Absence of cardiotoxicity of the experimental cytotoxic drug cyclopentenyl cytosine (CPEC) in rats.
The experimental anticancer drug cyclopentenyl cytosine (CPEC) was associated with cardiotoxicity in a phase I study. The aim of the present study was twofold; first we investigated whether the observed effects could be reproduced in in-vitro and in-vivo rat models. Second, we intended to investigate the underlying mechanism of the possible cardiotoxicity of CPEC. Effects on frequency and contractility were studied on the isolated atria of 18 male Wistar rats. Atria were incubated with 0.1 mmol L(-1) (n = 6) or 1 mmol L(-1) (n = 6) CPEC for 1.5 h and compared with control atria (incubation with buffer solution, n = 6). The cardiac apoptosis-inducing potential was studied in-vivo on 66 rats by 99mTc-Annexin V scintigraphy, followed by postmortem determination of radioactivity in tissues, histological confirmation with the TUNEL assay (late-phase apoptosis), and immunohistochemical staining for cleaved caspase 3 and cytochrome C (early-phase apoptosis). Serum levels of the necrotic cardiomyopathy marker troponin T were also determined. No effect on heart frequency was found in the isolated atria after CPEC treatment. A trend towards a decrease of contraction force was observed. However, the differences were not statistically significant. 99mTc-Annexin V scintigraphy showed no increase in cardiac uptake ratio upon CPEC treatment in the in-vivo rat model, which was confirmed by determination of radioactivity in heart versus blood ratios. At each section a few individual isolated late apoptotic cells (< 5) could be identified by the TUNEL assay in the highest CPEC dose group (90 mg kg(-1)) but not in controls or in rats treated with 60 mg kg(-1) CPEC. Staining for the early apoptosis markers cleaved caspase 3 and cytochrome C did not reveal any significant differences between treated and control rats. Cardiac troponin T levels were not increased after CPEC treatment. CPEC does not affect heart frequency or contraction force in our cardiotoxicity models. Moreover, we did not find an indication of CPEC-induced apoptosis in heart tissue.
Schimmel
Kirsten
K
Department of Clinical Pharmacy and Toxicology, Leiden University Medical Centre, Albinusdreef 2, Postbox 9600, 2300 RC, Leiden, The Netherlands. k.j.m.schimmel@lumc.nl
Bennink
Roel
R
de Bruin
Kora
K
Leen
Rene
R
Sand
Karsten
K
van den Hoff
Maurice
M
van Kuilenburg
André
A
Vanderheyden
Jean-Luc
JL
Steinmetz
Neil
N
Pfaffendorf
Martin
M
Verschuur
Arnauld
A
Guchelaar
Henk-Jan
HJ
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D009202:Cardiomyopathies / Q000097:blood / Q000139:chemically induced* / Q000473:pathology; D003562:Cytidine / Q000031:analogs & derivatives* / Q000633:toxicity; D004195:Disease Models, Animal; D006321:Heart / Q000000981:diagnostic imaging / Q000187:drug effects*; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D020287:In Situ Nick-End Labeling; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000473:pathology; D015609:Organotechnetium Compounds; D051381:Rats; D017208:Rats, Wistar; D015899:Tomography, Emission-Computed, Single-Photon; D020107:Troponin T / Q000097:blood
D017304:Annexin A5; D000970:Antineoplastic Agents; D015609:Organotechnetium Compounds; D020107:Troponin T; C417036:technetium Tc 99m annexin V; D003562:Cytidine; C045911:cyclopentenyl cytosine