| Background:Bladder cancer(BCa)is a malignant tumor originating from the urothelium of the bladder,which is divided into non-muscle invasive bladder cancer(NMIBC:Tis,Ta,T1)and muscle invasive bladder cancer(MIBC:T2,T3,T4).Due to the high incidence and high relapse rate,BCa endangers human health.The newly diagnosed NMIBC of BCa account for approximately 75%,and the majority are histologically low-grade.The high recurrence rate after transurethral resection of bladder tumor(TURBT)has become a difficulty in clinical treatment.Routine surveillance involving cystoscopic examination is needed to monitor the BCa recurrence.The repeat TURBT remains the first-line treatment for BCa recurrence.In recent years,studies have shown that tumor recurrence and metastasis depend on the intrinsic properties of the tumor cells and the tumor microenviroment.Previous research found that submucosal injection of anti-tumor drugs(pirarubicin)after standard TURBT was an effective method to reduce superficial tumor recurrence.Gemcitabine is a pivotal chemotherapeutic agent widely used in systemic and intravesical chemotherapy for BCa because of its low toxicity.Data from our experimental and clinical studies also indicated that submucosal injection of gemcitabine before TURBT significantly decreased BCa recurrence.However,the underlying mechanisms of submucosal injection of gemcitabine are still not clear.As a newly emerging technology,metabolomics has been used to identify potential biomarkers of BCa and to reveal potential mechanisms associated with disease processes.Metabolomics has also been applied to cancer treatment and drug target discovery.Recently,studies employing different analytical platforms mainly focus on the metabolomics of BCa by using urine samples.The metabolomic research on BCa tissues is relatively scarce.Therefore,it is necessary to study whether the new metabolites associated with BCa in the tissues have diagnostic value and predict recurrence,and that metabolic changes mediate the exact effects of gemcitabine in the treatment of BCa.Objective:1.To determine metabolic changes in BCa tissues and cancer-related metabolic pathways through liquid chromatography(LC)-Q-Exactive mass spectrometry-based metabolomic technology;2.To identify differentially expressed metabolites and altered metabolic pathways,and to explore the potential targets of submucosal injection of gemcitabine and its effects on normal tissues.Methods:1.Metabolic changes in BCa tissues and cancer-related metabolic pathways:Tissue metabolomics analysis of bladder tissue samples was used to compare differential expression of metabolites between BCa and normal tissues,to determine BCa-related metabolites,and to preliminarily explore metabolic pathways that are involved through bioinformatics analysis.2.Candidate targets of submucosal injection of gemcitabine and its effects on normal tissues:Based on targeted metabolomics analysis,metabolites between post-gemcitabine treated BCa an d pre-gemcitabine treated normal tissues are compared,among the BCa-related metabolites,to explore the possible targets of submucosal injection of gemcitabine for the treatment of BCa;Similarly,metabolomes of pre-and post-gemcitabine treated normal tissues are compared,and to investigate the effects of gemcitabine treatment on normal bladder tissues.Results:1.The current study showed that there were 34 differentially expressed metabolites between BCa and normal tissues.Metabolic pathway analysis revealed that 3 pathways were significantly associated with BCa,namely glutathione metabolism,purine metabolism,and thiamine metabolism.And glutathione metabolism was further confirmed in the enrichment analysis.2.According to targeted metabolomic analysis,we discovered that in the comparison between pre-gemcitabine treated normal vs post-gemcitabine treated BCa tissues,32 metabolites were found to keep significant changes with identical trends in BCa-related metabolites,confirming that the results of differential metabolites in BCa are reliable.Significantly decreased bilirubin and retinal recovered to insignificant expression levels after gemcitabine treatment,suggesting that these two metabolites are likely the targets of submucosal injection of gemcitabine for the treatment of BCa.There were 10 significantly changed metabolites in normal tissues after submucosal injection,and only 2 metabolites,histamine and thiamine,were associated with BCa.We deduced that histamine may have the ability to prevent BCa recurrence,whereas thiamine may be involved in treatment-related side effects.Conclusion:This study initially explored the biomarkers and mechanisms of submucosal injection of gemcitabine in the treatment of BCa.We concluded that:1.34 key metabolites are related to BCa,which can be used as potential biomarkers of BCa.Bioinformatics analysis indicates that 3 metabolic pathways are involved in cell proliferation,oxidative stress,and other processes in BCa.2.Among 34 BCa-associated metabolites,submucosal injection of gemcitabine can increase the abundance of bilirubin and retinal in BCa,suggesting that these two metabolites may be the biomarkers of gemcitabine treatment for BCa.In addition,submucosal injection of gemcitabine had no adverse effects on normal bladder tissues metabolism.3.Ultra-performance liquid chromatography-high resolution mass spectrometry(UPLC-HRMS)-based metabolomics analysis provides comprehensive metabolite profiling data,paving the way to a novel approach to BCa research. |
PDF Full Text Request