Induction of apoptosis in HeLa cells with siRNA expression vector targeted against bcl-2

RNA interference (RNAi) is the process by which double-stranded RNA (dsRNA) directs sequence-specific gene silencing in animal and plant cells. In mammalian cells, 21- or 22-nucleotide (nt) RNAs with 2-nt 3' overhangs small inhibitory RNAs (siRNAs) exhibit an RNAi effect. Very recently, we and others have developed a vector-based siRNA expression system that can induce RNAi in mammalian cells. In this report, to apply this system to oncogene therapy, we tried to suppress the expression of the bcl-2 gene, which is known as a key molecule in the regulation of apoptosis or programmed cell death, by using the siRNA expression system. Western blotting analysis revealed that this siRNA expression vector against bcl-2 suppressed the expression of the bcl-2 protein. Furthermore, HeLa cells which were transiently transfected with the siRNA expression vector against bcl-2 and were subsequently treated with doxorubicin efficiently underwent apoptosis, concomitant with the repression of the bcl-2 gene. These results demonstrate that the siRNA expression vector against bcl-2 has a potential as therapeutic agent for a variety of cancers by down-regulating bcl-2 gene expression.