Chemosensitization of breast carcinoma cells with the use of bcl-2 antisense oligodeoxynucleotide

This study was designed to observe whether the rates of apoptosis induced in the breast cancer cell line MCF-7 by 5-fluorouracil (5-FU) could be enhanced by transfecting bcl-2 antisense oligonucleotide (ASODN). In our experiment, bcl-2 ASODNs and control ODNs including untreated control, sense ODN and scrambled ODN, were transfected into MCF-7 cells. Changes in expression of the bcl-2 gene were examined by Western blot; cell growths were detected by MTT assay, and apoptosis rates were detected by flow cytometry (FCM). Expression of bcl-2 protein after transfection of bcl-2 ASODN was significantly lower than control ODNs. Moreover, incubation of MCF-7 with bcl-2 ASODN prior to 5-FU treatment caused remarkable loss of viable cells compared with all other control ODNs (P<0.01). FCM showed the apoptosis rates for ASODN, untreated control, sense ODN and scrambled ODN (29.8±7.4)%, (8.0±2.3)%, (15.0±5.1)% and (16.5±7.1)%, respectively. Compared with control ODNs, ASODN achieved the strongest effect in terms of enhancing apoptosis (P<0.01). These results suggest that combining bcl-2 ASODN with 5-FU led to synergistic cytotoxicity.