14 DAY TRIAL // It is the monster lurking most men: prostate will swell, urinating and having sex will turn painful and the operation may mean not sex at all (impotence). Moreover, the prostate cancer can spread and kill you. But those Chinese, with their tofu, know the secret: a new research published in the journal Cancer Research shows that a chemical encountered in soybean almost completely stopped the spread of human prostate cancer in mice.
The molecule is an antioxidant called genistein and worked in amounts no higher than those delivered by a soybean-rich diet. The team from Northwestern University discovered that genistein impeded the spread of prostate cancer to the lungs by 96 % as compared to mice which did not received the chemical.
"Certain chemicals have beneficial effects and now we have all the preclinical studies we need to suggest genistein might be a very promising chemopreventive drug," said senior investigator Dr. Raymond C. Bergan, director of experimental therapeutics for the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
The same team had previously showed, in prostate cancer cell cultures, that genistein stops the detachment of cancer cells from a primary prostate tumor, impeding their spread. The chemical inactivates p38 MAP kinases, molecules controlling the pathways of the proteins that release cancer cells from tumors, allowing 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.
The mice in the study were fed on genistein, then implanted 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," said Bergan.
Genistein didn't affect the size of prostate cancer tumors, it ceased the cancer spread to the lung almost completely. The researchers measured the size of tumor cells' nuclei to see if the cells had flattened out for migrating to other body parts.
"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. We found that mice fed genistein expressed higher levels of genes that are involved in cancer cell migration which at first might not make sense in light of the study's conclusion. 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," said Bergan.
The team signals that genistein could have stronger effect only in people who have eaten soy all their lives compared to those stating to consume genistein. Associative researches showed that the spread of prostate cancer is decreased in men who eat soy-rich foods, but it is not clear if soybean also impedes the emergence of prostate cancer.
"Results of some laboratory studies of genistein have also been mixed, but most have shown favorable results, demonstrating that genistein can inhibit a variety of cell molecules including tyrosine kinases, which activate proteins by attaching them to phosphate chemicals," said Bergan.