Muscle wasting, or loss of muscle tissue or ‘cachexia’, is a common problem for people with cancer, but the exact mechanisms behind it have long escaped the mind of doctors and scientists. Now, a study is shedding new lights on how muscle wasting occurs at the cellular level of ovary cancer. Using a mouse model of ovarian cancer, researchers found that cancer progression resulted in fewer skeletal muscle ribosomes, particles in the cell that produce proteins. Since muscle tissues are mainly determined by protein synthesis, fewer ribosomes are likely to explain why muscles dwindle in cancer.
Gustavo Nader, associate professor of kinesiology and physiology at Penn State, said that the results suggest a mechanism for muscle wasting that could be relevant to not only cancer patients, but also to other diseases such as malnutrition, people with COVID-19 and HIV-AIDS among others. Muscle loss is a common problem that has no cure in the present times. But now that we understand the mechanism better, we can go ahead and try to find ways to reverse this mechanism. Significant cachexia occurs for about 80% of people with cancer and as per the researchers 30% of cancer deaths are results of impaired quality of life, problems with chemotherapy and lower survival rates where cachexia is often the killer, not the tumor.
Nader said that since there is currently no treatment for cachexia, it is important that scientists understand exactly how and why it occurs. Nader’s team wanted to approach the problem from a new angle. Most of the attention has gone to protein breakdown; where people have tried to prevent protein from being cut or broken down to prevent muscle loss, as said by Nader. Many of efforts have gone in vain because we have forgotten about the aspect of protein synthesis, that is, the process of the formation of new proteins.
For the study, the team used a preclinical mouse model of ovarian cancer with significant muscle loss. Using mice, the researchers were able to study the progression of cancer cachexia over time and they found that, the mice with tumors experienced rapid loss of muscle mass and a dramatic decrease in the ability to synthesize new proteins, which can be explained by a decrease in the number of ribosomes in their muscles.
