About 80% of people with cancer suffer from significant muscle wasting or loss of muscle tissue, and 30% of these patients die from the condition. New research in mice found that the severity of muscle wasting correlated with the type, size, and location of the tumor.
“The killer is usually muscle wasting, not the tumor itself,” said Gustavo Nader, associate professor of kinesiology at Penn State. “Therefore, it’s important to study what’s going on at the cellular level in skeletal muscle, which may contribute to the problem of attenuation.”
Nader’s previous research on ovarian cancer revealed that muscle loss is associated with decreased production of ribosomes, or protein-making particles in the cell. Still, relatively little is known about the mechanisms that reduce muscle protein synthesis and wastage in cancer patients, he said.
In new research published in two articles in the same issue, Journal of Applied PhysiologyThe team investigated the mechanisms involved in muscle wasting in lung cancer and colorectal cancer in mice. The researchers found that the type, size, and location of the tumor affected the severity of muscle wasting through different mechanisms.
In the lung cancer study, the team examined the effects of two different lung cancer-derived tumors – LP07 and Lewis lung carcinoma (LLC). Tumor growth caused significant muscle weakness in mice with tumor type LP07, which was also associated with a reduction in ribosome production, whereas muscle wasting in the LLC tumor type caused muscle wasting but did not produce weakness or lower ribosomal levels.
In the colorectal cancer study, the team examined two types of colorectal tumors (HCT116 and C26), using two models to describe the role of tumor burden on muscle wasting. Tumor burden is the number of cancer cells, the size of a tumor, the amount of cancer in the body, or the severity of tumor-related disease. The findings show that the location of the tumor is an important factor in determining the severity of muscle wasting, but it also depends on the type of tumor.
“There is no effective treatment for muscle wasting in cancer patients,” said Nader. “We are starting to understand how different tumors cause muscle wasting, which is very important because cancer treatments are less effective in patients with low muscle mass.”
The Penn State team collaborated with David Waning of Hershey Medical Center, Esther Barreiro of Universitat Pompeu Fabra in Barcelona, and Andrea Bonetto of Indiana University. Research in the Nader lab is supported by the National Institutes of Health.
materials provided by Penn State. The original was written by Sara LaJeunesse. Note: Content can be edited for style and length.