Abstract
Novel data showing an important role of microRNAs in mediating tumour progression opened a new field of possible molecular targets for cytotoxic ribonucleases. Recently, antitumour and antimetastatic activities of pancreatic ribonuclease A were demonstrated and here genome-wide profiles of microRNAs in the tumour and blood of mice bearing Lewis lung carcinoma after treatment with RNase A were analysed by high-throughput Sequencing by Oligonucleotide Ligation and Detection (SOLiD™) sequencing technology. Sequencing data showed that RNase A therapy resulted in the boost of 116 microRNAs in tumour tissue and a significant drop of 137 microRNAs in the bloodstream that were confirmed by qPCR. The microRNA boost in the tumour was accompanied by the overexpression of microRNA processing genes: RNASEN (Drosha), xpo5, dicer1, and eif2c2 (Ago2). Ribonuclease activity of RNase A was shown to be crucial for the activation of both microRNA synthesis and expression of the microRNA processing genes. In the tumour tissue, RNase A caused the upregulation of both oncomirs and tumour-suppressor microRNAs, including microRNAs of the let-7 family, known to negatively regulate tumour progression. Our results suggest that the alteration of microRNA signature caused by RNase A treatment leads to the attenuation of tumour malignancy.
Highlights
During the last decade, at the forefront of molecular and cellular biology is the identification and study of non-coding RNAs, microRNAs. miRNAs have emerged as a novel class of potent regulatory molecules that enforce posttranscriptional silencing of gene expression through the RNA interference pathway [1,2,3,4], and are responsible for the modulation of fundamental physiological processes inside the cell and at the level of the whole organism [5,6,7]
To study the possible mechanism of RNase A-mediated antitumour effect we evaluated the alteration of miRNA profiles in the tumour tissue and blood serum of mice with Lewis lung carcinoma (LLC) after treatment with the enzyme
High-throughput SOLiDTM sequencing technology was applied to analyse genome-wide profiles of miRNAs in the tumour and serum of LLC-bearing mice after multiple i.m. administration of RNase A at the dose provided for antitumour and antimetastatic effects [24]
Summary
At the forefront of molecular and cellular biology is the identification and study of non-coding RNAs, microRNAs (miRNAs). miRNAs have emerged as a novel class of potent regulatory molecules that enforce posttranscriptional silencing of gene expression through the RNA interference pathway [1,2,3,4], and are responsible for the modulation of fundamental physiological processes inside the cell and at the level of the whole organism [5,6,7]. Ample studies suggest that the dysregulation of individual miRNAs or miRNA families is associated with the initiation of pathogenesis and progression of a wide spectrum of diseases, including oncology [8,9]. Novel miRNA-targeting oligonucleotide-based tools have been developed and progress was achieved with a cure of specific diseases by turning off certain miRNAs [10,11,12]. A number of investigations were devoted to the direct cytotoxic effect of natural ribonucleases on tumour cells associated with intracellular coding and non-coding RNA cleavage [25,26,27,28,29,30]. No studies have been conducted to evaluate the potential alterations in tumour-specific and/or circulating miRNA profiles and investigate the association of miRNA expression pattern and therapeutic efficacy of treatment with ribonucleases in vivo
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