PB1918 THE EXPRESSION OF LEVEL MIR203A GENE IN PATIENTS WITH CHRONIC MYELOID LEUKEMIA IN DIFFERENT PHASES OF DISEASE
Authors: A. Lyamkina, M. Perepechaeva, A. Grishanova, O. Berezina, I. Kovynev, T. Pospelova
Journal: HemaSphere (2019)

Background: MicroRNAs (miRNAs) play an important role in the regulation of migration, survival, proliferation, and sensitivity to chemotherapy of tumor cells. The use of miRNAs in the future can predict tumor development. Its outcomes are promising, but their prognostic value still needs to be studied. It has been shown that miR203 expression in solid tumor cell lines inhibits cell proliferation and migration, increases sensitivity to apoptosis, and inhibits oncogenesis in vivo. It has been shown in the literature that low expression of miR203 is in patients with solid tumors (glioblastomas, tumors of the stomach, breast, and others). Aims: To study the expression of the miR203a gene in clinical material in patients with chronic myeloid leukemia (CML) with different results of antitumor therapy: with major molecular response (MMR), complete cytogenetic response (CCR) and in progressive phases of the disease (chronic phase (CP) and acceleration phase (AP) CML in primary patients and patients resistant to specific therapy). Methods: It was studied bone marrow, peripheral blood and extracellular microvesicles in 56 patients with CML from the City Hematology Center of Novosibirsk. All patients received therapy with tyrosine kinase inhibitors (imatinib, nilotinib, dasatinib) at the recommended therapeutic doses. The patients were divided into 3 groups: group I ‐ 28 people in CP, MMR (MO ≥3 , BCR/ABL &lt;0.1%), group II ‐ 15 people in CP, CCR (Ph + 0%, MO &lt;3.0 , BCR/ABL &gt;0.1%); group III ‐ 10 people ‐ primary patients and resistant to therapy in CP without CCR and AP. Total RNA, including miRNA, was obtained using TRIzol reagent (Ambion, USA) according to the manufacturer's instructions. RNA was translated into complementary DNA using miRNA‐specific primers of the hairpin structure and M‐MuLV – RH reverse transcriptase (Biolabmix, Russia). The expression level of miR203a was assessed using real‐time PCR using the TaqMan principle on iCycler CFX96 equipment. Small nuclear RNA U6 was used as an internal standard. All reactions were carried out in a triplet. For data analysis, the 2‐ΔCt method was used. Statistical data processing was performed using the STATISTICA program (StatSoft, Inc., USA). Results: The expression level of the mir203a gene was significantly higher (ρ &lt; 0.05) in group I microvesicles than in group III. When evaluating the results in group II, significant differences were obtained between all studied substrates of group II and group III, except for myelocytes from bone morrow of group II and plasma of group III. There were no significant differences between the groups that reached the MMR (group I) and those who reached the CCR (group II), which indicates the significant role of achieving a complete cytogenetic response. Also, a significant inverse correlation has obtained between the level of expression of the mir203a gene in bone morrow myelocytes, lymphocytes and plasma (ρ &lt; 0.05) and the severity of the CML phase. The experiments were performed using equipment of the Institute of Molecular Biology and Biophysics (IMBB), center of «Proteomic analysis» (Novosibirsk, Russia). Summary/Conclusion: The results demonstrate that the expression decreases depending on the progression of the severity of hemoblastosis, which can lead to a decrease in tumor cell apoptosis, an increase in migration and resistance to antitumor therapy.