OBJECTIVETo screen effective sequences of short hairpin RNA on brain-derived neurotrophic factor (BDNF) gene and the effect of RNA interference on the proliferation and apoptosis of HeLa cells, a cervix carcinoma cell line with high expression of BDNF.

METHODSTwo recombinant eukaryotic human-BDNF siRNA expression vectors were designed and constructed. Sequences were confirmed by restrictive endonuclease digestion and DNA sequencing. The empty vector pGenesil-1 and two recombinant plasmids, pGenesil-shRNA-BDNF1 and pGenesil-shRNA-BDNF2, were transfected into HeLa cells using Lipofectamine 2000 (groups: P(0), P(1) and P(2), respectively). The mRNA and protein levels of BDNF in HeLa cells were detected by RT-PCR and Western blot, respectively. The cellular proliferation rates were determined by MTT assay and the apoptotic rates were measured by flow cytometry and Hoechest 33258.

RESULTSThe recombinant eukaryotic BDNF siRNA expression vectors were successfully constructed. The expression of mRNA and protein of BDNF in P(1) group were significantly decreased, comparing with non-transfected group, P(0) and P(2) groups (F = 48.19, P < 0.01). P(2) group failed to meet the expected results (P > 0.05). In addition, the proliferation activity was reduced in P(1) group and the peak point of proliferation curve was prolonged. Moreover, the early cell apoptotic rates were statistically increased in P(1)[(53.4 +/- 4.2)%] VS. non-transfected [(0.8 +/- 0.4)%], P(0) [(5.1 +/- 1.8)%] and P(2)[(7.9 +/- 2.4)%] groups (F = 269.77, P < 0.01).

CONCLUSIONHeLa cells express a high level of BDNF. BDNF gene silencing by RNA interference increases the apoptosis of HeLa cells and inhibits cell proliferation, offering a possible target for efficient tumor therapy.