Anticancer drugs induce increased mitochondrial cytochrome c expression that precedes cell death

• Published in: Cancer research (Chicago, Ill.) Vol. 61; no. 3; pp. 1038 - 1044
• Main Authors: Sánchez-Alcázar, J A, Khodjakov, A, Schneider, E
• Format: Journal Article
• Language: English
• Published: United States 01.02.2001
• Subjects: Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Apoptosis - physiology; Breast Neoplasms - enzymology; Breast Neoplasms - pathology; Caspase 3; Caspase 9; Caspases - metabolism; Cell Adhesion - physiology; Cytochrome c Group - biosynthesis; Cytochrome c Group - metabolism; DNA Fragmentation - drug effects; Electron Transport - drug effects; Electron Transport - physiology; Electron Transport Complex IV - biosynthesis; Electron Transport Complex IV - metabolism; Enzyme Activation; Humans; Intracellular Membranes - drug effects; Intracellular Membranes - physiology; Membrane Potentials - drug effects; Microscopy, Fluorescence; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondria - physiology; Poly(ADP-ribose) Polymerases - metabolism; Teniposide - pharmacology; Tumor Cells, Cultured; Up-Regulation - drug effects
• ISSN: 0008-5472

Recent studies have demonstrated that cytochrome c plays an important role in cell death. In the present study, we report that teniposide and various other chemotherapeutic agents induced a dose-dependent increase in the expression of the mitochondrial respiratory chain proteins cytochrome c, subunits I and IV of cytochrome c oxidase, and the free radical scavenging enzyme manganous superoxide dismutase. The teniposide-induced increase of cytochrome c was inhibited by cycloheximide, indicating new protein synthesis. Elevated cytochrome c levels were associated with enhanced cytochrome c oxidase-dependent oxygen uptake using TMPD/ascorbate as the electron donor, suggesting that the newly synthesized proteins were functional. Cytochrome c was released into the cytoplasm only after maximal levels had been reached in the mitochondria, but there was no concomitant decrease in mitochondrial membrane potential or caspase activation. Our results suggest that the increase in mitochondrial protein expression may play a role in the early cellular defense against anticancer drugs.