Matrix Metalloproteinase Inhibitors Attenuate Doxorubicin‐Induced Heart Failure by Preventing Cardiac Titin Proteolysis

Abstract

Heart failure remains a major, long‐term complication with doxorubicin (DXR) cancer chemotherapy. We investigated the mechanism of DXR cardiotoxicity in order to develop new strategies to prevent heart injury when treating cancer patients. The cardiotoxicity of DXR is associated with increased oxidative stress in cardiomyocytes. Intracellular matrix metalloproteinase‐2 (MMP‐2) activity is enhanced by oxidative stress by two means: a) direct activation of 72 kDa MMP‐2 by peroxynitrite‐mediated S‐glutathiolation and, b) de novo expression of an N‐terminal truncated isoform (NTT‐MMP‐2). We have shown that MMP‐2 is enriched in the Z‐disc of the sarcomere where it cleaves titin following oxidative stress caused by ischemia‐reperfusion injury. We determined whether MMP‐2 mediated titin proteolysis contributes to DXR‐induced heart failure in vivo. 8‐week old male C57BL/6J mice were treated with DXR weekly (6 mg/kg, i.p.) or saline vehicle (control) ± MMP inhibitors (by daily gavage) doxycycline (15 mg/kg) or ONO‐4817 (60 mg/kg) for 4 weeks. Cardiac function was assessed by M‐mode echocardiography before and after treatment (n=10 mice per group) and then the hearts were collected for biochemical analysis. MMP‐2 mRNA expression, protein levels, and activity were measured by qPCR, Western blot and gelatin zymography, respectively. N2BA and N2B titin isoforms and the primary titin degradation product levels were measured by agarose gel electrophoresis. DXR caused systolic and diastolic dysfunction marked by a significant reduction in left ventricular ejection fraction (64±2% vs. 45±2%, p<0.05), fractional shortening (35±2% vs. 22±1%, p<0.05), and E′/A′ ratio (1.07±0.04 vs. 0.85±0.06, p<0.05) compared to control. Doxycycline or ONO‐4817 prevented these changes. DXR caused significant cardiac remodeling including the thinning of the posterior wall (0.99±0.03 vs 1.16±0.04 mm, p<0.05) and increased left ventricular internal diameter (2.93±0.09 vs 2.55±0.09 mm, p<0.05) during systole, an effect that was prevented by doxycycline, but not ONO‐4817. DXR upregulated NTT‐MMP‐2 mRNA in the heart to 195±16% (p<0.05) of control and increased MMP‐2 protein levels (149±19% vs. control, p<0.05), accompanied by a trend to increased MMP‐2 gelatinolytic activity (200±14% vs. control, p=0.06). These biochemical changes were prevented by doxycycline or ONO‐4817. DXR did not alter cardiac titin isoform expression (N2BA:N2B) in the heart but increased titin degradation (T2/T1 ratio) to 258±7% (p<0.05) which was reduced by ONO‐4817 (169±10%) but not doxycycline (203±16%). MMP‐2 activation contributes to DXR‐induced heart failure in mice by proteolyzing cardiac titin in an MMP‐2‐dependent manner. Moreover, two orally available MMP inhibitors prevented heart failure, suggesting that their use may be a potential prophylactic strategy to prevent heart during cancer chemotherapy.Support or Funding InformationCanadian Institutes of Health Research (to RS); Women and Children's Health Research Institute Graduate Studentship (to BC).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.