Inhibitory effect of PPARγ agonist on the proliferation of human pterygium fibroblasts

The effects of DK2, a peroxisome proliferator-activated receptor γ agonist, on cultured human pterygium fibroblasts (HPFs) in virto were studied. The HPFs were incubated with 0–200 μmol/L DK2 for 12–72 h. The MTT method was used to assay the bio-activity of DK2 at different doses and time. The cytotoxic effect of DK2 was measured by LDH release assay. The cell cycle distribution and apoptosis were flow cytometrically detected. The expression of proliferating cell nuclear antigen (PCNA) in each group was detected by real-time PCR (RT-PCR) and Western blotting. The results showed that administration of 1–75 μmol/L DK2 for 12–72 h could significantly inhibit HPF proliferation in a dose- and time-dependent manner. DK2-treated cells did not release significant amount of LDH as compared with rosiglitazone-treated cells. After treatment with DK2 at concentrations of 15, 25 μmol/L for 24 h, the number of HPFs in G0/G1 phase was significantly increased while that in S phase was significantly decreased (P<0.05), leading to arrest at G0/G1 phase. The apoptosis rates of HPF cells in drug-treated groups were significantly higher than the rate of control group (P<0.05). At the dosage range between 15–25 μmol/L, DK2 could inhibit the expression of PCNA mRNA and protein in HPFs in a dose-dependent fashion (P<0.05). It was concluded that PPARγ agonist can significantly inhibit HPF proliferation, resulting in the arrest at G0/G1 phase, induce the apoptosis of HPFs, and suppress the synthesis of PCNA, in dose- and time-dependent manners.