The TGF-β1/COX-2-dependant pathway serves a key role in the generation of OKC-induced M2-polarized macrophage-like cells and angiogenesis.

An odontogenic keratocyst (OKC) is a common oral cyst arising from the odontogenic epithelium, which has the characteristics of a tumor. Previous studies have demonstrated that M2-polarized macrophages and angiogenesis have important roles in the progression of OKCs. As transforming growth factor (TGF)-β1 is important in growth and developmental processes, and early studies have indicated that TGF-β1 is upregulated in OKCs, the present study aimed to investigate the expression levels of TGF-β1 as a first step. Flow cytometric analysis suggested that TGF-β1 induced M2-polarization of macrophages in a dose-dependent manner. Expression levels of cyclooxygenase (COX)-1 and -2 were measured after treatment of M2 macrophages with TGF-β1 and OKC homogenate supernatant. COX-2 expression was influenced by TGF-β1 in a concentration-dependent manner and in OKC induction. In addition, inhibition of COX-2 resulted in the induction of M2-polarization of macrophages via TGF-β1 and OKC disruption. Because the extracellular matrix (ECM) is altered in individuals with chronic diseases, the present study analyzed the expression of matrix metalloproteinase (MMP)-9, which is able to degrade the ECM. The present study observed a decrease in MMP-9 activity following treatment with TGF-β1 and OKC homogenate supernatant. Additionally, the present study analyzed tube formation caused by OKC with or without a COX-2 inhibitor. The results of the present study suggested that angiogenesis increased following treatment with OKC homogenate supernatant but decreased after treatment with a COX-2 inhibitor. These findings indicated that the TGF-β1/COX-2 pathway may have an important role in the progression of OKC.