P108

• Published in: European journal of cancer supplements 2015-11, Vol.13 (1), p.37-37
• Main Authors: Moiseeva, N, Ezhova, N, Kazakova, V, Rybalkina, E, Stavrovskaya, A
• Format: Article
• Language: English
• Subjects: Hematology, Oncology and Palliative Medicine
• ISSN: 1359-6349
• DOI: 10.1016/j.ejcsup.2015.08.066

Background multidrug resistance (MDR) remains a major problem in the fight against tumors. MDR – multidimensional phenomenon, which occurs as a consequence of activation of several systems, associated both with the release of xenobiotics from the cell by ABC-transporters, and with stimulation of pathways that enhance cell survival. One of the possible regulators of MDR is multifunctional protein YB-1. YB-1 acting as a transcription factor in cell’s nucleus, can upregulate expression of MDR1, as well as some other ABC-transporters genes. Furthermore, YB-1 is secreted by cells and binds to the protein Notch3, and that stimulates proliferation and migration of cells. Also, resistance of cells may increase upon stimulation of VEGF-VEGER systems. Our aim was to study the mechanisms of MDR at various levels in the pairs of parental and resistant breast cancer cells: changes in the expression and localization of YB-1, evaluation expression of ABC-transporters, activation of protein Notch, as well as changes in the VEGF system. Materials and methods Long-term cultivation of cells MCF-7 (breast adenocarcinoma) and HBL-100 (transformed cells) in the presence of doxorubicin to obtain resistant sublines, MTT assay,real-time PCR, immunocytochemistry, flow cytofluorometry. Results we obtained the sublines of cells MCF-7 and HBL-100 resistant to doxorubicin: MCF-7/D7 and HBL-100/D85, respectively. The level of resistance to doxorubicin in resistant MCF-7/D6 was 7 times higher than in parent MCF-7 (IC50 was 0.7 ± 0.01 mcM vs 0.1 ± 0.002 mcM, respectively), and the level of resistance HBL-100/D85 was 44.7 times higher than the HBL-100 (IC50 8.5 ± 0.17 mcM vs 0.19 ± 0.03 mcM). Also, MCF-7/D7 acquired cross-resistance to cisplatin (6.7 ± 0.1 mcM vs 48 ± 0.2 mcM) and paclitaxel (2 ± 0.03 nM vs 50 ± 1 nM), but not to vinblastine and 5-fluorouracil, and HBL-100/D85 – about 100 times to paclitaxel (13 ± 0.2 nM vs 1100 ± 19 nM) and vinblastine (2.4 ± 0.3 nM vs 250 ± 5 nM), but not to the cisplatin and 5-fluorouracil. The expression profile of ABC-transporter genes showed significant activation of the MDR1 expression in subline HBL-100/D85 (more than 1000 times), but not in MCF-7/D6. Expression of other genes of the family ABC-transporters - MRP1, BCRP, MVP - increased slightly. Expression of mRNA YB-1 was almost unchanged. YB-1 protein detected in cytoplasm of parental lines, but it detected in nuclei in resistant sublines. Also, protein Notch3 translocated from membrane into nuc