title: Superoxide anion and proteasomal dysfunction contribute to curcumin-induced paraptosis of malignant breast cancer cells.
abstract: Curcumin is considered a pharmacologically safe agent that may be useful in cancer chemoprevention and therapy. Here, we show for the first time that curcumin effectively induces paraptosis in malignant breast cancer cell lines, including MDA-MB-435S, MDA-MB-231, and Hs578T cells, by promoting vacuolation that results from swelling and fusion of mitochondria and/or the endoplasmic reticulum (ER). Inhibition of protein synthesis by cycloheximide blocked curcumin-induced vacuolation and subsequent cell death, indicating that protein synthesis is required for this process. The levels of AIP-1/Alix protein, a known inhibitor protein of paraptosis, were progressively downregulated in curcumin-treated malignant breast cancer cells, and AIP-1/Alix overexpression attenuated curcumin-induced death in these cells. ERK2 and JNK activation were positively associated with curcumin-induced cell death. Mitochondrial superoxide was shown to act as a critical early signal in curcumin-induced paraptosis, whereas proteasomal dysfunction was mainly responsible for the paraptotic changes associated with ER dilation. Notably, curcumin-induced paraptotic events were not observed in normal breast cells, including mammary epithelial cells and MCF-10A cells. Taken together, our findings on curcumin-induced paraptosis may provide novel insights into the mechanisms underlying the selective anti-cancer effects of curcumin against malignant cancer cells.
authors.affiliation: Department of Molecular Science & Technology, Institute for Medical Sciences, Ajou University School of Medicine, Suwon, 443-749, Korea.
authors.forename: Mi Jin
authors.initials: MJ
authors.lastname: Yoon
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Kim
authors.forename: Jun Hee
authors.initials: JH
authors.lastname: Lim
authors.forename: Taeg Kyu
authors.initials: TK
authors.lastname: Kwon
authors.forename: Kyeong Sook
authors.initials: KS
authors.lastname: Choi
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016923:Cell Death / Q000187:drug effects*; D045744:Cell Line, Tumor; D003474:Curcumin / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D042361:Mammary Glands, Human / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008561:Membrane Fusion / Q000187:drug effects; D008933:Mitochondrial Swelling / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C103265:aryl hydrocarbon receptor-interacting protein; D013481:Superoxides; D003513:Cycloheximide; D048049:Extracellular Signal-Regulated MAP Kinases; D048670:MAP Kinase Kinase 4; D046988:Proteasome Endopeptidase Complex; D003474:Curcumin