Abstract: PURPOSE: To investigate the effects of radiation on cell proliferation and expression of TGF-β₁ and Smad3/P-Smad3 in MC3T3-E1 cells. METHODS: The mouse embryos ossification cell line MC3T3-E1 was used, which was given a single dose of 8 Gy by 4MV linear accelerator. Cell proliferation after irradiation was detected by CCK-8, real-time PCR and Western blot, respectively. Gene and protein expression of TGF-β₁, Smad3 was detected by 2^-ΔΔct and densitometric analysis were used to analyze the expression level of genes and proteins, respectively. SPSS 13.0 software package was used for statistical analysis. RESULTS: After irradiation of 8 Gy, cell growth slowed significantly compared with the control group; the gene expression of Smad3 and TGF-β₁ had no significant change after irradiation for 0.5 h and 1 h (P>0.05), until 1.5 h (P<0.05); the protein expression of P-Smad3 and TGF-β₁ raised obviously on the first day. The difference between exposure group and control group gradually decreased on day 3 and 5. The protein expression of TGF-β₁ and P-Smad3 reached peak on the first and third day, respectively. CONCLUSIONS: 8 Gy dose irradiation inhibits cell proliferation and increases the expression of TGF-β₁ and Smad3/P-Smad3 on gene and protein level.

Key words: Radiation, MC3T3-E1, TGF-β1, Smad3, P-Smad3