Georgia researchers find that some erectile dysfunction drugs activate an enzyme that helps to protect gastrointestinal linings from inflammation. This anti-inflammatory protection seems to shield these tissues from attacks by cancerous cells.
Erectile dysfunction drugs like Viagra, Levitra, and Cialis belong to a class of medications called PDE5 inhibitors that have revolutionized both the discussion and treatment of ED.
These drugs appear to have a number of other uses as well, some of which have absolutely nothing to do with sexual function. PDE5 inhibitors have shown promise in treating conditions from altitude sickness to benign prostate enlargement, and researchers are continuing to explore how these drugs affect a number of different processes in the body. Some of this research indicates that these drugs may be useful in the prevention or treatment of colon cancer.
What PDE5 Inhibitors Do
As their name suggests, PDE5 inhibitors block the action of an enzyme known as phosphodiesterase-5, which breaks down another substance called cyclic guanosine monophosphate, or cGMP, in the smooth muscle cells that line blood vessel walls. When there’s more cGMP to go around, this smooth muscle lining blood vessels relaxes, and the result is increased blood flow. Each of the major PDE5 inhibitors works a little differently, with some targeting PDE5 more exclusively, and some affecting other types of the PDE enzyme as well. The slightly different formulations mean that some PDE5 inhibitors are better at treating certain non-ED conditions than others. For example, Cialis is believed to target a type of PDE that affects the prostate gland, and now Cialis is FDA-approved for treating symptoms of benign prostate enlargement.
PKG2 and Its Role in the Colon
Darren Browning, a researcher at the Georgia Regents University Cancer Center and faculty member at the Medical College of Georgia, a few years back reported exciting news: “We’ve found a way of activating a tumor suppressive pathway in the gut using drugs already in use for erectile dysfunction.” Browning and his colleagues discovered that an enzyme called 2 protein kinase G, or PKG2, plays a role in the protection of cells that make up the lining of the colon and also in the prevention of inflammation. So they looked for ways to increase PKG2 activation in the colon.
PDE5 inhibitors, by expanding blood vessels, appear to help regulate the mucosal lining of the colon. This lining turns over regularly every few days, but when this turnover cycle is disrupted, holes can form. These holes can allow substances to enter the colon, causing inflammation. By signaling cGMP in the lining of the colon, PDE5 inhibitors appear to make the colon lining more resilient under stress. The problem with inflammation of the lining of the colon is that over the long term, it greatly increases the risk of colon cancer.
Possible Help for Colitis Patients
More immediate benefits could become available to people who suffer from colitis, or inflammation of the colon. Currently, doctors use drugs like steroids to treat the inflammation, but steroids bring on side effects and risks that make them only suitable for short-term use. By making the lining of the colon more resilient, PDE5 inhibitors may offer a new option. “We have a novel way potentially of treating it. Instead of shutting down the immune system, which is responding to a weakened barrier, we found a way to strengthen the barrier.”
Browning received a $1.8 million grant from the National Cancer Institute to explore how and how well these drugs may be used in the prevention of colon cancer. Using two different mouse models – one with genetic predisposition to colon cancer, and another with inflammatory colon disease – the research team will administer the drugs to see if they prevent or reduce the incidence of colon cancer in the mice.
They also plan to learn which drug works best and bolster evidence that PKG2 is in fact the central point of action that results in better colon barrier protection. And the payoff could be sooner due to the fact that the drugs are already on the market. Said Browning, “If the drugs continue to work as our studies to date have indicated, the next stage is clinical trials because these drugs are in the clinic already.”
For men who use Viagra or one of the other PDE5 inhibitors to treat symptoms of ED, ordering those drugs from a reputable online facilitator such as eDrugstore.com can often save both time and money. Based in Tempe, Arizona, eDrugstore stocks a full range of ED drugs, including both brand-name and generic products. To learn more, visit eDrugstore’s Erectile Dysfunction page.
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