Assessment of nucleosides as putative tumor biomarkers in prostate cancer screening by CE–UV

Discovery and validation of bladder cancer related excreted nucleosides biomarkers by dilution approach in cell culture supernatant and urine using UHPLC-MS/MS

The exploration of nucleoside changes in human biofluids has profound potential for cancer diagnosis. Herein, we developed a rapid methodology to quantify 17 nucleosides by UHPLC-MS/MS. Five pairs of isomers were successfully separated within 8 min. The ME was mostly eliminated by sample dilution folds of 1000 for urine and 40 for CCS. The optimized method was firstly applied to screen potential nucleoside biomarkers in CCS by comprising bladder cancer cell lines (5637 and T24) and normal human bladder cell line SV-HUC-1 together with student's t-test and OPLS-DA. Nucleosides with significant differences in the supernatant of urine samples were also uncovered comparing BCa with the non-tumor group, as well as a comparison of BCa recurrence group with the non-recurrence group. By intersecting the differential nucleosides in CCS and urine supernatant, and then further confirmed using validation sets, the combination of m³C and m¹A with AUC of 0.775 was considered as a potential biomarker for bladder cancer diagnosis. A panel of m³C, m¹A, m¹G, and m²₂G was defined as potential biomarkers for bladder cancer prognosis with an AUC of 0.819. Above all, this method provided a new perspective for diagnosis and recurrence monitoring of bladder cancer. SIGNIFICANCE: The exploration of nucleoside changes in body fluids has profound potential for the diagnosis and elucidation of the pathogenesis of cancer. In this study, we developed a rapid methodology for the simultaneous quantitative determination of 17 nucleosides in the supernatant of cells and urine samples using UHPLC-MS/MS to discover and validate bladder cancer related excreted nucleoside biomarkers. The results of this paper provide a new strategy for diagnosis and postoperative recurrence monitoring of bladder cancer and provide theoretical support for the exploration of its pathogenesis.

Mass Spectrometry-Based Targeted Serum Monomethylated Ribonucleosides Profiling for Early Detection of Breast Cancer

RNA methylation plays a significant regulatory role in various of physiological activities and it has gradually become a hotspot of epigenetics in the past decade. 2′-O-methyladenosine (Am), 2′-O-methylguanosine (Gm), 2′-O-methylcytidine (Cm), 2′-O-methyluridine (Um), N⁶-methyladenosine (m⁶A), N¹-methylguanosine (m¹G), 5-methylcytidine (m⁵C), and 5-methyluridine (m⁵U) are representative 2′-O-methylation and base-methylation modified epigenetic marks of RNA. Abnormal levels of these ribonucleosides were found to be related to various diseases including cancer. Serum is an important source of biofluid for the discovery of biomarkers, and novel tumor biomarkers can be explored by measuring these ribonucleoside modifications in human serum. Herein, we developed and applied a hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) method to determine the content of monomethylated ribonucleosides in human serum. The developed method enabled sensitive and accurate determination of these monomethylated ribonucleosides. By applying this robust method, we demonstrated the presence of Gm and Um in human serum for the first time, and we successfully quantified m⁶A, Gm, m¹G, Cm, Um and m⁵U in serum samples collected from 61 patients with breast cancer and 69 healthy controls. We discovered that the levels of Gm, m¹G, Cm, Um and m⁵U in serum were all significantly decreased in breast cancer patients whereas m⁶A was increased. We performed receiver operating characteristic (ROC) curve analysis, and obtained highest area under curve (AUC) value when combining these six monomethylated ribonucleosides together. These results suggest that m⁶A, Gm, m¹G, Cm, Um and m⁵U might have great potential to be novel biomarkers for detection of breast cancer in the early stage. In addition, this study may stimulate future investigations about the regulatory roles of monomethylated ribonucleosides on the initiation and development of breast cancer.

Quantifying RNA modifications by mass spectrometry: a novel source of biomarkers in oncology

