Abstract: Objective To investigate the effects on anti-expression of Osteopontin (OPN) by an antisense oligodeoxynucleotide (ASODN) targeting to low free energy region of OPN mRNA and its effects on proliferation and apoptosis of human breast carcinoma cell line MCF-7. Methods Designing and synthesizing an ASODN based on minimum free energy algorithm in vitro, which targets to the low free energy region of OPN mRNA. Transfecting it into breast carcinoma cell line MCF-7 which expresses OPN in high level. The cell proliferation-inhibitory rate was determined by MTT method; The morphologic changes was observed by transmission electron microscope (TEM); The OPN mRNA expression level was checked by RT-PCR method; Cell cycle and apoptosis rate were detected by flow cytometry (FCM) after transfection ,respectively. Results OPN ASODN could inhibit the proliferation of the cells in both time and concentration dependent manner (P<0.05).Characteristic morphologic apoptosis changes was observed after incubated with 16?mol/L OPN ASODN for 72h. OPN mRNA expression in ASODN groups were notably decreased. there was a significant high apoptosis rate in ASODN groups (P<0.01). Conclusions OPN ASODN transfection significantly inhibits the proliferation of human breast carcinoma MCF-7 cells and induces cell apoptosis in vitro. It's a reliable method to design ASODN based on minimum free energy algorithm.

Key words: Osteopontin, Antisense oligodeoxynucleotide, Free energy, Breast carcinoma, Apoptosis