BLOOMINGTON, Ind. -- Bisphenol A, a common industrial chemical claimed to speed the growth of human breast and ovarian cancers, retains its carcinogenic properties even after being modified by body processes, report Indiana University and University of California at Berkeley scientists in the Aug. 28th issue of Chemistry & Biology, a Cell Press journal.

Defenders of bisphenol A's use have argued that its natural modification inside the human body renders the estrogen-like chemical harmless.

"We tested whether this chemical modification -- the addition of sulfate to BPA -- keeps the chemical from being absorbed by breast tumor cells," said IU Bloomington biochemist Theodore Widlanski, who led the project. "We've shown that modified versions of bisphenol A likely to be formed in the body do stimulate breast tumor cell growth in vitro. Enzymes present on the surface of breast tumor cells appear to convert the modified BPA back into BPA."

BPA is a plasticizer present at low levels in mineral water bottles, CDs and DVDs, car parts and other household products. A recent U.S. Center for Disease Control and Prevention study found trace amounts of BPA in 95 percent of urine samples collected from American adults.

The researchers present a model for the selective uptake of BPA into breast cancer cells by implicating human enzymes that sulfate and de-sulfate BPA.

One of those enzymes, estrogen sulfotransferase, adds sulfate to estrogen, making the molecule water soluble and easily transportable through the bloodstream. Widlanski's collaborators showed that BPA, too, can be sulfated by estrogen sulfotransferase.

Breast cancer cells are known to overproduce an enzyme that other, healthier cells don't -- aryl sulfatase C. Aryl sulfatase C removes sulfate from estrogen, allowing the hormone's absorption into cells. In the present Chemistry & Biology paper, Widlanski's group shows aryl sulfatase C can also de-sulfate BP
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Contact: David Bricker
brickerd@indiana.edu
812-219-8308
Indiana University
25-Aug-2006