Crosstalk between oxidative stress, autophagy and apoptosis in hemoporfin photodynamic therapy treated human umbilical vein endothelial cells

Background: Photodynamic therapy (PDT) provides a treatment for port-wine stain (PWS) using hemoporfin (hematoporphyrin monomethyl ether, HMME), a novel photosensitizer, reporting better efficacy and lower recurrence rate. This study investigated the effects of HMME-PDT on human umbilical vein endothelial cells (HUVECs) as well as underlying mechanisms. Methods: Cell proliferation ability was measured by CCK8 assay and cell apoptosis was determined by TUNEL assay and Western blot analysis. Confocal fluorescence microscopy monitoring RFP-GFP-LC3 transfected HUVECs and Western blot analysis were used to evaluate autophagy. 3-Methyladenine (3-MA), Z-VAD-FMK, Nacetylcysteine (NAC) were used for inhibitor studies. Results: HMME-PDT decreased cell proliferation ability in an HMME concentration and light dose-dependent manner. Oxidative stress played an important role in HMME-PDT induced cell apoptosis and autophagy in HUVECs. Pretreatment with Z-VAD-FMK, the inhibitor of apoptosis, enhanced HMME-PDT induced autophagy. 3-MA, the suppressor of autophagy, significantly increased HMME-PDT induced apoptosis rates. Conclusions: Our study demonstrated that HMME-PDT induced both apoptosis and autophagy in HUVECs via oxidative stress. Our data suggested that HMME-PDT-induced autophagy was able to prevent apoptotic cell death of HUVECs and rendered them more resistant to HMME-PDT induced toxicity.