MicroRNAs (miRNAs) are small (22 nt), single-stranded, non-coding RNAs known as regulators of gene expression at the mRNA level. Their impact on the final translation product is significant, therefore it is suitable to study them as biomarkers of various diseases namely diabetes, cardiovascular, neurodegenerative, viral diseases and cancer . Our attention was aimed at the research of miR-34a-5p related to head and neck cancer (HNC) and also prostate cancer (PCa) where we obtained significant differences in miR-34a-5p expression status between health controls and patients with PCa. This miRNA, belonging to the miR-34 family is directly linked to p53 and Wnt pathways . The tight connection between loss of tumor suppressor function and activation of oncogenic signaling has been proven for this miRNA. Beside the classical molecular–biological methods studying miRNAs, such as PCR, Northern Blotting (NB), microarrays technologies, new biophysical approaches were applied . The results from the PCR analysis were complemented with UV absorption spectra, CD spectra and linear sweep voltammetry in connection with adsorptive transfer stripping (AdTS) technique . Both data of miR-34a-5p were completed by results of DNA(U), having the same oligonucleotide sequence as miR-34a-5p. The comparison of miRNA with DNA bearing uracil instead of thymine (DNA(U)) showed significant differences in structure-function relation. The stabilities of RNA and DNA structures were studied using CD and UV-absorption spectroscopy and expressed as melting points (32 oC for RNA and 46.5 oC for DNA(U)). The effect of substitution of ribose for deoxyribose was shown and structural diversity was confirmed also by electrochemical methods.
This research was supported by the Project CZ.1.05/1.1.00/02.0068 (Central European Institute of Technology -CEITEC), SIX CZ.1.05/2.1.00/03.0072 and by the projects KONTAKT II (LH13053) of the Ministry of Education of the Czech Republic and P205/12/0466 from the Grant Agency of the Czech Republic.