β-Elemonic acid inhibits the cell proliferation of human lung adenocarcinoma A549 cells: The role of MAPK, ROS activation and glutathione depletion.

Abstract

β-elemonic acid, a known triterpene, exhibits anti-inflammatory effects, yet research on the pharmacological effects of β-elemonic acid is rare. We investigated the anticancer effects and the related molecular mechanisms of β-elemonic acid on human non-small cell lung cancer (NSCLC) A549 cells. The effects of β-elemonic acid on the growth of A549 cells were studied using a 3-(4,5)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was detected using Annexin V staining. The effect of β-elemonic acid on the cell cycle of A549 cells was assessed using the propidium iodide method. The change in reactive oxygen species (ROS) was detected using a dichlorodihydrofluorescein diacetate (DCFH-DA) assay with microscopic examination. The expression levels of Bcl-2 family proteins, mitogen-activated protein kinase (MAPK) family proteins and cyclooxygenase 2 (COX-2) were detected using western blot analysis. Our data revealed that β-elemonic acid strongly induced human A549 lung cancer cell death in a dose- and time-dependent manner as determined by the MTT assay. β-elemonic acid-induced cell death was considered to be apoptotic when the phosphatidylserine exposure was observed using Annexin V staining. The death of human A549 lung cancer cells was caused by apoptosis induced by activation of ROS activity, increase in the sub-G1 proportion, downregulation of Bcl-2 expression, upregulation of Bax expression and inhibition of the MAPK signaling pathways. These results clearly demonstrated that β-elemonic acid inhibits proliferation by inducing hypoploid cells and cell apoptosis. Moreover, the anticancer effects of β-elemonic acid were related to the MAPK signaling pathway, ROS activation and glutathione depletion in human A549 lung cancer cells.