Zeng Xianliang, Zhao Li, Chen Sizeng, Li Xiantao
Department of Gastrointestinal Surgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian 350004, P.R. China.
Department of Dermatology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian 350004, P.R. China.
Oncol Lett. 2021 Feb;21(2):124. doi: 10.3892/ol.2020.12385. Epub 2020 Dec 17.
Cancer cachexia is a life-threatening syndrome characterized by muscle atrophy. Cancer cachectic muscle atrophy (CCMA) is associated with mitochondrial injury. Mitochondrial calpains have been reported to induce mitochondrial injury in mouse cardiomyocytes and pulmonary smooth muscle. In the present study, the presence of calpain in the mitochondria of skeletal muscle and its potential role in CCMA were investigated. Transwell plates were used to develop a myotube-carcinoma cell co-culture model to simulate the cancer cachexia environment . The calpain inhibitors, calpastatin (CAST) and calpeptin (CAPT), were used to inhibit calpain activity in myotubes during co-culture. Calpain-1, calpain-2 and CAST were found to be present in mouse myotube mitochondria. Co-culture activated calpain in both cytoplasm and mitochondria, which caused myotube atrophy. CAST and CAPT treatment prevented calpain activation in both cytoplasm and mitochondria, which inhibited myotube atrophy during co-culture. Additionally, CAST and CAPT treatment increased mitochondrial complex I activity, decreased mitochondrial permeability transition pore opening and improved mitochondrial membrane potential in myotubes during co-culture. In addition, CAST and CAPT treatment increased AKT/mTOR activity, inhibited FoxO3a activity and decreased atrogin-1 content in myotubes during co-culture. The present findings provide new insights to understand the mechanism of CCMA and further help the development of focused approaches to treat CCMA by manipulating the mitochondrial and cytosolic calpain activity.
癌症恶病质是一种以肌肉萎缩为特征的危及生命的综合征。癌症恶病质肌肉萎缩（CCMA）与线粒体损伤有关。据报道，线粒体钙蛋白酶可诱导小鼠心肌细胞和肺平滑肌中的线粒体损伤。在本研究中，研究了骨骼肌线粒体中钙蛋白酶的存在及其在CCMA中的潜在作用。使用Transwell板建立肌管-癌细胞共培养模型以模拟癌症恶病质环境。在共培养期间，使用钙蛋白酶抑制剂钙蛋白酶抑制蛋白（CAST）和钙肽素（CAPT）抑制肌管中的钙蛋白酶活性。发现钙蛋白酶-1、钙蛋白酶-2和CAST存在于小鼠肌管线粒体中。共培养激活了细胞质和线粒体中的钙蛋白酶，导致肌管萎缩。CAST和CAPT处理可防止细胞质和线粒体中的钙蛋白酶激活，从而在共培养期间抑制肌管萎缩。此外，CAST和CAPT处理可增加共培养期间肌管中线粒体复合物I的活性，降低线粒体通透性转换孔的开放，并改善线粒体膜电位。此外，CAST和CAPT处理可增加共培养期间肌管中AKT/mTOR的活性，抑制FoxO3a的活性，并降低atrogin-1的含量。本研究结果为理解CCMA的机制提供了新的见解，并进一步有助于通过操纵线粒体和细胞质钙蛋白酶活性来开发治疗CCMA的针对性方法。
