Administration of trastuzumab with heart irradiation induced acute cardiotoxicity in mice

Cardiac toxicity is one of the major advese effect associated with thoracic irradiation. Breast cancer patients with human epidermal factor receptor-2 (Her-2) overexpression could be indicated for both radiation and anti-Her2 target therapy. We aimed to investigate the early detection of radiation and Trastuzumab (TRZ) induced acute cardiotoxicity in mice. In the present study, the heart of animal was subjected to irradiation (IR, 14 Gy/1 Fx), TRZ was intraperitonealy (i.p.) administrated to mice in 2 weeks (6 fractions). The IR plus TRZ group received heart IR after TRZ. We found that body weight of mouse in treatment groups reduced significantly as compared with that of mouse in control group (P<0.05). At day 21, the diastolic function of mice decreased significantly in IR plus TRZ group compared with control group measured by E/E' parameter using echocardiography (57.72 vs 40.82, P<0.05). The left ventricular posterior wall (LVPW) and interventricular septum (IVS) were also increased significantly in diastolic phase at day 21 in the combined group compared with TRZ alone (LVPW: 0.95 mm vs 0.70 mm, P<0.05; IVS: 0.94 mm vs 0.65 mm P<0.05). Moreover, hematoxylin and eosin (HE) staining of cardiac tissue showed that the arrangement of myocardial cell was disordered in the combined group with vacuolar and adipocyte changes, as well as the loose of structure of myocardial cells and the pyknosis of the nucleus. Moderate damage was observed in irradiation-treated group and TRZ-treated group. The expressions of γ-H2AX, vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand Factor (vWF) were remarkedly appeared in co-treatment group. Heart irradiation combined with TRZ treatment simultaneously might cause acute cardiac toxicity in terms of the parameter of E/E', LVPW and IVS. Our results suggest that the diastolic function could detect the early stage of acute cardiotoxicity in heart exposed to irradiation and TRZ co-treatment in mice. The DNA injury and microangiopathy might involve in cardiac injury that aggravated by radiation and Trastuzumab treatments.