TY - JOUR T1 - Clodronate-Induced Cell Apoptosis in Human Thyroid Carcinoma Is Mediated via the P2 Receptor Signaling Pathway JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 613 LP - 623 DO - 10.1124/jpet.109.152447 VL - 330 IS - 2 AU - De-Ming Yang AU - Hsiao-Chuan Teng AU - Kuan-Hsuan Chen AU - Ming-Long Tsai AU - Ting-Kuei Lee AU - Yueh-Ching Chou AU - Chin-Wen Chi AU - Shi-Hwa Chiou AU - Chen-Hsen Lee Y1 - 2009/08/01 UR - http://jpet.aspetjournals.org/content/330/2/613.abstract N2 - Clodronate, a halogenated bisphosphonate, can inhibit the growth of human thyroid carcinoma (TC) cells. Previously, we found that a clodronate-induced Ca2+ transient was correlated with clodronate-induced growth inhibition in TC cells. However, the details of the signaling process underlying the antiproliferative effect of clodronate on TC cells are not clear. In this study, we investigated the antiproliferative mechanism of clodronate on papillary TC (PTC) cells and xenotransplanted animals using a combination of pharmacological drugs. Reverse transcription-polymerase chain reaction analysis confirmed the endogenous expression of P2Y receptor isoforms in PTC cells. The P2 antagonist suramin not only inhibited the antiproliferative effect of clodronate and ATP on TC cells but also blocked all the Ca2+ transients induced by clodronate and ATP. The release of Ca2+ from the endoplasmic reticulum and membrane depolarization of mitochondria was observed during the clodronate-induced Ca2+ transients. The results of terminal deoxynucleotidyltransferase dUTP nick-end labeling assays and flow cytometry with annexin V and caspase-3 staining suggest that both ATP and clodronate induce apoptosis. Significant inhibition of tumor invasion and colony formation was also observed in clodronate-treated PTC cells. We further demonstrated that only the cAMP inhibitor 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (SQ22536), and not inhibitors of phospholipase C [1-[6-[[17β-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122)] or store-operated Ca2+ entry (2-aminoethyl diphenylborinate), can significantly reverse the effect of clodronate. Finally, in vivo animal and green fluorescent protein imaging studies further proved that the tumor inhibitory effect of clodronate on xenotransplanted CG3 cells can be reversed by treatment with suramin. In conclusion, we demonstrated that clodronate-induced PTC cell apoptosis and tumor inhibition are partially mediated by the P2Y receptor-cAMP cascade. The American Society for Pharmacology and Experimental Therapeutics ER -