Genistein, a component of soy, switches off cell stress response
LOS ANGELES, Mar. 4 -- Scientists have long proposed that diets high in soy may contribute to the lower incidence of certain cancers seen in Asian countries. Now, a University of Southern California/Norris study of genistein, an active component of soy products, provides one explanation of how soy could act to protect cells against cancer.
"The study links a natural component of our diet to the control of the cellular stress response, which plays an important role in many kinds of cancer and cancer drug resistance," says Amy Lee, Ph.D., holder of the Freeman Cosmetic Chair, professor of biochemistry and molecular biology at the USC School of Medicine and the associate director of basic research at the Norris Comprehensive Cancer Center.
In an article appearing in the March 4 Journal of the National Cancer Institute, Lee reports how genistein turns off the defense mechanism that cells use to survive under stressful conditions, such as starvation, malnutrition, lack of oxygen, infection, extreme heat , and cancer. In hard times, cells turn on these so-called stress response genes to protect the body. But in cancer cells, scientists think stress proteins may inadvertently worsen disease, helping tumor cells to elude the body's immune system and resist chemotherapy and other cancer treatments.
"Our group has showed, for the first time, how genistein is able to directly suppress the mammalian stress response," says Lee, who has investigated the stress response for nearly two decades. Working with graduate research assistant Yanhong Zhou, Lee found that, in cell cultures, genistein blocks the activity of a cellular protein, a transcription activating factor, that switches on the stress response genes.
"It's clear that most cancer cells make a lot more stress proteins than normal
cells do, and genistein prevents that from happening. In animal models,
Contact: Eva Emerson
University of Southern California