І. Brodetskyi

Bogomolets National Medical University, Kyiv

Introduction. The most common tumor remains pleomorphic adenoma – 60.0-90.0 % of all benign tumors of the salivary glands. The modern genetic area of focus in the diagnosis of salivary gland tumors is the study of the role of miRNA molecules. MiRNAs are small non-coding RNAs that regulate the cell cycle, apoptosis, metabolism, cell development and differentiation. Of the greatest interest among them is proapoptotic miRNA-34a. It is expressed in 96.0 % of the pleomorphic adenomas of the salivary glands. There are no articles that would describe the clinical-genetic and inter-genetic correlations with miRNA-34a in other biopsy specimens, except for the tumor, – the salivary gland tissue adjacent to the tumor, the intact gland (control group), and blood.

The aim of the study. Clinical-genetic and inter-genetic (with expression of miRNA-34а) correlation analysis in tissue of pleomorphic adenomas of the large salivary glands that adjacent to the tumor of the tissue of the salivary gland, intact tissue of the salivary gland, was out of touch with the tumor and venous blood.

Materials and methods. 22 patients with benign tumors of the large salivary glands (pleomorphic adenomas) were used examination materials. The expression of miRNA-34a was evaluated using reverse transcription and quantitative polymerase chain reaction (qPCR) in real time. Total RNA was isolated from benign tumors (pleomorphic adenomas) of the large salivary glands (tumor tissue adjacent to the tumor salivary gland, intact salivary gland tissue that was not contiguous  to the tumor) and venous blood by the method of  phenol-chloroform  extraction. Then we measured the concentration and purity of the RNA with a ND1000 spectrophotometer (NanoDrop Technologies Inc, USA). The results were analyzed with the help of the statistical environment R (version 3.5). A. N. Kolmohorov – N. V. Smirnov, H. Leven, B. L. Welch’s, B. M. Brown – A. B. Forsythe, S. E. Bonferroni tests and E. S. Pearson correlation criteria were used for further statistical analysis.

Results. Conducted correlation analysis of clinical (age, size of the tumor, duration of the disease, distance from the surface of the skin to the tumor) and genetic indices for the level of expression miRNA-34a in different biological tissues (tumor, tissue adjacent to the tumor salivary gland tissue, intact salivary gland that was out of touch with the tumor and venous blood) in patients with pleomorphic adenoma of the large salivary glands revealed absence of statistically significantly association. The absence of a statistically significant relationship between clinical and genetic parameters (by expression of 34a-miRNA) in patients with pleomorphic adenomas of the large salivary glands indicates that neither age nor duration of the disease nor tumor size nor distance from the surface of the skin affect the miRNA molecules in various fragments of biological tissues (tumor tissue adjacent to the tumor salivary gland, intact salivary gland tissue that was not contiguous to the tumor, and venous blood). Therefore, it can be stated beforehand that the expression of miRNA-34a is genetically deterministic and the enhancement of its expression is a display of the protective mechanisms of the human body in response to the emergence of the tumor process. 

Conclusions. The conducted clinical-genetic correlation analysis by the parameter of miR-34a expression of different fragments of biological tissues in patients with pleomorphic adenomas of the large salivary glands revealed the absence of statistically significant associations. The conducted intergenetic correlation analysis of patients with pleomorphic adenomas of the large salivary glands with different fragments of biopsy material revealed that the miR-34a expression statistically significantly differs between the groups (adjacent gland – intact salivary gland tissue).

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