Stress May Speed Melanoma Progression
In laboratory tests, the researchers exposed samples of three melanoma cell lines to the stress hormone norepinephrine and looked for changes in the levels of certain proteins released by the cells: vascular endothelial growth factor (VEGF), which stimulates the growth of new blood vessels to feed a growing tumor; and interleukin-6 (IL-6) and interleukin-8 (IL-8), which play a role in tumor growth.
When exposed to norepinephrine, all three melanoma cell lines increased production of the three proteins. In C8161 cells -- the most aggressive and advanced form of melanoma -- there was "a 2,000 percent increase in IL-6. In untreated samples from this cell line, you normally can't detect any IL-6 at all," Eric V. Yang, a research scientist at the Institute for Behavioral Medicine Research, said in an OSU news release.
"What this tells us is that stress might have a worse effect on melanoma that is in a very aggressive or advanced stage, and that one marker for that might be increased levels of IL-6," Yang said.
The researchers found that norepinephrine molecules bind to receptors on the surface of cancer cells, which stimulates the release of the pro-cancer proteins.
Further tests showed that common beta-blocker blood pressure drugs significantly reduced melanoma cells' production of IL-6 and the other two proteins. The drugs did this by blocking the receptors on the surface of the cancer cells.
The findings, published in the February issue of the journal Brain, Behavior and Immunity, suggest that beta-blockers may help slow the progression of melanoma, Yang and colleagues said.
Each year in the United States, almost 48,000 cases of melanoma are diagnosed and nearly 8,000 people die of the disease, according to the American Cancer Society.
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