J. Biochem, 2003, Vol. 134, No. 3 359-364
© 2003 Japanese Biochemical Society
CELL |
Vacuolar H+-ATPase Inhibitor Induces Apoptosis via Lysosomal Dysfunction in the Human Gastric Cancer Cell Line MKN-1
1 Third Department of Internal Medicine, 2 Department of Environmental and Molecular Medicine and 3 Department of Endoscopic Medicine, Mie University School of Medicine, Tsu, Mie, 514-8507; and 4 Department of Hematology/Oncology, Graduate School of Medicine, Kyoto University, Kyoto, 606-8397
We investigated the mechanism of apoptosis induced by bafilomycin A1, an inhibitor of vacuolar H+-ATPase. Bafilomycin A1 significantly inhibited the growth of MKN-1 human gastric cancer cells. Bafilomycin A1 induced apoptosis as demonstrated by DNA ladder formation and the TUNEL method. We designed a flow cytometric assay to detect the alteration in lysosomal pH using a fluorescent probe, fluorescein isothiocyanate-conjugated dextran. This assay revealed that bafilomycin A1 dramatically increased lysosomal pH. However, bafilomycin A1 induced neither significant decrease in mitochondrial transmembrane potential nor the release of mitochondrial cytochrome c into the cytoplasm. Western blotting showed that cathepsin D, but not cathepsin L, was released into the cytoplasm. The activity of caspase-3 was significantly increased by bafilomycin A1. However, cathepsin D did not directly cleave procaspase-3. These findings suggest that bafilomycin A1-induced apoptosis in MKN-1 cells is mediated by other proteases released after lysosomal dysfunction followed by activation of caspase-3 in a cytochrome c-independent manner. The present study showed that flow cytometric analysis of lysosomal pH can be useful to evaluate lysosomal protease-mediated apoptosis.
* To whom correspondence should be addressed. Tel: +81-59-231-5011, Fax: +81-59-231-5011, E-mail: kawanisi{at}doc.medic.mie-u.ac.jp
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  R. Reinehr, A. Sommerfeld, V. Keitel, S. Grether-Beck, and D. Haussinger Amplification of CD95 Activation by Caspase 8-induced Endosomal Acidification in Rat Hepatocytes J. Biol. Chem., January 25, 2008; 283(4): 2211 - 2222. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. De Milito, E. Iessi, M. Logozzi, F. Lozupone, M. Spada, M. L. Marino, C. Federici, M. Perdicchio, P. Matarrese, L. Lugini, et al. Proton Pump Inhibitors Induce Apoptosis of Human B-Cell Tumors through a Caspase-Independent Mechanism Involving Reactive Oxygen Species Cancer Res., June 1, 2007; 67(11): 5408 - 5417. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.-H. Lim, J.-W. Park, M.-S. Kim, S.-K. Park, R. S. Johnson, and Y.-S. Chun Bafilomycin Induces the p21-Mediated Growth Inhibition of Cancer Cells under Hypoxic Conditions by Expressing Hypoxia-Inducible Factor-1{alpha} Mol. Pharmacol., December 1, 2006; 70(6): 1856 - 1865. [Abstract] [Full Text] [PDF]
|
|