[Antitumor effect of recombinant T7 phage vaccine expressing xenogenic vascular endothelial growth factor on Lewis lung cancer in mice].
OBJECTIVE
Angiogenesis plays an important role in growth and metastasis of tumors. Vascular endothelial growth factor (VEGF) is considered as a fundamental regulator for angiogenesis. This study was to construct a recombinant T7 phage vaccine expressing xenogenic VEGF on the capsid, and test its inhibitory effect on Lewis lung cancer cells in mice.


METHODS
VEGF gene was cloned by reverse transcription-polymerase chain reaction (RT-PCR) from human lung cancer tissues, and inserted into phage using T7 Select10-3b kit to construct T7 Select10-3b_VEGF vaccine. The titer of prepared phage reached 1x10(13) pfu/ml. C57BL/6J mice were randomly divided into 3 groups: T7 Select10-3b_VEGF vaccine group (T7-VEGF), T7 phage (T7) group, normal saline (NS) group (10 mice/group). Each mouse was injected with Freundos adjuvant mixed with 1x10(12) pfu/200 microl T7 Select10-3b_VEGF, or T7, or normal saline once a week for 4 weeks. Lewis lung carcinoma model (LL/2) was established in C57BL/6J mice after 4-week immunization. Tumor growth and mouse's physical status were observed during immunization. Tumor weight and serum level of specific anti-VEGF antibody were measured by enzyme-linked immunosorbent assay (ELISA). Microvessel density (MVD) of tumors was detected by immunohistochemistry 14 days after the inoculation of tumor cells.


RESULTS
Tumor weight of T7-VEGF vaccine group,T7 group, and NS group were (0.543+/-0.259)g, (0.982+/-0.359)g, (1.169+/-0.460)g, respectively. Tumor weight of T7-VEGF vaccine group was significantly lower than that of NS group (P<0.01). Serum anti-VEGF antibody level in T7-VEGF vaccine group was 1:1,000. MVD was significantly lower in T7-VEGF vaccine group than in NS group (8.5+/-0.8 vs 18.5+/-1.6, P<0.05). MVD in T7 group was 16.4+/-1.3.


CONCLUSIONS
Recombinant T7 phage vaccine expressing xenogenic VEGF can break immunologic tolerance against self-VEGF and inhibit the growth of Lewis lung cancer cells.
Li
Xiao-Hui
XH
Department of Cardiosurgery, Henan Provincial Peopleos Hospital, Zhengzhou, Henan, 450003, P. R. China.
Tang
Liang
L
Liu
Dong
D
Sun
Hong-Mei
HM
Zhou
Cai-Cun
CC
Tan
Li-Song
LS
Wang
Li-Ping
LP
Zhang
Pei-De
PD
Zhang
Shang-Quan
SQ
D000818:Animals; D017123:Bacteriophage T7 / Q000235:genetics*; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology*; D018827:Carcinoma, Lewis Lung / Q000098:blood supply / Q000473:pathology*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D005260:Female; D006801:Humans; D007114:Immunization; D008175:Lung Neoplasms / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D011994:Recombinant Proteins / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
D019496:Cancer Vaccines; D012333:RNA, Messenger; D011994:Recombinant Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A