Despite significant progress in targeted therapies, cancer recurrence remains a major cause of mortality worldwide. Identification of accurate biomarkers, through molecular profiling in healthy and cancer patient samples, will improve diagnosis and promote personalized medicine. While genetic and epigenetic alterations of DNA are currently exploited as cancer biomarkers, their robustness is limited by tumor heterogeneity. Recently, cancer-associated changes in RNA marks have emerged as a promising source of diagnostic and prognostic biomarkers. RNA epigenetics (also known as epitranscriptomics) is an emerging field in which at least 150 chemical modifications in all types of RNA (mRNA, tRNA, lncRNA, rRNA, and microRNA) have been detected. These modifications fine-tune gene expression in both physiological and pathological processes. A growing number of studies have established links between specific modified nucleoside levels in solid/liquid biopsies, and cancer onset and progression. In this review, we highlight the potential role of epitranscriptomic markers in refining cancer diagnosis and/or prognosis. RNA modification patterns may contain important information for establishing an initial diagnosis, monitoring disease evolution, and predicting response to treatment. Furthermore, recent developments in mass spectrometry allow reliable quantification of RNA marks in solid biopsies and biological fluids. We discuss the great potential of mass spectrometry for identifying epitranscriptomic biomarker signatures in cancer diagnosis. While there are various methods to quantify modified nucleosides, most are unable to detect and quantify more than one type of RNA modification at a time. Mass spectrometry analyses, especially GC-MS/MS and LC-MS/MS, overcome this limitation and simultaneously detect modified nucleosides by multiple reaction monitoring. Indeed, several groups are currently validating mass spectrometry methods that quantify several nucleosides at one time in liquid biopsies. The challenge now is to exploit these powerful analytical tools to establish epitranscriptomic signatures that should open new perspectives in personalized medicine. This review summarizes the growing clinical field of analysis of RNA modifications and discusses pre-analytical and analytical approaches, focusing in particular on the development of new mass spectrometry tools and their clinical applications.

An Overview of Pretreatment and Analysis of Nucleotides in Different Samples (Update since 2010)

Nucleotides, which are important low-molecular-weight compounds present in organisms, are precursors of nucleic acids and participate in various regulatory and metabolic functions. Sensitive and valid methods for monitoring and determining nucleotides and nucleosides in different samples are urgently required. Due to the presence of numerous endogenous interferences in complex matrices and the high polarity of the molecules of the phosphate moiety, the determination of nucleotide content is challenging. This review summarizes the pretreatment and analysis methods of nucleotides in different samples. Advanced pretreatment methods, including different microextraction methods, solid-phase extraction based on novel materials, QuEChERS, are clearly displayed, and continuous progress which has been made in LC, LC-MS/MS and capillary electrophoresis methods are discussed. Moreover, the strengths and weaknesses of different methods are discussed and compared. Highlight:Advanced pretreatment and detection methods of nucleotides were critically reviewed.Microextraction technology was one of the trends of nucleotides pretreatment in the future.Applications of novel materials and supercritical fluid were highlighted.The evolution and advance of HRMS analyzers were in detailed.

Pseudouridine as a novel biomarker in prostate cancer

Epitranscriptomic analysis has recently led to the profiling of modified nucleosides in cancer cell biological matrices, helping to elucidate their functional roles in cancer and reigniting interest in exploring their use as potential markers of cancer development and progression. Pseudouridine, one of the most well-known and the most abundant of the RNA nucleotide modifications, is the C5-glycoside isomer of uridine and its distinctive physiochemical properties allows it to perform many essential functions. Pseudouridine functionally (a) confers rigidity to local RNA structure by enhancing RNA stacking, engaging in a cooperative effect on neighboring nucleosides that overall contributes to RNA stabilization (b) refines the structure of tRNAs, which influences their decoding activity (c) facilitates the accuracy of decoding and proofreading during translation and efficiency of peptide bond formation, thus collectively improving the fidelity of protein biosynthesis and (e) dynamically regulates mRNA coding and translation. Biochemical synthesis of pseudouridine is carried out by pseudouridine synthases. In this review we discuss the evidence supporting an association between elevated pseudouridine levels with the incidence and progression of human prostate cancer and the translational significance of the value of this modified nucleotide as a novel biomarker in prostate cancer progression to advanced disease.

Targeted metabolomics: Liquid chromatography coupled to mass spectrometry method development and validation for the identification and quantitation of modified nucleosides as putative cancer biomarkers

A notable change in the body fluids nucleosides of cancer patients has been actively highlighted in searches for new biomarkers to early cancer detection. For this reason, improvements of bioanalytical methods for these compounds focused on a noninvasive sampling trend are of great importance. Therefore, this work aimed firstly to develop efficient methods for nucleoside analysis in urine and serum by liquid chromatography-tandem mass spectrometry (LC-MS/MS), applying different strategies to quantify nine nucleosides, and further identify other untargeted nucleosides. Sample preparation was based on protein precipitation and affinity-solid phase extraction (SPE), whereas quantification was performed using a triple quadrupole (QqQ) mass analyzer operating in the selected reaction monitoring (SRM) mode. Surrogates matrices were proposed as an alternative to standard addition calibration. Specifically, to quantitate creatinine, a simple LC-MS/MS method was validated and used for normalization of urinary metabolites quantitation. To identify the other nucleosides, LC methods using different MS scans modes were evaluated on a quadrupole-time of flight (Q-TOF) or a hybrid triple quadrupole linear ion trap (Q-trap). Validation was performed for nucleosides quantification using the synthetic matrices of urine and serum, and selectivity, linearity, accuracy, reproducibility, matrix effect, LOD's and LOQ's were accessed, providing trustworthy results for bioanalysis purposes. Both LC-Q-Trap/MS and LC-Q-TOF/MS methods showed proper sensitivity for structural characterization on assays with urine and serum samples from healthy volunteers and could also be used in the identification of untargeted nucleosides. The investigated approaches delivered in-depth results and seem promising for future applications on urine and serum samples analyses aiming to validate nucleosides as cancer biomarkers.

