Zinc Induces Mixed Types of Cell Death, Necrosis, and Apoptosis, in Molt-4 Cells

• Published in: Journal of biochemistry (Tokyo) Vol. 128; no. 6; pp. 933 - 939
• Main Authors: Hamatake, Michiko, Iguchi, Kazuhiro, Hirano, Kazuyuki, Ishida, Ryoji
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-12-2000
• Subjects: annexin; Apoptosis - drug effects; caspase; caspase inhibitor; Caspases - metabolism; Cell Death - drug effects; Cell Division - drug effects; Enzyme Activation; Flow Cytometry; Humans; Necrosis; phosphatidylserine externalization; Tumor Cells, Cultured; zinc; Zinc - pharmacology
• ISSN: 0021-924X
• DOI: 10.1093/oxfordjournals.jbchem.a022844

To investigate the mode of zinc-induced cell death, the associated morphological changes, and biological events were examined in zinc-treated Molt-4 cells. Fluorescence microscope observations with double staining of zinc-treated cells with Hoechst 33342 and propidium iodide (PI) indicated that the metal induced both necrosis and apoptosis. To confirm this, cells were stained with both PI and FITC-labeled annexin V, which binds phosphatidylserine, and then analyzed by flow cytometry. The results also confirmed that zinc induces mixed types of cell death, necrosis and apoptosis, and that the former induction occurs earlier and at a greater frequency. Hallmarks of apoptosis such as abnormal chromosome condensation and release of cytochrome c, as well as the appearance of annexin-positive cells, appeared along with the expression of mitochondrial membrane protein 7A6. However, zinc did not induce increases in caspase-3 like protease and caspase-8 activities, and caused slightly hypodiploid cells. Furthermore, the induction of cell death and annexin-positive cells was not blocked by the caspase inhibitors Ac-YVAD-CHO and Ac-DEVD-CHO. These results indicate that zinc induces both necrosis and apoptosis, without caspase-3 activation.