Novel o-naphthoquinones induce apoptosis of EL-4 T lymphoma cells through the increase of reactive oxygen species

DI ROSSO ME; BARREIRO ARCOS ML; ELINGOLD I; STERLE HA; FERREIRA SB; FERREIRA VF; GALLEANO M; CREMASCHI G; DUBIN M

TOXICOLOGY IN VITRO : AN INTERNATIONAL JOURNAL PUBLISHED IN ASSOCIATION WITH BIBRA.

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 vol. 7 p. 2094 - 2104

0887-2333

Novel b-lapachone analogs 2-phenyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ1), 2-p-tolyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ3) and 2-methyl-2-phenyl-3,4-dihydro-2H-benzo[h]chromene-5,6-dione (NQ7), which have trypanocidal activity, were assayed for cytotoxic effects on murineEL-4 T lymphoma cells. The NQs inhibited the proliferation of EL-4 cells at concentrations above 1 lM.Nuclear staining of the EL-4 cells revealed chromatin condensation and a nuclear morphology compatiblewith the induction of apoptosis. Flow cytometry assays with annexin V-FITC and propidium iodide confirmedthe cell death by apoptosis. Using electron paramagnetic resonance (EPR), a semiquinone radicalwas detected in EL-4 cells treated with NQs. In addition, a decrease in the GSH level in parallel with reactiveoxygen species (ROS) production was observed. Preincubation with n-acetyl-l-cysteine (NAC) wasable to reverse the inhibitory effects of the NQs on cell proliferation, indicating that ROS generation isinvolved in NQ-induced apoptosis. In addition, the NQs induced a decrease in the mitochondrial membranepotential and increased the proteolytic activation of caspases 9 and 3 and the cleavage of Poly(ADP-Ribose) Polymerase (PARP). In conclusion, these results indicate that redox cycling is induced bythe NQs in the EL-4 cell line, with the generation of ROS and other free radicals that could inhibit cellularproliferation as a result of the induction of the intrinsic apoptosis pathway.