Abstract
PURPOSE: Transcatheter arterial embolization or transcatheter arterial chemoembolization has become a critical therapy for unresectable hepatocarcinoma. Although hypoxia caused by embolization can induce apoptosis and necrosis of the majority of tumor cells, a small proportion of cells can survive with hypoxia and chemotherapy resistance. HIF-1α induced by hypoxia is the key factor rendering surviving tumor cells invasive and metastatic properties. Thus, we generated a synthetic hypoxia-replicative oncolytic adenovirus (HYAD) expecting to further eliminate the surviving tumor cells, which expressed HIF-1α. MATERIALS AND METHODS: In our study, we detected protein expression, proliferation, apoptosis, and necrosis of hepatic tumor cell line when infected with HYAD under hypoxia and normoxia. And we constructed VX2 hepatic cancer rabbit models to explore the therapeutic effect of transcatheter arterial embolization combined with HYAD perfusion under digital subtraction angiography. Inhibition of tumor growth and invasion was detected by histopathological examination and contrast-enhanced CT scan. RESULTS: Experiments in vitro verified that HYAD expressed and replicated along with HIF-1α expression or hypoxia. Compared with wild adenovirus type 5 (WT), HYAD expressed much more under hypoxia, which was the main principle of HYAD killing surviving tumor cells posttransarterial embolization. In vivo experiment of VX2 models, HYAD perfusion combined with polyvinyl alcohol (PVA) embolization achieved the highest expression quantity and the longest expression duration compared with simple HYAD perfusion, WT perfusion combined with PVA embolization, and simple WT perfusion. Because adenovirus expression protein E1A had the properties of promoting apoptosis, inhibiting invasion, and inhibiting metastasis, HYAD perfusion combined with PVA embolization group efficiently repressed tumor growth and intrahepatic metastases compared to other processing groups. CONCLUSION: HYAD can overcome the hypoxic tumor microenvironment postembolization and target the surviving tumor cells with specificity. In turn, HYAD perfusion combined with PVA embolization can bring out the best effect in each other.