Abstract
Purpose: :
Cationic antimicrobial peptides (CAPs) can exhibit cytotoxicity to some mammalian cells which has implications for CAP involvement in disease processes but which may possibly be capitalized on for the development of CAPs as an anti-cancer treatment. The purpose of this study is to characterize the cytotoxicity profiles of human neutrophil peptide-1 (HNP-1), LL-37, Magainin II and Cecropin B on ocular cells, and to determine if an apoptotic mechanism is involved.
Methods: :
Primary human corneal epithelial cells (HCEC), SV40-HCEC and OCM8 uveal melanoma cells were incubated with a range of concentrations (1-1000 ug/ml) of the peptides for 24 hours, and cytotoxicity was quantified using an MTT assay. A fluorescence TUNEL based assay was used to determine if there was an apoptotic component to the cytotoxicity observed.
Results: :
HNP-1, LL-37, Magainin II and Cecropin B all demonstrated a dose dependent cytotoxicity to the cell types tested (n=1-3). HNP-1 showed some cytotoxicity (25-32% cell death) to SV40-HCEC and primary HCEC starting at 1 ug/ml and maximal cytotoxicity (79-80% cell death) at 100 ug/ml. LL-37 showed minimal cytotoxicity (7% cell death) to OCM8 cells at 10 ug/ml and maximal cytotoxicity (94% cell death) at 100 ug/ml. LL-37 displayed near complete cytotoxicity (82-92% cell death) to primary HCEC starting at 10-50 ug/ml. Magainin II showed cytotoxicity to SV40-HCEC and OCM8 at much higher concentrations, with complete cytotoxicity (95-98% cell death) beginning at 500 ug/ml. Primary cells were more resistant, with maximum cytotoxicity (73% cell death) at 1000 ug/ml of Magainin II. Cecropin B did not cause complete cytotoxicity to SV40-HCEC (77% cell death) nor primary HCEC (52% cell death) even at 1000 ug/ml. HNP-1 (100ug/ml) and Magainin II (500ug/ml) treatment resulted in intense fluorescence staining for both SV40-HCEC and OCM8 cells, indicative of positive TUNEL labeling.
Conclusions: :
HNP-1, LL-37, Magainin II and Cecropin B are cytotoxic to ocular cells, but at different peptide concentrations. HNP-1 appeared to be the most cytotoxic, and Magainin II and Cecropin B appear to be the least cytotoxic. HNP-1 and Magainin II appear to effect their cytotoxicity through an apoptotic pathway.
Keywords: apoptosis/cell death • cornea: epithelium • oncology