Effects of 4-hydroxy-2(3H)-benzoxazolone on proliferation and apoptosis of pancreatic cancer L3.6 cells

Abstract

This study explored the effects of 4-hydroxy-2(3H)-benzoxazolone(HBOA) on the proliferation and apoptosis of pancreatic cancer cells and its molecular mechanism. The L3.6 cells cultured in vitro were treated with HBOA of 0-1.0 mmol·L~(-1). The cell viability was detected by the cell counting kit-8(CCK-8) method, and the half inhibitory concentration(IC_(50)) was analyzed to determine the drug concentration and time. The cell morphology was observed under an inverted microscope and by acridine orange(AO) staining. The ability of proliferation and self-renewal were evaluated through live cell counting and colony formation experiments. The cell cycle progression and cell apoptosis rate were detected by flow cytometry. The morphology of cell apoptosis was observed by scanning electron microscopy. The mRNA expression of proliferating cell nuclear antigen(PCNA), cyclinA1, cyclinA2, cyclin dependent kinase 2(CDK2), and cyclin dependent kinase inhibitor 1A(P21) were determined by qPCR. The level of reactive oxygen species(ROS), lipid peroxide, and mitochondrial membrane potential were measured by flow cytometry. The activity of protein kinase B(Akt)/mammalian target of rapamycin(mTOR) signaling pathway was detected by Western blot. Compared with the control group, the cells treated with HBOA exhibited a significant decrease in viability. Then the optimal concentration and intervention time of HBOA were determined to be 0.4 mmol·L~(-1), 0.6 mmol·L~(-1), and 48 h. Compared with the control group, groups with HBOA of 0.4 mmol·L~(-1 )and 0.6 mmol·L~(-1) showed a significant suppression in cell proliferation and colony formation ability, down-regulated mRNA of PCNA, cyclinA1, cyclinA2, and CDK2, up-regulated P21 mRNA, S-phase cell cycle arrest, and increased cell apoptosis rate. There was an appearance of apoptotic bodies, increased ROS and lipid peroxide, decreased mitochondrial membrane potential(with a significant decrease in 0.6 mmol·L~(-1) group), and down-regulated p-Akt and p-mTOR proteins. The results show that HBOA inhibits the proliferation of pancreatic cancer L3.6 cells and induces cell apoptosis, which may be related to the increase in reactive oxygen species and the inhibition of the Akt/mTOR pathway.