Proapoptotic effect and the mechanism of action of pingyangmycin on cavernous hemangiomas

This study aimed to investigate the proapoptotic effects and the mechanism of action of pingyangmycin (PY) on cavernous hemangioma. The rat spleen was used as a model of cavernous hemangioma. PY was injected into the spleen and the pathological changes were observed at different time-points. Apoptosis was detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and transmission electron microscopy (TEM). The expression levels of the apoptosis-related protein, caspase-3, were determined using immunohistochemistry and image analysis. Rats injected with normal saline were the control group. Injection of normal saline did not damage rat spleens. On days 2 and 5 following PY injection, the spleens exhibited slight swelling. On days 8 and 14, atrophic changes were observed and the splenic sinus endothelial cells were damaged. At various time-points following PY injection, the apoptotic cells were observed by TEM. The TUNEL assay showed that apoptosis occurred widely among the splenic sinus endothelial cells and other splenic cells. The apoptotic rate and caspase-3 expression levels increased with prolonged PY exposure. PY induced apoptosis of splenic sinus endothelial cells through the caspase-3 activation pathway, and resulted in endothelial cell necrosis and fibroblast hyperplasia.