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Caspase-independence and characterization of bisnaphthalimidopropyl spermidine induced cytotoxicity in HL60 cells.

Bestwick, Charles S.; Milne, Lesley; Dance, Anne-Marie; Cochennec, Gaela; Cruickshank, Gillian; Allain, Eflamm; Constable, Lynda; Duthie, Susan J.; Lin, Paul Kong Thoo


Charles S. Bestwick

Lesley Milne

Anne-Marie Dance

Gaela Cochennec

Gillian Cruickshank

Eflamm Allain

Lynda Constable


Bisnaphthalimides are DNA intercalators of potential use as chemotherapeutics but for which the range of mechanism of action is only gradually being elucidated. Using human promyelocytic HL-60 cells, we extend characterization of the cytotoxicity of bisnaphthalimidopropylspermidine (BNIPSpd) and examine the relationship with caspase-activity. Within 4 h exposure, BNIPSpd (1-10 μM) induced significant DNA strand breakage. Evidence of apoptosis was progressive through the experimental period. Within 6 h, BNIPSpd increased the proportion of cells exhibiting plasma membrane phosphatidylserine exposure. Within 12 h, active caspase expression increased and was sustained with 5 and 10 μM BNIPSpd. Flow cytometric analysis revealed caspase activity in cells with and without damaged membranes. By 24 h, 5 and 10 μM BNIPSpd increased hypodiploid DNA content and internucleosomal DNA fragmentation (DNA ladders) typical of the later stages of apoptosis. 1 μM BNIPSpd exposure also increased hypodiploid DNA content by 48 h. Polyamine levels decreased by 24 h BNIPSpd exposure. The pan-caspase inhibitor, z-VAD-fmk, significantly decreased DNA degradation (hypodiploid DNA and DNA ladders) and cytotoxicity. Despite this, cell growth and viability remained significantly impaired. We propose that BNIPSpd cytotoxicity arises through DNA damage and not polyamine depletion and that cytotoxicity is dominated by but not dependent upon caspase driven apoptosis.


BESTWICK, C., MILNE, L., DANCE, A.-M., COCHENNEC, G., CRUICKSHANK, G., ALLAIN, E., CONSTABLE, L., DUTHIE, S.J. and KONG THOO LIN, P. 2018. Caspase-independence and characterization of bisnaphthalimidopropyl spermidine induced cytotoxicity in HL60 cells. Toxicology in vitro [online], 52, pages 342-350. Available from:

Journal Article Type Article
Acceptance Date Jun 29, 2018
Online Publication Date Jul 23, 2018
Publication Date Oct 31, 2018
Deposit Date Aug 10, 2018
Publicly Available Date Jul 24, 2019
Journal Toxicology in Vitro
Print ISSN 0887-2333
Electronic ISSN 1879-3177
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 52
Pages 342-350
Keywords Apoptosis; Bisnaphthalimides; Caspaseinhibition; Cytotoxicity; Genotoxicity; HL60 cells
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