Sensitization of human colon adenocarcinoma cells (LoVo) to reactive oxygen species by a lysosomotropic compound.
The in situ formation of cytotoxic metabolites by an enzyme-catalyzed reaction is a recent approach in cancer therapy. The present results show that multidrug-resistant human colon adenocarcinoma cells (LoVo) are significantly more sensitive than corresponding wild-type cells to hydrogen peroxide and aldehydes, the products of bovine serum amine oxidase (BSAO)-catalyzed oxidation of spermine. Pre-treatment of the cells with N1,N4-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72527), a lysosomotropic compound, sensitized both cell lines to the subsequent exposure to spermine metabolites, as was evident from the decrease of cell survival by a log unit. The sensitizing effect was greater in the case of the multidrug-resistant cell line, an aspect of particular importance with respect to potential therapeutic applications of the method, since conventional cancer therapy suffers from the development of drug resistance. Cell viability was determined using a clonogenic assay. MDL 72527 (at 300 microM) produced numerous cytoplasmic vacuoles, presumably of lysosomal origin, after 6-h exposure, which decreased in size and number (in the presence of the drug) by 24 h and had almost disappeared completely at 48 h. Mitochondrial damage, as observed by transmission electron microscopy, seemed to correlate better with the cytotoxic effects of the treatment than the formation of vacuoles. We suggest that the release of lysosomal enzymes into the cytosol by MDL 72527 is the main reason for its sensitizing effect. It is known that lysosomotropic compounds, which release lysosomal enzymes, produce oxidative stress and apoptosis.
Agostinelli
Enzo
E
Department of Biochemical Sciences 'A. Rossi Fanelli', University of Rome 'La Sapienza', I-00185 Rome, Italy. enzo.agostinelli@uniroma1.it
Vedova
Laura Dalla
LD
Belli
Francesca
F
Condello
Maria
M
Arancia
Giuseppe
G
Seiler
Nikolaus
N
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000648:ultrastructure; D000447:Aldehydes / Q000378:metabolism; D006631:Amine Oxidase (Copper-Containing) / Q000627:therapeutic use*; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D002417:Cattle; D002470:Cell Survival; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000648:ultrastructure; D019008:Drug Resistance, Neoplasm; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology; D011700:Putrescine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000447:Aldehydes; D017382:Reactive Oxygen Species; C044445:MDL 72527; D013096:Spermine; D006861:Hydrogen Peroxide; D006631:Amine Oxidase (Copper-Containing); D011700:Putrescine