Experimental study of Endostar injection concomitant with cryoablation on lung adenocarcinoma A549 xenografts.

OBJECTIVE

To explore the inhibiting effect and mechanism of Endostar injection concomitant with cryoablation on lung adenocarcinoma A549 xenografts in nude mice.

MATERIALS AND METHODS

A total of 24 nude mice with subcutaneous xenografts of the A549 cell line were established and divided into 4 groups when the maximal diameters 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, tumour tissues 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 SP test 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 the combination 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 lung adenocarcinoma A549, and the mechanism is probably associated with its function as an inhibitor of tumour neo-angiogenesis through down-regulating VEGF expression.