LncRNA MALAT1 Promotes Prostate Cancer Progression Through Glucose Metabolic Reprogramming

Background:Prostate cancer(PCa)ranks among the forefront of malignant tumors in morbidity and mortality globally,which seriously threatens men’s health.There are two significant characteristics of PCa in China:1)The incidence rate is increasing rapidly;2)The proportion of patients with advanced PCa is high in the first diagnosis.Therefore,early-stage diagnosis and effective treatment of late-stage are the focus of PCa prevention and treatment in China.The most widely using PCa molecular markers,prostate-specific antigen(PSA),have low specificity,resulting in a large number of unnecessary prostate biopsies,which brings physical and mental harm and heavy economic burden to patients.Therefore,there is an urgent need to find biomarkers with higher specificity for early diagnosis of PCa to improve the detection rate of significant PCa and reduce over-diagnosis and treatment.Recent studies have shown that circulating exosomal RNAs(ex RNAs)can serve as potential biomarkers for cancer detection.However,urinary exosomal long noncoding RNAs have not been adequately studied as an easily collectible and noninvasive source of cancer biomarkers.Long noncoding RNA(lnc RNA)plays a significant role in the occurrence and development of tumors.We previously explored PCa-associated lnc RNAs by RNA-seq,and MALAT1 was most differentially expressed in cancerous and adjacent tissues.Urine exosomes have the characteristics of high stability,traceability,and absolute non-invasiveness,so we further explored the value of urine exosomes MALAT1 in the early diagnosis of PCa based on previous studies.When PCa progresses to the CRPC stage,drug therapy becomes very difficult.Lnc RNAs are involved in tumor progression through multiple mechanisms.Previous studies have found that MALAT1 plays an essential role in developing CRPC.Further Ch IRP-MS studies found that MALAT1 binds to many critical genes in glucose metabolism in CRPC cells,and we hypothesized that MALAT1 was involved in glucose metabolism in CRPC cells in the cytoplasm.Therefore,based on previous studies,we explored the molecular mechanism of MALAT1 promoting PCa progression through glycometabolic reprogramming.Purpose:This research explores the diagnostic utility of urinary exosomal lnc RNA MALAT1 in PCa and provides a theoretical foundation for developing diagnostic kits.Another aim is to reveal the mechanism of lnc RNA MALAT1 in promoting tumor progression through glucose metabolism reprogramming and to find novel druggable targets.Methods:Using a standardized,post-digital rectal exam(DRE)collection,urine sample processing,and RNA quantification method,we examined MALAT1 expression levels in urinary exosomes in 565 patients undergoing prostate biopsy.Univariate logistic regression and receiver operating characteristic curve analyses were used to assess the ability of urinary exosomal MALAT1 to diagnose PCa and clinically significant prostate cancer(cs PCa).Decision curve analysis was used to estimate the benefit of using urinary exosomal MALAT1 in biopsied participants.The association between MALAT1 and tumor progression was analyzed using sequencing data and public databases,and MALAT1-overexpressing/knockout prostate cancer cell lines were constructed and verified by cell function experiments.Chromatin isolation by RNA purification-mass spectrometry analysis(Ch IRP-MS)technology,RNA scope technology,and transcriptome sequencing technology were used to investigate the critical enzymes in metabolic pathways associated with MALAT1.Results:In both the training set(365 patients)and validation set(200 patients),the urinary exosomal MALAT1 levels in PCa and cs PCa patients were significantly higher than those in control(P<0.001).ROC-AUC evaluation in the validation set showed that the AUC of urinary exosomal MALAT1 in the diagnosis of PCa was 0.791,which was superior to PSA(P<0.001),f/t PSA(P=0.007),and clinical indicator-constructed basal model(P=0.02).In diagnosing cs PCa,urinary exosomal MALAT1 had an AUC of 0.806,superior to PSA(P<0.001),f/t PSA(P<0.001),and the basal model(P<0.001).In the validation set,urinary exosomal MALAT1 had an AUC of 0.764 in the diagnosis of PCa,which was superior to PSA(P=0.008)and f/t PSA(P=0.0079).In diagnosing cs PCa,the AUC of urinary exosomal MALAT1 was 0.735,better than PSA,f/t PSA,and the basal model,but the P-value did not reach 0.05.DCA curve analysis showed that using urine MALAT1 in the diagnosis of PCa and cs PCa in both training and the validation set was beneficial to patients by avoiding26.9% of unnecessary biopsies,which only missed 3.1% of cs PCa(sensitivity at 90%).In the sequencing data of 136 and 65 pairs of PCa and paracancerous tissues,respectively,lnc RNA MALAT1 was greatly higher in cancer tissues than adjacent tissues(P<0.001).GSE6919 and GSE21034 data showed that MALAT1 content in PCa metastatic tissue was higher than in primary and control(P<0.05).TCGA database showed that MALAT1 gradually increased with tumor progression and metastasis(P<0.05)and that the prognosis of patients with high MALAT1 expression was poorer(P<0.05).Cell phenotype confirmed that interference of MALAT1 in PCa cells changed cell proliferation,migration.To elucidate the underlying mechanisms of MALAT1 in promoting tumor progression,Ch IRP-MS was used and identified 865 proteins that specifically bind to lnc RNA MALAT1.KEGG analysis showed that these proteins were associated with glycolytic pathways significantly.The Seahorse test,glucose uptake test,and lactate content test in MALAT1-overexpressing cells demonstrated that the glycolytic activity of tumor cells was greatly enhanced.To further clarify the target of lnc RNA MALAT1 and verify the results of Ch IRP-MS,we performed transcriptome sequencing analysis in PCa tumor cells overexpressing MALAT1.We found four genes/proteins in glucose metabolism,namely GPI,ALDOC,PGK1,ALDOA,that might play a key role.Further experiments confirmed that lnc RNA MALAT1 could reprogram tumor cell glycolysis and promote tumor progression by stabilizing the expression of ALDOA and PGK1 proteins.Conclusion:This study demonstrates that urinary exosomal lnc RNA MALAT1 can be a biomarker for diagnosis of PCa and cs PCa through a standardized methodology consisting of post-DRE collection,urine sample processing,and RNA quantification.Mechanistic study of lnc RNA MALAT1 in glycolysis found that lnc RNA MALAT1 can reprogram glycolysis in tumor cells and promote tumor progression by stabilizing the protein expressions of ALDOA and PGK1.