Fig. 1

DFO/Dp44mT-induced vacuolation leads to non-apoptotic/necrotic cell death in MDA-MB-231 breast cancer cells. a Representative images of MDA-MB-231 cells treated with 100 μM DFO or with 5 μM Dp44mT. The cells were treated with the iron chelators for 48 h and photographed under an optical microscope. Scale bars: 100 μm. b MDA-MB-231 cells treated with 100 μM DFO or with 5 μM Dp44mT to determine the effects of the two iron chelators on cell proliferation. An MTT assay analysis indicated that after 24 h, cells treated with DFO or Dp44mT showed a slight decrease in cell proliferation. After Dp44mT treatment for 48 h, cell proliferation was reduced by 69%, whereas DFO treatment elicited a decrease in cell proliferation by 45%. After 72 h, Dp44mT treatment resulted in a considerable decrease in cell proliferation (75%), whereas DFO treatment reduced cell proliferation by 56%. Finally, after 120 h, proliferation was effectively blocked in MDA-MB-231 cells treated with both chelators. c Determination of the expressions of PARP, HMGB1, BCL-2, phosphorylated p38, JNK, AMPK, and mTOR, following treatment of MDA-MB-231 cells with DFO or Dp44mT. Cells were treated with 100 μM DFO or 5 μM Dp44mT and the protein levels were examined over a period of 24–72 h. In control samples, no PARP-1 expression was observed at 72 h. At 116 kDa corresponding to full-length PARP-1, immunoreactivity was detectable in the 24, 48, and 72 h-treated samples. No cleavage products of PARP-1 were seen at 48 h and 72 h. Weak increase in HMGB1 expression was noted in treated cells after 72 h. No change in the protein levels of BCL-2 was observed. The increased levels of phosphorylated p38, JNK, AMPK, and mTOR suggest that DFO and Dp44mT induce cell death by maintaining multiple activated pathways. Tubulin was used as a loading control. d Schematic representation of the effects observed with DFO or Dp44mT treatments