Quercetin Influences Phospholipase A2 Products in A549 Adenocarcinoma Cells

Abstract

The effect of quercetin on phospholipase A2 activity and its products has been investigated in A549 adenocarcinoma cells. Quercetin is a polyphenol of medico-biological significance, which has been reported to show antioxidant and anti-tumour beneficial effects. Phospholipids are functionally active molecules, which participate in various cellular processes, acting as second messengers, enzyme activators, membrane transporters, etc. Although there are many studies dealing with the influence of quercetin on the lipid metabolism of different types of cancer cells, the mechanism of this effect
 remains largely unclear. The present study showed that quercetin treatment of A549 cells induced activation of phospholipase A2 (PLA2) activity, the latter being known as a source of pro-inflammatory intermediate metabolites. The phospholipid analysis of membranes from A549 cells revealed reduction of
 phosphatidylcholine (PC) and an increase of the level of lysophosphatidylcholine (LPC). In addition, acyl chain analysis showed an elevation of some polyunsaturated fatty acids, such as arachidonic acid (AA), the latter being a major product of PLA2. The content of lipid peroxides was also elevated in membranes from quercetin-treated A549 cells, which we presume is related to the higher content of polyunsaturated fatty acids, which are an excellent target of oxidative destruction.
 In conclusion, the present results show that treatment of A549 adenocarcinoma cells with the polyphenol quercetin induces activation of membrane-bound PLA2, which is a source polyunsaturated fatty acids, the
 latter producing lipid peroxides. We presume that this mechanism underlies the reported by other authors elevation of oxidative stress, which is induced by quercetin treatment of cancerous cells.