Reactive oxygen species involved in trichosanthin-induced apoptosis of human choriocarcinoma cells

Citation
Cy. Zhang et al., Reactive oxygen species involved in trichosanthin-induced apoptosis of human choriocarcinoma cells, BIOCHEM J, 355, 2001, pp. 653-661
Citations number
47
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL JOURNAL
ISSN journal
0264-6021 → ACNP
Volume
355
Year of publication
2001
Part
3
Pages
653 - 661
Database
ISI
SICI code
0264-6021(20010501)355:<653:ROSIIT>2.0.ZU;2-M
Abstract
The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad sp ectrum of biological and pharmacological activities, including abortifacien t, anti-tumour and anti-HIV activities. We have found for the first time th at TCS stimulated the production of reactive oxygen species (ROS) in JAR ce lls (a human choriocarcinoma cell line) in a time- and concentration-depend ent manner by using the fluorescent probe 2',7'-dichlorofluorescein diaceta te with confocal laser scanning microscopy. ESR spectral studies and the in hibition of ROS formation by the superoxide radical anion (O-2(-.)) scaveng er superoxide dismutase, the H2O2 scavenger catalase and the hydroxyl radic al (OH.) scavenger mannitol suggested the involvement of O-2(-.), H2O2 and OH.. TCS-induced ROS formation was shown to be dependent on the presence of both extracellular and intracellular Ca2+; moreover, ROS production parall eled the intracellular Ca2+ elevation induced by TCS, suggesting that ROS p roduction might be a consequence of Ca2+ signalling. TCS-induced activation of caspase-3 was initiated within 2 h; however, TCS-induced production of ROS was initiated within 5 min, suggesting that the production of ROS prece ded the activation of caspase-3. Simultaneous observation of the nuclear mo rphological changes via two-photon laser scanning microscopy and ROS produc tion via confocal laser scanning microscopy revealed that ROS is involved i n the apoptosis of JAR cells. The involvement of ROS was also confirmed by the inhibition of TCS-induced cell death by the antioxidant Trolox and the ROS scavengers catalase and mannitol. Diethylene-triaminepenta-acetic acid, an inhibitor of metal-facilitated OH. formation, markedly inhibited TCS-in duced cell death, suggesting that TCS induced OH. formation via the Fenton reaction. The finding that ROS is involved in the TCS-induced apoptosis of JAR cells might provide new insight into the antitumour and anti-HIV mechan ism of TCS.