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Background. Breast cancer (BC) is the most common type of malignant neoplasm among women, with a high rate of metastasis. Early non-invasive diagnosis is required to increase the effectiveness of anticancer therapy.Objective: to determine the content of circulating tumor cells (CTCs) and their derivatives in the peripheral blood using the MDA-231 aptamer, compare the results obtained with the clinical and molecular characteristics of BC.Materials and methods. The study included 22 patients with BC. Detection of CTCs and circulating tumor microemboli was carried out in 3.5 ml of the blood of BC patients with the help of the MDA-231 aptamer which is affine for breast cancer cells, labeled with the fluorescent Cy3 dye. The count of CTCs in the blood samples was performed using fluorescent and laser scanning microscopy.Results and conclusions. The content of CTCs and circulating tumor microemboli in the peripheral blood of patients with BC of various molecular subtypes was analyzed using the MDA-231 aptamer. The relationship between the number of CTCs and the molecular biological subtype was revealed. The obtained results show the possible prognostic value of CTCs use for monitoring effectiveness of anticancer therapy and control of recurrence of BC.

The aim of this work is the development and demonstration of the method of simultaneous detection of several biomarkers of lung cancer in the blood plasma of patients using a multiplex electrochemical testing system based on DNA aptamers. DNA aptamers are a new class of synthetic affinity probes obtained by in vitro or in vivo selection procedure by the systematic evolution of ligands by exponential enrichment (SELEX).Materials and methods. A set of aptamers obtained previously by selection for postoperative lung cancer tissue was used to create a multiplex electrochemical biochip. Identification of aptamer target proteins was performed using a modified affinity enrichment method (AptaBID). Molecular targets for the used set of aptamers to lung cancer were defined as vimentin, defensin, a light chain of myosin, tubulin alpha 1-B, neutrophil elastase and A1 elongation factor 1.Measurements of the presence of these biomarker proteins in blood plasma were carried out using electrochemical detection. The difference between peak heights before and after plasma deposition on the electrodes modified by aptamers was considered as a response of the system to the presence of protein onco-markers in blood plasma. Blood plasma of healthy volunteers was used as control.Results. Research showed that in the blood plasma of all the patients with lung cancer the content of biomarker proteins that bind to aptamers on electrode surfaces was increased. The increased content of these proteins in the blood plasma of patients suggests the presence of invasiveness and metastasis of tumors and their chemo-resistance.