Combined treatment of carfilzomib and z-VAD-fmk inhibits skeletal proteolysis and apoptosis and ameliorates cancer cachexia.

The purpose of the study was to evaluate the therapeutic benefit of treatments with carfilzomib (CFZ) and z-VAD-fmk in a mouse model of cancer-induced cachexia. The model of cancer-associated cachexia was generated by injecting murine C26 adenocarcinoma cells into BALB/C mice. CFZ and z-VAD-fmk were administered individually or in combination at 5 and 12 days after inoculation. Changes in body weight, gastrocnemius muscle mass, tumor burden, spontaneous activity, survival, and metabolic profiles were noted. Also evaluated were the circulatory levels of renin and angiotensin II, and levels of apoptotic, proteolytic, and renin-angiotensin system-associated markers and transcription factor 2 (ATF2) in gastrocnemius muscle. The CFZ and z-VAD-fmk treatments were associated with less muscle wasting, reduced tumor burden, modulated metabolism, higher levels of glucose, albumin, and total proteins, and lower levels of triglyceride fatty acids, more spontaneous physical activity, and longer survival in C26-inoculated mice compared with PBS-treated cachectic mice. CFZ and z-VAD-fmk treatments resulted in higher levels of caspase-3 and BAX and lower level of BCL-XL in gastrocnemius muscles and altered the level of proteins in the renin-angiotensin system. The combined treatment administered 5 days after C26 inoculation was more effective than other regimens. Combined treatment with CFZ and z-VAD-fmk early in the development of cachexia was associated with signs of less proteolysis and apoptosis and less severe cachexia in a mouse model of cancer-induced cachexia.

MG132-mediated inhibition of the ubiquitin-proteasome pathway ameliorates cancer cachexia.

PURPOSE: To evaluate the effect of proteasome inhibitor MG132 in cancer cachexia and to delineate the molecular mechanism underlying. METHODS: We established an experimental cancer cachexia model by subcutaneously implanting colon 26 cells into the armpits of BALB/c mice. Following administration of MG132 at various time points, body weight, food intake, gastrocnemius muscle weight, spontaneous activity and survival of tumor-bearing mice were examined along with tumor growth. Moreover, cachectic markers including glucose, triglyceride, albumin and total proteins as well as levels of the proinflammatory cytokines TNF-α and IL-6 in serum and gastrocnemius tissue were measured. Finally, mRNA and protein levels of p65, IκBα, and ubiquitin E3 ligases MuRF1 and MAFbx in gastrocnemius muscle were assessed. RESULTS: MG132 treatment significantly alleviated cancer cachexia as demonstrated by attenuated weight loss, altered carbohydrate metabolism and muscle atrophy and increased spontaneous activity and survival time of tumor-bearing mice. MG132 reduced tumor growth and the levels of TNF-α and IL-6 in serum and gastrocnemius tissue. NF-κB, MuRF1 and MAFbx were also inhibited by MG132. Unexpectedly, MG132 was more efficient when administrated during the early stages of cachexia. MG132 had no effect on food intake of tumor-bearing mice. CONCLUSION: Our results demonstrate that MG132-induced inhibition of the ubiquitin-proteasome pathway in cancer cachexia decreased the activity of NF-κB and the degradation of IκBα, and reduced the levels of TNF-α and IL-6 in serum and gastrocnemius tissue, accompanied by downregulation of MuRF1 and MAFbx. These data suggest that MG132 is a potential therapeutic and preventive agent for cancer cachexia.