Potent Anticancer Activities of Beauvericin Against KB Cells In Vitro by Inhibiting the Expression of ACAT1 and Exploring Binding Affinity

Background and Objective: Beauvericin (BEA), a cyclic hexadepsipeptide mycotoxin, is a potent inhibitor of the acyl-CoA: cholesterol acyltransferase enzyme 1 (ACAT1), involved in multiple tumor-correlated pathways. However, the binding mechanisms between BEA and ACAT1 were not elucidated. Methods: BEA was purified from a mangrove entophytic Fusarium sp. KL11. Single-crystal X-ray diffraction was used to determine the structure of BEA. Wound healing assays of BEA against KB cell line and MDA-MB-231 cell line were evaluated. Inhibitory potency of BEA against ACAT1 was determined by ELISA assays. Molecular docking was carried out to illuminate the bonding mechanism between BEA and ACAT1. Results: The structure of BEA was confirmed by X-ray diffraction, indicating a monoclinic crystal system with P21 space group (alpha = 90 degrees, beta = 92.2216(9)degrees, gamma = 90 degrees). BEA displayed migration-inhibitory activities against KB cells and MDA-MB-231 cells in vitro. ELISA assays revealed that the protein expression level of ACAT1 in KB cells was significantly decreased after BEA treatment (P < 0.05). Molecular docking demonstrated that BEA formed hydrogen bond with His425 and pi-pi staking with Tyr429 in ACAT1. Conclusion: BEA sufficiently inhibited the proliferation and migration of KB cells and MDA-MB-231 cells by downregulating ACAT1 expression. In addition, BEA potentially possessed a strong binding affinity with ACAT1. BEA may serve as a potential lead compound for the development of a new ACAT1-targeted anticancer drug.