The mechanism of acetyl-L-carnitine on colorectal cancer and its metabolomic study.

Colorectal cancer (CRC) is a prevalent malignancy worldwide, with increasing incidence and mortality rates. Acetyl-L-carnitine (ALC), a natural form of L-carnitine, possesses anti-inflammatory, free radical-scavenging, and mitochondrial membrane-stabilizing properties. However, its precise mechanism of action in CRC remains unclear. To articulate the mechanism of action of ALC in CRC, we investigated its biological activity in HCT116 cells and a nude mouse xenograft model. The effects of ALC on HCT116 cells using CCK-8, colony formation, migration, invasion, and cell cycle assays. And detected oxidative stress-related indexes including reactive oxygen species (ROS), glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD). The inhibitory effect of ALC on colorectal tumor growth was further validated in a nude mouse xenograft model, and untargeted metabolomic analysis was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry. The results showed that ALC can inhibit the proliferation and migration of HCT116 cells, induce cell cycle arrest and apoptosis, and affect the changes of oxidative stress indexes, and exacerbating cellular oxidative stress damage. In vivo experiments demonstrated that ALC effectively suppressed colorectal tumor growth in a dose-dependent manner. Plasma metabolomic analysis identified 10 differential metabolites between the ALC group and the control group, including meisoindigo, indole-3-acetaldehyde, etc., and 4 tumor differential metabolites, including L-proline, 3,4,5-Trimethoxytoluene, etc. Pathway enrichment analysis revealed that ALC altered 6 metabolic pathways in plasma, including tryptophan metabolism and glycine, serine, and threonine metabolism, and 5 pathways in tumor tissue, including arginine and proline metabolism and the sphingolipid signaling pathway. These findings provide novel theoretical evidence for the antitumor mechanisms of ALC in CRC.