ATP stimulates chemokine production via a store-operated calcium entry pathway in C6 glioma cells

• Published in: BMC cancer Vol. 9; no. 1; p. 442
• Main Authors: Jantaratnotai, Nattinee, Choi, Hyun B, McLarnon, James G
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 15.12.2009; BioMed Central; BMC
• Subjects: Adenosine triphosphate; Adenosine Triphosphate - pharmacology; Animals; Calcium - metabolism; Cell Line, Tumor; Cell Movement - genetics; Chemokine CCL2 - genetics; Chemokine CCL2 - metabolism; Chemokines; Chemokines - genetics; Chemokines - metabolism; Development and progression; Enzyme-linked immunosorbent assay; Gene Expression Regulation, Neoplastic - drug effects; Glioma - diagnosis; Glioma - genetics; Glioma - metabolism; Glioma - pathology; Gliomas; Health aspects; Interleukin-8 - genetics; Interleukin-8 - metabolism; Microglia - pathology; Muscle proteins; Neoplasm Invasiveness; Prognosis; Rats; Receptors, Purinergic P2 - genetics; Receptors, Purinergic P2 - metabolism; Risk factors; Signal Transduction - drug effects; Signal Transduction - genetics
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/1471-2407-9-442

Glioma present as one of the most challenging cancers to treat, however, understanding of tumor cell biology is not well understood. Extracellular adenosine triphosphate (ATP) could serve as a critical signaling molecule regulating tumor development. This study has examined pharmacological modulation of calcium (Ca2+) entry through store-operated channels (SOC) on cellular expression and production of immune-cell mobilizing chemokines in ATP-stimulated C6 glioma cells. Calcium spectrofluorometry was carried out to measure mobilization of intracellular Ca2+ [Ca2+]i following ATP stimulation of rat C6 glioma cells. Pretreatment with two inhibitors of SOC, SKF96365 or gadolinium, was used to examine for effects on [Ca2+]i. RT-PCR was performed to determine effects of purinergic stimulation on C6 cell expression of metabotropic P2Y receptors (P2YR) and the chemokines, monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8). ELISA was carried out to measure production of MCP-1 and IL-8 with ATP stimulation of glioma cells. Application of ATP (at 100 microM) to C6 glioma induced an increase in [Ca2+]i with the response exhibiting two components of decay. In the presence of the SOC inhibitors, SKF96365 or gadolinium, or with Ca2+-free solution, ATP responses lacked a slow phase suggesting the secondary component was due to SOC-mediated influx of Ca2+. RT-PCR confirmed expression of purinergic P2Y-subtype receptors in C6 cells which would serve as a precursor to activation of SOC. In addition, ATP-stimulated C6 cells showed enhanced expression of the chemokines, MCP-1 and IL-8, with SKF96365 or gadolinium effective in reducing chemokine expression. Gadolinium treatment of ATP-stimulated C6 cells was also found to inhibit the production of MCP-1 and IL-8. These results suggest ATP-induced Ca2+ entry, mediated by activation of SOC in C6 glioma, as a mechanism leading to increased cellular expression and release of chemokines. Elevated levels of MCP-1 and IL-8 are predicted to enhance the mobility of tumor cells and promote recruitment of microglia into developing tumors thereby supporting tumor growth.