| Objective:Colorectal cancer(CRC)is a malignant tumor with high morbidity and mortality.At present,the unclear occurrence and development mechanism of CRC is the main bottleneck for prevention and treatment.Therefore,it is urgent to explore the potential molecular mechanism of CRC and discover reliable prognostic biomarkers for improving prognosis and treatment.With the in-depth study of metabolic reprogramming,researchers gradually realized the importance of fatty acid metabolism in CRC.Dysregulation of long noncoding RNAs(lncRNAs)is widespread in malignant tumor and can promote tumorigenesis and progression through ceRNA-related mechanisms.However,the relationship between lncRNA and fatty acid metabolism in CRC is still unclear.This study aims to establish a ceRNA network related to fatty acid metabolism in CRC,and to establish a prognostic risk model and nomogram based on fatty acid metabolism-related lncRNAs to assist in prognostic risk stratification in CRC patients,and to explore the effects of lncRNA TSPEAR-AS2 in the model on fatty acid metabolism and malignant phenotype of CRC.Methods:1.The gene expression data and clinical data of CRC samples were downloaded from The Cancer Genome Atlas(TCGA)database for format conversion and collation,and the list of genes related to fatty acid metabolism pathway was obtained in the Kyoto Encyclopedia of Gene and Genome(KEGG)database.The gene set variation analysis(GSVA)was used to verify the correlation between fatty acid metabolism pathway and overall survival(OS)and clinicopathological parameters of CRC patients.2.Differentially expressed lncRNAs,miRNAs,and fatty acid metabolism-related mRNAs were screened from CRC samples and normal samples in TCGA database,and the interactions among them were obtained by the collection relationships of miRTarBase,miRDB,TargetScan and StarBase databases.Finally,the relationship between genes was integrated to obtain ceRNA network relationship.3.The CRC samples with complete data were randomly divided into the training cohort and validation cohort in a ratio of 7:3.In the training cohort,the prognostic risk model was constructed by univariate Cox regression analysis,least absolute shrinkage and selection operator(LASSO)regression analysis,and multivariate Cox regression analysis.And the Kaplan-Meier survival analysis,time-dependent receiver operating characteristic(ROC)curves,risk heatmaps and chi-square test were used to assess the predictive performance of the prognostic risk model.Subsequently,a nomogram was constructed in combination with the model and clinical variables.Calibration plots,Kaplan-Meier survival analysis,ROC curves,and decision curve analysis(DCA)were used to compare the predictive ability and clinical applicability of nomogram and clinical variables.Finally,the same method is used to verify the repeatability of the prognostic risk model and nomogram in the validation cohort.4.The effects of lncRNA TSPEAR-AS2 on fatty acid metabolism and proliferation of SW480 and SW620 cells were verified by cell transfection,qRT-PCR,intracellular triglyceride assay,western blotting and CCK-8 assay.Results:1.Kaplan-Meier survival analysis showed that there was a significant difference in OS between the two groups divided by the median GSVA enrichment score as the cut-off value.The boxplot results also showed that samples with different tumor stages,distant metastasis,and lymph node status had significantly different GSVA enrichment scores.2.After screening differentially expressed RNAs,a fatty acid metabolism-related ceRNA network was constructed based on four databases.Finally,a prognostic risk model was established based on eight fatty acid metabolism-related lncRNAs(AC156455.1,AC011462.4,TSPEAR-AS2,AL137782.1,LINC01857,ALMS1-IT1,AC022613.2,AC022144.1).In addition,after integrating the prognostic risk model and clinical variables to construct the nomogram,it was found to have the good predictive ability and clinical applicability.3.After the expression of lncRNA TSPEAR-AS2 was downregulated,the triglyceride content and protein expression levels of key enzymes of fatty acid synthesis and metabolism(FASN and ACC1)were significantly decreased in SW480 and SW620 cells.Meanwhile,the CCK-8 assay showed that the downregulation of lncRNA TSPEAR-AS2 significantly reduced the proliferation ability of SW480 and SW620 cells.Conclusion:1.The fatty acid metabolism pathway is closely related to OS and clinicopathological parameters of CRC patients.2.In this study,eight fatty acid metabolism-related lncRNAs with the potential prognostic value were identified and a prognostic risk model was constructed.The nomogram constructed by integrating the prognostic risk model with the age and tumor stage of CRC patients has the good predictive ability and clinical practicability,and can objectively and accurately evaluate the OS of CRC patients.3.lncRNA TSPEAR-AS2 can not only affect the fatty acid metabolism of CRC cells,but also promote the proliferation of CRC cells,and it may be a potential therapeutic target of CRC. |
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