Prediction of clusters of miRNA binding sites in mRNA candidate genes of breast cancer subtypes.

The development of breast cancer (BC) subtypes is controlled by distinct sets of candidate genes, and the expression of these genes is regulated by the binding of their mRNAs with miRNAs. Predicting miRNA associations and target genes is thus essential when studying breast cancer. The MirTarget program identifies the initiation of miRNA binding to mRNA, the localization of miRNA binding sites in mRNA regions, and the free energy from the binding of all miRNA nucleotides with mRNA. Candidate gene mRNAs have clusters (miRNA binding sites with overlapping nucleotide sequences). mRNAs of EPOR, MAZ and NISCH candidate genes of the HER2 subtype have clusters, and there are four clusters in mRNAs of MAZ, BRCA2 and CDK6 genes. Candidate genes of the triple-negative subtype are targets for multiple miRNAs. There are 11 sites in CBL mRNA, five sites in MMP2 mRNA, and RAB5A mRNA contains two clusters in each of the three sites. In SFN mRNA, there are two clusters in three sites, and one cluster in 21 sites. Candidate genes of luminal A and B subtypes are targets for miRNAs: there are 21 sites in FOXA1 mRNA and 15 sites in HMGA2 mRNA. There are clusters of five sites in mRNAs of ITGB1 and SOX4 genes. Clusters of eight sites and 10 sites are identified in mRNAs of SMAD3 and TGFB1 genes, respectively. Organizing miRNA binding sites into clusters reduces the proportion of nucleotide binding sites in mRNAs. This overlapping of miRNA binding sites creates a competition among miRNAs for a binding site. From 6,272 miRNAs studied, only 29 miRNAs from miRBase and 88 novel miRNAs had binding sites in clusters of target gene mRNA in breast cancer. We propose using associations of miRNAs and their target genes as markers in breast cancer subtype diagnosis.

The Binding Sites of miR-619-5p in the mRNAs of Human and Orthologous Genes.

BACKGROUND: Normally, one miRNA interacts with the mRNA of one gene. However, there are miRNAs that can bind to many mRNAs, and one mRNA can be the target of many miRNAs. This significantly complicates the study of the properties of miRNAs and their diagnostic and medical applications. RESULTS: The search of 2,750 human microRNAs (miRNAs) binding sites in 12,175 mRNAs of human genes using the MirTarget program has been completed. For the binding sites of the miR-619-5p the hybridization free energy of the bonds was equal to 100% of the maximum potential free energy. The mRNAs of 201 human genes have complete complementary binding sites of miR-619-5p in the 3'UTR (214 sites), CDS (3 sites), and 5'UTR (4 sites). The mRNAs of CATAD1, ICA1L, GK5, POLH, and PRR11 genes have six miR-619-5p binding sites, and the mRNAs of OPA3 and CYP20A1 genes have eight and ten binding sites, respectively. All of these miR-619-5p binding sites are located in the 3'UTRs. The miR-619-5p binding site in the 5'UTR of mRNA of human USP29 gene is found in the mRNAs of orthologous genes of primates. Binding sites of miR-619-5p in the coding regions of mRNAs of C8H8orf44, C8orf44, and ISY1 genes encode the WLMPVIP oligopeptide, which is present in the orthologous proteins. Binding sites of miR-619-5p in the mRNAs of transcription factor genes ZNF429 and ZNF429 encode the AHACNP oligopeptide in another reading frame. Binding sites of miR-619-5p in the 3'UTRs of all human target genes are also present in the 3'UTRs of orthologous genes of mammals. The completely complementary binding sites for miR-619-5p are conservative in the orthologous mammalian genes. CONCLUSIONS: The majority of miR-619-5p binding sites are located in the 3'UTRs but some genes have miRNA binding sites in the 5'UTRs of mRNAs. Several genes have binding sites for miRNAs in the CDSs that are read in different open reading frames. Identical nucleotide sequences of binding sites encode different amino acids in different proteins. The binding sites of miR-619-5p in 3'UTRs, 5'UTRs and CDSs are conservative in the orthologous mammalian genes.

miR-1322 Binding Sites in Paralogous and Orthologous Genes.

We searched for 2,563 microRNA (miRNA) binding sites in 17,494 mRNA sequences of human genes. miR-1322 has more than 2,000 binding sites in 1,058 genes with ΔG/ΔG m ratio of 85% and more. miR-1322 has 1,889 binding sites in CDSs, 215 binding sites in 5' UTRs, and 160 binding sites in 3' UTRs. From two to 28 binding sites have arranged localization with the start position through three nucleotides of each following binding site. The nucleotide sequences of these sites in CDSs encode oligopeptides with the same and/or different amino acid sequences. We found that 33% of the target genes encoded transcription factors. miR-1322 has arranged binding sites in the CDSs of orthologous MAMLD1, MAML2, and MAML3 genes. These sites encode a polyglutamine oligopeptide ranging from six to 47 amino acids in length. The properties of miR-1322 binding sites in orthologous and paralogous target genes are discussed.

MiR-3960 binding sites with mRNA of human genes.

The importance of miRNA in cellular regulation is gaining momentum. Therefore, it is of interest to study miRNA in human genes. Hence, the humanmRNA sequences (12,175) were searched for miRNA binding sites and 2,563predicted sites were found. We observed that the miR-3960 has more than 1000mRNA binding sites with high affinity (with ΔG/ΔGm values greater than or equal to 90%) for 375genes. The miR-3960 has 565 binding sites in the 5'UTRs and 515 sites in theCDS of mRNAs. Nucleotide sequences of the binding sites in CDS encode for polyalanine orpolyproline. It is observed that miR-3960 has binding sites in 73 mRNAs of target genesencoded transcription factors. Thus, we document predictedproperties (polysites, sites in CDS) of uncharacterized miR-3960 binding sites. The studying of the miRNA properties is important for creation of diagnostic methods of cancer.

The properties of binding sites of miR-619-5p, miR-5095, miR-5096, and miR-5585-3p in the mRNAs of human genes.

The binding of 2,578 human miRNAs with the mRNAs of 12,175 human genes was studied. It was established that miR-619-5p, miR-5095, miR-5096, and miR-5585-3p bind with high affinity to the mRNAs of the 1215, 832, 725, and 655 genes, respectively. These unique miRNAs have binding sites in the coding sequences and untranslated regions of mRNAs. The mRNAs of many genes have multiple miR-619-5p, miR-5095, miR-5096, and miR-5585-3p binding sites. Groups of mRNAs in which the ordering of the miR-619-5p, miR-5095, miR-5096, and miR-5585-3p binding sites differ were established. The possible functional and evolutional properties of unique miRNAs are discussed.