15d-PGJ2 Induces Apoptosis of MCF-7 and MDA-MB-231 Cells via Increased Intracellular Calcium and Activation of Caspases, Independent of ER and ER

Reports indicate that 15deoxydelta12,14prostaglandinJ2 (15dPGJ2) has anticancer activities, but its mechanisms of action have yet to be fully elucidated We therefore investigated the effects of 15dPGJ2 on the human breast cancer cell lines, MCF7 (estrogen receptor ERER) and MDAMB231 (ERER) Cellular proliferation and cytotoxicity were determined using the 3(4,5dimethylthiazol2yl)2,5diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays while apoptosis was determined by fluorescence microscopy and flow cytometry using annexin Vpropidium iodide (PI) staining ER expression was determined by Western blotting Intracellular calcium was stained with Fluo4 AM while intracellular caspase activities were detected with CaspaseFLICA and measured by flow cytometry We showed that 15dPGJ2 caused a significant increase in apoptosis in MCF7 and MDAMB231 cells ER protein expression was reduced in treated MCF7 cells but preincubation with the ER inhibitor ICI 182 780 did not affect the percentage of apoptotic cells The expression of ER was unchanged in both cell lines In addition, 15dPGJ2 increased intracellular calcium (Ca) staining and caspase 8, 9 and37 activities We therefore conclude that 15dPGJ2 induces caspasedependent apoptosis that is associated with an influx of intracellular Ca with no involvement of ER signaling