Predicted Role of Acetyl-CoA Synthetase and HAT p300 in Extracellular Lactate Mediated Lactylation in the Tumor: In vitro and In silico Models

As per the Warburg effect, cancer cells are known to convert pyruvate into lactate. The accumulation of lactate is associated with metabolic and epigenetic reprogramming, which has newly been suggested to involve lactylation. However, the role of secreted lactate in modulating the tumor microenvironment through lactylation remains unclear. Specifically, there are gaps in our understanding of the enzyme responsible for converting lactate to lactyl-CoA and the nature of the enzyme that performs lactylation by utilizing lactyl-CoA as a substrate. It is worth noting that there are limited papers focused on metabolite profiling that detect lactate and lactyl-CoA levels intracellularly and extracellularly in the context of cancer cells. Here, we have employed an in-house developed vertical tube gel electrophoresis (VTGE) and LC-HRMS assisted profiling of extracellular metabolites of breast cancer cells treated by anticancer compositions of cow urine DMSO fraction (CUDF) that was reported previously. Furthermore, we used molecular docking and molecular dynamics (MD) simulations to determine the potential enzyme that can convert lactate to lactyl-CoA. Next, the histone acetyltransferase p300 (HAT p300) enzyme (PDB ID: 6GYR) was evaluated as a potential enzyme that can bind to lactylCoA during the lactylation process. We collected evidence on the secretion of lactate in the extracellular conditioned medium of breast cancer cells treated by anticancer compositions. MD simulations data projected that acetyl-CoA synthetase could be a potential enzyme that may convert lactate into lactyl-CoA similar to a known substrate acetate. Furthermore, a specific and efficient binding (docking energy -9.6 kcal/mol) of lactyl-CoA with p300 HAT suggested that lactyl-CoA may serve as a substrate for lactylation similar to acetylation that uses acetyl-CoA as a substrate. In conclusion, our data provide a hint on the missing link for the lactylation process due to lactate in terms of a potential enzyme that can convert lactate into lactyl-CoA. This study helped us to project the HAT p300 enzyme that may use lactyl-CoA as a substrate in the lactylation process of the tumor microenvironment.