DataSheet1_Pharmacological Inhibition of HMGB1 Prevents Muscle Wasting.pdf

Background: Cachexia is a multifactorial disorder characterized by weight loss and muscle wasting, making up for about 20% of cancer-related death. However, there are no effective drugs to combat cachexia at present.
Methods: In this study, the effect of CT26 exosomes on C2C12 myotubes was observed. We compared serum HMGB1 level in cachexia and non-cachexia colon cancer patients. We further explored HMGB1 expression level in CT26 exosome. We added recombinant HMGB1 to C2C12 myotubes to observe the effects of HMGB1 on C2C12 myotubes and detected the expression level of the muscle atrophy-related proteins. Then, we used the HMGB1 inhibitor glycyrrhizin to reverse the effects of HMGB1 on C2C12 myotubes. Finally, HMGB1 inhibitor glycyrrhizin was utilized to relieve cachexia in CT26 cachexia mouse model.
Results: Exosomes containing HMGB1 led to muscle atrophy with significantly decreased myotube diameter and increased expression of muscle atrophy-related proteins Atrogin1 and MuRF1. Further, we detected that HMGB1 induced the muscle atrophy mainly via TLR4/NF-κB pathway. Administration of the HMGB1 inhibitor glycyrrhizin could relieve muscle wasting in vitro and attenuate the progression of cachexia in vivo.
Conclusion: These findings demonstrate the cachectic role of HMGB1, whether it is soluble form of HMGB1 or secreted from tumor cells as part of exosomes. HMGB1 inhibitor glycyrrhizin might be a promising drug in colon cancer cachexia.

背景：恶病质（Cachexia）是一种多因子紊乱性疾病，以体重减轻与肌肉消耗为核心特征，约占癌症相关死亡病例的20%。但目前尚无特效药物可用于治疗恶病质。
方法：本研究首先观察了CT26细胞外泌体（exosomes）对C2C12肌管的作用；比较了恶病质与非恶病质结肠癌患者血清中高迁移率族蛋白B1（HMGB1）的水平，并进一步探究了CT26细胞外泌体中HMGB1的表达情况。随后，本研究向C2C12肌管中加入重组HMGB1，以观察其对肌管的影响，并检测肌肉萎缩相关蛋白的表达水平；同时使用HMGB1抑制剂甘草酸（glycyrrhizin）逆转HMGB1对C2C12肌管的作用。最后，在CT26细胞诱导的恶病质小鼠模型中，应用HMGB1抑制剂甘草酸以缓解小鼠的恶病质症状。
结果：携带HMGB1的外泌体可诱导肌肉萎缩，表现为肌管直径显著缩小，且肌肉萎缩相关蛋白Atrogin1与MuRF1的表达水平显著升高。进一步研究发现，HMGB1主要通过Toll样受体4（TLR4）/核因子κB（NF-κB）信号通路诱导肌肉萎缩。给予HMGB1抑制剂甘草酸可在体外有效缓解肌肉消耗，并在体内延缓恶病质的疾病进展。
结论：本研究结果证实了HMGB1的恶病质诱导活性，无论其为可溶性形式，还是作为外泌体组分由肿瘤细胞分泌。HMGB1抑制剂甘草酸有望成为治疗结肠癌恶病质的潜在候选药物。