Skipjack tuna bone-derived biocalcium ameliorates osteoblast and osteoclast differentiation through microRNA21 regulation

Alternative calcium sources are needed to enhance osteoporosis management. This study investigated the osteoprotective effects of skipjack tuna bone-derived biocalcium (Bio). Bio enhanced MC3T3-E1 osteoblast and C3H10T1/2 cell differentiation, increasing alkaline phosphatase activity and calcium deposition. Conversely, Bio inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in RAW 264.7 macrophages, reducing tartrate-resistant acid phosphatase (TRAP) activity and bone resorption. Bio suppressed intracellular ROS and downregulated primary, precursor and mature microRNA (miR)-21. miR-21 inhibitor suppressed TRAP activity and Cathepsin K expression, as opposed to miR-21 mimic. In an osteoblast-osteoclast crosstalk environment, Bio synergistically enhanced miR-21 target genes (PTEN and PDCD4) expression, whereas PTEN knockdown suppressed NFATc1 osteoclast marker expression via miR-21 inhibition. Molecular docking confirmed binding affinities between mouse and human miR-21 and both targets. Western blot showed β-catenin upregulation and total NF-κB p65 suppression after Bio treatment. Collectively, Bio exerts dual anti-osteoporotic actions, offering a potential functional supplement for bone remodeling disorders.