Effect Of Lentivirus-mediated NK4 Overexpression On The Growth Of Lung Adenocarcinoma Tumor In Nude Mice

Background:Poor prognosis and a low survival rate are commonly observed in patients with non-small-cell lung cancer.NK4,a hepatocyte growth factor antagonist and angiogenesis inhibitor,can inhibit malignant behaviour of a variety of cells.This study evaluated the feasibility of lentivirus-mediated NK4 overexpression for suppressing tumor growth and lung metastasis.Objective:To study the effect of NK4 overexpression mediated by intratumoral injection of lentivirus on the growth,invasion,metastasis and microangiogenesis of lung adenocarcinoma xenografts in nude mice.Methods:A549 cells were implanted into the right flank of BALB/c mice.When the tumor diameters were approximately 5 mm,the mice were randomly divided into three groups:the LV-NK4 group,the LV-con group and the PBS group.Every group were received intratumoral injections of LV-NK4(50μl;6×10~8TU/ml),LV-con(50μl;6×10~8TU/ml)and PBS(50 μl)respectively.After 28 days treatment,all animals were sacrificed and tumor tissues were excised for analysis via hematoxylin-eosin staining,immunohistochemical staining and Td T-mediated DUTP nick end labeling(TUNEL).Microvessel density(MDV)was used to detect angiogenesis.Results:After 28 days of treatment,the volume of tumor in LV-NK4 group was(316.166±89.290 mm~3),smaller than LV-con group(812.714±348.967mm~3)and PBS group(838.598±390.780mm~3),with statistically significant differences(F=4.612,P<0.05).The tumor weight was significantly decreased in LV-NK4group(0.4344±0.1234g),and the difference was statistically significant(F=5.689,P<0.05)compared with LV-con group(0.7018±0.2227g)and PBS group(0.7829±0.1510g).The necrosis and apoptosis in tumor tissue of nude mice in the LV-NK4 group was significantly more than that in the LV-con group and PBS group.The MVD in LV-NK4 group(11.2±2.78)was significantly reduced,and the difference was statistically significant(F=18.954,P<0.01)compared with that in the LV-con group(18.90±3.479)and PBS group(22.00±5.40).There were no obvious lung metastases in the LV-NK4 group.The expression of c-Met protein in tumor tissue was significantly decreased in the LV-NK4 group.Real-time PCR and Western blot analysis showed that NK4 were expressed higher in LV-NK4 group.Conclusions:Lentivirus-mediated NK4 overexpression affects tumor growth and may also suppress the intravasation of tumor cells,resulting in the inhibition of lung metastasis.