Chemokine (C-C motif) ligand 18 is highly expressed in glioma tissues and promotes invasion of glioblastoma cells.

Abstract

The objective of the study is to evaluate levels of chemokine (C-C motif) ligand 18 (CCL18) in human glioma tissues and effects of CCL18 on U251 glioma cells. By using the real-time reverse transcription polymerase chain reaction and immunochemically histological staining, we determined the mRNA and protein levels of CCL18 in tissues of 60 patients with World Health Organization (WHO) Grades II, III and IV glioma and the normal brain. Cultured U251 glioma cells were incubated with CCL18 and then subjected to transwell. The scratch wound-healing and cell count kit (CCK-8) assays were performed to detect the possible effects of CCL18 on the cell invasion, migration, and proliferation. In the tissues of the normal brain (n = 10), glioma Grade II (n = 26), III (n = 18), and IV (n = 16), CCL18 mRNA expression levels were 1.00 ± 0.09, 6.02 ± 1.26, 26.35 ± 3.98, and 112.21 ± 13.25 fold, respectively (P < 0.01); the percentage of CCL18-positive glioma cells was 0%, 58.8%, 70.0%, and 100% in the normal brain, glioma WHO Grade II, III, and IV, respectively (P < 0.01). Different concentrations of CCL18 (0, 5, and 10 ng/ml) enhanced the of U251 glioma cell invasion in 24 h transwell assays [from 43.5 ± 8.3 to 202.0 ± 18.5 and 279.7 ± 18.6 cells (P < 0.01)], increased the cell migration quantified by comparing the areas of the scratch (pixel) [at 12 h, 498.4 ± 75.3, 381.3 ± 21.4, and 347.7 ± 14.2; at 24 h, 299.5 ± 15.3, 284.6 ± 7.8, and 237.3 ± 20.6 (P < 0.05)], and significantly increased the cell growth in CCK-8 assay [from 1.000 ± 0.019-1.260 ± 0.094 and 2.070 ± 0.138 fold in CCL18, respectively (n = 20/each group) (P < 0.01)]. We have found that CCL18 is highly expressed in glioma tissues and enhances the invasion, migration, and proliferation of U251 glioma cells. Therefore, CCL18 may be a potential biomarker for detecting and grading human glioma.