To delineate the molecular link between mitochondrial dysfunction and inflammation in cancer cachexia (CC), analyses were performed across in vitro, in vivo, and human models. In vitro, differentiated skeletal muscle myotubes exposed to conditioned media from cachexia-inducing cancer cells (C26 and LLC) displayed clear signs of atrophy compared to control conditions (GM and MC38), as evidenced by reduced myotube diameter and altered expression of mitochondrial and inflammatory markers. These findings were recapitulated in vivo in the C26 mouse model of CC, where tumor-bearing mice showed progressive body weight loss, impaired muscle strength, and reduced muscle mass relative to PBS-treated controls. Mitochondrial gene and protein expression and functional analyses confirmed considerable mitochondrial dysfunction in all three models, accompanied by increased expression of pro-inflammatory cytokines in both skeletal muscle and plasma. In this regard, IL6 shows a consistent remarkable upregulation in all three models compared to the rest of cytokines assessed. Importantly, analyses of skeletal muscle biopsies from patients with non-small cell lung cancer (NSCLC) further supported these preclinical findings (Fig. 3). Patients exhibited molecular signatures consistent with mitochondrial impairment and enhanced inflammatory activation, mirroring the changes observed in the experimental models. Altogether, these data consistently demonstrate that mitochondrial dysregulation and IL6-mediated inflammation are closely intertwined in CC, and they validate the translational relevance of the MIEXIA experimental framework spanning cell culture, animal, and human contexts.
Gene expression analyses showed no significant changes in LRPPRC mRNA levels across the three CC models examined. However, a modest reduction in LRPPRC protein abundance was observed in skeletal muscle from both C26 tumor-bearing mice and patients with non-small cell lung cancer (NSCLC). These results only partially replicate the preliminary findings from the host laboratory described in the MIEXIA proposal. The discrepancy may stem from the heterogeneity in disease severity among the analyzed samples, as both the C26 mice and NSCLC patients displayed variable degrees of cachexia, likely increasing data variability.
Unexpectedly, imKO mice did not display overt muscle atrophy, mitochondrial dysfunction, or inflammation under basal conditions. Nevertheless, complementary work conducted in parallel by members of the host laboratory—including the researcher—has since demonstrated that these phenotypes emerge in aged imKO mice, confirming that LRPPRC plays a critical role in sustaining skeletal muscle integrity under metabolic stress.
Finally, subcellular interactome analyses revealed that LRPPRC associates with multiple proteins implicated in RNA processing and stability, both within mitochondria and in the cytosol. This provides the first direct experimental evidence that LRPPRC performs mRNA-stabilizing functions beyond mitochondria, extending to the cytosolic compartment. These findings support complementary ongoing research at the host institution, which suggests that LRPPRC may also participate in mitochondria–nucleus communication pathways.
Oxygen consumption analyses performed on skeletal muscle samples from patients with NSCLC demonstrated that exercise training enhanced mitochondrial respiratory capacity, particularly under maximal and uncoupled conditions. This indicates a beneficial effect of exercise on mitochondrial efficiency and overall oxidative metabolism in this patient population. Interestingly, when the data were stratified by sex, this improvement was observed exclusively in female participants, suggesting potential sex-specific adaptations to exercise in the context of cancer and mitochondrial function.
