Involvement of hydrogen peroxide in the differentiation and apoptosis of preosteoclastic cells exposed to arsenite

• Published in: Biochemical pharmacology 2006-09, Vol.72 (6), p.761-769
• Main Authors: Szymczyk, K.H., Kerr, B.A.E., Freeman, T.A., Adams, C.S., Steinbeck, M.J.
• Format: Article
• Language: English
• Subjects: Acid Phosphatase - metabolism; Animals; Apoptosis; Apoptosis - physiology; Arsenite; Arsenites - toxicity; Biological and medical sciences; Caspase 3; Caspases - metabolism; Cell Differentiation - physiology; Cell Line; Cell Survival - physiology; Hydrogen peroxide; Hydrogen Peroxide - metabolism; In Situ Nick-End Labeling; Isoenzymes - metabolism; Medical sciences; Mice; Osteoclasts; Osteoclasts - cytology; Osteoclasts - drug effects; Pharmacology. Drug treatments; Sodium Compounds - toxicity; Tartrate-Resistant Acid Phosphatase; Tartrate-resistant acid phosphatase (TRAP)
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2006.06.027

Long-term exposure to sodium arsenite (AsO 2) promotes the development of various cancers. Paradoxically, arsenic also induces pro-myelomonocytic leukemia cell differentiation, and at higher concentrations, apoptosis. The present study investigated the effects of AsO 2 on preosteoclasts. When treated with 2.5–5 μM AsO 2, RAW264.7 cells underwent osteoclast differentiation as evidenced by an increase in the number of multinucleate cells expressing tartrate resistant acid phosphatase (TRAP). The appearance of these phenotypic markers was preceded by a low level increase in extracellular production of H 2O 2 and was prevented by the addition of catalase (4.5 μg/ml), an enzyme that removes H 2O 2. Only at high concentrations (10–25 μM) of AsO 2 was a significant loss of cell viability and a high level increase in H 2O 2 production (1.5 μM) observed. Apoptosis was blocked by pretreatment with diphenylene iodonium chloride (2 μM), a NAD(P)H-flavoprotein inhibitor, suggesting the involvement of NADPH-oxidase. The data show that AsO 2, dose-dependently, stimulates increasing amounts of H 2O 2 production. Moreover, at concentrations found in tissues of individuals exposed to geochemical AsO 2, osteoclasts underwent an H 2O 2-dependent differentiation. Therefore, chronic exposure to low-level amounts of AsO 2 could result in increased bone resorption and contribute to bone related pathologies.