pedal of your car," says Dr. Schoenlein, corresponding author on the study. "The cancer cell is in idle, unable to grow or replicate. But the cell is smart enough to use component parts generated by macroautophagy for the most necessary things required for survival." She notes that macroautophagy can't be maintained indefinitely; cells can actually self-digest. "This is a time-buying strategy."
Chemotherapeutic drugs are more direct killers but also kill healthy cells and can be tolerated by patients only for relatively short periods. Antiestrogen therapy is more specific, targeting breast cancer cells that express es
|Contact: Toni Baker|
Medical College of Georgia