Search

Breast cancer is the most common cancer among women worldwide. The use of mammography screening for women, in the age range the most at risk to breast cancer, has led to a significant reduction in mortality from this disease. However, mammography shows a significant number of false positives in women at a younger age. This problem indicates the need to find new reliable, minimally invasive and cheap biomarkers of breast cancer. The relevance of the research is determined by the fact that breast cancer in Kazakh women often develops at a young age. The aim of this study was to test the diagnostic value of six plasma miRNAs in Kazakh women. For this, using the quantitative PCR technique, we compared the levels of the miRNAs in the plasma of breast cancer patients (n = 27) and healthy controls (n = 33), as well as in the breast tumor and adjacent normal tissue (n = 28). Quantitative data were normalized relative to endogenous control miR-16-5p. Plasma concentrations of miR-145-5p, miR-191-5p, and miR-21-5p were significantly increased in patients compared to controls (P = 6.58e-7, 2.70e-5, and 0.049, respectively). The levels of miR-191-5p and miR-210-3p were significantly increased, while the level of miR-145-5p was significantly reduced in the tumor compared to normal tissue (1.88e-6, 6.56e-7 and 9.66e-4, respectively). To test the hypothesis of the secretory origin of the studied plasma miRNAs, we analyzed the correlation of miRNA levels in plasma, tumor, and healthy breast tissue. Correlation analysis showed that there may be a relationship between plasma and tumor levels of miR-145-5p. Plasma level of miR-210-3p correlated with tissue ∆∆Ct, plasma level of miR-222-3p correlated with its expression in healthy tissue; however, the concentrations of these miRNAs did not differ in plasma of breast cancer patients and healthy controls. To test whether our circulating miRNAs can be used to differentiate breast cancer patients from healthy individuals, we performed a ROC analysis. The largest area under the ROC-curve (AUC) was obtained for miR-145-5p (0.854), slightly less for miR-191-5p (0.818), and miR-21-5p was significantly inferior in this indicator (0.649). Using three microRNAs together, it was possible to separate patients from healthy women with 85 % accuracy, high specificity (94 %) and medium sensitivity (74 %). When assessing the potential of the studied miRNAs as markers of tumorigenesis in breast tissue, we found that using miR-191-5p or miR-210-3p, it is possible to distinguish cancer from healthy tissue with equally high accuracy (84% each). Although individually miR-145-5p showed medium separation accuracy (71 %), it complemented two other miRNAs in both paired and triple models. Thus, miR-145-5p and miR-191-5p can be considered potential plasma biomarkers, while miR-191-5p, miR-210-3p, and miR-145-5p can be considered potential tissue biomarkers for the diagnosis of breast cancer. The findings need to be confirmed on a more representative cohort of samples.

The variability of nucleotide repeats is considered one of the causes of diseases, but their biological function is not understood. In recent years, the interaction of miRNAs and piRNAs with the mRNAs of genes responsible for developing neurodegenerative and oncological diseases and diabetes have been actively studied. We explored candidate genes with nucleotide repeats to predict associations with miRNAs and piRNAs. The parameters of miRNAs and piRNA binding sites with mRNAs of human genes having nucleotide repeats were determined using the MirTarget program. This program defines the start of the initiation of miRNA and piRNA binding to mRNAs, the localization of miRNA and piRNA binding sites in the 5′-untranslated region (5′UTR), coding sequence (CDS) and 3′-untranslated region (3′UTR); the free energy of binding; and the schemes of nucleotide interactions of miRNAs and piRNAs with mRNAs. The characteristics of miRNAs and piRNA binding sites with mRNAs of 73 human genes were determined. The 5′UTR, 3′UTR and CDS of the mRNAs of genes are involved in the development of neurodegenerative, oncological and diabetes diseases with GU, AC dinucleotide and CCG, CAG, GCC, CGG, CGC trinucleotide repeats. The associations of miRNAs, piRNAs and candidate target genes could be recommended for developing methods for diagnosing diseases, including neurodegenerative diseases, oncological diseases and diabetes.

Trinucleotide repeat expansion disorders constitute a group of dominantly inherited neurological diseases that are incurable and ultimately fatal. In the present work, miRNA binding sites were predicted by the MirTarget program. It was given characteristics of miRNAs binding sites in 5' and 3' UTR mRNAs genes of non-polyglutamine trinucleotide disorders with CGG, GCC, CUG repeats. Binding sites of 2567 miRNAs with mRNAs of 17494 human genes were determined. 206 genes with nucleotide repeats, mRNAs of which are bind with miRNA in the 5'UTR and 3'UTR, were observed. From thus, 2668 miRNAs binding sites are located in the 5'UTR, 3853 – in the 3'UTR with ΔG/ΔGm values equal to 85 % and more. It was found that 34 gene’s mRNA having trinucleotide (CGG\GCC\CUG) repeats were targets for miR-4258, miR-3960 miR-211-3p and miR-3155b. miR-4258 binds to mRNA of ADARB1, C11orf87 and CBFB genes with free binding energy - 93 kJ/mole and ΔG/ΔGm 91%, to mRNA of ARHGEF7, BCR, BRSK2 and C9orf91 genes with free binding energy - 91 kJ/mole and ΔG/ΔGm 89%. miR-3960 binds in GCC repeats to mRNA of ABCC1 and BLMH genes with free binding energy - 116 kJ/mole. miR-211-3p and miR-3155b interact with mRNA of ACACA and ANKRD13D genes in 5’-3’untranslated regions. Studying binding characteristics of miRNA and genes will help identify association of miRNAs with genes with trinucleotide repeats for recommending for the diagnosis of nucleotide repeat expansion disorders.

Background Breast cancer (BC) is the most common cancer among women worldwide. At present, there is a need to search for new, accurate, reliable, minimally invasive and cheap biomarkers in addition to existing methods for the diagnosis and prognosis of BC. The main goal of this study was to test the diagnostic value of six circulating miRNAs in Kazakh women. Materials and methods TaqMan-based miRNA profiling was conducted using plasma specimens from 35 BC women patients and 33 healthy women samples (control group). Results The level of all seven miRNAs (including endogenous control) normalized by synthetic cel-miR-39 were significantly elevated in the group of BC patients. Normalization using miR-222-3p as endogenous control reduced differences in level of miRNAs between groups; as a result, only three miRNAs were significantly upregulated in the group of BC patients—miR-145-5p (P = 6.5e−12), miR-191-5p (P = 3.7e−10) and miR-21-5p (P = 0.0034). Moreover, ROC analysis showed that the use of miR-145-5p and miR-191-5p, both individually (AUC = 0.931 and 0.904, respectively) or in combination (AUC = 0.984), allows to accurately differentiate BC patients from healthy individuals. Conclusions Two plasma miRNAs—miR-145-5p and miR-191-5p—are potential biomarkers for diagnosis of BC in the Kazakh population. The findings need to be further substantiated using a more representative sample.