SUMO2介导的RRM1类泛素化修饰调控胰腺导管腺癌吉西他滨耐药OA

Background and purpose:Pancreatic ductal adenocarcinoma(PDAC)is one of the most lethal malignancies,with a 5-year survival rate below 10%.Gemcitabine remains a first-line chemotherapeutic agent for PDAC;however,its efficacy is frequently compromised by the development of acquired drug resistance.SUMOylation,a key post-translational modification,has been implicated in cancer progression and chemoresistance,yet its role in gemcitabine resistance in PDAC remains insufficiently defined.This study aimed to investigate the contribution of SUMOylation to PDAC chemoresistance and to identify the critical SUMO isoform and its downstream substrates.Methods:A gemcitabine-resistant PANC1 cell line(PANC1_GR)was established,and the expression of SUMO1,SUMO2,and SUMO3 was assessed by Western blot.The SUMO-activating enzyme inhibitor ML-792 was used to suppress global SUMOylation,and cell proliferation and apoptosis were evaluated using the cell counting kit-8(CCK-8)assay and flow cytometry,respectively.Lentiviral-mediated knockdown of SUMO1,SUMO2,SUMO3,and RRM1 was performed to assess changes in gemcitabine sensitivity(IC50)and apoptosis.SUMO2 immunoprecipitation combined with mass spectrometry was employed to identify SUMO2-modified target proteins.Transcriptomic sequencing following gemcitabine plus ML-792 treatment was used to analyze differentially expressed genes and pathway enrichment.Statistical analyses were conducted using Student's t-tests or one-way ANOVA.This study was approved by the Animal Ethics Committee of the Experimental Center of Fudan University Shanghai Cancer Center(ethics approval No.FUSCC-IACUC-2023280).Results:SUMO1,SUMO2,SUMO3 conjugation levels were markedly elevated in gemcitabine-resistant cells,and ML-792 effectively reduced global SUMO2,SUMO3 modification while enhancing gemcitabine-induced apoptosis.Among the SUMO isoforms,only SUMO2 knockdown significantly increased gemcitabine sensitivity.SUMO2,SUMO3 Co-IP combined with mass spectrometry identified RRM1 as a major SUMO2-modified substrate,with its SUMOylation markedly enhanced in resistant cells and significantly suppressed by ML-792.RRM1 knockdown phenocopied the effects of SUMO2 inhibition,promoting apoptosis and reducing the IC50 of gemcitabine.Transcriptomic analysis further revealed that inhibition of SUMO2 modification disrupted key pathways associated with drug resistance,including DNA replication and mismatch repair,thereby diminishing cellular chemoresistance.Collectively,these findings indicate that SUMO2-mediated SUMOylation of RRM1 may play a regulatory role in gemcitabine resistance in PDAC.Conclusion:The SUMO2-RRM1 axis may be associated with the development of gemcitabine resistance in PDAC,and modulation of SUMO2-mediated RRM1 modification could offer a potential direction for further investigation.