The effective and efficient management of cancer patients relies upon early diagnosis and/or the monitoring of treatment, something that is often difficult to achieve using standard tissue biopsy techniques. Biological fluids such as blood hold great possibilities as a source of non-invasive cancer biomarkers that can act as surrogate markers to biopsy-based sampling. The non-invasive nature of these “liquid biopsies” ultimately means that cancer detection may be earlier and that the ability to monitor disease progression and/or treatment response represents a paradigm shift in the treatment of cancer patients. Below, we review one of the most promising classes of circulating cancer biomarkers: microRNAs (miRNAs). In particular, we will consider their history, the controversy surrounding their origin and biology, and, most importantly, the hurdles that remain to be overcome if they are really to become part of future clinical practice.

https://www.mdpi.com/1422-0067/17/5/627/pdf

New Concepts in Cancer Biomarkers: Circulating miRNAs in Liquid Biopsies

// Ning-Bo Hao 1, * , Ya-Fei He 2, * , Xiao-Qin Li 3 , Kai Wang 4 and Rui-Ling Wang 1 1 Department of Gastroenterology, General Hospital of the PLA Rocket Force, Beijing, China 2 Intensive Medical Center, 302 Hospital of PLA, Beijing, China 3 Department of Ophthalmology, General Hospital of the PLA Rocket Force, Beijing, China 4 New Era Stoke Care and Research Institute, General Hospital of the PLA Rocket Force, Beijing, China * These authors contributed equally to this work Correspondence to: Rui-Ling Wang, email: wang.rui.lin.g@163.com Keywords: gastric cancer, miRNA, lncRNA Received: April 03, 2017      Accepted: June 20, 2017      Published: July 12, 2017 ABSTRACT Gastric cancer is one of the most common cancers and has the highest mortality rate worldwide. It is worthwhile to explore the mechanism of gastric cancer progression. An increasing number of studies have found that non-coding RNAs including miRNA and lncRNA play important roles in gastric cancer progression. This review summarized the role of ectopic miRNA in gastric cancer proliferation, growth, migration, invasion and apoptosis. Meantime, aberrantly expressed miRNA also received a great deal of attention as potential biomarker for gastric cancer diagnosis and therapy. Over the last decade, lncRNA was considered to regulate gastric cancer progression at the transcript and post-transcript level. At the transcript level, lncRNA induced gastric cancer progression by changing chromatin modification and mRNA stabilization to regulate mRNA and miRNA expression. Furthermore, lncRNA regulated gastric cancer progression by completely combining with miRNA to produce ceRNA or promote protein stabilization at the post-transcript level. Greater attention of miRNA and lncRNA in gastric cancer can provide new insight of mechanism of cancer development and may be acted as a new anticancer target.

/pdf/the-role-of-mirna-and-lncrna-in-gastric-cancer-3swuy7ttkh.pdf

The role of miRNA and lncRNA in gastric cancer.

Conventional tumor markers for non-invasive diagnosis of gastric cancer (GC) exhibit insufficient sensitivity and specificity to facilitate detection of early gastric cancer (EGC). We aimed to identify EGC-specific exosomal lncRNA biomarkers that are highly sensitive and stable for the non-invasive diagnosis of EGC. Hence, in the present study, exosomes from the plasma of five healthy individuals and ten stage I GC patients and from culture media of four human primary stomach epithelial cells and four gastric cancer cells (GCCs) were isolated. Exosomal RNA profiling was performed using RNA sequencing to identify EGC-specific exosomal lncRNAs. A total of 79 and 285 exosomal RNAs were expressed at significantly higher levels in stage I GC patients and GCCs, respectively, than that in normal controls. Through combinational analysis of the RNA sequencing results, we found two EGC-specific exosomal lncRNAs, lncUEGC1 and lncUEGC2, which were further confirmed to be remarkably up-regulated in exosomes derived from EGC patients and GCCs. Furthermore, stability testing demonstrates that almost all the plasma lncUEGC1 was encapsulated within exosomes and thus protected from RNase degradation. The diagnostic accuracy of exosomal lncUEGC1 was evaluated, and lncUEGC1 exhibited AUC values of 0.8760 and 0.8406 in discriminating EGC patients from healthy individuals and those with premalignant chronic atrophic gastritis, respectively, which was higher than the diagnostic accuracy of carcinoembryonic antigen. Consequently, exosomal lncUEGC1 may be promising in the development of highly sensitive, stable, and non-invasive biomarkers for EGC diagnosis.

