title: Intracellular signaling in the induction of apoptosis in a human breast cancer cell line by water extract of Mekabu.
abstract: BACKGROUND
  We previously reported that water extract of Mekabu, a kind of seaweed, induced apoptosis in a human breast cancer cell line. In the present study we investigated intracellular signaling in apoptosis, with a focus on caspases.
  
  
  METHODS
  Mekabu extract, obtained with ultrapure water, was used to induce apoptosis in a human breast cancer cell line, MDA-MB231, and DNA fractionation was investigated by flow cytometry and electrophoresis. In addition, using the caspase detection kit Caspa Tag, activation of caspases 3, 6, 8, and 9 was observed under a fluorescence microscope. Furthermore, using antibodies to caspases 3, 8, 9, and Bid, we conducted a protein analysis by Western blotting to determine the activation of these substances.
  
  
  RESULTS
  Obvious ladder formation demonstrating DNA fractionation was seen, confirming that Mekabu extract induced apoptosis. In the fluorescence microscope observations, activation of caspases 3, 6, and 8, but not caspase 9, was seen. Activated caspases 3 and 8 were detected in the Western blotting analysis, but no proteins of activated caspase 9 or Bid were detected.
  
  
  CONCLUSIONS
  Mekabu extract activates caspases 3, 6, and 8 and contributes to intracellular signaling to induce apoptosis in a human breast cancer cell line. This signaling is not via the mitochondria.
authors.affiliation: Second Department of Surgery, Nagoya University School of Medicine, Nagoya 466-8550, Japan. endocrina@ybb.ne.jp
authors.forename: Masanori
authors.initials: M
authors.lastname: Sekiya
authors.forename: Hiroomi
authors.initials: H
authors.lastname: Funahashi
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Tsukamura
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Imai
authors.forename: Akemi
authors.initials: A
authors.lastname: Hayakawa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kiuchi
authors.forename: Akimasa
authors.initials: A
authors.lastname: Nakao
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000473:pathology*; D020169:Caspases / Q000378:metabolism*; D018736:DNA Adducts; D004249:DNA Damage; D005260:Female; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology*; D012624:Seaweed / Q000737:chemistry*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D018736:DNA Adducts; D010936:Plant Extracts; D020169:Caspases