Caren Yu-Ju Wu: Graduate Institute of Biomedical Sciences, Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Taoyuan, Taiwan.
Chia-Hua Chen: Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Chun-Yen Lin: Department of Gastroenterology and Hepatology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Li-Ying Feng: Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Yung-Chang Lin: Department of Gastroenterology and Hepatology, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Kuo-Chen Wei: Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Chiung-Yin Huang: Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Jia-You Fang: Graduate Institute of Biomedical Sciences, Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Taoyuan, Taiwan.
Pin-Yuan Chen: Department of Neurosurgery, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan.
BACKGROUND: Glioma-associated microglia/macrophages (GAMs) comprise macrophages of peripheral origin and brain-intrinsic microglia, which support tumor progression. Chemokine C-C ligand 5 (CCL5) is an inflammatory mediator produced by immune cells and is involved in tumor growth and migration in several cancers, including glioma. However, the mechanisms detailing how CCL5 facilitates glioma invasion remain largely unresolved. METHODS: Glioma migration and invasion were determined by wound healing, transwell assay, and 3D µ-slide chemotaxis assay. The expression levels of CCL5, CD68, matrix metalloproteinase 2 (MMP2), phosphorylated Ca2+/calmodulin-dependent protein kinase II (p-CaMKII), p-Akt, and phosphorylated proline-rich tyrosine kinase 2 were determined by cytokine array, quantitative PCR, western blot, or immunohistochemistry. Zymography and intracellular calcium assays were used to analyze MMP2 activity and intracellular calcium levels, respectively. RESULTS: CCL5 modulated the migratory and invasive activities of human glioma cells in association with MMP2 expression. In response to CCL5, glioma cells underwent a synchronized increase in intracellular calcium levels and p-CaMKII and p-Akt expression levels. CCL5-directed glioma invasion and increases in MMP2 were suppressed after inhibition of p-CaMKII. Glioma cells tended to migrate toward GAM-conditioned media activated by granulocyte-macrophage colony-stimulating factor (GM-CSF) in which CCL5 was abundant. This homing effect was associated with MMP2 upregulation, and could be ameliorated either by controlling intracellular and extracellular calcium levels or by CCL5 antagonism. Clinical results also revealed the associations between CCL5 and GAM activation. CONCLUSION: Our results suggest that modulation of glioma CaMKII may restrict the effect of CCL5 on glioma invasion and could be a potential therapeutic target for alleviating glioma growth.
