Anti-BrdUrd labeling of newly synthesized DNA in HL-60 cells triggered to apoptosis

Cytometry
L ZamaiM Vitale

Abstract

Apoptosis is an active process that takes place during pre- and postnatal life. It can be viewed as the essential counterpart to cell proliferation, both phenomena being aimed at the maintenance of tissue and organ homeostasis. Because apoptosis often takes place during the S phase of the cell cycle, we describe the spatial and temporal correlation between DNA synthesis and DNA cleavage taking place in the same nucleus at the same time as a result of the action of camptothecin on proliferating HL-60 cells in vitro. The relationship between DNA synthesis and DNA fragmentation was studied at the single-cell level by bromodeoxyuridine (BrdUrd) incorporation revealed by flow cytometry, electron microscopy, and confocal microscopy. Most HL-60 cells are triggered to apoptosis during the first hour of treatment with camptothecin, and only cells in early-middle S phase are sensitive to the drug effect, whereas late S phase cells appear insensitive to camptothecin-induced apoptosis. Our data, therefore, reinforce the hypothesis of a DNA strand break threshold that may exist in the cell, beyond which the apoptotic program is activated. Moreover, DNA synthesis activity in the nucleus committed to apoptosis is gradually downregulated; afte...Continue Reading

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Apoptosis

Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis