International Journal of Nanomedicine (Apr 2017)
Role of Hedgehog–Gli1 signaling in the enhanced proliferation and differentiation of MG63 cells enabled by hierarchical micro-/nanotextured topography
Abstract
Yao Lin,1 Yinghe Huang,1 Junbing He,2 Feng Chen,2 Yanfang He,2 Wenying Zhang2 1Department of Stomatology, Taishan People’s Hospital, Affiliated to Guangdong Medical University, Taishan, 2Guangdong Key Laboratory of Age-Related Cardiac and Cerebral Diseases, Institute of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, People’s Republic of China Abstract: Hedgehog–Gli1 signaling is evolutionarily conserved and plays an essential role in osteoblast proliferation and differentiation as well as bone formation. To evaluate the role of the Hedgehog–Gli1 pathway in the response of osteoblasts to hierarchical biomaterial topographies, human MG63 osteoblasts were seeded onto smooth, microstructured, and micro-/nanotextured topography (MNT) titanium to assess osteoblast proliferation and differentiation in terms of proliferative activity, alkaline phosphatase (ALP) production, and osteogenesis-related gene expression. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression of Sonic hedgehog (Shh), Smoothened (Smo), and Gli1, and the protein levels were assayed by Western blotting. MG63 cells treated with the Smo inhibitor cyclopamine were seeded onto the titanium specimens, and the cell proliferation and differentiation were studied in the presence or absence of cyclopamine. Our results showed that compared to the smooth and microstructured surfaces, the MNTs induced a higher gene expression and protein production of Shh, Smo, and Gli1 as well as the activation of Hedgehog signaling. The enhanced proliferative activity, ALP production, and expression of the osteogenesis-related genes (bone morphogenetic protein-2, ALP, and runt-related transcription factor 2) enabled by the MNTs were significantly downregulated by the presence of cyclopamine to a similar level as those on the smooth and acid-etched microstructured surfaces in the absence of cyclopamine. This evidence explicitly demonstrates pivotal roles of Hedgehog–Gli1 signaling pathway in mediating the enhanced effect of MNTs on MG63 proliferation and differentiation, which greatly advances our understanding of the mechanism involved in the biological responsiveness of biomaterial topographies. These findings may aid in the optimization of hierarchical biomaterial topographies targeting Hedgehog–Gli1 signaling. Keywords: Hedgehog–Gli1, MG63, proliferation, differentiation, micro-/nanotextured topography
