Calpain inhibitors ameliorate muscle wasting in a cachectic mouse model bearing CT26 colorectal adenocarcinoma

Abstract

Cancer-related cachexia involves increased protein breakdown through various proteolytic pathways, including the ubiquitin-proteasome pathway (UPP). We hypothesized that a calcium- and calpain-dependent pathway might play a crucial role during the proteolytic procedure, and that pathway interventions would ameliorate cancer cachexia in vivo. After being inoculated with CT26 adenocarcinoma cell culture subcutaneously, BALB/c mice developed cachexia in 12 days. They were then administered with different types of calpain inhibitors individually or in combination for 7 consecutive days. Eighteen healthy mice were also assessed as a control group. Changes in body weight, gastrocnemius muscle mass, tumor volume, food intake, survival time, and serum nutritional markers were monitored. Also measured were the levels of calpains, E3 ubiquitin ligases, and apoptosis-associated markers in gastrocnemius muscle. Our study showed that the intraperitoneal administration of calpain inhibitors significantly improved tumor-free body weight and gastrocnemius muscle mass in all treatment groups. Treatment with calpain inhibitors also ameliorated cachexia-associated negative effects in metabolic profiles and increased survival time in most of the tumor-bearing mice compared with the cachexia controls. Furthermore, calpain inhibitors reduced the calpain activity and the expression of MuRF-1 and atrogin-1 in all treatment groups, while increasing the level of cleaved caspase-3 and BAX and lowering the level of BCL-2 in some groups. These results justify further evaluation of calpain inhibitors both alone and in combination with other candidate agents as a potential new therapeutic strategy for treating cancer cachexia.

Acylated and unacylated ghrelin inhibit atrophy in myotubes co-cultured with colon carcinoma cells

“…Furthermore, active calpain can promote muscle atrophy by inhibiting Akt activity [ 20 ] and activating FoxO3a, NF-κB, and ubiquitin E3 ligases [ 19 , 21 , 22 ]. A recent study [ 23 ] in our laboratory confirmed that an activated calpain system, as indicated by an increased calpain/calpastatin ratio, contributed to skeletal muscle wasting in cachexic tumor-bearing mice, and calpain inhibitors reversed this effect.…”

“…We recently demonstrated that the presence of tumors increased calpain activity and decreased calpastatin expression in the skeletal muscle of cachexic mice [ 23 ]. Here, we performed western blot and RT-qPCR studies to investigate whether co-culture and AG/UnAG affected the expression of calpains and calpastatin in myotubes.…”

Modulating Metabolism to Improve Cancer‐Induced Muscle Wasting

“…Despite the literature report data supporting the involvement of Ca 2+ -dependent proteolysis in the pathogenesis of cancer-induced muscle wasting, protein hypercatabolism was not downregulated in preparations of isolated muscles obtained from tumor-bearing animals and incubated in the presence of calpain inhibitors [ 19 , 33 , 34 ]. More recently, both pharmacological and genetic approaches aimed at inhibiting the Ca 2+ -dependent proteolytic system were not able to prevent or delay cancer-induced muscle wasting [ 21 ], although contrasting results were reported in this regard [ 35 ].…”

Inhibition of mitochondrial and cytosolic calpain attenuates atrophy in myotubes co‑cultured with colon carcinoma cells

“…CT26 colorectal adenocarcinoma cell conditioned medium is often used to induce myotube atrophy to simulate CCMA in vitro (29,30). In addition, CT26 colorectal adenocarcinoma and BALB/c mice can be used to develop cancer cachectic tumor-bearing mice, as previously described (4). Thus, in the present study, CT26 cells were used to develop a cell co-culture model with myoblasts to simulate CCMA.…”