Ke Zen

Characterization of microRNAs in serum: a novel class of biomarkers for diagnosis of cancer and other diseases

Dysregulated expression of microRNAs (miRNAs) in various tissues has been associated with a variety of diseases, including cancers. Here we demonstrate that miRNAs are present in the serum and plasma of humans and other animals such as mice, rats, bovine fetuses, calves, and horses. The levels of miRNAs in serum are stable, reproducible, and consistent among individuals of the same species. Employing Solexa, we sequenced all serum miRNAs of healthy Chinese subjects and found over 100 and 91 serum miRNAs in male and female subjects, respectively. We also identified specific expression patterns of serum miRNAs for lung cancer, colorectal cancer, and diabetes, providing evidence that serum miRNAs contain fingerprints for various diseases. Two non-small cell lung cancer-specific serum miRNAs obtained by Solexa were further validated in an independent trial of 75 healthy donors and 152 cancer patients, using quantitative reverse transcription polymerase chain reaction assays. Through these analyses, we conclude that serum miRNAs can serve as potential biomarkers for the detection of various cancers and other diseases.

Secreted Monocytic miR-150 Enhances Targeted Endothelial Cell Migration

MicroRNAs (miRNAs) are a class of noncoding RNAs that regulate target gene expression at the posttranscriptional level. Here, we report that secreted miRNAs can serve as signaling molecules mediating intercellular communication. In human blood cells and cultured THP-1 cells, miR-150 was selectively packaged into microvesicles (MVs) and actively secreted. THP-1-derived MVs can enter and deliver miR-150 into human HMEC-1 cells, and elevated exogenous miR-150 effectively reduced c-Myb expression and enhanced cell migration in HMEC-1 cells. In vivo studies confirmed that intravenous injection of THP-1 MVs significantly increased the level of miR-150 in mouse blood vessels. MVs isolated from the plasma of patients with atherosclerosis contained higher levels of miR-150, and they more effectively promoted HMEC-1 cell migration than MVs from healthy donors. These results demonstrate that cells can secrete miRNAs and deliver them into recipient cells where the exogenous miRNAs can regulate target gene expression and recipient cell function.

Serum MicroRNA Signatures Identified in a Genome-Wide Serum MicroRNA Expression Profiling Predict Survival of Non–Small-Cell Lung Cancer

PURPOSE Recent findings that human serum contains stably expressed microRNA (miRNA) have revealed a great potential of serum miRNA signature as disease fingerprints to predict survival. We used genome-wide serum miRNA expression analysis to investigate the role of serum miRNA in predicting prognosis of non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS To control disease heterogeneity, we used patients with stages I to IIIa lung adenocarcinoma and squamous cell carcinoma, who were treated with both operation and adjuvant chemotherapies. In the discovery stage, Solexa sequencing followed by individual quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assays was used to test the difference in levels of serum miRNAs between 30 patients with longer survival (alive and mean survival time, 49.54 months) and 30 patients with shorter survival matched by age, sex, and stage (dead and mean survival time, 9.54 months). The detected serum miRNAs then were validated in 243 patients (randomly classified into two subgroups: n = 120 for the training set, and n = 123 for the testing set). RESULTS Eleven serum miRNAs were found to be altered more than five-fold by Solexa sequencing between longer-survival and shorter-survival groups, and levels of four miRNAs (ie, miR-486, miR-30d, miR-1 and miR-499) were significantly associated with overall survival. The four-miRNA signature also was consistently an independent predictor of overall survival for both training and testing samples. CONCLUSION The four-miRNA signature from the serum may serve as a noninvasive predictor for the overall survival of NSCLC.

Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA

Our previous studies have demonstrated that stable microRNAs (miRNAs) in mammalian serum and plasma are actively secreted from tissues and cells and can serve as a novel class of biomarkers for diseases, and act as signaling molecules in intercellular communication. Here, we report the surprising finding that exogenous plant miRNAs are present in the sera and tissues of various animals and that these exogenous plant miRNAs are primarily acquired orally, through food intake. MIR168a is abundant in rice and is one of the most highly enriched exogenous plant miRNAs in the sera of Chinese subjects. Functional studies in vitro and in vivo demonstrated that MIR168a could bind to the human/mouse low-density lipoprotein receptor adapter protein 1 (LDLRAP1) mRNA, inhibit LDLRAP1 expression in liver, and consequently decrease LDL removal from mouse plasma. These findings demonstrate that exogenous plant miRNAs in food can regulate the expression of target genes in mammals.

