Stress hormones may speed cancer growth

New research suggests that hormones produced during times of stress may increase the growth rate of a particular type of cancer.

The new study showed that an increase in the stress hormone norepinephrine can stimulate tumor cells to produce two compounds. These compounds can break down the tissue around the tumor cells and allow the cells to more easily move into the bloodstream. They are then able to travel to another location in the body to form additional tumors. This is a process known as metastasis.

The research also suggests that the same hormone may also stimulate the tumor cells to release another compound that can aid in the growth of new blood vessels that feed cancer cells, thus precipitating the growth and spread of the cancer.

Ronald Glaser, a professor of molecular virology, immunology and medical genetics, and director of the Institute for Behavioral Medicine Research at Ohio State University said the research “opens up an entirely new way of looking at stress and cancer that’s different from current interpretations.”

Glaser and research scientist Eric Yang centered the research on the role of these three compounds. Two of them play a role in breaking down the “scaffolding” that cells attach to in order to maintain their shape. The third is a key player in the growth of new blood vessels into tumor cells.

Previous research by Anil Sood at the University of Texas showed that the same stress hormones can stimulate ovarian tumor cells to produce these three compounds. The key to that discovery was that the two stress hormones – epinephrine and norepinephrine – would bind to places on the surface of ovarian cancer cells and stimulate the release of the 3 compounds, which might then foster cancer growth. The researchers from Ohio State wanted to see if the same was true with other cancer cells.

They turned to cell lines Glaser had developed years ago to study nasopharyngeal carcinoma (NPC), a serious, incurable head and neck cancer that occurs mostly in people of Chinese descent.

They treated Glaser’s cell line with norepinephrine and, as expected, the cells all produced the aforementioned compounds. This showed that the receptors for this hormone were present on cells in Glaser’s cell line, but that may be just a laboratory aberration in the tissue cultures.

Glaser said, “We needed to see how relevant this finding was to what happened with actual tumors.” He asked colleagues for samples of actual NPC tumors to look for the presence of similar receptors. They studied tumor samples which included different types of NPC tumors. All had the receptors.

He added, “From this we can say that there is likelihood that all NPC tumors will have these receptors as well.”

Yang said that two of the compounds (MMP-2 and MMP-9) “contribute to the aggressiveness of these tumors,” and added that while not clear how they operate, they may work with the third (VEGF) compound to facilitate blood vessel growth in new tumors, allowing them to grow.

Clinicians dealing with patients with hypertension are familiar with the target receptors for these hormones. Typically, these patients are given beta-blockers to lower blood pressure levels.

Glaser and Yang wanted to see how these beta-blockers affected the tumor cells. They added propanol (a beta-blocker) to the tumor cells and then exposed them to both epinephrine and norepinephrine. With the addition of propanol, the compounds did not increase.

Glaser said these findings suggest “a new approach to possible fight some cancers – the prescribing of beta-blocker-type drugs that would block these receptors and perhaps slow the progression of the disease. Using this approach may not cure this cancer but perhaps we could slow down its growth, making the tumor more sensitive to anti-cancer therapy, and therefore extending the patients’ lifespan and improve their quality of life.”

SOURCES: Ronald Glaser, Eric Yang, Min Chen, Tim Eubank, Scott Jewell, Carl Morrison, Clay Marsh, Peir-En Yeh, Stanley Lemeshow, Nicholas Flavahan, Ohio State University, OH, USA. Yang Li, Anil Sood, MD Anderson Cancer Center, University of Texas, TX, USA.

© Copyright 2007 Insight Journal Online Magazine.

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