Antonina Khoruzhenko
National Academy of Sciences of Ukraine, Ukraine
Title: mTOR association with nucleoli and intermediate filaments in human breast cancer cells
Biography
Biography: Antonina Khoruzhenko
Abstract
Kinase mTOR is one of the main links in signal transduction from the variety of growth factors and hormones into the cell. mTOR participates in the regulation of protein synthesis, cell growth, survival, proliferation and migration. Significant overactivation/overexpression of mTOR in numerous malignant neoplasms was demonstrated earlier. Its inhibitors are used as anti-cancer drug. Information about mTOR subcellular localization could clarify its role in tumor growth. So, mTOR subcellular localization was detected in breast cancer and normal tissues, and MCF-7 cells (originated from breast cancer) in monolayer and 3D cultures. For this the antibodies generated to C-, N-terminus and central sites of mTOR were used. Detection of mTOR subcellular distribution with antibodies to mTOR C-terminus in all cases revealed its diffuse cytoplasmic localization. Application of the antibodies to the central region of the kinase revealed its nucleolar (additionally to cytoplasmic) localization in breast cancer cells. Determination of mTOR localization with anti N-terminal antibodies uncovered a stained network inside the cells. Confocal microscopy, co-immunoprecipitation and PLA showed strong co-localization of mTOR and intermediate filaments (cytokeratins) in breast cancer and normal cells. Decrease of mTOR activity by rapamycin, as well as cytokeratin disassembly by sodium orthovanadate, did not disturb mTOR/cytoceratin association. Also in breast cancer cells the relocalization of rpS6K (mTOR target) was revealed. Besides, there was observed the effect of mTOR activation/inhibition on cell motility. So, for the first time the nucleolar localization of mTOR was demonstrated. Moreover, it was revealed the co-localization of mTOR kinase and intermediate filaments.