The significance of polyADP ribosylation in 'magentosis', a new type of cell death: Molecular pathologic approaches to magentosis in a regressing stage of human lactating breast and other hormone-responsive organs

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Magentosis is a new mode of cell death that we found in a regressing stage of human lactating breast, histochemically featured by accumulation of single-stranded DNA in the PAS-positive (magenta-colored) nuclei. To clarify the biologic significance of magentosis, the following experiments were performed. 1) Varied human hormone-responsive organs were microscopically screened for this unique phenomenon. Except for a thyroid papillary carcinoma, magentotic nuclei were not demonstrated. Magentosis in thyroid cancer will be published soon. 2) We tried to identify magentosis in mouse lactating breast. In spite of the trials for compulsory early weaning, the magentotic phenmenon was not observed in the mouse lactating breast, where apoptosis was easily seen instead. 3) In order to correlate PAS positivity with the accumulation of single-stranded DNA in the magentotic nuclei, imunostaining for poly(ADP-ribose) was performed in the human breast. Allegedly, polyADP ribosylation of the nuclear proteins is regarded as an emergency host reaction against DNA damage. The magentotic nuclei were immunoreactive for poly(ADP-ribose), whose vicinal diol elements may explain the PAS reactivity in the magentotic nuclei.