THE COMBINATION OF LASER IRRADIATION AND DOXORUBICIN AS A FACTOR OF TUMOR CELL APOPTOSIS INDUCTION

Konovalenko S.V., Zadvornyy T.V.

• RE Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine

As an additional antitumor factor, laser radiation can be highly effective in the treatment of patients with malignant neoplasms, and can also be harmoniously combined with other known methods of therapy to enhance their effectiveness. Therefore, the study of various scenarios of laser irradiation and chemotherapeutic drugs combination is currently a relevant and promising area of experimental oncology. Aim: to assess in vitro the effectiveness of the combined action of low-energy laser radiation and doxorubicin (DOX) on the expression of molecular markers of apoptosis and proliferative activity in human breast cancer cells. Objects and methods: the study was conducted on two cultures of human breast cancer cells with different sensitivity to cytostatics: MCF-7 — sensitive and MCF-7DOX — resistant to DOX. Depending on the combinatorics of the active factors, taking into account the characteristics of irradiation, the doses of DOX used and the schemes of their use, the manufactured cytological preparations of tumor cells are divided into 18 groups: control, photobiomodulation (PBM) 660 nm, PBM 810 nm, DOX 2.0 μg/ml, DOX 0.5 μg/ml, PBM 660 nm + DOX 2.0 µg/ml, PBM 660 nm + DOX 0.5 µg/ml, PBM 810 nm + DOX 2.0 µg/ml, PBM 810 nm + DOX 0.5 µg/ml. Expression of molecular markers of apoptosis and proliferative activity was studied by immunocytochemical method using appropriate monoclonal antibodies. Results: in cells of the DOX-sensitive MCF-7 line, under the condition of combined exposure to DOX and lasers, a significant increase in the expression of p53 and Bax markers, as well as a decrease in Ki-67 activity, was observed. The antiproliferative effect was more pronounced using an infrared laser (810 nm) at a DOX concentration of 2.0 μg/ml. It was found also, that the combination of DOX in a relatively low concentration (0.5 μg/ml) and laser irradiation (810 nm) significantly increased the expression of Bax and p53 comparing with control indicators. The proliferation factor Ki-67 after the combined exposure to laser and chemotherapeutic agent showed a decrease in the level of expression, and it was especially noticeable when using a DOX concentration of 2.0 μg/ml, both in combination with the 660 and 810 nm laser. Conclusions: the results of the study allow us to consider the use of DOX in combination with photobiomodulation as a promising method of influencing tumor cells with the aim of initiating apoptosis processes in them.