TAK-242 inhibits toll-like receptor-4 signaling and attenuates cancer-associated muscle atrophy via the p38-C/EBPβ pathway

Background and Aims

Cancer cachexia is a paraneoplastic syndrome characterized by progressive muscle atrophy, which negatively impacts treatment efficacy, quality of life, and survival in individuals with cancer. Despite extensive research, no effective medical intervention has completely reversed cachexia, primarily due to an incomplete understanding of its pathogenesis. Toll-like receptor 4 (TLR4) plays an important role in inflammation and metabolic regulation. In this study, the role of TLR4 in muscle catabolism was investigated, with a focus on its regulation of the p38 mitogen-activated protein kinase (MAPK)-mediated activation of C/enhancer-binding protein beta (C/EBPβ) pathway.

Methods

TLR4 expression was silenced in C2C12 myotubes using specific small interfering RNAs (siRNAs). Conditioned medium derived from various cancer cell types was applied to C2C12 myotubes to simulate the tumor microenvironment. The pharmacological TLR4 inhibitor TAK-242 was administrated to C2C12 myotubes and C26 tumor-bearing mice to evaluate its effects on muscle atrophy. Western blot analysis and immunofluorescence microscopy were performed on C2C12 myotubes, while muscle tissues from C26 tumor-bearing mice, a model of cancer cachexia, were analyzed using western blot and histological examination.

Results

Exposure to conditioned medium from cachexia-associated cancer cell lines induced p38 MAPK–C/EBPβ in C2C12 myotubes, leading to upregulation of Ubr2 and Atrogin-1, myosin heavy chain degradation, and myotube atrophy. Silencing or inhibition of TLR4 using siRNA or TAK-242 prevented these catabolic effects in vitro. In C26 tumor-bearing mice, TAK-242 administration significantly attenuated cancer-associated muscle atrophy.

Conclusions

TLR4 plays a critical role in cancer-associated muscle atrophy through the p38β MAPK–C/EBPβ signaling pathway in both in vitro and in vivo models. Pharmacological inhibition of TLR4 with TAK-242 effectively attenuated muscle atrophy, highlighting its potential therapeutic value.