| Non-coding RNA (ncRNA) including microRNAs (miRNAs) have currently become one of the frontiers and hotspots of life science. MiRNAs are a large class of single-strand endogenous non-coding small RNA of approximately 22 nucleotides (nt) in length that encoded by miRNAs genes in genome and found in a wide varity of organisms. In recent years, it was uncovered that mature miRNAs function as one of the key components of RNA-induced silencing complex (RISC) to perform their post-trancriptional gene silencing (PTGS) effects, by binding to specific sites in the 3'-untranslated region (3'-UTR) of messenger RNAs (mRNAs) and then inhibiting the translation or inducing the degradation of mRNAs, and play ubiquitous roles in gene expression regulation contributing to diverse cellular processes such as cellular development, differentiation and apoptosis, etc.It was predicted bioinformatically that there exist more than 1000 miRNAs in human genome. The tempo-spatiality specific and tissue-specific expression patterns of miRNAs in different tissues/cells in various physiopathological conditions were well documented, and deregulated miRNAs expressions were consistently observed to involve in the initiations and developments of many diseases including human cancer. More recently, miRNAs in plasma/serum are emerging as a new class of potential biomarkers for minimally invasive diagnosis and monitoring of patients with several diseases such as cancer and cardiovascular disease. For instance, it was found that there are some abberrantly up-regulated miRNAs, such as miR-92 and miR-1, in the plasma and/or serum samples of patients with cancers or cardiovascular diseases, and therefore circulating miRNAs may serve as potential biomarkers for the diagnosis and prognosis of corresponding clinical conditions. Considering recent progresses in circulating miRNAs research field, we could speculate that the species and levels of miRNAs in plasma and/or serum may be maintained in homeostatic status under normal physiological conditions, however, if there are functional and/or metabolic abnormality or organ injuries in human body, the homeostasis of circulating miRNAs may be altered directly or indirectly and therefore result in various degree of variations of specific circulating miRNAs levels in blood.Currently, liver-related diseases such as hepatitis B virus (HBV) infection, chronic hepatitis B (CHB), liver fibrosis (LF), liver cirrhosis (LC) and hepatocellular carcinoma (HCC), etc, are still significant threats to human health worldwide. Therefore, it is still necessary to develop more specific and sensitive biomarkers to complement the traditional markers, such as ALT, AST and AFP, etc, to improve the diagnosis, assessment and health management of patients with liver pathologies.To investigate the feasibility of explorating circulating miRNAs as potential markers for the diagnosis of liver-related diseases, the present work firstly established the platform for quantifing circulating miRNAs in clinical serum samples by using real-time quantitative PCR (rt-qPCR). Thereafter, the quantitative PCR-based TaqMan low density arrays (TLDA) were employed to characterize the circulating miRNAs in the serum samples of normal control, HCC and LC patients, respectively, to investigate whether there are deregulated miRNAs in sera of patients with of liver-related diseases. Furthermore, five up-regulated miRNAs in HCC and LC serum samples, i.e. miR-146a,-215,-224,-574-3p and miR-885-5p were selected and validated in independent case-control studies. Finally, data mining based on a newly published literature was performed to understand the tissue distribution of miR-885-5p and the potential targets of miR-885-5p were predicted and analyzed by using bioinformatics softwares such as TargetScan, etc. This work achieves four main results. Firstly, Circulating miRNAs quantification platform is established in our Lab successfully. Second, The feasibility of using TLDA to quantify circulating miRNAs is evaluated. Third, Circulating miR-885-5p is found to be significantly increased in the serum samples of patients with HCC, CHB and LC, respectively. More importantly, miR-885-5p yield an AUC (area under the curve) of 0.904 in discriminating patients with liver pathologies from normal control, with specificity of 79.17% and sensitivity of 90.53%, respectively. Finally, data mining based on a newly published literature reveals that miR-885-5p is a relatively liver tissue-restricted miRNAs. Furthermore, bioinformatics analysis indicates that the ABCA1 (ATP-binding cassette sub-family A member 1, ABCA1), functioning as the gatekeeper of cholesterol reverse transport (CRT) and key modulator in phosphatide metabolism, is one of the potential targets of miR-885-5p.In summary, the technical platform established here can serve as reference for similar research related to miRNAs quantification, and more importantly, circulating miR-885-5p in serum may serve as a potential biomarker for liver-related diseases detection. |
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