Role of miR-143 targeting KRAS in colorectal tumorigenesis.

Dysregulated expression of microRNAs (miRNAs) is associated with a variety of diseases, including colorectal cancer. By comparing more than 200 miRNAs in 13 pairs of matched colorectal cancer and normal adjacent tissue samples through qRT-PCR and microarray analysis, we found a widespread disruption of miRNA expression during colorectal tumorigenesis. In particular, among a panel of presumed targets generated by in silico analysis that may interact with these aberrantly expressed miRNAs, KRAS oncogene has been further experimentally validated as the target of miR-143. First, an inverse correlation between KRAS protein and miR-143 in vivo was found. Second, KRAS expression in Lovo cells was significantly abolished by treatment with miR-143 mimic, whereas miR-143 inhibitor increased KRAS protein level. Third, luciferase reporter assay confirmed that miR-143 directly recognize the 3′-untranslated region of KRAS transcripts. Four, Lovo cells treated with miR-143 inhibitor showed a stimulated cell proliferation, whereas miR-143 overexpression had an opposite effect. Finally, inhibition of KRAS expression by miR-143 inhibits constitutive phosphorylation of ERK1/2. Taken together, the present study provides the first evidences that miR-143 is significant in suppressing colorectal cancer cell growth through inhibition of KRAS translation.

Secreted microRNAs: a new form of intercellular communication

In multicellular organisms, cell-to-cell communication is of particular importance for the proper development and function of the organism as a whole. Intensive studies over the past three years suggesting horizontal transfer of secreted microRNAs (miRNAs) between cells point to a potentially novel role for these molecules in intercellular communication. Using a microvesicle-dependent, or RNA-binding protein-associated, active trafficking system, secreted miRNAs can be delivered into recipient cells where they function as endogenous miRNAs, simultaneously regulating multiple target genes or signaling events. In this Opinion, we summarize recent literature on the biogenesis and uptake of secreted miRNAs, propose a possible working model for how secreted miRNAs might be sorted and transferred between cells and speculate on their biological significance.

Serum microRNA Profiles Serve as Novel Biomarkers for HBV Infection and Diagnosis of HBV-Positive Hepatocarcinoma

Diagnosis of hepatitis B virus (HBV)-positive hepatocellular carcinoma (HCC), particularly HCC independent of cirrhosis etiology, presents a great challenge because of a lack of biomarkers. Here we test the hypothesis that expression profiles of microRNAs (miRNAs) in serum can serve as biomarkers for diagnosis of HBV infection and HBV-positive HCC. We recruited 513 subjects (210 controls and 135 HBV-, 48 hepatitis C virus (HCV)-, and 120 HCC-affected individuals) and employed a strategy of initial screening by Solexa sequencing followed by validation with TaqMan probe-based quantitative reverse transcription-PCR assay. First, because of a close link between chronic hepatitis B and HCC, we compared miRNA expression profiles in HBV serum with that in control serum and successfully obtained 13 miRNAs that were differentially expressed in HBV serum. This 13-miRNA-based biomarker accurately discriminated not only HBV cases from controls and HCV cases, but also HBV-positive HCC cases from control and HBV cases. Second, we directly compared miRNA expressions in HCC serum with those in controls and identified 6 miRNAs that were significantly upregulated in HCC samples. Interestingly, 2 of these miRNAs, miR-375 and miR-92a, were also identified by our first approach as HBV specific. When we employed 3 of these miRNAs (miR-25, miR-375, and let-7f) as biomarkers, we could clearly separate HCC cases from controls, and miR-375 alone had an ROC of 0.96 (specificity: 96%; sensitivity: 100%) in HCC prediction. In conclusion, our study demonstrates for the first time that serum miRNA profiles can serve as novel and noninvasive biomarkers for HBV infection and HBV-positive HCC diagnosis.

