Consistent high concentration of the viral microRNA BART17 in plasma samples from nasopharyngeal carcinoma patients - evidence of non-exosomal transport

Abstract

BackgroundBecause latent Epstein Barr (EBV)-infection is a specific characteristic of malignant nasopharyngeal carcinoma (NPC), various molecules of viral origin are obvious candidate biomarkers in this disease. In a previous study, we could show in a few clinical samples that it was possible to detect a category of EBV microRNAs called miR-BARTs in the plasma of at least a fraction of NPC patients. The first aim of the present study was to investigate the status of circulating miR-BART17-5p (one of the miR-BARTs hereafter called miR-BART17) and EBV DNA in a larger series of NPC plasma samples. The second aim was to determine whether or not circulating miR-BART17 was carried by plasma exosomes.Patients and methodsPlasma samples were collected from 26 NPC patients and 10 control donors, including 9 patients with non-NPC Head and Neck squamous cell carcinoma and one healthy EBV carrier. Concentrations of miR-BART17 and two cellular microRNAs (hsa-miR-16 and -146a) were assessed by real-time quantitative PCR with spike-in normalization and absolute quantification. In addition, for 2 patients, exosome distributions of miR-BART17 and miR-16 were investigated following plasma lipoprotein fractionation by isopycnic density gradient ultrcentrifugation.ResultsThe miR-BART17 was significantly more abundant in plasma samples from NPC patients compared to non-NPC donors. Above a threshold of 506 copies/mL, detection of miR-BART17 was highly specific for NPC patients (ROC curve analysis: AUC=0.87 with true positive rate = 0.77, false positive rate = 0.10). In this relatively small series, the concentration of plasma miR-BART17 and the plasma EBV DNA load were not correlated. When plasma samples were fractionated, miR-BART17 co-purified with a protein-rich fraction but not with exosomes.ConclusionsDetection of high concentrations of plasma miR-BART17 is consistent in NPC patients. This parameter is, at least in part, independent of the viral DNA load. Circulating miR-BART17 does not co-purify with exosomes.

Diagnostic value of circulating microRNAs for nasopharyngeal cancer: A systematic review and meta-analysis

“…In addition, Jones and Athanasiou [22] briefly reported the AUC for EBV-miR-BART7 (AUC = 0.81), which had an expression level independent from the circulating EBV DNA level. This result is consistent with that of Gourzones et al, [25] suggesting that circulating EBV-encoded miRNA can be used as serological markers in the absence of circulating EBV-DNA. Only Lu et al [27] compared specific miRNA levels between loco-regional and metastasis samples, and demonstrated a high sensitivity (73.7%) and specificity (74.2%) along with a high AUC value (0.743).…”

“…Basing on the inclusion and exclusion criteria, we included seven publications that contain nine studies on the diagnostic accuracy of circulating miRNA in NPC patients. [23][24][25][26][27][28][29][30] The flow of search strategy is shown in Figure 1. Table 1 lists the characteristics of the seven publications that compared circulating miRNA expression between NPC patients and healthy individuals.…”

Profiling of Virus-Encoded MicroRNAs in Epstein-Barr Virus-Associated Gastric Carcinoma and Their Roles in Gastric Carcinogenesis

“…Some EBV miRNAs are secreted and may be detected in plasma of nasopharyngeal carcinoma patients (38)(39)(40). Thus, EBV miRNA can be used as a biomarker predicting tumor progression and therapeutic response.…”

Circulating Epstein–Barr virus microRNAs miR‐BART7 and miR‐BART13 as biomarkers for nasopharyngeal carcinoma diagnosis and treatment

“…33,34 Comparisons of levels of EBV BART microRNA among NPC patients and non-NPC controls have been described in a few reports. [35][36][37] These studies suggested that EBV BART micro-RNA could be used as a biomarker for NPC. Circulating miRNAs have been reported as potentially promising markers for early detection, diagnosis, staging, progression, prognosis and response to treatment.…”