Celecoxib (Cx), an inhibitor of cyclooxygenase 2, induces apoptosis of cancer cells. However, the mechanism of the chemopreventive effect remains not fully understood. We aimed to investigate the role of PRODH/POX that is involved in the regulation of apoptosis induced by celecoxib. MCF-7 breast cancer cell line and the corresponding MCF-7 cell line with silenced PRODH/POX (MCF-7shPRODH/POX) were used. The effects of Cx on cell viability, proliferation, and cell cycle were evaluated. The expressions of protein markers for apoptosis (Bax, caspase 9, and PARP) and autophagy (Atg5, Beclin 1, and LC3A/B) were investigated by Western immunoblotting. To analyze the proline metabolism, collagen biosynthesis, prolidase activity, proline concentration, and the expression of proline-related proteins were evaluated. The generation of ATP, ROS, and the ratio of NAD+/NADH and NADP+/NADPH were determined to test the effect of Cx on energetic metabolism in breast cancer cells. It has been found that Cx attenuated MCF-7 cell proliferation via arresting the cell cycle. Cx induced apoptosis in MCF-7 breast cancer cells, while in MCF-7shPRODH/POX, autophagy occurred more predominantly. In MCF-7 breast cancer cells, Cx affected proline metabolism through upregulation of proline biosynthesis, PRODH/POX and PYCRs expressions, PEPD activity, and downregulation of collagen biosynthesis. In MCF-7shPRODH/POX clones, these processes, as well as energetic metabolism, were remarkably suppressed. The data for the first time suggest that celecoxib induces apoptosis through upregulation of PRODH/POX in MCF-7 breast cancer cells.
Keywords: PRODH/POX; apoptosis; breast cancer; proline.