New (2009) Soy Publication

SCIENCE NEWS
January 3rd, 2009;
Vol.175 #1 (P. 15)
Soy compound revs up cancer
fighter in healthy tissue

Isoflavone genistein boosts PTEN protein in
breast cells, supporting a role for soy in
long-term resistance to breast cancer
By Nathan Seppa

SAN ANTONIO — A compound in soy believed to protect
against breast cancer revs up production of a protein
that suppresses cancer in healthy breast cells, a new
lab-dish study shows.

The finding provides biological data in support of survey
research suggesting that a diet high in soy is the reason
why women in Asian nations face a lower risk of breast
cancer than do Western women.

Soy isoflavone genistein boosts levels of the well-known
tumor-suppressor protein PTEN, say molecular biologist
Omar Rahal and endocrinologist Rosalia Simmen of the
University of Arkansas for Medical Sciences in Little
Rock. They presented these preliminary findings December
13 in Texas at the San Antonio Breast Cancer Symposium.

Previous lab investigations of soy's effect on PTEN
production in breast tissues have looked at the effects of
high doses of isoflavone genistein on cancer cells. In
this study, the researchers used amounts of the soy
compound that replicate the levels in the blood stream of
people who regularly consume soy products. And, the team
tested the compound in a cell line of healthy tissue with
characteristics of pre-pubescent breast cells.

"We were looking for early epigenetic changes that can
have an impact later in life," says Rahal. What the team
found was increased activity of the gene that encodes the
PTEN protein.

The lab-dish study showed that cells exposed to soy
isoflavone genistein gin up production of PTEN protein in
the nucleus, as well as p53, another tumor-suppressor
protein. This resulted in less cell proliferation, the
scientists report.

The findings support a hypothesis that a diet rich in soy
"can modify this mammary gland and make it more resistant
to future carcinogenic insults," says Rahal.
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Robert Cohen
http://www.notmilk.com