Loss of 5-hydroxymethylcytosine (5hmC) occurs frequently in a wide variety of tumours, including clear-cell renal cell carcinoma (ccRCC). It remains unknown, however, whether the restoration of 5hmC patterns in tumours could have therapeutic efficacy. Here, we used sodium L-ascorbate (vitamin C, AsANa) and the oxidation-resistant form L-ascorbic acid 2-phosphate sesquimagnesium (APM) for the restoration of 5hmC patterns in ccRCC cells. At physiological concentrations, both show anti-tumour efficacy during long-term treatment Strikingly, global 5hmC patterns in ccRCC cells after treatment resemble those of normal kidney tissue, which is observed also in treated xenograft tumours, and in primary cells from a ccRCC patient. Further, RNA-seq data show that long-term treatment with vitamin C changes the transcriptome of ccRCC cells. Finally, APM treatment induces less non-specific cell damage and shows increased stability in mouse plasma compared to AsANa. Taken together, our study provides proof of concept for an epigenetic differentiation therapy of ccRCC with vitamin C, especially APM, at low doses by 5hmC reprogramming.

Age-dependent loss of skeletal muscle mass and function is a feature of sarcopenia, and increases the risk of many aging-related metabolic diseases. Here, we report phenotypic and single-nucleus transcriptomic analyses of non-human primate skeletal muscle aging. A higher transcriptional fluctuation was observed in myonuclei relative to other interstitial cell types, indicating a higher susceptibility of skeletal muscle fiber to aging. We found a downregulation of FOXO3 in aged primate skeletal muscle, and identified FOXO3 as a hub transcription factor maintaining skeletal muscle homeostasis. Through establishment of a complementary experimental pipeline based on a human pluripotent stem cell-derived myotube model, we revealed that silence of FOXO3 accelerates human myotube senescence, whereas genetic activation of endogenous FOXO3 alleviates human myotube aging. Altogether, based on a combination of monkey skeletal muscle and human myotube aging research models, we unraveled the pivotal role of the FOXO3 in safeguarding primate skeletal muscle from aging, providing a comprehensive resource for development of clinical diagnosis and targeted therapeutic interventions against human skeletal muscle aging and the onset of sarcopenia along with aging-related disorders.