Abstract: Objective to explore effects of bFGF on proliferation of human hepatoma HepG2 and larynx carcinoma Hep2 cell lines by bFGF phosphorothioate oligonucleotides. Methods Oligonuleotides were transfected into HepG2 and Hep2 cell lines with jetPEI (polyethyleneimine). The relative cell proliferation was from MTT analysis. Location of FITC-labeled phosphorothioate oligonucleotides was observed with fluorescence microscope, and positive rates of tumor cells transfected with antisense/sense phosphorothioate oligonucleotides were analyzed by Flow CytoMeter. Results Positive cells transfected by FITC conjugated bFGF phosphorothioate oligonuleotides were above 90%, and above mean 3000 FITC were detected in each cell by FACS and mainly located in nuclei. Antisense phosphorothioate oligonuleotide inhibited the growth of HepG2 and Hep2 cells by 46.6% and 25.5% respectively, equivalent to that corresponding antisense phosphodiester oligonuleotide did by 50.6% and 34.6%. Mismatch nucleotide in antisense phosphorothioate oligonuleotide reduced it's inhibition to 17.9％ and 10.4％ respectively to HepG2 and Hep2 cells. Sense phosphorothioate oligonuleotides with inhibited the growth of HepG2 and Hep2 cells by 70.6% and 67.8% respectively in a dose-dependent manner, more efficiently than antisense phosphorothioate oligonuleotides. However, sense phosphodiester oligonuleotides just affected the growth of HepG2 and Hep2 cells by 19.7% and 9.3% respectively. And inhibition of sense phosphorothioate oligonuleotide didn't be reduced by mismatch nucleotide. Conclusions These findings suggested that phosphorothioate modification didn't significantly influence antisense oligonuleotide binding to nucleic acid and inhibiting tumor cell proliferation in a antisense manner, but sense oligonuleotide with phosphorothioate modification biding to bFGF or other proteins reduces tumor cell proliferation.

Key words: Basic fibroblast growth factor, bFGF, tumor, sense/antisense oligonucleotides