[Tumor targeting gene transfer mediated by electroporation for growth suppression of retinoblastoma in vivo].
OBJECTIVE
To explore the effects and mechanisms of electroporation on the therapy of transplanted retinoblastoma tumor (RB) by transferring the expressive plasmids of sFlk-1 and ExTek.


METHODS
The effects and mechanisms of sFlk-1 and ExTek on RB is validated both in vitro and in vivo. In vitro, pCI-sFlk-1 was transfected into HEK293 (human embryonic kidney 293) cells with DMRIE-C Reagent, and its supernatant was collected 24 h later to mix with RPMI-1640 medium as 1:1, 2:1 and 3:1. RB cells were cultured in the mixed medium and the cell growth curve were analyzed 6 days later. The suspension of 1 x 10(7) RB cells were inoculated in 40 nude mice subcutaneously. The nude mice with RB were divided into 2 groups. The experimental group was treated with transfer of pCI-sFlk-1 (15 microg) and pCI-ExTek (15 microg) by electroporation once a week, while the control group was treated with physiological saline solution. After 3 weeks' therapy, the animals were observed for one more week. During this period the tumors were measured to draw the growth curve of the tumors and to calculate the anti-tumor rate. The vessel endothelium were tagged with smooth muscle actin (SMA) by immunohistochemical methods to inspect the micro vessel density (MVD) of the tumors. Moreover, the expression of vascular endothelial growth factor (VEGF) and its receptor Flk-1 of the tumors was confirmed by immunohistochemical staining.


RESULTS
sFlk-1 exhibited no inhibiting effects on the growth of RB cells in vitro, while sFlk-1 combined with ExTek restrained the growth of the transplanted tumors obviously in vivo, and the anti-growth rate is 80.04%. The MVD of the experimental group is 26.69 +/- 2.95, which is evidently lower than that of the control group (44.51 +/- 6.11). The difference between these 2 groups was statistically significant (P < 0.05). As to the expression of VEGF, there was no significant difference between these 2 groups, while the expression of Flk-1 of the experimental group was much stronger than that of the control group.


CONCLUSIONS
Transfer the expressive plasmids of sFlk-1 and ExTek by electroporation in vivo restrained the growth of the transplanted RB tumor, and the effect is due to the inhibition of angiogenesis process.
Wang
Xiao-li
XL
Central Experimental Laboratory, Affiliated First People's Hospital, Shanghai Jiaotong University, Shanghai 200080, China.
Wang
Feng
F
Wu
Ji-hong
JH
Yi
Miao-ying
MY
Xu
Ping
P
Zhao
Xin-feng
XF
Xue
Yue-hua
YH
Huang
Qian
Q
D000818:Animals; D002460:Cell Line; D018274:Electroporation; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000473:pathology / Q000628:therapy*; D010957:Plasmids; D042787:Receptor, TIE-2 / Q000235:genetics*; D012175:Retinoblastoma / Q000473:pathology / Q000628:therapy*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics*
D042787:Receptor, TIE-2; D040301:Vascular Endothelial Growth Factor Receptor-2