A compound found in soybeans almost completely
prevented the spread of human prostate cancer
in mice, according to a study published in the
March 15 issue of Cancer Research, a journal
of the American Association for Cancer Research.
Researchers say that the amount of the chemical,
a powerful antioxidant known as genistein, used
in the experiments was no higher than what a
human would eat in a soybean-rich diet.
Investigators from Northwestern University found
that genistein decreased metastasis of prostate
cancer to the lungs by 96 percent compared with
mice that did not eat the compound in their chow --
making the study the first to demonstrate that the
antioxidant genistein can stop prostate cancer
metastasis in a living organism.
"These impressive results give us hope that
genistein might show some effect in preventing
the spread of prostate cancer in patients," said
the study's senior investigator, Raymond C.
Bergan, MD, director of experimental therapeutics
for the Robert H. Lurie Comprehensive Cancer Center
of Northwestern University.
"Diet can affect cancer and it doesn't do it by
magic," Bergan said. "Certain chemicals have
beneficial effects and now we have all the
pre-clinical studies we need to suggest genistein
might be a very promising chemopreventive drug."
Bergan and his team have previously demonstrated
in prostate cancer cell cultures that genistein
inhibits detachment of cancer cells from a primary
prostate tumor and represses cell invasion. It
does this by blocking activation of p38 MAP kinases,
molecules which regulate pathways that activate
proteins that loosen cancer cells from their
tight hold within a tumor, pushing them to migrate.
"In culture, you can actually see that when genistein
is introduced, cells flatten themselves in order to
spread out and stick strongly to nearby cells," he said.
In this study, investigators fed genistein to several
groups of mice before implanting them with an aggressive
form of prostate cancer .The amount of genistein in
the blood of the animals was comparable to human
blood concentrations after consumption of soy foods,
Bergan said.
The researchers found that while genistein didn't reduce
the size of tumors that developed within the prostate,
it stopped lung metastasis almost completely. They
repeated the experiment and found the same result.
They then examined tissue in the animals, measuring
the size of tumor cells' nuclei to determine if the
cells had flattened out in order to spread. "Within
a tumor, it is hard to tell where the borders of cells
stop, so one way to measure adherence is to look at
the size of the nuclei in cells and see if they are
wider due to cell spread," Bergan said. "And that
is what we found, demonstrating that the drug is
having a primary effect on metastasis."
He said that the study also found that mice fed
genistein expressed higher levels of genes that
are involved in cancer cell migration which, Bergan
says, at first might not make sense in light of
the study's conclusion that genistein almost
completely blocked metastasis.
"What we think is happening here is that the cells
we put in the mice normally like to move. When
genistein restricted their ability to do so, they
tried to compensate by producing more protein
involved in migration. But genistein prevented
those proteins from being activated," he said.
"This is really a lesson for researchers who
depend on biomarker studies to test whether a
treatment is working. They need to be aware that
those biomarkers might be telling only half of
the story."
Bergan cautioned that much is unknown about use of
genistein in preventing cancer spread. For example,
it may be that the effects of the compound in people
who have eaten soy all their lives is stronger than
benefit seen in patients who have only started to
use genistein.
According the Dr. Robert O. Young, a research scientist
at the pH Miracle Living Center states, "the antioxidant
genistein is a very powerful buffer of dietary and
metabolic acids that can lead to a cancerous condition
in the body. A diet that includes daily non-fermented
soy sprouts, edname, and tofu may help prevent or
reverse a cancerous condition by buffering
dietary and metabolic acids and thus keeping the
body alkaline."
"The isoflavone and antioxidant genistein
is found in higher amounts in sprouted soy beans then
in the soy bean itself. The benefits of eating organic
soy beans and soy sprouts has been known empirically for
thousands of years - scientific studies are now
documenting that fact."
"There has been much confusion in certain health and
wellness circles concerning the health benefits of
eating non-fermented and fermented soy products.
I have suggested for years that eating non-fermented
soy is beneficial and helpful is alkalizing the body
and buffering the acids that cause sickness and
dis-ease. This is not the case with fermented foods
and drinks, including fermented soy products such as
miso, tempeh, soy sauce, soy cheese, etc. that do not
alkalize the body and increase dietary acids that may
lead to sickness and dis-ease."
"In conclusion, the benefits of eating and drinking
organic soy and soy sprout products is good for the
body."
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