| Pancreatic cancer(PC)is a malignant tumor with a very high mortality rate,and its prominent features of high mortality,low survival rate and poor prognosis are mainly attributed to the high metastatic nature of PC.Early diagnosis is an important prerequisite for the treatment and even cure of PC,and the exploration of de novo markers associated with PC can bring new hope for early diagnosis and targeted treatment of PC.Oxidative lipidomics is a new multi-omics research method based on metabolomics,and an in-depth study of PC and its metastasis-related oxidative lipids is beneficial for the establishment of PC diagnostic models and the exploration of PC development and metastasis mechanisms,which are still rarely reported in China and abroad.The main objective of this study is to characterize the oxidized lipid metabolism in PC tissues under in vivo conditions by constructing an animal model of human-derived murine PC,and to clarify the differences in oxidized lipid metabolism profiles between groups of samples by multivariate statistical analysis based on a combined liquid chromatography-mass spectrometry(LC-MS/MS)platform,as well as the possible effects of the oncogene KAI1 on oxidized lipid metabolism in PC.In turn,the feasibility of oxidized liposomes as early diagnostic biomarkers of PC was investigated.Methods To construct a human-derived murine PC animal model,nine 4-6 week-old female BALB/c nude mice were randomly divided into three groups,and each group was injected with PANC-1 cell suspension in situ in the pancreas,KAI1-PANC-1 cell suspension,and PANC-1-ATX shRNA cell suspension in the spleen,and then dissected and sampled after tumor formation.Liquid Chromatography-Mass Spectrometry(LC-MS/MS)was applied to detect the changes in the expression of small molecules of oxidized lipid metabolites in PC tissues and metastatic tumor tissues.The data were analyzed by principal components analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA),combined with the Kyoto Gene and Genome Encyclopedia(Kyoto).The differential metabolites were screened and identified using the Kyoto Encyclopedia of Genes and Genomes(KEGG)database.Hierarchical clustering analysis as well as metabolic pathway enrichment were used to investigate the metabolic pathways in which they may be involved.Results 1.Based on the LC-MS/MS metabolomics platform and multivariate statistical methods such as PCA and OPLS-DA to profile the oxidized lipid metabolites,it was found that the established models for each group were of good quality and the relevant data showed an overall discrete inter-group and intra-group aggregation;2.Among all nine differentially paired groups(ATX-PC vs ATX-LC,KAI1-LC vs ATX-LC,KAI1-PC vs ATX-PC,KAI1-PC vs KAI1-LC,NC-LC vs ATX-LC,NC-LC vs KAI1-LC,NC-PC vs ATX-PC,NC-PC vs NC-PC vs KAI1-PC and NC-PC vs NC-LC),a total of 64 oxidized lipid metabolites were screened for differential expression,and all 64 oxidized lipid metabolites were themselves unsaturated fatty acid components.3.By comparing the oxidative lipid metabolic profiles of two differentially paired groups,KAI1-LC vs ATX-LC and NC-LC vs ATX-LC,it was found that the levels of prostaglandins(PGE2,PGD2)both showed a significant decrease in the liver metastasis tissues with ATX knockdown,as well as in PC liver metastasis tissues,ATX knockdown may be involved in tumor metastasis by causing down-regulation of downstream LPA leading to down-regulation of prostaglandin levels.4.KEGG pathway analysis combined with Student-t test revealed that the metabolism of Linolenic Acid(LA)was statistically significant(p≤0.05)in the NC-PC vs KAI1-PC group,among which 20 oxidized lipid metabolites were significantly different(19 up-regulated and 1 down-regulated),and the differential metabolites belonged to Arachidonic Acid(AA).Arachidnic acid(AA),LA,Eicosapentaenoic Acid(EPA)and Docosahexaenoic Acid(DHA)components.Bioconductivity analysis revealed that the upregulated expression of the oxidized lipid metabolite 12(13)-EpOME was involved in the KAI1/CD82 inhibition of PC transfer.Conclusion Oxidized lipid metabolism is involved in the process of PC onset,development and metastasis.PGs are involved in the process of PC liver metastasis induced by ATX-LPA axis.The oxidized lipid metabolite 12(13)-EpOME is involved in the inhibition process of PC metastasis by KAI1/CD82 gene,and this oxidized lipid metabolite may become a potential biomarker for early diagnosis of PC,which needs to be investigated in depth. |
