The Enhancement Of Anti-tumor Effect By ?-3PUFAs On Two Anti-tumor Drugs In Breast Cancer Cell And Its Mechanism

All-trans retinoic acid(ATRA),Rp(an mTOR inhibitor),and other targeted biological therapies provide a new method for improving cancer treatment.These agents can inhibit tumor growth and induce cell apoptosis,thereby exerting stronger anti-tumor effects.However,with the increasing use of ATRA and Rp,the application of this drug has been greatly restricted by lipid metabolism disorders and drug resistance.Epidemiological,clinical,and experimental studies have demonstrated that?-3PUFAs significantly reduce the incidence and mortality of breast cancer and prevent cardiovascular disease and hyperlipidemia.?-3PUFAs can inhibit breast cancer cell proliferation and induce apoptosis,thereby reducing the risk of breast cancer.Therefore,to reduce lipid dysfunction caused by retinoic acid and Rp and reinforce the anti-tumor effect,the aim of this study was to determine whether supplementing Rp or RA with?-3PUFAs enhanced its anti-tumor activity,reduced drug resistance,and improved metabolic disorders during breast cancer treatment.In this paper,we analyzed the growth of three subtypes of human breast cancer cells(ER~+MCF7,HER2~+SKBR-3 and triple-negative MDA-MB-231),xenograft and MMTV-PyVT transgenic mice models by treating with those two combinations.The following results:?-3PUFAs or ATRA treated alone has weak inhibitory effects on cell growth of three subtypes of human breast cancer cells.However,the number of breast cancer cells was significantly reduced when?-3PUFAs were combined with ATRA.Additionally,?-3PUFAs could significantly improve ATRA resistance in TNBC cells.In additional experiments,we found that the anti-tumor effect of the combined action was closely related to the activation of autophagy,which was dependent on p38 phosphorylation rather than mTOR or Beclin-1(two classical autophagic signal transduction pathways).The interaction between RAR?(receptor of and ATRA)and GPR40(receptor of?-3PUFAs)in lipid raft-activated scr kinase leads to p38 phosphorylation.We also found that tumor volume and tumor weight were significantly decreased in the combination-treated mice compared with mice treated alone and control mice in a xenograft model.The number of Ki67-stained-positive cells in EPA plus ATRA treated mice was obviously less than that of control and treated alone assessed detected by immunohistochemistry.We also tested the influence of combined treatment on autophagic function and signal transduction in xenograft.P38 phosphorylation and the number of autophagosomes were significantly increased in combination-treated mice.In addition,the serum levels of TC,TG,LDL-C and HDL-C were detected by a programmable automated biochemical analyzer.The results showed that EPA supplementation significantly reduced RA-induced metabolic disorders,which may be another explanation for the synergistic antitumor activity of?-3PUFAs and ATRA.?-3PUFAs combined with Rp significantly inhibited the three subtypes breast cancer cell growth,induced cell cycle arrest and apoptosis,and exerted synergistic antitumor activity.We also found that the anti-tumor effect of the combined action was closely related to ROS production,a key factor in cell death.ROS production is mainly derived from metabolic shifts triggered by the combined action.Metabolism inhibition of glycolysis and glutamineinducedfattyacidoxidationelevating(?-oxidationand oxidative phosphorylation),thereby lead to ROS accumulation.We also found that tumor volume and tumor weight were significantly decreased in combined-treated mice compared with treatment alone and control mice in xenograft and MMTV-PyVT models.Cancer metabolism was significantly changed in combination-treated mice,which was in accordance with the in vitro results.The serum levels of TC,TG,LDL-C,and HDL-C in the two models were detected by a programmable automated biochemical analyzer,and the results showed that the EPA supplement significantly reduced Rp-induced hyperlipidemia and metabolic disorders.These results show that the effects of?-3PUFAs combined with ATRA and Rp may provide an experimental reference for functional food auxiliary drug therapy of breast cancer patients.