Circulating MicroRNAs: a novel class of biomarkers to diagnose and monitor human cancers

Specific and sensitive non‐invasive biomarkers for the detection of human epithelial malignancies are urgently required to reduce the worldwide morbidity and mortality caused by cancer. MicroRNAs (miRNAs) are 19–24 nt noncoding RNAs that are frequently dysregulated in cancer and have shown great promise as tissue‐based markers for cancer classification. Once thought to be unstable RNA molecules, miRNAs are now shown to be stably expressed in serum, plasma, urine, saliva, and other body fluids. Moreover, the unique expression patterns of these circulating miRNAs are correlated with certain human diseases, including various types of cancer. Therefore, tumor‐derived miRNAs in serum or plasma are emerging as novel blood‐based fingerprints for the detection of human cancers, especially at an early stage. This review presented newly uncovered cellular and molecular mechanisms of the sources and stability of circulating miRNAs, revealing their great potential as a class of highly specific and sensitive biomarkers for tumor classification and prognostication. Meanwhile, this review also addressed certain critical issues that hinder the wide application of this new approach. Some potential challenges for the transition of circulating miRNAs from a research setting to a clinical application were also highlighted, with a future perspective of the incorporation of circulating miRNAs in the field of clinical oncology, especially their great potential from diagnostic to prognostic and predictive applications.  © 2010 Wiley Periodicals, Inc. Med Res Rev

A five-microRNA signature identified from genome-wide serum microRNA expression profiling serves as a fingerprint for gastric cancer diagnosis

BACKGROUND Prognosis of patients with gastric cancer (GC) is generally poor due to the lack of non-invasive tools for GC detection. The purpose of present study was to identify a serum microRNA (miRNA) expression profile that can serve as a novel diagnostic biomarker for GC detection and to assess its clinical applications in monitoring disease progression. METHODS Serum samples were taken from 164 GC patients and 127 age- and gender-matched tumour-free controls. An initial screening of miRNA expression by Solexa sequencing was performed using serum samples pooled from 20 patients and 20 controls, respectively. Differential expression was validated using hydrolysis probe-based stem-loop quantitative reverse transcription polymerase chain reaction (qRT-PCR) in individuals samples, the samples were arranged in two phases. RESULTS The Solexa sequencing results demonstrated that 19 serum miRNAs were markedly upregulated in the GC patients compared to the controls. The qRT-PCR analysis further identified a profile of five serum miRNAs (miR-1, miR-20a, miR-27a, miR-34 and miR-423-5p) as a biomarker for GC detection. The analysis results showed that the expression level of five serum miRNAs was correlated to tumour stage. The areas under the receiver operating characteristic (ROC) curve of this five-serum miRNA signature were 0.879 (95% confidence interval (CI) 0.822-0.936) and 0.831 (95% CI 0.767-0.898) for the two sets of serum samples, respectively, markedly higher than those of the biomarkers carcinoembryonic antigen (CEA) (0.503) and carbohydrate antigen 19-9 (CA19-9) (0.600). CONCLUSIONS We identified five-miRNA signature for GC diagnosis by genome-wide serum miRNA expression profiling. Expression levels of this serum miRNA-based biomarker also indicate tumour progression stages.

Molecular Mechanisms That Influence the Macrophage M1–M2 Polarization Balance

As an essential component of innate immunity, macrophages have multiple functions in both inhibiting or promoting cell proliferation and tissue repair. Diversity and plasticity are hallmarks of macrophages. Classical M1 and alternative M2 activation of macrophages, mirroring the Th1–Th2 polarization of T cells, represent two extremes of a dynamic changing state of macrophage activation. M1-type macrophages release cytokines that inhibit the proliferation of surrounding cells and damage contiguous tissue, and M2-type macrophages release cytokines that promote the proliferation of contiguous cells and tissue repair. M1–M2 polarization of macrophage is a tightly controlled process entailing a set of signaling pathways, transcriptional and posttranscriptional regulatory networks. An imbalance of macrophage M1–M2 polarization is often associated with various diseases or inflammatory conditions. Therefore, identification of the molecules associated with the dynamic changes of macrophage polarization and understanding their interactions is crucial for elucidating the molecular basis of disease progression and designing novel macrophage-mediated therapeutic strategies.