BACKGROUNDIn a previous study, we have verified that CXCR4 expression is correlated with tumor aggressive progression and poor prognosis in patients with epithelial ovarian cancer. The aim of this study was to explore the effect of CXCL12-CXCR4 axis on the metastasis of human ovarian cancer.

METHODSThe expressions of CXCR4 and CXCL12 mRNA and protein in human ovarian cancer cell line CAOV-3 was detected by RT-PCR and immunocytochemistry. Methythiazolyltetrazolium (MTT) was used to analyze the effect of different concentrations of CXCL12 on the proliferation of CAOV-3 cells. Transwell invasion chamber and matrigel were used to evaluate the effect of various concentrations of CXCL12 and ascites on the migration and invasion of CAOV-3 cells. The expressions of integrin beta(1) and vascular endothelial growth factor-C (VEGF-C) mRNA were detected by RT-PCR. Data were analyzed using ANOVA by SAS 6.12.

RESULTSUnder serum-free suboptimal culture conditions, CXCL12 (100 ng/ml) significantly enhanced the proliferation of CAOV-3 cells compared with the control and 10 ng/ml CXCL12 groups (0.428 +/- 0.051 vs. 0.325 +/- 0.045 and 0.328 +/- 0.039, P < 0.05). This enhancing effect of CXCL12 was significantly inhibited by 10 microg/ml neutralizing CXCR4 antibody or 1 microg/ml CXCR4 antagonist AMD3100. However, 10 microg/ml neutralizing CXCR4 antibody could not inhibit cell proliferation without CXCL12. The levels of migration and invasion of the CAOV-3 cells treated with 100 ng/ml CXCL12 were significantly higher than those in the control (migration: 523.3 +/- 25.2 vs 108.0 +/- 7.2; invasion: 39.3 +/- 4.0 vs. 4.0 +/- 1.0). The enhancing effect of CXCL12 on cell migration and invasion increased with the concentration of CXCL12 (100 ng/ml vs10 ng/ml: migration, 523.3 +/- 25.2 vs 211.7 +/- 24.7; invasion, 39.3 +/- 4.0 vs 15.7 +/- 3.1, P < 0.05), and was strongly inhibited by 10 microg/ml neutralizing CXCR4 antibody or 1 microg/ml AMD3100. The number of migrated and invading cells in the CAOV-3 added with ascites was significantly higher than those in the 100 ng/ml CXCL12 group (migration: 706.6 +/- 30.6 vs 523.3 +/- 25.2, invasion: 61.7 +/- 7.6 vs 39.3 +/- 4.0, P < 0.05). The level of integrin beta(1) mRNA was greatly increased at 3 hours after being treated with CXCL12 (0.53 +/- 0.10 vs. 1.53 +/- 0.16, P < 0.05), and VEGF-C mRNA displayed significant augment at 24 hours after being treated with CXCL12 (0.52 +/- 0.09 vs 1.11 +/- 0.15, P < 0.05).

CONCLUSIONSCXCL12 and its receptor CXCR4 can promote the proliferation, migration, invasion of ovarian cancer cell line CAOV-3 and enhance its secretion of integrin beta(1) and VEGF-C. These effects can be inhibited by neutralizing CXCR4 antibody or AMD3100. CXCL12-CXCR4 axis plays an important role in ovarian cancer growth and metastasis.