Showing papers by "Murray J. Cairns published in 2009"

Alterations in miRNA processing and expression in pleomorphic adenomas of the salivary gland

Abstract: Genome-wide microRNA (miRNA) expression profiling of salivary gland pleomorphic adenomas revealed a distinct expression signature consisting largely of upregulated miRNAs compared with matched normal tissue. Microarray data were confirmed by quantitative real time RT-PCR (q-RTPCR). Five miRNA genes upregulated in the tumours were found in close proximity to fragile sites and/or cancer associated genomic regions. Interestingly, q-RTPCR revealed an increase in the expression of components of the miRNA processing machinery (Dicer, Drosha, DGCR8 and p68) in tumours suggesting that the deregulation of miRNA expression may result from increased miRNA biogenesis. Target gene prediction analysis of the altered miRNAs indicated that genes in a number of signalling pathways important in tumourigenesis including WNT, MAPK and JAK-STAT were overrepresented. Significantly, the oncogene PLAG1 was overexpressed in our cohort and may be potentially regulated by these miRNAs. This is the first study to examine changes in the miRNA milieu in pleomorphic adenoma, the most common salivary gland tumour. This study has demonstrated an upregulation of both miRNAs genes and an upregulation of the miRNA processing machinery. These changes may be potential underlying mechanisms for the development of these benign tumours.

RNA modulators of complex phenotypes in mammalian cells

Abstract: RNA-mediated gene silencing, in the form of RNA interference (RNAi) or microRNAs (miRNAs) has provided novel tools for gene discovery and validation in mammalian cells. Here, we report on the construction and application of a random small RNA expression library for use in identifying small interfering RNA (siRNA) effectors that can modify complex cellular phenotypes in mammalian cells. The library is based in a retroviral vector and uses convergent promoters to produce unique small complementary RNAs. Using this library, we identify a range of small RNA-encoding gene inserts that overcome resistance to 5-fluorouracil (5-FU)- or tumour necrosis factor alpha (TNF-alpha)- induced cell death in colorectal cancer cells. We demonstrate the utility of this technology platform by identifying a key RNA effector, in the form of a siRNA, which overcomes cell death induced by the chemotherapeutic 5-FU. The technology described has the potential to identify both functional RNA modulators capable of altering physiological systems and the cellular target genes altered by these modulators.

Primer fabrication using polymerase mediated oligonucleotide synthesis

Abstract: Custom solid phase oligonucleotide synthesis is an important foundation supporting nearly every aspect of current genomics. In spite of the demand for oligonucleotide primers, their synthesis remains relatively expensive, time consuming and in many circumstances a wasteful process. In this methodology, described as polymerase mediated oligonucleotide synthesis (PMOS), a DNA polymerase is used to increase the hybridization affinity of one oligonucleotide by using another as a template for DNA synthesis. This self-assembly process provides an opportunity to instantly generate a very large number of useful gene-specific primers from a small library of simple precursors. PMOS can be used to generate primers directly in the end-users laboratory within the context of any DNA polymerase chemistry such as in PCR or sequencing reactions To demonstrate the utility of PMOS, a universal 768-member oligonucleotide library (UniSeq) was designed, fabricated and its performance optimized and evaluated in a range of PCR and DNA sequencing reactions. This methodology used to derive specific 11-mers, performed well in each of these activities and produced the desired amplification or sequencing analysis with results comparable to primers made by time consuming and expensive custom synthesis. On the basis of these experiments, we believe this novel system would be broadly applicable and could in many circumstances replace the need for conventional oligonucleotide synthesis.