Integrated bioinformatic and experimental analyses identify Lumican as a key regulator of LIPUS-induced osteogenesis through Integrin β1/FAK/ERK signaling.

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) is an established noninvasive therapy for bone regeneration; however, the extracellular matrix (ECM)-associated mechanisms underlying LIPUS-mediated mechanotransduction remain poorly understood. This study aimed to investigate the role of Lumican, an ECM proteoglycan, in LIPUS-induced osteogenic differentiation and its relationship with Integrin β1 signaling. METHODS: Transcriptomic analysis of the GEO dataset GSE45487 was performed to identify LIPUS-responsive genes and signaling pathways in MC3T3-E1 cells. Cell proliferation, alkaline phosphatase activity, matrix mineralization, quantitative real-time PCR, and Western blot analyses were conducted to evaluate osteogenic differentiation. Lumican and Integrin β1 expression were silenced using siRNA to investigate their functional roles in LIPUS-mediated osteogenesis. RESULTS: LIPUS significantly promoted MC3T3-E1 cell proliferation, osteogenic gene expression, alkaline phosphatase activity, and extracellular matrix mineralization. Bioinformatic analyses identified ECM-related biological processes and ECM-receptor interaction pathways as major transcriptional responses to LIPUS stimulation, with Lumican emerging as a highly connected hub gene. LIPUS markedly increased Lumican expression, whereas Lumican knockdown attenuated osteogenic differentiation and mineralization. Mechanistically, Lumican deficiency suppressed LIPUS-induced Integrin β1 expression and the phosphorylation of FAK and ERK. Furthermore, siRNA-mediated silencing of Integrin β1 recapitulated the inhibitory effects of Lumican knockdown and significantly impaired the expression of osteogenic markers. CONCLUSIONS: Lumican mediates the pro-osteogenic effects of LIPUS through activation of the Integrin β1/FAK/ERK signaling pathway. These findings identify a previously unrecognized ECM-centered mechanotransduction mechanism underlying LIPUS-induced osteogenesis and highlight Lumican as a potential therapeutic target for ultrasound-mediated bone regeneration.