Mayo Clinic-led study unravels biological pathway that controls the leakiness of blood vessels

December 17, 2012

JACKSONVILLE, Fla. -- A research team led by scientists at Mayo Clinic in Florida have decoded the entire pathway that regulates leakiness of blood vessels -- a condition that promotes a wide number of disorders, such as heart disease, cancer growth and spread, inflammation and respiratory distress.

They say their findings, published online Dec. 17 in the Journal of Cell Biology, suggest that several agents already being tested for other conditions might reverse vessel leakiness.

"Now that we understand a lot more about the pathway that leads to leaky blood vessels, we can begin to try to target it in an efficient way, and that is very exciting," says the study's lead investigator, Panos Z. Anastasiadis, Ph.D., chair of the Department of Cancer Biology at Mayo Clinic in Florida.

Physicians have attempted to regulate that pathway in cancer through use of VEGF inhibitors, such as Bevacizumab, but these drugs are not as effective as they might be if other parts of the pathway were also inhibited, Dr. Anastasiadis says.

The research team, led by Dr. Anastasiadis and Arie Horowitz, Ph.D., at Cleveland Clinic Foundation, found that VEGF is one of two different molecules that affect a key downstream protein, Syx, to regulate the permeability of blood vessels.

Blood vessels are made up of endothelial cells that have to fit tightly together to form a solid tubular structure that blood can flow through. The researchers discovered that VEGF turns off Syx, which normally ensures the junctions between endothelial cells are strong. Without Syx, adhesion between the cells is loose, and the blood vessels are leaky. When new blood vessels are needed -- such as to feed a growing tumor -- VEGF loosens up endothelial cells so new vessels can sprout.

Then, after new vessels are formed, a second molecule, angiopoietin-1 (Ang1) works to glue the cells back together, Dr. Anastasiadis says. "These molecules have opposing, yin and yang effects. VEGF kicks Syx out of the junctions between cells, promoting leakiness, and Ang1 brings it back in to stabilize the vessel," he says.

The issue in cancer, however, is that VEGF overwhelms the system. "There isn't enough Ang1 to glue the vessels back together, and this leakiness allows cancer cells to escape the tumor and travel to other parts of the body," Dr. Anastasiadis says. "In late stages of the cancer, it also promotes the leaking of liquids into organs, such as the lungs. This results in profound effects that are often lethal."

Other disorders, such as inflammation and sepsis, a deadly bacterial infection that can result from excess liquid in lungs, are also induced by a leaky vascular system, he says.

Based on a detailed analysis of molecules involved in the VEGF/Ang1/Syx pathway, Dr. Anastasiadis believes that several experimental agents might help reverse vascular leakiness. One of them inhibits protein kinase D1 (PKD1), which might prevent endothelial cells from coming apart from loss of adhesion, and the other is a Rho-kinase inhibitor that prevents endothelial cells from contracting -- which they must do to loosen up and become leaky.

"We now have new directions for both further basic research into leaky blood vessels and for potential clinical treatment," Dr. Anastasiadis says.

Investigators from Johns Hopkins University, Dartmouth Medical School, and Case Western Reserve University also contributed to the study.
-end-
The research was funded by grants from the National Institutes of Health, the Hitchcock Foundation, and the Mayo Graduate School, and an American Heart Association's Scientist Development Grant.

About Mayo Clinic Cancer Center As a leading institution funded by the National Cancer Institute, Mayo Clinic Cancer Center conducts basic, clinical and population science research, translating discoveries into improved methods for prevention, diagnosis, prognosis and therapy. For information on cancer clinical trials, call 507-538-7623.

About Mayo Clinic Mayo Clinic is a nonprofit worldwide leader in medical care, research and education for people from all walks of life. For more information, visit www.mayoclinic.com and www.mayoclinic.org/news.Journalists can become a member of the Mayo Clinic News Network for the latest health, science and research news and access to video, audio, text and graphic elements that can be downloaded or embedded.

Mayo Clinic

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.