Melatonin's Pro-Apoptotic Efficacy in Mitigating Postmenopausal Osteoporosis: A Mechanistic Investigation via the BMAL1/ROS/MAPK-p38 Signaling Axis in RAW264.7 Cells
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Department of Molecular Pharmacology, Institute of Biomedical Research, Geneva, Switzerland
Abstract
Background: Postmenopausal osteoporosis (PMOP) is a debilitating condition characterized by increased osteoclast activity leading to bone density loss. While melatonin has shown promise in modulating bone metabolism, its precise pro-apoptotic mechanisms in osteoclasts remain unclear. This study was designed to investigate the signaling pathways through which melatonin induces apoptosis in osteoclast-like cells, specifically focusing on the involvement of the BMAL1/ROS/MAPK-p38 axis.
Methods: RAW264.7 cells were treated with various concentrations of melatonin. Cell viability was assessed using CCK-8 assays, and apoptosis was quantified by Annexin V-FITC/PI staining and caspase-3/7 activity assays. We used qRT-PCR and Western blotting to evaluate the expression of BMAL1, pro- and anti-apoptotic proteins, and the phosphorylation status of p38. The roles of BMAL1, reactive oxygen species (ROS), and p38 were confirmed using specific inhibitors and a ROS scavenger.
Results: Melatonin treatment significantly inhibited RAW264.7 cell proliferation and induced apoptosis in a dose-dependent manner. This was accompanied by an upregulation of the pro-apoptotic protein Bax, a decrease in the anti-apoptotic protein Bcl-2, and increased cleavage of caspase-3. We demonstrated that melatonin robustly increased the expression of the core clock gene BMAL1, and that BMAL1 inhibition abrogated the apoptotic effect. Furthermore, melatonin treatment led to a significant increase in intracellular ROS, and a ROS scavenger successfully prevented both the apoptotic response and the subsequent phosphorylation of p38. Finally, a specific p38 inhibitor reversed melatonin-induced apoptosis, confirming its critical role as a downstream effector.
Conclusion: Our findings establish a novel mechanistic pathway in which melatonin induces apoptosis in osteoclast-like cells. Melatonin's pro-apoptotic effect is mediated by the upregulation of BMAL1, which subsequently promotes ROS generation. This increase in ROS acts as a signaling molecule to activate the MAPK-p38 pathway, ultimately leading to apoptosis. This study provides a strong rationale for further investigating melatonin as a potential therapeutic agent for PMOP by targeting this specific signaling axis.
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📄Dou C, Ding N, Xing J, et al. Dihydroartemisinin attenuates lipopolysaccharideinduced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway. Cell Death Dis. 2016;7(3):e2162.
📄Roodman GD. Cell biology of the osteoclast. Bone. 1999;24(1):21s–27s.
📄Teitelbaum SL, Ross FP. Genetic regulation of osteoclast development and function. Science. 2003;299(5603):54–58.
📄Dou C, Ding N, Xing J, et al. Dihydroartemisinin attenuates lipopolysaccharideinduced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway. Cell Death Dis. 2016;7(3):e2162.
📄Dou C, Ding N, Xing J, et al. Dihydroartemisinin attenuates lipopolysaccharideinduced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway. Cell Death Dis. 2016;7(3):e2162.
📄Green DR, Evan GI. A matter of life and death. Cancer Cell. 2002;1(1):19–30.
📄Liu YD, Liu JF, Liu B. N,N-Dimethylformamide inhibits high glucose-induced osteoporosis via attenuating MAPK and NF-κB signalling. Bone Joint Res. 2022;11(4):200–209.
📄Hao Y, Huang Y, Chen J, et al. Exopolysaccharide from Cryptococcus heimaeyensis S20 induces autophagic cell death in non-small cell lung cancer cells via ROS/p38 and ROS/ERK signalling. Cell Prolif. 2020;53(8):e12869.
📄Dou C, Ding N, Xing J, et al. Dihydroartemisinin attenuates lipopolysaccharideinduced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway. Cell Death Dis. 2016;7(3):e2162.
How to Cite
Dr. Liana V. Petrov. (2025). Melatonin’s Pro-Apoptotic Efficacy in Mitigating Postmenopausal Osteoporosis: A Mechanistic Investigation via the BMAL1/ROS/MAPK-p38 Signaling Axis in RAW264.7 Cells. Global Journal of Medical and Pharmaceutical Sciences, 4(11), 1-15. https://www.grpublishing.org/journals/index.php/gjmps/article/view/195
