Novel triterpenoid 25-hydroxy-3-oxoolean-12-en-28-oic acid induces growth arrest and apoptosis in breast cancer cells.
25-Hydroxy-3-oxoolean-12-en-28-oic acid (Amooranin-AMR) is a triterpene acid isolated from the stem bark of a tropical tree (Amoora rohituka) grown wild in India. A herbal preparation used for the treatment of cancer by the Ayurvedic system of medicine contains the stem bark of Amoora rohituka as one of the ingredients. In this paper, we show that AMR displays a strong inhibitory effect on survival of human breast carcinoma MDA-468, breast adenocarcinoma MCF-7 cells compared to breast epithelial MCF-10A control cells. A 50% decrease in cells (IC50) ranged from 1.8 to 14.6 microM and cell growth was suppressed by arresting cell cycle at G2 + M phase. AMR effectively induces apoptosis and triggered a series of effects associated with apoptosis including cleavage of caspase-8, -9, -3, Bid and ER stress in MDA-468 cells and caspase- 8, -9, -6 and Bid in MCF-7 cells, release of cytochrome c from the mitochondria, cleavage of poly (ADP-ribose) polymerase (PARP) and DNA fragmentation with a concomitant upregulation of p53, Bax and down-regulation of Bcl-2 in MDA-468 cells, but Bax unchanged in MCF-7 cells. The use of caspase blocking peptides and acridine orange staining confirmed the involvement of primarily caspase-9 and -3 in MDA-468 cells with mutated p53 and primarily caspase-8, -9 and -6 in MCF-7 cells expressing wt p53. We also observed in MCF-7/p53siRNA cells AMR treatment caused reduced expression of Bcl-2 without affecting levels of Bax similar to MCF-7 cells treated with AMR and proteolytic activation of Bax in MDA-468 cells. These results suggest that AMR induces apoptosis in human breast carcinoma cells via caspase activation pathway and likely it is a p53-independent apoptosis.
Rabi
Thangaiyan
T
Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA. rabit@ccf.org
Wang
Liming
L
Banerjee
Sipra
S
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D061945:Caspase Inhibitors; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D015394:Molecular Structure; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014315:Triterpenes / Q000737:chemistry / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D034741:RNA, Small Interfering; D014315:Triterpenes; D016159:Tumor Suppressor Protein p53; C453733:amooranin; D045304:Cytochromes c; D053148:Caspase 3; D053179:Caspase 7; D053453:Caspase 9