title: Absence of cardiotoxicity of the experimental cytotoxic drug cyclopentenyl cytosine (CPEC) in rats.
abstract: 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.
authors.affiliation: 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
authors.forename: Kirsten
authors.initials: K
authors.lastname: Schimmel
authors.forename: Roel
authors.initials: R
authors.lastname: Bennink
authors.forename: Kora
authors.initials: K
authors.lastname: de Bruin
authors.forename: Rene
authors.initials: R
authors.lastname: Leen
authors.forename: Karsten
authors.initials: K
authors.lastname: Sand
authors.forename: Maurice
authors.initials: M
authors.lastname: van den Hoff
authors.forename: André
authors.initials: A
authors.lastname: van Kuilenburg
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vanderheyden
authors.forename: Neil
authors.initials: N
authors.lastname: Steinmetz
authors.forename: Martin
authors.initials: M
authors.lastname: Pfaffendorf
authors.forename: Arnauld
authors.initials: A
authors.lastname: Verschuur
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Guchelaar
mesh_terms: 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
chemical_list: D017304:Annexin A5; D000970:Antineoplastic Agents; D015609:Organotechnetium Compounds; D020107:Troponin T; C417036:technetium Tc 99m annexin V; D003562:Cytidine; C045911:cyclopentenyl cytosine