Mechanism Of Gemcitabine Combined With Cisplatin Inducing Ferroptosis Of Pancreatic Cancer

Background and objective:Studies have shown gemcitabine and cisplatin combination therapy is an effective treatment options for pancreatic cancer,but the mechanism remains less understood.Recently,ferroptosis has been identified as a new type of programmed cell death characterized by an iron-and ROS-dependent lipid peroxidation and closely related to chemotherapy and prognosis of cancer.The purpose of this study was to explore whether gemcitabine combined with cisplatin can effectively induce ferroptosis in PAAD and explore the mechanism.On this basis,we further explore the predictive value of ferroptosis signature as a risk model for the prognosis of PAAD.Methods:Firstly,we measured the synergistic effect of gemcitabine combined with cisplatin in cells and subcutaneous transplanted tumor nude mouse models of PAAD.The relationship between the combination therapy and ferroptosis was detected by ferroptotic parameters such as lipid reactive oxygen species,Fe²⁺,GSH and MDA.Subsequently,we identified SAT1 through bioinformatics methods.The role of SAT1in ferroptosis was investigated through ferroptotic parameters and protein markers in PAAD cells after transfection with the SAT1 plasmid or si RNA.Then,based on the function of SAT1 gene,we measured polyamine level in cells upon combination therapy and transfected with the SAT1 plasmid or si RNA.Exogenous polyamine was used to treat chemotherapy-induce ferroptosis in vitro.Finally,we comprehensively analyzed ferroptosis related genes（FGRs）and constructed a prognostic risk model through Lasso-penalized Cox regression analysis.Time-dependent receiver operating characteristic curves and univariate/multivariate Cox regression analysis were utilized to evaluate the predictive value of the prognostic model.Results:Gemcitabine combined with cisplatin had the synergistic effect and can induce ferroptosis through promoting the accumulation of lipid ROS and Fe2⁺.The levels of SAT1 m RNA and protein were significantly increased after combined chemotherapy.Overexpression of SAT1 can induce ferroptosis while knockdown of SAT1 can effectively inhibit ferroptosis induced by combined chemotherapy.The combination of gemcitabine and cisplatin can reduce the level of polyamines in cells by activating SAT1.Exogenous Polyamine can reverse the ferroptosis induced by the combination of gemcitabine and cisplatin.The ferroptosis signature consisting of SAT1 and other six FRGs can effectively classify high-risk and low-risk patients,and had significant prognostic value for PAAD patients.Conclusion:Gemcitabine combined with cisplatin can induce ferroptosis in PAAD through SAT1/polyamine pathway.SAT1 plays a vital role in the chemotherapy and prognosis of patients.The FRGs model can effectively predict the prognosis of PAAD patients.