Purdue researchers find 'switch' for skeletal-muscle atrophy

May 24, 2006

WEST LAFAYETTE, Ind. - Researchers in Purdue University's School of Veterinary Medicine have discovered genetic and drug-treatment methods to arrest the type of muscle atrophy often caused by muscle disuse, as well as aging and diseases such as cancer.

The findings might eventually benefit people who have been injured or suffer from diseases that cause them to be bedridden and lose muscle mass, or sometimes limbs, due to atrophy, said Amber Pond, a research scientist in the school's Department of Basic Medical Sciences.

"The weight loss and muscle wasting that occurs in patients with cancer or other diseases seriously compromises their well-being and is correlated with a poor chance for recovery," Pond said. "In addition, muscle weakness caused by atrophy during aging can lead to serious falls and bone loss. Exercise is the most beneficial strategy to treat atrophy. However, many individuals are too ill to adequately participate in exercise programs.

"We've found a chemical 'switch' in the body that allows us to turn atrophy on, and, from that, we also have learned how to turn atrophy off."

Findings based on the research, funded in large part by the American Heart Association, are detailed in a study available online today (Wednesday, May 24) in The FASEB Journal, published by the Federation of American Societies for Experimental Biology. The study will be in the journal's print edition in July.

The research team found atrophy of skeletal muscle in mice could be inhibited with both gene therapy and drug treatment using astemizole (as-TEM-uh-zole), an antihistamine. This new insight has potential in many different areas of research, Pond said.

"We have discovered a direct link between atrophy and a protein in the skeletal muscle," Pond said. "This led us to develop methods that would block the protein's ability to cause atrophy. Through drug treatment, we were able to block atrophy, allowing muscle to retain 97 percent of its original fiber size in the face of atrophy."

Astemizole, which was withdrawn from the market in 2000 because of its potential to cause serious cardiovascular problems, wouldn't be suitable for use in humans, Pond said. The drug can be used in mice because it doesn't affect their hearts to the same extent.

"Astemizole administration to humans poses too great a risk," Pond said. "There's a need for more study to avoid those side effects, but the key is that we found a protein capable of sensing muscle disuse and initiating atrophy."

In the drug study, researchers used four groups of mice: a control group, a second group that was given astemizole, and two additional groups in which muscle atrophy was introduced. One of these two groups received astemizole while the second did not. Both of these groups were placed in cages constructed to elevate them so that they were unable to place any weight on their back legs.

"Use of the custom cages to produce atrophy was established in the '80s for simulation of NASA space flight; you can't mimic these effects on muscle and bone in cell culture," said Kevin Hannon, associate professor of developmental anatomy and one of the study's authors. "The mice were able to move around the cage and eat and drink on their own. We monitored their food and water intake and overall health and ensured that they were playing and eating normally."

This method allowed the scientists to demonstrate the effects of skeletal muscle atrophy and investigate reasons for the link with the Merg1a protein. The Merg1a protein is a channel that normally passes a small electrical current across the cell.

The researchers implanted a gene into the skeletal muscle that resulted in a mutant form of this protein that combines with the normal protein and stops the current. The researchers found that the mutant protein would inhibit atrophy in mice whose ability to use their back legs was limited.

Because gene therapy is not yet a practical treatment option in humans, the researchers decided to go a step further and stop the function of the protein with astemizole, which is a known "Merg1a channel blocker." The researchers found that the drug produced basically the same results as the gene therapy. In fact, muscle size increased in mice in the group that were given the drug without any other treatment.

"We are now looking at the differences in the structure of the heart and the skeleton to give us clues on how to specifically target muscles without the cardiac side effects," Pond said.
-end-
This research also was partially supported by the U.S. Department of Agriculture and Purdue's basic medical sciences department.

Writer: Maggie Morris, (765) 494-2432, maggiemorris@purdue.edu

Sources: Amber Pond, (765) 494-6185, pond@purdue.edu
Kevin Hannon, (765) 494-5949, hannonk@purdue.edu

Related Web sites:
Purdue School of Veterinary Medicine: http://www.vet.purdue.edu/
FASEB Journal: http://www.fasebj.org/
STORY AND PHOTO CAN BE FOUND AT: http://news.uns.purdue.edu/UNS/html4ever/2006/060524.Pond.atrophy.html

PHOTO CAPTION:

Amber Pond, a research scientist at Purdue University's School of Veterinary Medicine, tests skeletal muscle and heart tissue as Xun Wang, a graduate student in basic medical sciences, takes notes. The two are part of a research team investigating treatments that arrest the muscle atrophy caused by cancer and other diseases. (Purdue News Service photo/David Umberger)

A publication-quality photo is available at http://news.uns.purdue.edu/images/+2006/pond-atrophy.jpg

Purdue University

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.