Objective    To observe the effects of radiation on the growth and expression of cysteine-rich 61 (Cyr61/CCN1) of L929 cells and investigate the relationship between CCN1 expression and radiation injury.     Methods    L929 cells were cultured and divided into 2 groups

cells irradiated with 4 Gy γ-irradiation as radio-group and untreated cells as control group. The cell proliferation was measured by MTT assay and plate colony formation testing. Flow cytometry was utilized to quantify the cell cycle distribution. CCN1 expression at protein and mRNA level

s were determined by immunocytochemistry (ICC) and RT-PCR respectively.     Results    Significant inhibition of proliferation (

P

<

0.01) and colony formation (

P

<

0.05) were found in cells of radio-group. Meanwhile

cells were arrested at G

2

phase at 24 h after radiation. The expression of CCN1 mRNA was down-regulated at 6 h (

P

<

0.01)

but moderately increased at 24 h (

P

<

0.05). The expression of CCN1 protein was obviously decreased at 24 to 48 h after radiation (

P

<

0.01).     Conclusion    Radiation inhibits the growth and CCN1 expression of cultured fibroblasts

indicating CCN1 may be involved in the suppression of fibroblasts.