/pdf/tumor-originated-exosomal-lncuegc1-as-a-circulating-3q2z559tzm.pdf

Tumor-originated exosomal lncUEGC1 as a circulating biomarker for early-stage gastric cancer

Owing to late diagnosis in advanced disease stages, prognosis of patients with epithelial ovarian cancer (EOC) is poor. The quantification of deregulated levels of microRNAs could facilitate earlier diagnosis and improve prognosis of EOC. Seven microRNAs (miR-7, miR-16, miR-25, miR-93, miR-182, miR-376a and miR-429) were quantified in the serum of 180 EOC patients and 66 healthy women by TaqMan PCR microRNA assays. Median follow-up time was 21 months. The effects of miR-7 and miR-429 on apoptosis, cell proliferation, migration and invasion were investigated in two (EOC) cell lines. Serum levels of miR-25 (P=0.0001) and miR-93 (P=0.0001) were downregulated, whereas those of miR-7 (P=0.001) and miR-429 (P=0.0001) were upregulated in EOC patients compared with healthy women. The four microRNAs discriminated EOC patients from healthy women with a sensitivity of 93% and a specificity of 92%. The levels of miR-429 positively correlated with CA125 values (P=0.0001) and differed between FIGO I–II and III–IV stages (P=0.001). MiR-429 was an independent predictor of overall survival (P=0.011). Overexpressed miR-429 in SKOV3 cells led to suppression of cell migration (P=0.037) and invasion (P=0.011). Increased levels of miR-7 were associated with lymph node metastases (P=0.0001) and FIGO stages III–IV (P=0.0001). Overexpressed miR-7 in SKOV3 cells resulted in increased cell migration (P=0.001) and invasion (P=0.011). Additionally, the increased levels of miR-376a correlated with FIGO stages III–IV (P=0.02). Our data indicate the diagnostic potential of miR-7, miR-25, miR-93 and miR-429 in EOC and the prognostic potential of miR-429. This microRNA panel may be promising molecules to be targeted in the treatment of EOC.

/pdf/diagnostic-and-prognostic-potential-of-serum-mir-7-mir-16-3grnb7p6jk.pdf

Diagnostic and prognostic potential of serum miR-7, miR-16, miR-25, miR-93, miR-182, miR-376a and miR-429 in ovarian cancer patients.

Gastric cancer (GC) is the fourth most common cancer and the third leading cause of cancer mortality worldwide. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the most popular non-coding RNAs in cancer research. To date, the roles of miRNAs and lncRNAs have been extensively studied in GC, suggesting that miRNAs and lncRNAs represent a vital component of tumor biology. Furthermore, circulating miRNAs and lncRNAs are found to be dysregulated in patients with GC compared with healthy individuals. Circulating miRNAs and lncRNAs may function as promising biomarkers to improve the early detection of GC. Multiple possibilities for miRNA secretion have been elucidated, including active secretion by microvesicles, exosomes, apoptotic bodies, high-density lipoproteins and protein complexes as well as passive leakage from cells. However, the mechanism underlying lncRNA secretion and the functions of circulating miRNAs and lncRNAs have not been fully illuminated. Concurrently, to standardize results of global investigations of circulating miRNAs and lncRNAs biomarker studies, several recommendations for pre-analytic considerations are put forward. In this review, we summarize the known circulating miRNAs and lncRNAs for GC diagnosis. The possible mechanism of miRNA and lncRNA secretion as well as methodologies for identification of circulating miRNAs and lncRNAs are also discussed. The topics covered here highlight new insights into GC diagnosis and screening.

Circulating microRNAs and long non-coding RNAs in gastric cancer diagnosis: An update and review.

Gastric cancer (GC) is one of the most threatening diseases. The symptoms of GC are complex and hard to detect, which also contribute to the poor prognosis of GC. Besides, the current diagnosis for GC is expensive and invasive. Thus, a fast, noninvasive biomarker is urgently needed for GC screening. MicroRNAs (miRNAs) are small noncoding RNAs, which are involved in a great variety of pathological processes, particularly carcinogenesis. MiRNAs are stable in gastric juice, plasma as well as serum, which facilitate it to be a promising biomarker for cancer. In this study, we selected three novel miRNAs, i.e., miR-233, miR-16, and miR-100, to investigate their potential diagnostic value in GC screening. A total of 50 GC patients and 47 healthy controls were involved in this study. Blood serum samples were collected; RNAs were extracted and normalized with U6 snRNA as the internal control; qRT-PCR was performed for relative expression of target miRNAs. Levels of miRNAs expression were compared by Student’s t test for the comparison between two groups, and one-way ANOVA was used for multiple comparisons. The expression of miR-223, miR-16, and miR-100 was all significantly higher in GC patients than controls (all P < 0.001). All the tested miRNAs were manifested to be valuable biomarkers for GC. Relative expression of these miRNAs was significantly correlated with clinical characteristics of GC patients, such as TNM stage (P = 0.036 for miR-223; P < 0.001 for miR-100), metastatic status (P = 0.045 for miR-223; P = 0.031 for miR-16; P = 0.006 for miR-100), tumor size (P = 0.042 for miR-223; P = 0.031 for miR-16; P < 0.001 for miR-100), and differentiation grade (P = 0.036 for miR-223; P = 0.030 for miR-16; P = 0.034 for miR-100). However, in T classification, which considered both tumor size and direct extent of primary tumor, the difference in target miRNAs expression was not significant. In summary, we confirmed the diagnostic value of serum miR-223, miR-16, and miR-100 in GC. Significantly elevated expression of the three miRNAs was also observed in advanced GC patients, which suggested their availability in cancer staging.

Rong Sun

Papers

Three dysregulated microRNAs in serum as novel biomarkers for gastric cancer screening