Like predators following prey, cancer cells migrate to other locations in the body, taking over the machinery of key cells, then killing them. This is known as metastasis. In some cancers like prostate cancer, the cells can migrate into the bone, where they exploit stem cell activity, proliferate, and eventually, spread throughout the body. The effects are, of course, lethal. Prostate cancer is the second-leading cause of cancer-related deaths in men in the United States.
Stopping this from happening, or at least slowing it done considerably, has been a long-time goal of many cancer researchers. Hormone suppression therapies have been developed that inhibit testosterone, but eventually, cancer cells develop resistance to this treatment, and continue to metastasize.
But recently, a graduate team of cell biologists at the University of California Riverside, led by Professor Manuela Martins-Green, were able to isolate and identify several components of pomegranate juice that seem to keep cancer cells stuck together, inhibiting their migratory tendencies.
The team treated in vitro (cultured) prostate cancer cells that were resistant to the male hormone with a pomegranate juice extract. Analysis showed that cells which survived the treatment showed increased cell adhesion. This increased cell adhesion works counter to metastasis, which is one major way that a cancer survives and avoids the body’s immune responses.
The actively anti-metastatic compounds identified in pomegranate juice are: phenylpropanoids, hydrobenzoic acids, flavones and conjugated fatty acids. Saturated forms of the latter compounds can contribute to clogging of the arteries, but, by that same capacity, apparently, inhibit cancer cells from spreading by keeping them stuck together.
Cancer cells are able to metastasize to specific organs by following certain molecular signals, or chemo-attractants, secreted by cancer cells as they migrate away from the initial site of the cancer. In the case of prostate-to-bone metastasizing, the cancer cells are attracted to a protein signal in the bone. Fortunately, as a dual benefit, these pomegranate compounds seem to interfere with this chemical signaling between cancer cells and the bone protein.
The UC Riverside team is planning on conducing in vivo research (i.e., on a living patient, or animal model) in the not too distant future.
The team’s research results were presented recently (Dec. 12, 2010) at the 50th annual meeting of the American Society for Cell Biology, in Philadelphia.
The pomegranate figures symbolically in many ancient myths (such as the Greek myth of Persephone) and was one of the first fruits brought to Moses as proof that the promised land was indeed fruitful. It’s astringent juice has been prized since ancient times as a medicinal treatment for diarrhea, dysentery and intestinal parasites. The pomegranate is also utilized in the Indian Ayurvedic health system (based upon the four classical elements), where it is associated with fire (pitta), due to its acidic qualities, and is used to protect the heart and throat. The name is Greek for “apple seeded”.
top image: Illustration by Otto Wilhelm Thomé, 1885
photo: Manuela Martins-Green, UC Riverside; UCR Strategic Communications.