Urinary microRNA can be concentrated, dried on membranes and stored at room temperature in vacuum bags

Urinary MicroRNAs as Emerging Class of Noninvasive Biomarkers

MicroRNAs (miRNAs) are endogenous noncoding RNAs, which regulate gene expression on the post-transcriptional level. Since miRNAs are involved in the regulation of apoptosis, cellular proliferation, differentiation, and other important cellular processes, their deregulation is important for the development of a wide range of diseases including cancer. Apart from tissue, specific disease-related miRNA signatures can be found in body fluids as well. Especially for urologic diseases or injuries, urine miRNAs represent a promising group of biomarkers. Despite a large number of studies describing the importance of urinary miRNAs, there is a lack of recommendations for urine management and subsequent miRNA analysis. Thus, in this chapter, we aim to describe the origin and functions of urinary miRNAs and discuss the technical aspects of their detection including the pre-analytical phase principles and new directions in quantification, which could forward urine miRNA into clinical practice.

Profiling of lysine-acetylated proteins in human urine

A biomarker is a measurable indicator associated with changes in physiological state or disease. In contrast to the blood which is under homeostatic controls, urine reflects changes in the body earlier and more sensitively, and is therefore a better biomarker source. Lysine acetylation is an abundant and highly regulated post-translational modification. It plays a pivotal role in modulating diverse biological processes and is associated with various important diseases. Enrichment or visualization of proteins with specific post-translational modifications provides a method for sampling the urinary proteome and reducing sample complexity. In this study, we used anti-acetyllysine antibody-based immunoaffinity enrichment combined with high-resolution mass spectrometry to profile lysine-acetylated proteins in normal human urine. A total of 629 acetylation sites on 315 proteins were identified, including some very low-abundance proteins. This is the first proteome-wide characterization of lysine acetylation proteins in normal human urine. Our dataset provides a useful resource for the further discovery of lysine-acetylated proteins as biomarkers in urine.

Regional Differences of the Urinary Proteomes in Healthy Chinese Individuals

Objective Urine is a promising biomarker source for clinical proteomics studies. Regional physiological differences are common in multi-center clinical studies. In this study, we investigate whether significant differences are present in the urinary proteomes of individuals from different regions in China. Methods In this study, morning urine samples were collected from healthy urban residents in three regions of China (Haikou, Xi'an and Xining) and urinary proteins were preserved using a membrane-based method (Urimem). The urine proteomes of 27 normal samples were analyzed using LC-MS/MS and compared among three regions. Functional annotation of the differential proteins among the three areas was analyzed using the DAVID online database, and pathway enrichment of the differential urinary proteins was analyzed using KEGG. Results We identified 1898 proteins from Urimem samples using label-free proteome quantification, of which 56 urine proteins were differentially expressed among the three regions (P < 0.05). Hierarchical clustering analysis showed that inter-regional differences caused less significant changes in the urine proteome than inter-sex differences. After gender stratification, 16 differential proteins were identified in male samples and 84 differential proteins were identified in female samples. Among these differential proteins, several proteins have been previously reported as urinary disease biomarkers. Conclusions Urimem will facilitate urinary protein storage for large-scale urine sample collection. Regional differences are a confounding factor influencing the urine proteome and should be considered in future multi-center biomarker studies.

Collection and preservation of urinary proteins, using a fluff pulp diaper

Change is the most fundamental property of a biomarker. In contrast to the blood, which is under homeostatic controls, urine reflects changes in the body earlier and is more sensitive, thus making it a better biomarker source. Moreover, drawing blood from infants and toddlers is difficult and not tolerated well. For patients limited by language, communicating their chief complaint is difficult. Thus, monitoring biomarkers in urine can provide valuable clues for the diagnosis of diseases, especially pediatric diseases. Collecting urine from young children and some adult patients is more challenging than collecting it from healthy adults. Here, we propose a method that uses a fluff pulp diaper to collect urine. Urinary proteins are then eluted and adsorbed onto a piece of nitrocellulose membrane, which can be dried and stored in a vacuum bag. SDS-PAGE and LC-MS/MS analysis indicated that this method is reproducible, and similar proteins were identified as those obtained by an acetone precipitation method. With this simple and economical method, it is possible to collect and preserve urine samples from infants, toddlers, and patients with special needs, even for large-scale biomarker studies.

Expression Level of Urinary MicroRNA-146a-5p Is Increased in Patients With Bladder Cancer and Decreased in Those After Transurethral Resection

BACKGROUND

Bladder cancer is the most prevalent malignancy involving the urinary system and exhibits a markedly high recurrence rate. Therefore, reliable and noninvasive diagnostic and surveillance methods are desperately needed.

PATIENTS AND METHODS

Candidate microRNAs (miRNAs) were selected from the miRNAs that were differentially expressed in bladder cancer cell lines (T24 and RT4) compared to normal ureteral epithelial tissue using miRNA-microarray analysis. The candidate miRNAs were validated by quantitative reverse transcription polymerase chain reaction assay using voided urine samples.

RESULTS

We identified 3 miRNAs (miR-301b, -563, and -146a-5p) that demonstrated > 2-fold higher expression levels in cancer cell lines than in the normal ureteral epithelial tissue. Of these, only miR-146a-5p was consistently and significantly higher in urine samples from the patients with bladder cancer than in those from the normal individuals (P = .0014). The patients with high-grade tumors exhibited significantly higher urinary miR-146a-5p levels than those with low-grade tumors, and the patients with invasive tumors tended to show higher urinary miR-146a-5p levels than those with noninvasive tumors. Elevated urinary miR-146a-5p levels in patients with bladder cancer were decreased to the normal level after transurethral resection of the tumors (P = .0214).

CONCLUSION

Our study suggested that urinary miR-146a-5p might be useful as a new noninvasive diagnostic marker, therapeutic target, or anticancer agent for bladder cancer, as well as for increasing our understanding of cancer biology.