by: S. L. Baker, features writer
January 19, 2012
When natural health advocates warn against mainstream medicine’s arsenal of weapons used to fight cancer, including chemotherapy and radiation, their concerns often revolve around how these therapies can weaken and damage a person’s body in numerous ways. But scientists are finding other reasons to question some of these therapies. It turns out that while chemotherapies may kill or shrink tumors in the short term, they may actually be causing malignancies to grow more deadly in the long term.
For example, NaturalNews previously reported (http://www.naturalnews.com/029042_cancer_cells_chemotherapy.html) that scientists at the University of Alabama at Birmingham (UAB) Comprehensive Cancer Center and UAB Department of Chemistry are currently investigating the very real possibility that dead cancer cells left over after chemotherapy spark cancer to spread to other parts of the body (metastasis). And now comes news that a little-explored specific cell type, the pericyte, found in what is called the microenvironment of a cancerous tumor actually may halt cancer progression and metastasis. And by destroying these cells, some anti-cancer therapies may inadvertently be making cancer more aggressive as well as likely to spread and kill.
A study just published in the January 17 issue of the journal Cancer Cell concludes that anti-angiogenic therapies (which shrink cancer by cutting off tumors’ blood supply) may be killing the body’s natural defense against cancer by destroying pericyte cells that likely serve as important gatekeepers against cancer progression and metastasis. Pericytes cover blood vessels and support their growth.
For the new research, Raghu Kalluri, MD, PhD, Chief of the Division of Matrix Biology at Beth Israel Deaconess Medical Center (BIDMC) and Professor of Medicine at Harvard Medical School (HMS), investigated whether targeting pericytes could inhibit tumor growth in the same way that other antiangiogenic cancer drugs do.
Dr. Kalluri and his research team worked with mice genetically engineered to support drug-induced depletion of pericytes in growing tumors. Next, they removed pericytes in implanted mouse breast cancer tumors, decreasing pericyte numbers by 60 percent.
Compared with control animals, there was a 30 percent decrease in the size of cancerous tumors over 25 days. But there was a serious catch to these results. Contrary to conventional mainsteam medical wisdom, the scientists discovered the number of secondary lung tumors in the engineered mice had increased threefold compared to the control mice, indicating that the tumors had metastasized.
How cancer drugs can spread cancer cells
“If you just looked at tumor growth, the results were good,” Dr. Kalluri said in a press statement. “But when you looked at the whole picture, inhibiting tumor vessels was not controlling cancer progression. The cancer was, in fact, spreading. This suggested to us that without supportive pericytes, the vasculature inside the tumor was becoming weak and leaky — even more so than it already is inside most tumors– and this was reducing the flow of oxygen to the tumor.”
That change, he explains, makes cancer cells more mobile, so they can travel through those leaky vessels to new locations. It also makes cancer cells behave more like stem cells, so they are better able to survive.