Featured Researcher—Shiuan Chen, Ph.D.
Dr. Chen is the Director of the Department of Surgical Research, Division of Surgery in the Beckman Research Institute of the City of Hope.
Developing Breast Cancer Prevention from Natural Products
Dr. Chen has studied the chemopreventive properties of the aromatase inhbitors in grape seed and white button mushrooms. Aromatase is an enzyme responsible for making estrogen. Dr. Chen has found that the activity in extracts from grape seed and in white button mushrooms is capable of blocking tumor growth in animals. Based on these observations, he is developing a breast cancer chemopreventive drug. Read more about Dr. Chen’s work >
Ask an Expert
If you’d like to ask Dr. Chen a question about his research, please email your question to firstname.lastname@example.org any time between March 12 and April 30. New questions and answers will be posted regularly, so check back for updates.
- Q. How much grape juice would you have to drink to prevent
A. Based on animal studies, we estimate that 250 – 300 ml of grape juice per day could have a protective effect against breast cancer. The use of grape seed extract may avoid concerns about the sugar content in grape juice. We can only get precise dosage after human trial.
The City of Hope has an active clinical trial to determine the dosages of grape seed extract that can suppress estrogen formation (i.e., aromatase suppression) in postmenopausal women.
- Q. How many mushrooms would you have to
eat to have an effect on aromatase activity?
A. Based on animal studies, we need to eat 150 – 200 g of white button mushrooms everyday. The City of Hope plans to initiate clinical trials to determine the exact dosages of mushrooms for suppressing estrogen production in postmenopausal women.
- Q. Do ALL mushrooms affect aromatase activity? Do some
work better than others?
A. As indicated in our paper published in the Journal of Nutrition in 2001, most types of mushrooms we tested can suppress aromatase activity. The good news is that the most common type of mushrooms, white button mushrooms, are equally effective as some unusual types of mushrooms. From our preclinical studies, the anti-aromatase effect of mushrooms remains even after they are cooked.
- Q. Are the aromatase inhibitors that you find in grapes
different from the ones you find in mushrooms? If they are different,
which ones seem to be more effective?
A. Yes, the anti-aromatase chemicals we isolated from grapes (i.e., procyanidin dimers) and from mushrooms (i.e., conjugated linoleic acid) are different. From our studies, the chemicals in grapes (grape seeds) seem to be more potent than those in mushrooms. In addition, the modes of action of these chemicals are not exactly identical.
- Q. In what ways could the inhibitors
that you've found in grapes be different than the ones currently
used in the clinic?
A. The inhibitors in grapes are clearly less potent than those currently used in the clinic. Therefore, they may be useful in prevention, with less side effects (that associated with the elimination of estrogen in our body). In addition, grape chemicals are found to suppress the expression of the protein aromatase, and also to inhibit aromatase activity. Based on such results, we would like to hypothesize that grape chemicals may also be useful against premenopausal breast cancer. The synthetic aromatase inhibitors are shown to be only effective for postmenopausal breast cancer.
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