Multifocal osteonecrosis secondary to occupational exposure to aluminum

Melatonin Attenuates AlCl3-Induced Apoptosis and Osteoblastic Differentiation Suppression by Inhibiting Oxidative Stress in MC3T3-E1 Cells

Aluminum (Al) inhibits osteoblast-mediated bone formation by oxidative stress, resulting in Al-induced bone disease. Melatonin (MT) has received extensive attention due to its antioxidant and maintenance of bone health effect. To evaluate the protective effect and mechanism of MT on AlCl₃-induced osteoblast dysfunction, MC3T3-E1 cells were treated with MT (100 μM) and/or AlCl₃ (8 μM). First, MT alleviated AlCl₃-induced osteoblast dysfunction, presenting as the reduced apoptosis rate as well as increased cell viability, alkaline phosphatase (ALP) activity, and type I collagen (COL-1) level. Then, MT significantly attenuated AlCl₃-induced oxidative stress, presenting as the reduced reactive oxygen species and 8-hydroxy-2'-deoxyguanosine levels as well as increased glutathione level and superoxide dismutase activity. Finally, MT protected MC3T3-E1 cells against p53-dependent apoptosis and differentiation suppression, as assessed by Caspase-3 activity, protein levels of p53, Bcl-2-associated X protein (Bax), B cell lymphoma gene 2 (Bcl-2), cytosolic Cytochrome c, Runt-related transcription factor 2 (Runx2), and Osterix, as well as the mRNA levels of Bax, Bcl-2, Runx2, Osterix, ALP, and COL-1. Overall, our findings demonstrate MT attenuates AlCl₃-induced apoptosis and osteoblastic differentiation suppression by inhibiting oxidative stress in MC3T3-E1 cells.