Glial cell line-derived neurotrophic factor promotes proliferation of neuroglioma cells by up-regulation of cyclins PCNA and Ki-67.

OBJECTIVE: We wished to test whether glial cell line-derived neurotrophic factor (GDNF) stimulates proliferation of gliomas by up-regulating expression of nuclear cyclins PCNA and Ki37. MATERIALS AND METHODS: As a model, we tested rat C6 glioma cell line exposed to basal conditions, vehicle control, or exogenous GDNF at different concentrations (0-90 µg/L) or different times (0-72 hours). Cell proliferation was quantified by MTT test, cell cycle by flow cytometry and propidium iodide staining, expression of PCNA and Ki67 by intracellular antibody staining and flow cytometry. RESULTS: We first observed that cell proliferation was most stimulated by GDNF at concentration of 70 µg/L and incubation time of 48 hours. Using this concentration and incubation time, we next documented that GDNF increased the percentage of cells in the S phase (47.98% vs. 32.57% in basal cells; p < 0.05), while not affecting the percentage of cells in G0/G1 or G2/M phases. Finally, we demonstrated that expression of both PCNA and Ki67 was significantly increased in cells exposed to GDNF. CONCLUSIONS: We demonstrate that GDNF stimulates proliferation of glioma cells by up-regulating expression of cyclins PCNA and Ki-67.