Effect Of Low-Dose Metronomic Chemotherapy On VE-Cadherin, VEGF-C/Flt-4, PTEN And Apoptosis Of A549 Pulmonary Adenocarcinoma

Objective To compare the antitumor effect and toxicity of low-dose metronomic(LDM) and maximum tolerable dose(MTD) cyclophosphamide (CTX); To investigate the effect and mechanism on VE-Cadherin, anti-oncogene PTEN,VEGF-C/Flt-4 axis and apoptosis of tumor grafts on nude mice resulted by different dose CTX.Methods: 1.To modulate the concentration of cultured A549 cell to 1×10~7 /ml , per nude mouse was subcutanously injected under the anterior right leg with cultured A549 cell suspend fluid 0.1ml. 2. 18 nude mice bearing A549 pulmonary adenocarcinoma were randomly divided into three groups ,r eceived LDM CTX(20mg.kg-1.d-1 , intraperitoneal injection, continuous 21d), MTD CTX(100mg.kg-1,intraperitoneal injection, every other day, 3 times) and saline( 0.1ml.d-1 ,intraperitoneal injection, continuous 21d ) respectively . Tumor volume and weight of nude mice were measured in each group every week. All nude mice were killed until to the 21th day,then took the tumors. All tumors were embed by paraffin and stored in -80℃icebox respectively.3. Immunohistochemistry SP (Strepatacidin peroxidase System For Immunohistological Staining) was used to detect the expressions of the protein of VE-Cadherin, PTEN,VEGF-C and Flt-4 ; RT-PCR was used to detct the mRNA of VE-Cadherin, VEGF-C and Flt-4; TUNEL (terminal deoxynucleotidy transfer mediated dUTP-biotin nick end labeling )was used to detct the apoptosis in 18 cases of nude mice tumor tissues.Results: 1. The difference in the weight of all nude mice and the volume of all the tumor grafts were not statistically significant when chemotherapy started(P>0.05) ; the tumor grafts appeard to grow slowly and weight loss of nude mice in LDM and MTD group after chemotherapy 7 days, compared with control group respectively were statistically significant(P<0.05); the growth rate of tumor grafts in LDM group was significantly slower than that of the other 2 groups (P<0.05) and all nude mice of 3 groups appeard to weight loss especially the MTD group (P<0.05) after chemotherapy 14days; the tumor grafts of MTD group growed accelerately in later stage of chemotherapy, the difference of the volume of tumor grafts in 3 groups were significantly(P<0.05),the weight of the nude mice of MTD group were significantly lower than that of the other 2 groups at the end of experiment(21d) (P<0.05 ) . 2. The expression of PTEN protein and apoptotic index of tumor tissues has a significantly positive correlation (r=0.866,P<0.01 ),which in LDM group significantly higher than that either in MTD group or control group (P<0.05). The expression of protein and mRNA of VE-Cadherin, VEGF-C and Flt-4 significantly lower than that in the other 2 groups.Conclusion: The low-dose metronomic chemotherapy of CTX can significantly increase the antitumor efficacy,upgrade the level of PTEN protein of A549 pulmonary adenocarcinoma and induce the more apoptosis consequently with decreased toxicity. On the other side ,the low-dose metronomic chemotherapy of CTX can down regulate the expressions of the protein and the mRNA of VE-Cadherin, VEGF-C and Flt-4.