[Inhibition of K562 cell growth and tumor angiogenesis in nude mice by transfection of anti-VEGF hairpin ribozyme gene into the cells].

OBJECTIVE: To explore the effect of anti-VEGF hairpin ribozyme gene on the tumor cell growth and tumor angiogenesis in nude mice.

METHODS: The recombinant eukaryotic expression plasmid pcDNA-RZ containing anti-VEGF hairpin ribozyme gene and the empty vector plasmid pcDNA were introduced separately into K562 cells by lipofectamine mediation and positive clones were screened by G418. Ribozyme gene in K562 cells was confirmed by PCR. Fluorescent real time RT-PCR and Western blot were used to detect the expression of VEGF mRNA and protein in the leukemia cells. The tumorigenicity of transfected K562 cells were transplanted in nude mice and tumor microvascular density (MVD) were observed by morphology and vWF immunohistochemistry stain.

RESULTS: Stable expression of the ribozyme gene in K562 cells was confirmed by PCR. The level of VEGF mRNA and protein decreased dramatically in K562/RZ cells when compared with K562 or K562/PC (K562 cells transfected with empty vector) cells. The tumor volumes were (4.43 +/- 0.87), (3.96 +/- 0.94), (2.24 +/- 0.56) cm3; tumor weight was (4.43 +/- 0.87), (3.96 +/- 0.94), (2.24 +/- 0.56)g; and tumor microvascular density was 4.70 +/- 1.25, 4.67 +/- 1.31, 1.80 +/- 1.55 in K562, K562/PC and K562/RZ cell groups, respectively.

CONCLUSION: Transfection with anti-VEGF ribozyme gene can inhibit tumor growth and vessel formation by down-regulating the VEGF gene expression in K562 cells.