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In order to determine the biological functions of extracellular RNA, we have designed and synthesized single- and double-stranded analogues of human extracellular RNAs and analyzed the influences of these analogues on both the proliferation and the viability of cultured human adenocarcinoma cells MCF-7. Transfection of MCF-7 cells by snoRNA analogues, which were targeted to de novo 2′-O-methylation of nucleotides of pre-mRNA, resulted in a partial impairment of pre-mRNA splicing. SnoRNA analogues directed to rRNA induced 2′-O-methylation of targeted nucleotides of rRNA. Transfection by Alu RNA reduced the viability of MCF-7 cells. These data emphasize the role of circulating RNA as efficient inter-cellular messengers and highlight the structures of circulating RNA as a promising basis for the development of new biologically active substances. [ABSTRACT FROM AUTHOR]

The structure of human plasma circulating nucleic acids is currently extensively studied for an acquisition and extension of fundamental knowledge on DNA and RNA functions inside cells as well as between cells – in extracellular fluids of both humans and animals. Previously, we reported data on the general analysis of DNA sequences from plasma of 10 healthy individuals and 12 prostate cancer patients. In order to further characterize this array of sequences we performed comparative analysis of chromosome distribution, repeat content and epigenetic characteristics of plasma DNA. It was found that Long terminal repeats (LTR) [Endogenous retrovirus-related (ERVL) and Mammalian apparent LTR-retrotransposon (MaLR)] DNA were elevated in plasma of healthy individuals while repeats of other classes were at the same or lowered frequency compared to random genome DNA. Satellite repeats attributed to chromosome 12 were elevated in plasma of prostate cancer patients. Epigenome and chromatin structure attributes of circulating DNA emphasized an elevated frequency of histone H3 containing the dimethylated lysine 27 (H3K27me2) associated DNA. The elevated frequency of LTR repeats in circulating human DNA can implicate the possibility of a hypothetical active DNA release mechanism in human cells, and histone H3K27me2 may be involved in this process. [ABSTRACT FROM AUTHOR]

Circulating DNA is comprised of fragments of genomic and mitochondrial DNA that can be isolated from the blood and body fluids of vertebrates. The potential use of these fragments as biomarker(s) for cancer and other diseases has been investigated extensively, but still the exact mechanism of origin and the function or significance of these molecules have not been explained. We attempted to elucidate this question by means of parallel tagged sequencing of circulating DNA on the GSFLX sequencer from 454 life sciences. Circulating DNA from 22 consenting individuals of which 12 were prostate cancer patients and 10 were controls were sequenced simultaneously on one 16th of a picotiter plate. A total of ~3,600 unique sequences were analyzed, these were distributed over the human genome and a slightly higher mutation rate could be observed for DNA obtained from the cancer patients compared to the control group. We concluded that the distribution of circulating DNA over the genome is similar for both groups even though some sequence related differences might be observed. Circulating DNA can be seen as a representation of genomic DNA in the blood of an individual. [ABSTRACT FROM AUTHOR]