Abstract: Objective: To investigate the effects of endothelin B receptor (ETBR) agonist on the biological behaviors of cementoblast cell line OCCM-30 of the mice, and to provide the experimental basis for odontogenic root restoration.Methods: The cementoblasts of the mice in logarithmic growth phase were selected and divided into experiment group and control group. The cells in experiment group were treated with ETBR agonist at a concentration of 10^-6 mol·L^-1, and the cells in control group did not receive any treatment. MTT method was used to detect the inhibitory rates of proliferation of the cementoblasts in two groups at different time points (24,48, and 72 h). Flow cytometry was used to detect the apoptotic rates of cells in two groups different time points (24, 48, and 72 h);alkaline phosphatase staining and alizarin red staining were performed to detect the cell differentiation and mineralization;real-time PCR was used to determine the expression levels of differentiation-related or mineralization-related genes such as Runx2, BSP, OCN, Col1, and Osterix.Results: MTT assay showed that compared with control group, the inhibitory rates of proliferation of the cells in experimental group were significantly increased after cultured for 24, 48 and 72 h(P<0.05), and the inhibitory rate of proliferation was the highest at 48 h of culture.The flow cytometry results showed that compared with control group, the apoptotic rate of cementoblasts in experimental group did not change significantly.In alkaline phosphatase and alizarin red staining experiments, compared with control group, the cells in experiment group showed lighter color rendering and fewer mineralized nodules.In real-time PCR detection, compared with control group, there were no significant differences in the expression levels of Runx2, Osterix, BSP, OCN and Col1 in the cells in experiment group at 24 h after culture, and the expression levels of Runx2, Osterix, BSP, OCN and Col1 in experiment group were decreased at 48 h after culture;at 72 h after culture, the expression levels of Runx2, Osterix, BSP and Col1 in experiment group were significantly decreased(P<0.01).Conclusion: ETBR agonist can inhibit the proliferation and differentiation of cementoblasts, but it has no effect on apoptosis.

Key words: cementoblast, endothelin B receptor, cell proliferation, apoptosis, cell differentiation