Therapeutic target discovery and drug development for sarcopenia and cancer

Abstract

Skeletal muscles constitute approximately 35% of total body weight and plays essential roles in support, movement, and metabolism. Muscle regeneration, primarily driven by muscle satellite cells (MuSCs), is crucial for maintaining muscle homeostasis. However, the myogenic capacity of MuSCs declines with age, leading to age related muscle atrophy known as sarcopenia. Therefore, identifying therapeutic targets that regulate skeletal muscle regeneration has significant potential for treating sarcopenia. In this study, we identify carbonic anhydrase 3 (Car3) as a novel regulator of skeletal muscle regeneration and myogenesis. Inhibition of Car3 enhances skeletal muscle regeneration and restores the regenerative capacity of aged satellite cells by activating non-canonical AKT-GSK3β-PGC1α signaling to promote mitochondrial function and myogenesis. These findings suggest Car3 as a potential therapeutic target for sarcopenia. This study provides the first evidence showing that Car3, previously considered a negative target for muscle atrophy, is therapeutically relevant as a promoter of skeletal muscle regeneration. Additionally, sarcopenia can occur due to an imbalance between protein degradation and synthesis, where muscle protein breakdown exceeds protein synthesis. This process arises from the excessive activation of factors involved in protein degradation, such as the ubiquitin-proteasome system (UPS). Specifically, the UPS is regulated by the transcriptional activity of the transcription factor FoxO3. In aged muscle, excessive transcriptional activity of FoxO3 leads to the overexpression of E3 ligase genes such as Atrogin-1 and MuRF-1, which in turn contributes to sarcopenia. FoxO3 also functions as a transcription factor regulating the expression of cell death-related genes in cancer cells. Activation of FoxO3 in cancer cells induces cell death by expressing cell death genes such as FasL and Bim. Therefore, in this study, we introduced a screening system capable of measuring FoxO3's transcriptional activity to select FoxO3 activators as anticancer therapeutic candidates and FoxO3 suppressors as sarcopenia therapeutic candidates. We screened a total of 2,484 compounds: 1,016 from an FDA-approved library and 1,468 from a natural compound library. Compound A was identified as a FoxO3 transcriptional activity inhibitor, and compound B was identified as a FoxO3 transcriptional activity activator. Compound A restored 51.04% of the atrophy in C2C12 myotubes induced by Dexamethasone, while compound B reduced the survival rate of HCT116 cells by 60.02% without affecting the survival rate of normal CCD18-CO cells. Overall, we identified Car3 as a novel factor regulating muscle regeneration. And by screening FoxO3 transcription activators and inhibitors, we discovered candidate compounds for sarcopenia treatment and anticancer therapy, thereby presenting new possibilities for promoting muscle regeneration, treating sarcopenia, and advancing anticancer treatment.