Objective: To explore the inhibiting effect and mechanism of Endostar injection concomitant with cryoablationon lung adenocarcinoma A549 xenografts in nude mice. Materials and
Methods: A total of 24 nude mice withsubcutaneous xenografts of the A549 cell line were established and divided into 4 groups when the maximaldiameters of tumors became 1 cm: control group, Endostar group, cryoablation group and combination group(Endostar concomitant with cryoablation). The nude mice were sacrificed after 21-days treatment, tumourtissues were removed to measure their volume, in situ test of TdT-mediated dUTP nick end labeling (TUNEL)was adopted to determine the cellular apoptosis around freezing injury zones, and immunohistochemical SPtest was applied for the detection of micro-vessel density (MVD) and vascular endothelial growth factor (VEGF)expression levels.
Results: At 21-days after treatment, the growth velocities of control group, Endostar group,cryoablation group and combination group were 236.7±51.2%, 220.0±30.6%, 159.5±29.3% and 103.3±25.5%(P<0.01), while cellular apoptosis rates of tumors were 21.7±2.34%, (22.17±1.47)%, 38.3±1.37% and 49.2±1.72%,(P<0.01), respectively, according to the immunohistochemical test. MVD and VEGF expression levels in thecombination group were both lower than in other groups (P<0.01), also being positively related (r=0.925, P<0.01).
Conclusions: Endostar can significantly improve the inhibitory effects of cryoablation on xenografts of lungadenocarcinoma A549, and the mechanism is probably associated with its function as an inhibitor of tumourneo-angiogenesis through down-regulating VEGF expression.