Combined administration of fucoidan ameliorates tumor and chemotherapy-induced skeletal muscle atrophy in bladder cancer-bearing mice

Abstract

Cancer cachexia is characterized by anorexia, skeletal muscle atrophy, and systemic inflammation. Fucoidan extracted from brown algae exhibits anti-inflammatory and anticancer activities. However, whether fucoidan ameliorates tumour and chemotherapy-induced muscle atrophy and -related cachectic symptoms remains unknown. Compared with mice with bladder cancer treated with chemotherapy alone (TGC group), those treated with a combination of low molecular weight fucoidan (LMWF) and chemotherapy drugs such as gemcitabine and cisplatin (TGCF) showed a significant reduction of body weight loss, muscle atrophy, and intestinal injury and dysfunction. Moreover, myostatin, activin A, and pro-inflammatory cytokine production, FoxO3 expression and activation, NF-κB activation, MuRF-1 and MAFbx/atrogin-1 expression, and proteasome activity in muscle were significantly decreased in the TGCF group compared with the TGC group. In addition, insulin-like growth factor 1 (IGF-1) expression and formation, and IGF-1-regulated mTOR/p70S6k/4EBP-1 protein synthesis signalling were elevated in the TGCF group compared with the TGC group. Taken together, these results suggest that LMWF is a potential agent for preventing cancer cachexia-associated muscle atrophy during chemotherapy. Furthermore, the beneficial effect of LMWF may be attributed to suppressing NF-κB-evoked inflammation, myostatin and activin A production, and subsequent muscle proteolysis, and enhancing IGF-1-dependent protein synthesis.

Keywords: cancer cachexia; chemotherapy; fucoidan; inflammation; muscle atrophy.

Figure 1. Effects of LMWF on tumor growth, food intake and intestinal damage and function

The LMWF structure and experimental design was shown A. The bladder weight B. daily food intake C. the morphological changes and the digestive enzyme activity of intestines D. in different groups were determined. Data was expressed as mean ± SEM (n=5-10). *P < 0.05, **P < 0.01 versus normal group; #P < 0.05, ##P < 0.01 versus TGC group.

Figure 2. Effects of LMWF on survival rate and muscle atrophy

The survival rate and body weight A. a representative image of the muscle of limb, and the weight of gastrocnemius and soleus muscle were photographed or measured B. The morphological changes of gastrocnemius muscle stained with H&E (magnification, ×200) C. and the proteasome activity D. in muscle were determined. Data was expressed as mean ± SEM (n=5-10). *P < 0.05, **P < 0.01, ***P < 0.001 versus normal group. ##P < 0.01 versus TGC group.

Figure 3. Effects of LMWF on muscle proteolysis-related gene expression

The atrogenic gene expression A. and the formation of myostatin, and activin A B. in muscle were determined. The amounts of FoxO3, MuRF-1 and MAFbx determined by immunofluorescence staining assay C. and the association of p-FoxO3a with 14-3-3 chaperone protein D. FoxO3a transcription factor activity E. in skeletal muscle were examined. Data was expressed as mean ± SEM (n=5-10). *P < 0.05, **P < 0.01, ***P < 0.001 versus normal group. #P < 0.05, ##P < 0.01, ###P < 0.001 versus TGC group.

Figure 4. Effects of LMWF on pro-inflammatory cytokine expression and NF-κB activation

The protein levels of pro-inflammatory cytokines, CRP, A. and NF-κB B. and phospho-NF-κB C. in muscle were determined by immunofluorescence staining or Western blotting assay. Data was expressed as mean ± SEM (n=5-10). *P < 0.05, **P < 0.01, ***P < 0.001 versus normal group. #P < 0.05, ##P < 0.01 versus TGC group.

Figure 5. Effects of LMWF on IGF-1-regulated signalling and the proposed mechanisms accounting for the anti-cachectic activity

The IGF-1-regulated protein synthesis-related signalling pathway and IGF-1 generation in muscle of various groups were determined A. Data was expressed as mean ± SEM (n=5-10). *P < 0.05, **P < 0.01, ***P < 0.001 versus normal group. #P < 0.05, ##P < 0.01, ###P < 0.001 versus TGC group. Combined treatment with LMWF inhibits myostatin/activin A/FoxO3 signaling, NF-κB activation, and pro-inflammatory cytokine formation, which in turn attenuates MAFbx and MuRF1 expression and UPS-induced protein degradation. Meanwhile, LMWF also can elevate IGF-1 formation and its regulated protein synthesis, and prevent intestinal damage and dysfunction. These actions of LMWF ultimately ameliorate tumor and chemotherapy-induced skeletal muscle atrophy B.