Paracrine action of sFLT-1 secreted by stably-transfected Ehrlich ascites tumor cells and therapy using sFLT-1 inhibits ascites tumor growth in vivo.
BACKGROUND
Vascular endothelial growth factor (VEGF) is known to play a major role in angiogenesis. A soluble form of Flt-1, a VEGF receptor, is potentially useful as an antagonist of VEGF, and accumulating evidence suggests the applicability of sFlt-1 in tumor suppression. In the present study, we have developed and tested strategies targeted specifically to VEGF for the treatment of ascites formation.


METHODS
As an initial strategy, we produced recombinant sFLT-1 in the baculovirus expression system and used it as a trap to sequester VEGF in the murine ascites carcinoma model. The effect of the treatment on the weight of the animal, cell number, ascites volume and proliferating endothelial cells was studied. The second strategy involved, producing Ehrlich ascites tumor (EAT) cells stably transfected with vectors carrying cDNA encoding truncated form of Flt-1 and using these cells to inhibit ascites tumors in a nude mouse model.


RESULTS
The sFLT-1 produced by the baculovirus system showed potent anti-angiogenic activity as assessed by rat cornea and tube formation assay. sFLT-1 treatment resulted in reduced peritoneal angiogenesis with a concomitant decrease in tumor cell number, volume of ascites, amount of free VEGF and the number of invasive tumor cells as assayed by CD31 staining. EAT cells stably transfected with truncated form of Flt-1 also effectively reduced the tumor burden in nude mice transplanted with these cells, and demonstrated a reduction in ascites formation and peritoneal angiogenesis.


CONCLUSIONS
The inhibition of peritoneal angiogenesis and tumor growth by sequestering VEGF with either sFlt-1 gene expression by recombinant EAT cells or by direct sFLT-1 protein therapy is shown to comprise a potential therapy.
Ramachandra
Sunitha
S
Department of Studies in Biotechnology, University of Mysore, Mysore, 570006 Karanataka, India.
D'Souza
Saritha Sandra
SS
Gururaj
Anupama E
AE
Shaila
Melkote S
MS
Salimath
Bharathi P
BP
D000818:Animals; D001201:Ascites / Q000473:pathology* / Q000628:therapy*; D016367:Baculoviridae; D049109:Cell Proliferation; D051379:Mice; D009389:Neovascularization, Pathologic; D019899:Paracrine Communication; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D012995:Solubility; D014162:Transfection; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics* / Q000627:therapeutic use*
D011994:Recombinant Proteins; D040281:Vascular Endothelial Growth Factor Receptor-1