Effects of anti-ganglioside GD2 14G2a monoclonal antibody (mAb) alone or in combination with ET A receptor (ETAR) antagonist on phosphatidylinositide 3-kinase (PI3K) activity in osteosarcoma (OS) cells.
PI3K activities were determined with a PI3K Activity ELISA kit (Echelon Biosciences) in Saos-2 (A), MG-63 (B) and SJSA-1 (C) OS cells treated with control IgG (PK136 mAb, 50 µg/mL), 14G2a mAb (50 µg/mL), selective ETAR antagonist BQ123 (5 µM), and 14G2a (50 µg/mL)+BQ123 (5 µM) for 48 hours. Cells with knockdown of ETAR (ETAR-shRNA) with or without 14G2a mAb treatment were also tested. Cells treated with selective phosphatidylinositide 3-kinase (PI3K) inhibitor BKM120 (50 µM) was used as a positive control. The PI3K activity was shown as fold changes to that of the untreated control cells (designated as 1). Each experiment was repeated for three times in duplicates. Data values were expressed as Mean+SD. ap<0.05 vs. control or control IgG; bp<0.05 vs. BQ123; cp<0.05 vs. ETAR-shRNA; dp<0.05 vs. 14G2a; ep<0.05 vs. 14G2a+BQ123; fp<0.05 vs. 14G2a+ETAR-shRNA.