MicroRNAs (miRNAs) belong to a class of noncoding, regulatory RNAs that is involved in oncogenesis and shows remarkable tissue specificity. Their potential for tumor classification suggests they may be used in identifying the tissue in which cancers of unknown primary origin arose, a major clinical problem. We measured miRNA expression levels in 400 paraffin-embedded and fresh-frozen samples from 22 different tumor tissues and metastases. We used miRNA microarray data of 253 samples to construct a transparent classifier based on 48 miRNAs. Two-thirds of samples were classified with high confidence, with accuracy >90%. In an independent blinded test-set of 83 samples, overall high-confidence accuracy reached 89%. Classification accuracy reached 100% for most tissue classes, including 131 metastatic samples. We further validated the utility of the miRNA biomarkers by quantitative RT-PCR using 65 additional blinded test samples. Our findings demonstrate the effectiveness of miRNAs as biomarkers for tracing the tissue of origin of cancers of unknown primary origin.

AimsDiagnosis and risk stratification of patients with heart failure remain a challenge. The small non-coding RNAs known as microRNAs regulate gene expression and seem to play an important role in the pathogenesis of heart failure. In the current study, we aim to characterize the levels of microRNAs in the sera of chronic systolic heart failure patients vs. controls and assess the possible correlation between elevation in the levels of specific microRNAs and clinical prognostic parameters in heart failure patients. Methods and resultsThe levels of 186 microRNAs were measured in the sera of 30 stable chronic systolic heart failure patients and 30 controls using quantitative reverse transcription -polymerase chain reaction (qRT -PCR). The differences in micro-RNA levels between the two groups were characterized, and a score, based on the levels of four specific microRNAs with the most significant increase in the heart failure group (miR-423-5p, miR-320a, miR-22, and miR-92b), was defined. The score was used to discriminate heart failure patients from controls with a sensitivity and specificity of 90%. Moreover, in the heart failure group, there was a significant association between the score and important clinical prognostic parameters such as elevated serum natriuretic peptide levels, a wide QRS, and dilatation of the left ventricle and left atrium (r ¼ 0.63, P ¼ 3e-4; P ¼ 0.009; P ¼ 0.03; and P ¼ 0.01, respectively). ConclusionsElevated serum levels of specific microRNAs: miR-423-5p, miR-320a, miR-22, and miR-92b, identify systolic heart failure patients and correlate with important clinical prognostic parameters.--

In an attempt to identify and characterize chloroplast proteases, we performed an immunological analysis of chloroplasts using an antibody against Escherichia coli FtsH protease, which is an ATP-dependent metalloprotease bound to the cytoplasmic membrane. A cross-reacting protein of 78 kDa was found in the thylakoid membrane of spinach, but not in the soluble stromal fraction. Alkali and high salt washes, as well as trypsin treatment of thylakoid membranes, suggest that the chloroplastic FtsH protein is integral to the membrane, with its hydrophilic portion exposed to the stroma. The protein is not bound to any photosynthetic complex and is exclusively located in the stromally exposed regions of the thylakoid membrane. Its expression is dependent on light, as it is present in green pea seedlings, but absent from etiolated ones. An Arabidopsis cDNA was isolated, and the deduced amino acid sequence demonstrated high similarity to the E. coli FtsH protein, especially in the central region of the protein, containing the ATP-and zinc-binding sites. The product of this clone was capable of import into isolated pea chloroplasts, where it was processed to its mature form and targeted to the thylakoid membrane. The trans-bilayer orientation and lateral location of the FtsH protein in the thylakoid membrane suggest its involvement in the degradation of both soluble stromal proteins and newly inserted or turning-over thylakoid proteins.Numerous examples of protein degradation in chloroplasts have been accumulated over the years. These include degradation of unassembled proteins, apoproteins lacking their prosthetic groups or pigments, photo-or otherwise-damaged proteins, and developmentally or environmentally regulated proteins (see Ref. 1, and references therein). In particular, emphasis has been placed on the degradation of the D1 protein in connection with photoinhibitory damage of the PSII 1 reaction center (2, 3). However, despite extensive documentation of these processes, little is known about the identity of the proteases involved. Only recently, the existence of Clp protease, a homologue of a well characterized bacterial ATP-dependent serine protease (4, 5), has been demonstrated in chloroplasts of higher plants (1, 6 -8). The occurrence of Clp subunits in plants subjected to a variety of environmental conditions suggests its function in chloroplasts as a housekeeping protease.The existence of a protein related to a bacterial protease in the chloroplast, together with other prokaryotic characteristics of this organelle, led us to hypothesize that additional chloroplast proteases may resemble prokaryotic ones. This notion was recently substantiated by the finding that the chloroplast genomes of red and brown algae (9, 10) contain genes homologous to another bacterial protease, FtsH. FtsH and related proteins are found in different bacteria and yeast mitochondria; it was demonstrated to be a 74-kDa (11), ATP-dependent metalloprotease, involved in the response of Escherichia coli to heat shock (12, 13), degradation o...

AimsThe distinction between benign and malignant thyroid nodules has important therapeutic implications. Our objective was to develop an assay that could classify indeterminate thyroid nodules as benign or suspicious, using routinely prepared fine needle aspirate (FNA) cytology smears.MethodsA training set of 375 FNA smears was used to develop the microRNA-based assay, which was validated using a blinded, multicentre, retrospective cohort of 201 smears. Final diagnosis of the validation samples was determined based on corresponding surgical specimens, reviewed by the contributing institute pathologist and two independent pathologists. Validation samples were from adult patients (≥18 years) with nodule size >0.5 cm, and a final diagnosis confirmed by at least one of the two blinded, independent pathologists. The developed assay, RosettaGX Reveal, differentiates benign from malignant thyroid nodules, using quantitative RT-PCR.ResultsTest performance on the 189 samples that passed quality control: negative predictive value: 91% (95% CI 84% to 96%); sensitivity: 85% (CI 74% to 93%); specificity: 72% (CI 63% to 79%). Performance for cases in which all three reviewing pathologists were in agreement regarding the final diagnosis (n=150): negative predictive value: 99% (CI 94% to 100%); sensitivity: 98% (CI 87% to 100%); specificity: 78% (CI 69% to 85%).ConclusionsA novel assay utilising microRNA expression in cytology smears was developed. The assay distinguishes benign from malignant thyroid nodules using a single FNA stained smear, and does not require fresh tissue or special collection and shipment conditions. This assay offers a valuable tool for the preoperative classification of thyroid samples with indeterminate cytology.

Hepatocellular carcinoma (HCC) is generally a fatal disease due to a paucity of effective treatment options. The identification of oncogenic microRNAs that exert pleiotropic effects in HCC cells may offer new therapeutic targets. In this study, we have identified the human microRNA miR-191 as a potential target for HCC therapy. Inhibition of miR-191 decreased cell proliferation and induced apoptosis in vitro and significantly reduced tumor masses in vivo in an orthotopic xenograft mouse model of HCC. Additionally, miR-191 was found to be upregulated by a dioxin, a known liver carcinogen, and was found to be a regulator of a variety of cancer-related pathways. Our findings offer a preclinical proof of concept for miR-191 targeting as a rational strategy to pursue for improving HCC treatment. Cancer Res; 70(20); 8077-87. ©2010 AACR.