S240 Abstracts / Toxicology Letters 229S (2014) S40–S252

Many efficacious cancer treatments cause significant cardiacmorbidity, yet biomarkers or functional indices of early damage,which would allow monitoring and intervention, are lacking. Inthis study we have utilised a rat model of progressive doxorubicin-induced cardiomyopathy, applying multiple approaches, includingcardiac MRI, to provide the most comprehensive characterisa-tion to date of the timecourse of serological, pathological andfunctional events underlying this toxicity. Hannover Wistar Ratswere dosed with 1.25 mg/kg doxorubicin weekly for 8 weeksfollowed by a 4-week off-dosing ‘recovery’ period. Electronmicroscopy of the myocardium revealed subcellular degenerationand marked mitochondrial changes after a single dose. Histopatho-logical analysis revealed progressive cardiomyocyte degeneration,hypertrophy/cytomegaly and extensive vacuolation after 2 doses.Extensive replacement fibrosis (quantified by Sirius red staining)developed during the off-dosing period. Functional indices assessedby cardiac MRI (including left ventricular ejection fraction (LVEF),cardiac output and E/A ratio) declined progressively, reaching sta-tistical significance after 2 doses and culminating in ‘clinical’ LVdysfunction by 12 weeks. Significant increases in peak myocar-dial contrast enhancement and serological cardiac troponin I (cTnI)emerged after 8 doses, importantly preceding the LVEF declineto <50%. Troponin I levels positively correlated with delayed andpeak gadolinium contrast enhancement, histopathological gradingand diastolic dysfunction. In summary, subcellular cardiomyocytedegeneration was the earliest marker, followed by progressivefunctional decline and histopathological manifestations. Myocar-dial contrast enhancement and elevations in cTnI occurred later.However, all indices pre-dated ‘clinical’ LV dysfunction and thuswarrant further evaluation as predictive biomarkers.

http://dx.doi.org/10.1016/j.toxlet.2014.06.800

P-4.113Understanding the preclinical toxicity profile ofstandard of care oncology agent carboplatin:Effect of a 7-cycle treatment on bone marrowand peripheral cell depletion and recovery inthe Han Wistar rat

Janet Kelsall ∗, Clare Walker, Claire Sadler, Peter Cotton, NickMoore, Ian Slater, Jen Barnes, Lenka Oplustilova

Astrazeneca, Alderley Park, Macclesfield, UK

Carboplatin, a cisplatin analogue, inhibits cell growth by form-ing interstrand DNA crosslinks and is used to treat various forms ofcancer. Bone marrow toxicity is the major dose limiting side effectin the clinic and is managed by intermittent dosing. The objectiveof this study was to investigate the haematological parameters andrecovery profile in Han Wistar rats following repeated intravenousdoses of 40 mg/kg carboplatin for seven 14-day cycles. Effects onperipheral blood components and bone marrow progenitors andtheir differentiation potential were explored. Reticulocytes wereseverely depleted by day 7 of each cycle with recovery 2-3X abovecontrol animals by day 14 of each cycle. A moderately lower plateletcount (up to 60%) was observed on day 7 of each cycle of treated ani-mals with signs of recovery between each dosing cycle. Total whitecell counts were lower throughout the study when compared tocontrol animals, falling below the reference range on occasions withperiods of partial recovery. Bone marrow cell distribution analysisat the end of the 7th treatment cycle revealed reduction in pro-portion of myeloid and lymphoid populations (CD45+). Conversely,CD71+ and CD90+/Lin− cells, representative of the erythroid lin-eage and multipotent progenitor cells, respectively, were increasedsupporting reticulocyte recovery in the peripheral blood.

More importantly, although the total number of bone marrowcells isolated at the end of treatment was severely depleted, theprogenitor cells of the erythroid and myeloid lineages that survivedwere functionally viable as shown by CFC-GM and BFU-E colonyformation analysis.

http://dx.doi.org/10.1016/j.toxlet.2014.06.801

P-4.114The role of Pin1 in liver fibrosis: Regulation ofTgf-�1 expression and Smad2/3phosphorylation

Jin Won Yang ∗, Keon Wook

Kang College of Pharmacy and Research Institute of PharmaceuticalSciences, Seoul National University, Seoul, Republic of Korea

Pin1, a peptidyl-prolyl isomerase, plays an important patho-physiological role in several diseases, including neurodegenerationand cancer. Herein, we determined whether Pin1 regulates liverfibrogenesis and examined its mechanism of action by focusingon TGF�1 signalling and hepatic stellate cell (HSC) activation.Pin1 expression was elevated in human and mouse fibrotic livertissues, and Pin1 inhibition improved dimethylnitrosamine (DMN)-induced liver fibrosis in mice. Pin1 inhibition reduced the mRNAor protein expression of TGFb1 and a-smooth muscle actin (�-SMA) by DMN treatment. Pin1 knockdown suppressed TGF�1 geneexpression in both LX-2 and MEF cells. Pin1-mediated TGF�1gene transcription was controlled by extracellular signal-regulatedkinase (ERK)- and phosphoinositide 3-kinase/Akt-mediated acti-vator protein-1 (AP-1) activation. Moreover, TGF�1-stimulatedSmad2/3 phosphorylation and plasminogen activator inhibitor-1expression were inhibited by Pin1 knockdown. In summary, Pin1induction during liver fibrosis is involved in hepatic stellate cellactivation, TGF�1 expression, and TGF�1-mediated fibrogenesissignalling.

http://dx.doi.org/10.1016/j.toxlet.2014.06.802

P-4.115Sex differences in hepatic and intestinalcontributions for nevirapine biotransformation

Pedro F. Pinheiro 1,2, Aline T. Marinho 3, Alexandra M.M.Antunes 2, M. Matilde Marques 2, Matilde F. Castro 1, Sofia A.Pereira 3,4, Joana P. Miranda 1,∗,4

1 Research Institute for Medicines – iMed.ULisboa, Faculdade deFarmácia, Universidade de Lisboa, Lisboa, Portugal, 2 Centro deQuímica Estrutural, Instituto Superior Técnico, Universidade deLisboa, Lisboa, Portugal, 3 Centro de Estudos de Doencas Crónicas,Faculdade de Ciências Médicas, Universidade NOVA, Lisboa, Portugal

The understanding of the intestine contribution to drugbiotransformation has improved significantly in recent years. How-ever, a better evaluation of the sources of inter-individual variabil-ity in intestinal drug biotransformation, namely sex-differences, isstill necessary. Nevirapine (NVP) is an orally taken drug associatedwith severe idiosyncratic reactions elicited by toxic metabolites,with women at increased risk. As such, NVP is a good model drugto assess sex-dimorphic metabolism. In this work, a comparativeprofiling of NVP biotransformation in intestine and liver was per-

1 JPM and SAP contributed equally.