The Role And Mechanism Of Monounsaturated Fatty Acids In Ferroptosis

Monounsaturated fatty acids(MUFAs)refers to fatty acids containing one double bond,including oleic acid(OA),palmitoleic acid(PA)and erucic acid,etc.Monounsaturated fatty acids are widely existed in the diet.Ferroptosis is a new way of cell death that is distinct from apoptosis,necrosis and autophagy.As a new mode of cell death caused by an overwheling of lipid peroxides,the role played by fatty acids in ferroptosis remain enigmatic.Studies have shown that polyunsaturated fatty acids such as arachidonic acid(AA)can promote ferroptosis.The role of monounsaturated fatty acids has not yet been discovered.In order to explore the role of monounsaturated fatty acids in ferroptosis,and to provide basis for applying ferroptosis to clinical activities,we used a variety of different fatty acids to treat seven different cancer cells in combination with erastin,and to construct a variety of nude mice exnograft tumors.The main results are as following:(1)MTT cell viability assay was used to investigate the effects of various fatty acids on ferroptosis induced by erastin in seven cancer cells.After treatment with 5 ?M erastin and 10 ?M fatty acids,the monounsaturated fatty acid OA was found to have a significantly inhibitory effect on ferroptosis in erastin-sensitive non-small cell lung cancer cells A549 and H1299.(2)We used SCD1 gene over-expression,SCD1 and SCD5 gene silencing experiments and lentivirus SCD1 overexpression A549 cell line for nude mice in vivo transplantation experiments to explore whether endogenous monounsaturated fatty acids are consistent with exogenous monounsaturated fatty acids in ferroptosis.The results showed that the silencing of SCD1 gene reduced the synthesis of endogenous monounsaturated fatty acids and made the cells more susceptible to ferroptosis.However,lentivirus SCD1 overexpression A549 cell lines had a certain inhibitory effect on ferroptosis caused by erastin in exnograft tumors,SCD1 overexpressed tumor cells have a certain resistance to ferroptosis caused by erastin.The above results indicated that endogenous monounsaturated fat also has an inhibitory effect on ferroptosis caused by erastin.(3)Flow cytometry was used to analyze the level of ROS and iron pool in the cells.Western blot was used to detect the level of transferrin receptors which regulated intracellular iron pool.The experimental results showed that monounsaturated fatty acids can significantly reduce intracellular ROS levels and iron levels and down-regulate the expression levels of transferrin receptor 1 in ferroptosis caused by erastin,indicating that monounsaturated fatty acids cause ROSdecreased intermediated by down-regulated transferrin receptor 1 to decrese iron to inhibiteferroptosis.(4)Use of SCD1 inhibitor and erastin combined cell experiments and in vivo transplantation tumor experiments,and the use of immunohistochemistry to detect the expression of SCD1 protein in human pathological sections to explore the clinical application of monounsaturated fatty acid inhibition of ferroptosis.SCD1 inhibitor combined with RSL3,an ferroptosis trigger,can significantly inhibit the growth of prostate cancer cell PC3 and the growth of xenograft tumors in nude mice.Moreover,the pathological section of human prostate cancer found that compared with non-cancer patients,the expression of SCD1 protein in prostate cancer patients was significantly increased,suggesting that our findings have important clinical application.In conclusion,we demonstrated that both exogenous and endogenous monounsaturated fatty acids can inhibit ferroptosis,and reduce intracellular ROS by reducing intracellular iron ion levels mediated by reducing transferrin receptor expression to suppress ferroptosis.Overexpression of SCD1 increases endogenous monounsaturated fatty acids and has been shown to significantly inhibit ferroptosisboth in vitro and in vivo;likewise,genesilencing SCD1 and SCD5,or inhibitors on SCD1,at cellular and animal levels All can promote ferroptosis.These results shed light on the inhibitory effects of monounsaturated fatty acids on ferroptosis,o provide experimental and theoretical references,as well as dietary guidance with cancer patients.