Houston, TX (PRWEB) - A week after the latest miRBase update LC Sciences announced use of miRBase Version 17 probe content as new default for their miRNA microarrays. Arrays for all species included in the latest miRBase 17 release are available. Looking at the most common species: while the changes in probe content for rat are negligible, additions to the list of human miRNAs are substantial: 521 new unique human mature miRNA sequences were added (see our post miRBase Version 17 Update Released).
The full press release: http://www.prweb.com/releases/2011/5/prweb8404968.htm
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by Jeffrey M. Perkel
If PubMed is any guide, the microRNA field is smokin’ hot. Of the nearly 11,100 references that come up in a search for “microRNA,” nearly two-thirds (64%) were published since 2009.
It’s no wonder. Although microRNAs (miRNAs) may be small—they average 22 nucleotides in length—they carry a big stick, biologically speaking. “We can say with confidence that over 60% of human protein-coding genes are conserved targets of miRNAs,” wrote David Bartel and colleagues in 2009. [1]
To date, some 16,772 miRNAs have been discovered and logged in miRBase, including 1,424 in humans. The question for researchers probing these molecules’ biology is, which miRNAs are active under a given set of experimental conditions, and how does that pattern change in the dynamic cellular environment?
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Accumulating evidence suggests that microRNAs (miRNAs) are important gene regulators, which can have critical roles in diverse biological processes including tumorigenesis. In this study, researchers from Nanjing University School of Medicine analyzed the miRNA expression profiles in non-small cell lung carcinoma (NSCLC) by use of a miRNA microarray platform and identified 40 differentially expressed miRNAs.
They showed that miRNA (miR)-451 was the most downregulated in NSCLC tissues. The expression level of miR-451 was found to be significantly correlated with tumor differentiation, pathological stage and lymph-node metastasis. Moreover, low miR-451 expression level was also correlated with shorter overall survival of NSCLC patients (P<0.001). Ectopic miR-451 expression significantly suppressed the in vitro proliferation and colony formation of NSCLC cells and the development of tumors in nude mice by enhancing apoptosis, which might be associated with inactivation of Akt signaling pathway. Interestingly, ectopic miR-451 expression could significantly inhibit RAB14 protein expression and decrease a luciferase-reporter activity containing the RAB14 3′-untranslated region (UTR). In addition, RNA interference silencing of RAB14 gene could recapitulate the tumor suppressor function of miR-451, whereas restoration of RAB14 expression could partially attenuate the tumor suppressor function of miR-451 in NSCLC cells. Furthermore, they also showed that strong positive immunoreactivity of RAB14 protein was significantly associated with downregulation of miR-451 (P=0.01).
These findings suggest that miR-451 regulates survival of NSCLC cells partially through the downregulation of RAB14. Therefore, targeting with the miR-451/RAB14 interaction might serve as a novel therapeutic application to treat NSCLC patients.
Wang R, Wang ZX, Yang JS, Pan X, De W, Chen LB. (2011) MicroRNA-451 functions as a tumor suppressor in human non-small cell lung cancer by targeting ras-related protein 14 (RAB14). Oncogene [Epub ahead of print]. [abstract]
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The incredible enthusiasm for miRNAs as a novel class of functional regulators of tissue maintenance and stress responses demands for appropriate and reliable research tools. This review summarizes many of the currently available basic tools and describes the most widely used approaches for miRNA research to date. Although it will be the combination of several validated research methods that will enable researchers to validate the relevance or contribution of a miRNA to a certain phenotype, some caution should be taken to circumvent erroneous interpretation of data.
van Rooij E. (2011) The Art of MicroRNA Research. Circ Res 108(2), 219-34. [article]
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Renal cell carcinoma (RCC) represents a spectrum of histologic subtypes that are morphologically and cytogenetically distinct. Distinguishing RCC subtypes is of clinical importance because they have different prognoses and subsequently different management plans. Attempts to distinguishing between the subtypes are usually made by morphologic assessment, which is often inconclusive and not always accurate. This can be caused by the complexity and mixed patterns of morphological features as well as simple observer variability in diagnosing subtypes among pathologists.
Researchers at the University of Toronto set out to identify microRNA signatures that can distinguish the different RCC subtypes accurately. Knowing the specific microRNA signature for each subtype provides the basis of a specific targeted therapy for the particular subtype by seeking the microRNAs.
MicroRNA microarray analysis was performed on fresh frozen tissues of three common RCC subtypes (clear cell, chromophobe, and papillary) and on oncocytoma (n=94). Results were validated on the original as well as on an independent set of tumours, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis with microRNA-specific primers.
From the microarray data, the researchers able to develop a classification system that can distinguish the different RCC subtypes using unique microRNA signatures in a maximum of four steps. The system has a sensitivity of 97% in distinguishing normal from RCC, 100% for clear cell RCC (ccRCC) subtype, 97% for papillary RCC (pRCC) subtype, and 100% accuracy in distinguishing oncocytoma from chromophobe RCC (chRCC) subtype. This system was cross-validated and showed an accuracy of about 90%. The oncogenesis of ccRCC is more closely related to pRCC, whereas chRCC is comparable with oncocytoma. They also developed a binary classification system that can distinguish between two individual subtypes.
Youssef YM, White N, Grigull J, Krizova A, Samy C, Mejia-Guerrera S, Evans A, Youse GM. (2011) Accurate Molecular Classification of Kidney Cancer Subtypes Using MicroRNA Signature. European Urology [Epub ahead of print]. [abstract]
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