Effects of Antioxidant Amino Acids on Cancer Sarcopenia.

Cancer sarcopenia is highly prevalent in patients with advanced cancer, which is closely related to the disease prognosis. Overcoming cancer sarcopenia is important for cancer treatment. Cystine and theanine (CT), antioxidant amino acids, have been applied to the nutritional intervention of various diseases but their effects remain unclear on cancer sarcopenia. We attempt to examine the effect of CT on cancer sarcopenia. Both mouse and in vitro cachexia models showed that CT reduced oxidative stress, inhibited autophagy and apoptosis, improved oxidative phosphorylation and the suppression of high mobility group box-1 production, and improved sarcopenia and muscle maturity. When treated with 5-fluorouracil in a mouse cachexia model, tumor weight decreased but oxidative stress increased and muscle weight and muscle maturity were suppressed regardless of diet. However, in the CT group, oxidative stress was reduced and the exacerbation of sarcopenia by 5-fluorouracil was suppressed. Thus, in cancer cachexia, oxidative stress plays a major role in skeletal muscle damage, and CT, which has an anti-oxidative stress effect, has a strong protective effect on skeletal muscle. In the future, it will be important to conduct clinical studies on nutritional intervention for cancer sarcopenia using CT.