Apoptosis in human leukemic cells induced by lactoferricin, a bovine milk protein-derived peptide: involvement of reactive oxygen species.
We examined the activity of bovine lactoferricin (Lfcin-B), a peptide derived from a bovine milk protein lactoferrin (LF-B), to induce apoptosis in THP-1 human monocytic leukemic cells. Treatment with Lfcin-B at up to 50 micrograms/ml induced cell death in THP-1 cells in dose- and time-dependent manner, showing apparent morphological changes, hypodiploid forms of genomic DNA and apoptotic DNA fragmentation, whereas LF-B was inactive even at a high dose (500 micrograms/ml). The apoptosis-inducing effect of Lfcin-B increased with reduction of serum concentration, but was inhibited by addition of Zn2+, a inhibitor of Ca2+/Mg(2+)-dependent endonucleases in a dose-dependent manner. Furthermore, Lfcin-B-induced apoptosis in THP-1 cells was completely abolished by addition of antioxidants such as N-acetyl-L-cysteine (NAC) and glutathione (GSH), but not by various cytokines and mitogen which can activate monocytic cells. In addition, THP-1 cells treated with Lfcin-B, but not LF-B, showed high levels of intracellular reactive oxygen species (ROS) from the early period (20 min) of Lfcin-B treatment. And the production of ROS by Lfcin-B was dependent upon the dose of Lfcin-B added. These results suggested that Lfcin-B, a LF-B-derived peptide, but not LF-B itself, is able to induce apoptosis in THP-1 human monocytic tumor cells, and that its apoptosis-inducing activity is related to the pathway mediated by production of the intracellular ROS and activation of Ca2+/Mg(2+)-dependent endonucleases.
Yoo
Y C
YC
Institute of Immunological Science, Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
Watanabe
R
R
Koike
Y
Y
Mitobe
M
M
Shimazaki
K
K
Watanabe
S
S
Azuma
I
I
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002417:Cattle; D053938:DNA Fragmentation; D004273:DNA, Neoplasm / Q000187:drug effects; D004171:Diploidy; D005260:Female; D005978:Glutathione / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D007781:Lactoferrin / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000494:pharmacology; D007948:Leukemia, Monocytic, Acute; D008892:Milk / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; D017382:Reactive Oxygen Species; C082171:lactoferricin B; D007781:Lactoferrin; D005978:Glutathione; D000111:Acetylcysteine