Confocal spectral imaging analysis of intracellular interactions of mitoxantrone at different phases of the cell cycle

It is suggested that the cytotoxicity of anticancer agent mitoxantrone (MIT OX) is related to a complex combination of molecular interactions which lea d to slowing of S phase traverse and arresting of cells in G(2) phase of th e cell cycle ol el en to an apoptosis at high concentration of MITOX. Here intracellular molecular interactions of MITOX were visualised and studied r ising the confocal spectral imaging technique in synchronised K562 cells. L ocalisation, quantitative distributions of MITOX in the polar environment, MITOX bound to hydrophobic cellular structures (MITOXphob), nucleic acid-re lated complexes of MITOX (MITOXNA) and relative distributions of naphthoqui noxaline (NQX) metabolite and intrinsic cellular fluorescence of porphyrins were measured within cytoplasmic and nuclear compartments (chromosomes) of the G(2), S, and M cells treated with 10 or 2 mu M of MITOX for 1 hour. Co -localisation of MITOX, NQX metabolite and sites of intrinsic cellular fluo rescence indicates an accumulation of MITOX within or near mitochondria. On e may suppose that due to high concentration MITOX can compete with natural substrates for binding to the enzymes thus affecting the normal functionin g of a mitochondria. A remarkable redistribution of MITOX and its complexes occurs in the M cells. In particular, a prominent amount of MITOX is assoc iated with the surface of chromatids but not with the cytoplasmic structure s in M cells. At the present time the exact location of the sites of MITOX accumulation in the M cells is nor known. It is thought to be some cytoskel eton/ microtubule structures associated directly with the chromosomes. Sele ctive labelling of particular cytoskeleton structures and/or proteins in MI TOX treated cells is in the progress now and the question will be addressed rising the CSI technique.