NMR-based metabolomics analysis identifies discriminatory metabolic disturbances in tissue and biofluid samples for progressive prostate cancer

BACKGROUND

Prostate cancer (PCa) is one of the most common cancers in men, but its metabolic characteristics during tumor progression are still far from being fully understood.

METHODS

The metabolic profiles of matched tissue, serum and urine samples from the same patients were analyzed using a ¹H NMR-based metabolomics approach. We identified several important metabolites that significantly altered at different stages of PCa, including benign prostatic hyperplasia (BPH), early PCa (EPC), advanced PCa (APC), metastatic PCa (MPC) and castration-resistant PCa (CRPC). Metabolic correlation networks among tissue, serum and urine samples were examined using Pearson's correlation.

RESULTS

The changes in metabolic phenotypes during the progression of PCa were more noticeable in tissue samples when compared with serum and urine samples. Herein we identified a series of important metabolic disturbances, including decreased trends of citrate, creatinine, acetate, leucine, valine, glycine, lysine, histidine, glutamine and choline as well as increased trends of uridine and formate. These metabolites are mainly implicated in energy metabolism, amino acid metabolism, choline and fatty acid metabolism as well as uridine metabolism. We also found that energy metabolism in tumor tissues was positively associated with amino acid metabolism in serum and urine. Additionally, CRPC patients had a peculiar metabolic phenotype, especially decreased amino acid metabolism in serum.

CONCLUSIONS

The present study characterizes metabolic disturbances in both tissue and biofluid samples during PCa progression and provides potential diagnostic biomarkers and therapeutic targets for PCa.

Organized cryogel composites with 3D hierarchical porosity as an extraction adsorbent for nucleosides

Macroscopic monoliths are highly desirable in many fields of application. Herein, well organized organic-inorganic cryogel composite with a three-dimensional hierarchical meso- and macroporous structure are presented, which were produced by in situ copolymerization of mesoporous multifunctional silica (size: 1-20 μm; pore: 2-20 nm mostly) and monomers (hydroxyethyl methacrylate and diallyldimethylammonium chloride) in water below the freezing point. This copolymerization method effectively adjusted the macropores of the basic cryogel, and the nanosilica was more homogeneously dispersed in the basic cryogel. The specific surface area of the cryogel composite was increased 17 times versus than that of the basic cryogel. The abundant meso- and macroporous pores on the cryogel composite provided sufficient reactive sites favorable for the efficient mass transport of target compounds. When the cryogel composite, as solid phase extraction adsorbent, was coupled with high-performance liquid chromatography, an analytical tool, the nucleosides were quantified with good selectivity, lower detection limits (0.9-1.3 ng/mL) and satisfactory recoveries of greater than 80% from spiked human serum.

Vnn1 pantetheinase limits the Warburg effect and sarcoma growth by rescuing mitochondrial activity

Expression of the Vnn1 pantetheinase by sarcomas is tumor suppressive by limiting the use of aerobic glycolysis for growth and rescuing mitochondrial activity through CoA regeneration.

Like other tumors, aggressive soft tissue sarcomas (STS) use glycolysis rather than mitochondrial oxidative phosphorylation (OXPHOS) for growth. Given the importance of the cofactor coenzyme A (CoA) in energy metabolism, we investigated the impact of Vnn1 pantetheinase—an enzyme that degrades pantetheine into pantothenate (vitamin B5, the CoA biosynthetic precursor) and cysyteamine—on tumor growth. Using two models, we show that Vnn1⁺ STS remain differentiated and grow slowly, and that in patients a detectable level of VNN1 expression in STS is associated with an improved prognosis. Increasing pantetheinase activity in aggressive tumors limits their growth. Using combined approaches, we demonstrate that Vnn1 permits restoration of CoA pools, thereby maintaining OXPHOS. The simultaneous production of cysteamine limits glycolysis and release of lactate, resulting in a partial inhibition of STS growth in vitro and in vivo. We propose that the Warburg effect observed in aggressive STS is reversed by induction of Vnn1 pantetheinase and the rewiring of cellular energy metabolism by its products.

Urinary Nucleosides and Deoxynucleosides

Urinary nucleosides and deoxynucleosides are mainly known as metabolites of RNA turnover and oxidative damage of DNA. For several decades these metabolites have been examined for their potential use in disease states including cancer and oxidative stress. Subsequent improvements in analytical sensitivity and specificity have provided a reliable means to measure these unique molecules to better assess their relationship to physiologic and pathophysiologic conditions. In fact, some are currently used as antiviral and antitumor agents. In this review we provide insight into their molecular characteristics, highlight current separation techniques and detection methods, and explore potential clinical usefulness.