Researchers found that a medication used to ease symptoms of the common cold — called N-Acetylcysteine (NAC) — could also help to prevent the growth of cancer cells by depriving them of proteins that are important for their survival.
Study co-author Prof. Federica Sotgia, of the School of Environment and Life Sciences at the University of Salford in the United Kingdom, and colleagues recently reported their findings in the journal Seminars in Oncology.
Cancer remains one of the biggest health challenges of our time. In the United States, more than 1.6 million new cancer cases were diagnosed last year.
In terms of cancer treatment, we have come a long way over recent years. This is reflected in death rates from the disease, which fell by 13 percent between 2004 and 2013.
Still, cancer continues to the take the lives of more than half a million people in the U.S. every year, highlighting the need for new, more effective therapies.
Prof. Sotgia and colleagues hope that their new research will bring us closer to such treatments, after discovering how NAC could help to halt the spread of cancer cells.
NAC, oxidative stress, and cancer cells
NAC — sometimes referred to as acetylcysteine — is an over-the-counter medication and dietary supplement commonly used to help alleviate some cold and flu symptoms, such as coughing, wheezing, and thick mucus.
The medication also has antioxidant properties. This means that it has the ability to reduce cell damage caused by oxidative stress, which is an imbalance between potentially harmful reactive oxygen species and levels of detoxifying molecules.
Prof. Sotgia and team note that previous research has identified high levels of oxidative stress in the stromal cells of tumors, particularly breast cancer tumors. Stromal cells are cells that comprise connective tissue.
The researchers explain that when the stromal cells of tumors are exposed to oxidative stress, they release lactate and other "nutrients" that the cancer cells need to thrive.
With this in mind, the team hypothesized that the antioxidant properties of NAC might help to "starve" cancer cells of these nutrients.
To test their theory, the researchers conducted a trial on 12 women who had recently received a diagnosis of stage 0 or stage 1 breast cancer, and who were awaiting surgery for the disease.
For 3 weeks between their breast cancer diagnosis and surgery, each woman received NAC. The medication was administered intravenously at a dose of 150 milligrams per kilogram once weekly. On days when the subjects did not receive NAC intravenously, they received a twice-daily oral dose of 600 milligrams.
Biopsies of each woman's breast cancer tumor were taken both prior to and during surgery, and the researchers analyzed them for levels of three biomarkers of cancer aggressiveness: MCT4, CAV1, and Ki67.
The study revealed that levels of Ki67 in the tumors had reduced by 25 percent, while levels of MCT4 were reduced by a whopping 80 percent.
These findings indicate that treatment with NAC could be an inexpensive, non-toxic way to stop cancer cell growth and division.
"High levels of stromal MCT4 are extremely worrying," notes study co-author Prof. Michael Lisanti, also of the School of Environment and Life Sciences at the University of Salford, "as they are linked to aggressive cancer behavior and poor overall survival, so this is very encouraging result."
"Our idea was to repurpose an inexpensive FDA-approved drug, to examine if its antioxidant properties could target the feeding behavior of cancer cells. To be able to inhibit MCT4 protein expression, in a non-toxic way, is huge step forward."
Prof. Michael Lisanti