Granaatappel
mogelijk tegen borstkanker*
Uit een Amerikaans laboratoriumonderzoek blijkt dat bioactieve stoffen, te weten
ellagitannines uit granaatappels het enzym aromatase kunnen remmen. Onder invloed van het enzym aromatase kunnen bij vrouwen androgenen worden omgezet in oestrogenen, een van de belangrijkste groeiprikkel van hormonaal gevoelig borstkankerweefsel. Ellagitannines blijken dus ook als aromatase remmer de vorming van oestrogenen te kunnen tegengaan en daardoor de groei van hormonaal gevoelig borstkankerweefsel. Het is nog niet duidelijk hoeveel granaatappel nodig is als aromatase remmer en of de benodigde hoeveelheid wel gehaald kan worden.
Verdere studies met dieren en mensen moeten hier duidelijkheid over geven.
Pomegranate compounds may ease breast cancer risk
Enzyme-blocking chemicals in pomegranates may reduce the risk of estrogen-fueled breast cancers, U.S. researchers said on Tuesday.
An acid found in pomegranates appears to block aromatase, an enzyme that converts androgen to estrogen, a hormone that plays a role in the development of breast cancer, the researchers wrote in the journal Cancer Prevention Research.
"We identified some of these chemicals in pomegranates that actually have properties that can suppress aromatase," researcher Shiuan Chen, of the City of Hope cancer research and treatment center in Duarte, California, said in a telephone interview.
Many women who have had breast cancer take medicines called aromatase inhibitors -- such as Pfizer's Aromasin, Novartis' Femara and AstraZeneca Plc's Arimidex -- to keep estrogen from feeding tumors.
Chen and colleagues studied whether compounds, or phytochemicals, in pomegranates can suppress aromatase and ultimately block cancer growth. They found that 10 natural compounds in the fruit may potentially prevent estrogen-related breast cancer.
Chen said the compounds would not be a replacement for aromatase inhibitors.
"We do not recommend people start taking this as a replacement for the AI's," Chen said. "They (pomegranate compounds) are not as potent as the real drugs so we think that the interest probably is more on the prevention end rather than in a therapeutic purpose."
Other researchers not associated with the study told the journal that the results are promising, and suggested more studies involving animals and humans were needed to confirm the findings.
"It's not clear that these levels could be achieved in animals or in humans because the (compounds) are not well absorbed into blood when provided in the diet," said Gary Stoner of Ohio State University.
Dr. Powel Brown, an oncologist at the University of Texas, said in a statement that future studies should focus on testing pomegranate juice for its effect on estrogen levels, menopausal symptoms, breast density or even as a cancer preventive agent.
More than 400,000 women die from breast cancer globally every year. About 75 percent of breast cancers are estrogen-receptor positive, meaning they are fed by estrogen.
Previous research has shown that pomegranate juice is rich in antioxidants -- vitamins and other substances -- that may help prevent diseases such as cancer, heart disease and Alzheimer's
disease.
Pomegranate Ellagitannin–Derived Compounds Exhibit Antiproliferative and Antiaromatase Activity in Breast Cancer Cells In vitro
Lynn S. Adams1, Yanjun Zhang2, Navindra P. Seeram2, David Heber2 and Shiuan Chen1
Authors' Affiliations: 1 Division of Tumor Cell Biology, Beckman Research Institute of the City of Hope, Duarte, California and 2 Center for Human Nutrition, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California
Corresponding Author: Shiuan Chen, 1500 East Duarte Road, Duarte, CA 91010. Phone: 626-256-4673; Fax: 626-301-8972; E-mail: schen@coh.org.
Estrogen stimulates the proliferation of breast cancer cells and the growth of estrogen-responsive tumors. The aromatase enzyme, which converts androgen to estrogen, plays a key role in breast carcinogenesis. The pomegranate fruit, a rich source of ellagitannins (ET), has attracted recent attention due to its anticancer and antiatherosclerotic properties. On consumption, pomegranate ETs hydrolyze, releasing ellagic acid, which is then converted to 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one ("urolithin") derivatives by gut microflora. The purpose of this study was to investigate the antiaromatase activity and inhibition of testosterone-induced breast cancer cell proliferation by ET-derived compounds isolated from pomegranates. A panel of 10 ET-derived compounds including ellagic acid, gallagic acid, and urolithins A and B (and their acetylated, methylated, and sulfated analogues prepared in our laboratory) were examined for their ability to inhibit aromatase activity and testosterone-induced breast cancer cell proliferation. Using a microsomal aromatase assay, we screened the panel of ET-derived compounds and identified six with antiaromatase activity. Among these, urolithin B (UB) was shown to most effectively inhibit aromatase activity in a live cell assay. Kinetic analysis of UB showed mixed inhibition, suggesting more than one inhibitory mechanism. Proliferation assays also determined that UB significantly inhibited testosterone-induced MCF-7aro cell proliferation. The remaining test compounds also exhibited antiproliferative activity, but to a lesser degree than UB. These studies suggest that pomegranate ET–derived compounds have potential for the prevention of estrogen-responsive breast cancers. Cancer Prev Res; 3(1); 108–13
(Januari 2010)
