Premium
Purpurin‐18 in Combination with Light Leads to Apoptosis or Necrosis in HL60 Leukemia Cells ¶
Author(s) -
Stefano Anna Di,
Ettorre Anna,
Sbrana Silverio,
Giovani Cinzia,
Neri Paolo
Publication year - 2001
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2001)0730290picwll2.0.co2
Subject(s) - apoptosis , dna fragmentation , dna laddering , hl60 , fragmentation (computing) , necrosis , programmed cell death , phosphatidylserine , apoptotic dna fragmentation , biology , caspase , microbiology and biotechnology , photodynamic therapy , caspase 3 , chemistry , biochemistry , phospholipid , membrane , genetics , ecology , organic chemistry
Photodynamic therapy (PDT), a cancer treatment using a photosensitizer and visible light, has been shown to induce apoptosis or necrosis. We report here that Purpurin‐18 (Pu18) in combination with light induces rapid apoptotic cell death in the human leukemia cell line (HL60) at low doses and necrosis at higher concentrations. Cells treated with Pu18 and light under apoptotic conditions exhibited DNA laddering and an increase in both cellular content of subdiploid DNA and externalization of phosphatidylserine (PS), indicating DNA fragmentation and loss of membrane phospholipid asymmetry. In the absence of light activation, Pu18 at nanomolar concentrations had no detectable cytotoxic effect. Caspase‐3 activity was increased even after 1 h from treatment with low doses of Pu18 and light. The PS exposure and nuclear features of apoptosis were prevented by treatment of cells before illumination with caspase inhibitors benzyloxycarbonyl‐Val‐Ala‐Asp‐fluoromethylketone (Z‐VAD‐FMK) and benzyloxycarbonyl‐Asp‐Glu‐Val‐Asp‐fluoromethylketone (Z‐DEVD‐FMK). Conversely, the caspase‐1 inhibitor, acetyl‐Tyr‐Val‐Ala‐Asp‐aldehyde (Ac‐YVAD‐CHO) failed to suppress the apoptosis. No protective effect of the three caspase inhibitors was observed when the cells were exposed to necrotic concentrations of Pu18 and light. Our results show that caspase‐3, but not caspase‐1, is involved in the signaling of apoptotic events in PDT with Pu18‐induced apoptosis of HL60 cells. Moreover, both the time course of PS exposure and the effect of caspase inhibitors on it indicate that it is regulated in the same manner as DNA fragmentation.