Vascular endothelial growth factor and angiopoietin-1 protected cardiac myoblasts from apoptosis induced by H₂O₂

Aim: To explore the protective effects and involved mechanisms of two angiogenic growth factors, vascular endothelial growth factor (VEGF₁₆₅) and angiopoietin-1 in cardiac myoblasts. Methods: Replication-deficient adenovirus encoding for human VEGF₁₆₅ (Ad-VEGF₁₆₅) or angiopoietin-1 (Ad-Ang1) were transfected into H9C2 cardiac myoblasts. Recombinant adenovirus encoding for green fluorescent protein (Ad-GFP) was used as vehicle control. Twenty-four hours later, cell apoptosis was induced by 300 μmmol of H₂O₂. Genomic DNA was extracted and DNA fragmentation was analyzed in 1.6% agarose gels. Phosphatidylinositol-3 kinase(PI-3 K) activity and bcl-2 expression level were investigated in H9C2 after gene transfection 24 hours later by an immol/Lunoprecipitated kinase assay and Western blot assay respectively. The effect of wartmannin, a specific inhibitor of PI-3 K, on DNA fragmentation, PI-3 K activity and bcl-2 expression was also analyzed by a pre-treatment of 30 minutes before transfection. Results: Apoptotic DNA fragmentation induced by H₂O₂ was significantly inhibited by the transfaction of Ad-VEGF₁₆₅ and/or Ad-Ang1 but then aborted by the pretreatment of wartmannin. PI-3 K activity was significantly elevated after Ad-VEGF₁₆₅ + Ad-Ang1 transfection as compared to Ad-GFP transfection group(2.60 vs 1.32, P < 0.01). Anti-apoptotic factor bcl-2 expression was upregulated in Ad-VEGF₁₆₅ (2.1-fold), Ad-Ang1 (1.7-fold) and Ad-VEGF₁₆₅ + Ad-Ang1 (1.7-fold) treated groups as compared to Ad-GFP transfection group. Wortmannin suppressed PI-3 K activiation induced by Ad-VEGF₁₆₅ (from 1.83 to 0.69, P < 0.05). Ad-Ang1 (from 1.80 to 0.97, P = 0.07) or Ad-VEGF₁₆₅a + Ad-Ang1 (from 2.60 to 0.42, P < 0.01). However, upregulation of bcl-2 induced by Ad-VEGF₁₆₅ and/or Ad-Ang1 was not aborted by wortmannin pretreatment. Conclusions: VEGF₁₆₅ and/or Ang1 can protect cardiac myoblasts from apoptosis induced by H₂O₂ throught PI-3 K and bcl-2 pathway. The anti-apoptotic function of either VEGF₁₆₅ or Ang1 could be served as a now therapeutic target including their angiogenic benefits.