The kinetics of Fe and Ca for the development of radiation-induced apoptosis by micro-PIXE imaging

To study the interactions between the induction of radiation-induced apoptosis and trace elements kinetics, human leukemia cells were irradiated in vitro by 60Co γ rays, after which the cells were evaluated for the detection of apoptosis and trace element (Fe and Ca) imaging by micro-PIXE camera was carried out.In the early phase of apoptosis, high accumulation of Fe was observed in the cytosol. In the mid to end phase, the Fe accumulation was diminished; instead, Ca accumulated in the nucleus. The releasing of cytochrome-C agreed with the Fe accumulation. The caspase-3 and -8 activity agreed with the nuclear Ca accumulation in nucleus.There appear to be two steps for the development of apoptosis: (1) the signaling from cytosol to nucleus by cytochrome-C represented by Fe and (2) the degeneration of the nucleus by caspase represented by the nuclear Ca accumulation. [Copyright &y& Elsevier]